JAVA范例 十五）网络编程
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15.1 IP地址
实例270 获取计算机名与IP地址
import java.net.InetAddress;public class NetDemo_1 {public static void main(String[] args) {try {InetAddress ind = InetAddress.getLocalHost();System.out.println(ind);} catch (Exception e) {System.out.println("没有找到主机的地址！");}}}?
实例271 获取网址的IP地址?
import java.net.InetAddress;import java.net.UnknownHostException;public class NetDemo_2 {public static void main(String[] args) {try {InetAddress ind = InetAddress.getByName("192.108.33.32");System.out.println(ind.getHostName());InetAddress ind1 = InetAddress.getByName("www.sina.com");System.out.println(ind1);} catch (UnknownHostException e) {System.out.println(e);}}}?
实例272 判断两个网址的主机名是否一样?
import java.net.InetAddress;import java.net.UnknownHostException;public class NetDemo_3 {public static void main(String[] args) {try {// 创建两个InetAddress的对象InetAddress ind = InetAddress.getByName("www.sohu.com");InetAddress ind1 = InetAddress.getByName("sohu.com");if (ind.equals(ind1)) {// 判断两个网址是否一样System.out.println("这两个网址所显示的主机名一样！");} else {System.out.println("这两个网址所显示的主机名不一样。"); // 输出两个网址的主机名不一样}} catch (UnknownHostException e) {// 没有查找到网址对应的主机e.printStackTrace();}}}?
实例273 测试IP的类型
import java.net.InetAddress;import java.net.UnknownHostException;public class NetDemo_4 {public static int getVersion(InetAddress ia) {//定义一个整型的静态方法byte[] b = ia.getAddress();//定义一个字节型的数组，并初始化。if (b.length == 4) {//判断这个数组的长度是否等于4return 4;//返回数值4} else if (b.length == 16) {return 6;} else {return -1;}}public static char getClass(InetAddress ia) {//定义一个字符型的静态方法byte[] b = ia.getAddress();//定义一个字节型的数组，并初始化。if (b.length != 4) {//判断这个字符数组的长度是否不等于4throw new IllegalArgumentException("no ipv6 address");//抛出一个非法参数异常}int firstByte = b[0];//定义一个整型的变量//使用多个if-else语句判断这个整型的变量与十六进制码比较if ((firstByte & 0x80) == 0) {return 'A';} else if ((firstByte & 0xc0) == 0x80) {return 'B';} else if ((firstByte & 0xe0) == 0xc0) {return 'C';} else if ((firstByte & 0xF0) == 0xE0) {return 'D';} else if ((firstByte & 0xF8) == 0xF0) {return 'E';} else {return 'F';}}public static void main(String[] args) {InetAddress ia = null;try {ia = InetAddress.getByName("www.sina.com");//给定一个网络域名} catch (UnknownHostException e) {e.printStackTrace();}int len;char king;len = getVersion(ia);//调用方法求出地址的长度System.out.println("地址长度为：" + len);king = getClass(ia);//调用方法求出地址的类型System.out.println("地址的类型为：" + king);}}?
实例274 查找主机
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.InetAddress;import java.net.UnknownHostException;public class NetDemo_5 {private static String lookup(String host) {InetAddress ia;byte[] b = null;// 初始化一个byte类型的数组try {ia = InetAddress.getByName(host);} catch (UnknownHostException e) {return "没有找到主机！";}if (isHostName(host)) {//判断是否有主机String s = "";//定义一个字符串for (int i = 0; i < b.length; i++) {//循环遍历出主机的字符串int c = b[i] < 0 ? (b[i] + 256) : b[i];s += c;if (i != b.length - 1) {s += ",";}}return s; //返回一个字符串} else {return ia.getHostName();//返回一个字符串的}}private static boolean isHostName(String host) {//创建一个静态的方法char[] ch = host.toCharArray(); //定义一个字符数组，并初始化for (int i = 0; i < ch.length; i++) {if (!Character.isDigit(ch[i])) {if (ch[i] != '.') {return true;}}}return false;}public static void main(String[] args) {if (args.length > 0) {for (int i = 0; i < args.length; i++) { // 使用命令行System.out.println(lookup(args[i]));}} else {BufferedReader br = new BufferedReader(new InputStreamReader(System.in));System.out.println();while (true) {try {String s = br.readLine();if (s.equals("exit")) { //判断如果字符串与“exit”相同，就结束当前的语句块break;}System.out.println(lookup(s));} catch (IOException e) {System.err.println(e);}}}}}?
实例275 主机所支持的协议
15.2 URL类的使用
实例276 使用URL访问网页
import java.applet.Applet;import java.awt.GridLayout;import java.awt.Label;import java.net.MalformedURLException;import java.net.URL;public class NetDemo_7 extends Applet{public void init(){URL url = this.getDocumentBase();try {URL url1 = new URL(url,"a.html"); //实例化一个URL对象this.setLayout(new GridLayout(2,1));//设置布局//添加标签this.add(new Label(url.toString()));this.add(new Label(url1.toString()));} catch (MalformedURLException e) {e.printStackTrace();} }}?
实例277 URL的组成部分
import java.net.MalformedURLException;import java.net.URL;public class NetDemo_8 {public static void main(String[] args){for(int i=0;i<args.length;i++){try {URL url = new URL(args[i]);System.out.println("URL的地址是："+url);System.out.println("URL的协议是："+url.getProtocol());System.out.println("用户信息是："+url.getUserInfo());String s = url.getHost();if(s!=null){int it = s.indexOf('@');if(it!=-1){s= s.substring(it+1);System.out.println(s);}}else{System.out.println(args[i]+"域名为空！");}System.out.println("端口是："+url.getPort());System.out.println("路径是："+url.getPath());System.out.println("文件类型是："+url.getFile());System.out.println("主机名是："+url.getHost());} catch (MalformedURLException e) {System.out.println("不是一个URL地址！");}}}}?
实例278 通过指定的URL可以获取网页的源代码
import java.io.BufferedInputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.Reader;import java.net.MalformedURLException;import java.net.URL;public class NetDemo_9 {public static void main(String[] args) throws IOException{if(args.length>0){URL url;try {url = new URL(args[0]);InputStream in = url.openStream();in= new BufferedInputStream(in);Reader r = new InputStreamReader(in);int b;while((b = r.read())!=-1){System.out.print((char)b);}Object o = url.getContent();System.out.println(o.getClass().getName());} catch (MalformedURLException e) {e.printStackTrace();}catch (Exception e) {System.out.print(e);}}}}?
实例279 一对多通信模式
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.InetAddress;import java.net.ServerSocket;import java.net.Socket;public class MySocketServer { // 操作Socket服务器端的类public static void main(String[] args) { // java程序主入口处try {new StartServer(8080); // 传入端口实例化对象} catch (Exception e) { // 捕获异常System.out.println("服务器端进行监听出现异常：" + e.getMessage());}}}class StartServer extends ServerSocket { // socket面服务器端private int port; // 端口public StartServer(int port) throws IOException {super(port);// 继承其类的portthis.port = port;System.out.println("服务器启动成功，监听端口号为：" + port);System.out.println("正在等待客户连接.........");try {while (true) { // 循环挂起等待客户的请求Socket socketCon = accept();new RunServer(socketCon, port); // 建立服务线程}} catch (IOException e) {System.out.println("没有监听到客户端的信息......");} finally {close(); // 关闭通信资源}}}class RunServer extends Thread { // 继承线程类实现服务线程private int port; // 端口private Socket socketCon;private BufferedReader in;private PrintWriter out;public RunServer(Socket s, int port) throws IOException {this.port = port;this.socketCon = s;in = new BufferedReader(new InputStreamReader(socketCon.getInputStream(), "gb2312")); // 读取客户端的数据流// 获取写往客户端的数据输出流,true:自动刷新out = new PrintWriter(socketCon.getOutputStream(), true);out.println("服务器端连接成功........."); // 向客户发送连接信息out.println("输入quit断开与服务器的连接");start();// 启动线程}public String infoUpperCase(String line) { // 处理信息return line.toUpperCase(); // 将字符串大写}public void run() {try {boolean done = false;while (!done) {String line = in.readLine(); // 读取客户端每行的内容if (line == null)done = true;else { // 显示客户端发送的内容System.out.println("来自客户端的消息：" + line);String message = infoUpperCase(line); // 信息处理// 向客户端发送信息out.println("来自服务器端的消息：" + message);if (line.trim().equals("quit")) // 退出判断done = true;}}System.out.println("客户端终止发送信息......");socketCon.close(); // 关闭通信资源} catch (Exception e) { // 捕获异常System.out.println("启动服务器端出现错误：" + e.getMessage());}}} /**--------文件名：MyOneClient.java-------------*/class MyOneClient { // 操作Socket客户端类public static void main(String[] args) { // java程序主入口处try {new Client1("localhost", 8080); // IP地址为本机,端口为8080} catch (Exception e) { // 捕获异常System.out.println("测试客户端连接出错：" + e.getMessage());}}}class PointClient { // Socket点客户端private String host;// IP地址（域名）private int port;// 端口号public PointClient(String host, int port) { // 带参数构造方法进行初始化this.host = host;this.port = port;connectServer(); // 调用连接方法}public void connectServer() {// 连接方法try {Socket socketConn;// 声明Socket连接// 判断IP地址(域名)如果是本机localhostif (host.equals("localhost") || host.equals("127.0.0.1")) {// 创建本地连接socketConn = new Socket(InetAddress.getLocalHost(), port);} else { // 创建远程连接socketConn = new Socket(InetAddress.getByName(host), port);}BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in)); // 获得从键盘输入的流PrintWriter out = new PrintWriter(socketConn.getOutputStream(),true); // 获得服务器写内容的数据流BufferedReader in = new BufferedReader(new InputStreamReader(socketConn.getInputStream()));// 获得接收服务器发送内容的缓冲流System.out.println("服务器信息：" + in.readLine());// 从服务器获得信息System.out.println("服务器信息：" + in.readLine());System.out.print("请输入>"); // 用户输入boolean done = false;while (!done) {String line = stdin.readLine(); // 获得从键盘输入的每行字符out.println(line); // 发送到服务端if (line.equalsIgnoreCase("quit")) // 读到quit则结束循环done = true;String info = in.readLine(); // 从服务器读取字符串System.out.println("服务器信息:" + info);// 显示从服务器发送来的数据if (!done) // 用户输入System.out.print("请输入>");}socketConn.close(); // 关闭资源} catch (SecurityException e) { // 捕获安全性错误时引发的异常System.out.println("连接服务器出现安全问题！");} catch (IOException e) { // 捕获IO流异常System.out.println("连接服务器出现I/O错误！");}}} /**--------文件名：MyTwoClient.java-------------*/class MyTwoClient { // 操作Socket客户端类public static void main(String[] args) { // java程序主入口处try {new Client1("localhost", 8080); // IP地址为本机,端口为80} catch (Exception e) { // 捕获异常System.out.println("测试客户端连接出错：" + e.getMessage());}}}class Client1 { // Socket客户端private String host; // IP地址（域名）private int port; // 端口号public Client1(String host, int port) { // 带参数构造方法进行初始化this.host = host;this.port = port;connectServer(); // 调用连接方法}public void connectServer() { // 连接方法try {Socket socketConn; // 声明Socket连接// 判断IP地址(域名)如果是本机localhostif (host.equals("localhost") || host.equals("127.0.0.1")) {// 创建本地连接socketConn = new Socket(InetAddress.getLocalHost(), port);} else { // 创建远程连接socketConn = new Socket(InetAddress.getByName(host), port);}BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in)); // 获得从键盘输入的流PrintWriter out = new PrintWriter(socketConn.getOutputStream(),true); // 获得服务器写内容的数据流BufferedReader in = new BufferedReader(new InputStreamReader(socketConn.getInputStream()));// 获得接收服务器发送内容的缓冲流System.out.println("服务器信息：" + in.readLine());// 从服务器获得信息System.out.println("服务器信息：" + in.readLine());System.out.print("请输入>"); // 用户输入boolean done = false;while (!done) {String line = stdin.readLine(); // 获得从键盘输入的每行字符out.println(line); // 发送到服务端if (line.equalsIgnoreCase("quit")) // 读到quit则结束循环done = true;String info = in.readLine(); // 从服务器读取字符串System.out.println("服务器信息:" + info);// 显示从服务器发送来的数据if (!done) // 用户输入System.out.print("请输入>");}socketConn.close(); // 关闭资源} catch (SecurityException e) { // 捕获安全性错误时引发的异常System.out.println("连接服务器出现安全问题！");} catch (IOException e) { // 捕获IO流异常System.out.println("连接服务器出现I/O错误！");}}}?
实例280 自制浏览器
import java.awt.event.WindowEvent;import java.io.IOException;import javax.swing.JEditorPane;import javax.swing.JFrame;import javax.swing.JScrollPane;import javax.swing.event.HyperlinkEvent;import javax.swing.event.HyperlinkListener;//实现一个浏览器class LinkFollower implements HyperlinkListener{private JEditorPane jep;public LinkFollower(JEditorPane jep){this.jep= jep;}public void hyperlinkUpdate(HyperlinkEvent he){if(he.getEventType()==HyperlinkEvent.EventType.ACTIVATED){try {jep.setPage(he.getURL());} catch (IOException e) {e.printStackTrace();}}}}public class NetDemo_15{public static void main(String[] args){String initPage = "http://www.sina.com";if(args.length>0){initPage = args[0];JEditorPane jep = new JEditorPane();jep.setEditable(false);jep.addHyperlinkListener(new LinkFollower(jep));try {jep.setPage(initPage);} catch (IOException e) {e.printStackTrace();}JScrollPane jsp = new JScrollPane(jep);JFrame jf = new JFrame("简单浏览器");jf.setDefaultCloseOperation(WindowEvent.COMPONENT_SHOWN);jf.getContentPane().add(jsp);jf.setSize(512,324);jf.show();}}}?
实例281 扫描TCP端口
import java.io.IOException;import java.net.Socket;import java.net.UnknownHostException;public class NetDemo_16 {public static void main(String[] args){String str = "localhost";if(args.length>0){str = args[0];}for(int i=100;i<500;i++){//使用循环扫描端口try {Socket s = new Socket();System.out.println("There is a server on"+i+"of"+s);} catch (Exception e) {e.printStackTrace();break;} }}}?
实例282 TCP协议服务器
import java.io.BufferedReader;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.ServerSocket;import java.net.Socket;public class TCPSocketServer {public static void main(String[] args) { // java程序主入口处try {Server server = new Server(8080);// 传入端口号实例化对象} catch (Exception e) { // 捕获异常System.out.println("测试服务器端监听出错：" + e.getMessage());}}}class Server { // Socket服务器端private int port; // 端口public Server(int port) { // 带参数的构造方法进行初始化this.port = port;start(); // 调用启动服务器端的方法}public String infoUpperCase(String line) { // 处理信息return line.toUpperCase(); // 将字符串大写}public void start() { // 启动服务器端try {// 根据端口创建服务器端Socket对象ServerSocket serverSocket = new ServerSocket(port);// 显示连接信息System.out.println("服务器已启动，监听端口号为：" + port);System.out.println("正在等待客户端连接.........");// 挂起等待客户的请求Socket socketAccept = serverSocket.accept();BufferedReader in = new BufferedReader(new InputStreamReader(socketAccept.getInputStream()));// 获取读取客户端的数据流// 获取写往客户端的数据输出流,true:自动刷新PrintWriter out = new PrintWriter(socketAccept.getOutputStream(),true);out.println("服务器端连接成功........."); // 向客户发送连接信息out.println("输入quit断开与服务器的连接");boolean done = false;while (!done) {String line = in.readLine(); // 读取客户端每行的内容if (line == null) { // 没有写则不读取done = true;} else {// 显示客户端发送的内容System.out.println("来自客户端的信息：" + line);// 信息处理String message = infoUpperCase(line);// 向客户端发送信息out.println("来自服务器端的信息：" + message);if (line.trim().equals("quit")) // 退出判断done = true;}}socketAccept.close(); // 关闭通信资源} catch (Exception e) { // 捕获异常System.out.println("启动服务器端出现错误：" + e.getMessage());}}}?
实例283 TCP协议客户机
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.InetAddress;import java.net.Socket;public class TCPSocketClient {public static void main(String[] args) { // java程序主入口处try {new Client("localhost", 8080); // IP地址为本机,端口为80} catch (Exception e) { // 捕获异常System.out.println("测试客户端连接出错：" + e.getMessage());}}}class Client { // Socket客户端private String host; // IP地址（域名）private int port; // 端口号public Client(String host, int port) { // 带参数构造方法进行初始化this.host = host;this.port = port;connectServer(); // 调用连接方法}public void connectServer() { // 连接方法try {Socket socketConn; // 声明Socket连接// 判断IP地址(域名)如果是本机localhostif (host.equals("localhost") || host.equals("127.0.0.1")) {// 创建本地Socket连接socketConn = new Socket(InetAddress.getLocalHost(), port);} else { // 创建远程Socket连接socketConn = new Socket(InetAddress.getByName(host), port);}BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in)); // 获得从键盘输入的流PrintWriter out = new PrintWriter(socketConn.getOutputStream(),true); // 获得服务器写内容的数据流BufferedReader in = new BufferedReader(new InputStreamReader(socketConn.getInputStream()));// 获得接收服务器发送内容的缓冲流// 从服务器获得信息System.out.println("服务器信息：" + in.readLine());System.out.println("服务器信息：" + in.readLine());System.out.print("请输入>"); // 用户输入boolean done = false;while (!done) {String line = stdin.readLine(); // 获得从键盘输入的每行字符out.println(line); // 发送到服务端if (line.equalsIgnoreCase("quit")) // 读到quit则结束循环done = true;String info = in.readLine(); // 从服务器读取字符串System.out.println("服务器信息:" + info);// 显示从服务器发送来的数据if (!done) // 用户输入System.out.print("请输入>");}socketConn.close(); // 关闭资源} catch (SecurityException e) { // 捕获安全性错误时引发的异常System.out.println("连接服务器出现安全问题！");} catch (IOException e) { // 捕获IO流异常System.out.println("连接服务器出现I/O错误！");}}}?
实例284 Socket连接信息
import java.io.IOException;import java.net.Socket;import java.net.UnknownHostException;public class NetDemo_17 {public static void main(String[] args) {for (int i = 0; i < args.length; i++) {try {Socket s = new Socket(args[i], 80);System.out.println("Connected to" + s.getInetAddress()+ "on port" + s.getPort() + "from port"+ s.getLocalPort() + "of" + s.getLocalAddress());} catch (UnknownHostException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}}?
实例285 Echo服务的客户端是如何实现的？
import java.io.BufferedReader;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.net.Socket;import java.net.UnknownHostException;public class EchoClient {public static void main(String args[]) {try {Socket connection = new Socket("", 7);// 创建Socket对象，Echo协议对应的端口为7号System.out.println("已建立连接:");DataInputStream in = new DataInputStream(connection.getInputStream());// 根据返回的Socket对象的输入流创建数据输入流DataOutputStream out = new DataOutputStream(connection.getOutputStream());// 根据返回的Socket对象的输出流创建数据输出流String line = new String("");while (!line.toUpperCase().equals(".QUIT")) {System.out.println("输入字符串: ");line = EchoClient.readString();// 由键盘输入字符串System.out.println("\t字符串发送到服务器 ...");out.writeUTF(line);// 以UTF的编码形式将一个字符串写入数据输出流System.out.println("\t等待服务器响应 ...");line = in.readUTF();// 以UTF的编码形式从数据输入流中读字符串System.out.println("Received: " + line);// 将读取的字符串显示出来}in.close();out.close();connection.close();} catch (UnknownHostException e) {System.err.println("Unknown host: " + args[0]);} catch (IOException e) {System.err.println(e.getMessage());}}public static String readString() {String string = new String();BufferedReader in = new BufferedReader(new InputStreamReader(System.in));// 创建一个可键盘录入的字符串缓冲区try {string = in.readLine();} catch (IOException e) {}return string;}}?
实例286 检测本机的服务端口
import java.io.IOException;import java.net.ServerSocket;public class usrLocalPostScanner {public static void main(String[] args) {// 循环访问端口for (int port = 1; port <= 65535; port++) {try {// 建立新的服务端口// 如果在此端口已经有服务存在，则抛出异常ServerSocket server = new ServerSocket(port);} catch (IOException e) {// 打印出异常System.out.println("There is a server on port " + port + ".");}}}}?
实例287 下载的页面不丢失链接
import java.net.URLEncoder;//下载的页面不丢失链接public class NetDemo_11 {public static void main(String[] args){System.out.println(URLEncoder.encode("This string has spaces"));System.out.println(URLEncoder.encode("This*string*has*asterisks"));System.out.println(URLEncoder.encode("This%string%has%persent%signs"));System.out.println(URLEncoder.encode("This+string+has+pulses"));System.out.println(URLEncoder.encode("This/string/has/slashes"));System.out.println(URLEncoder.encode("This:string:has:colors"));System.out.println(URLEncoder.encode("This-string-has-tildes"));System.out.println(URLEncoder.encode("This(string)has(parentheses)"));System.out.println(URLEncoder.encode("This.string.has.periods"));System.out.println(URLEncoder.encode("This&string&has&ersands"));}}?
实例288 如何对网页进行重新定向
import java.applet.Applet;import java.net.MalformedURLException;import java.net.URL;//如何对网页进行重新定向public class NetDemo_12 extends Applet{public void init(){try {getAppletContext().showDocument(new URL("http://delfault.myetang.com"),"_blank");} catch (MalformedURLException e) {e.printStackTrace();}}}?
实例289 在Internet上搜索对象
import java.io.BufferedInputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.net.MalformedURLException;import java.net.URL;//在Intenet上搜索对象public class NetDemo_13 {public static void main(String[] args) throws IOException{String target = "";for(int i=0;i<args.length;i++){target +=args[i]+"";}target= target.trim();URL url;try {url = new URL("http://www.baidu.com/");InputStream in = new BufferedInputStream(url.openStream());InputStreamReader isr = new InputStreamReader(in);int b;while((b= isr.read())!=-1){System.out.print((char)(b));}} catch (MalformedURLException e) {e.printStackTrace();}}}?
实例290 LAN使用代理服务器
import java.io.IOException;import java.io.InputStream;import java.io.InterruptedIOException;import java.io.OutputStream;import java.lang.reflect.Constructor;import java.net.ServerSocket;import java.net.Socket;public class LANProxy extends Thread {// 操作实现代理服务器的类protected Socket socket; // 传入数据用的Socketprivate static String parent = null; // 上级代理服务器private static int parentPort = -1;public static int RETRIES = 5; // 在放弃之前尝试连接远程主机的次数public static int PAUSE = 5; // 在两次连接尝试之间的暂停时间public static int TIMEOUT = 50; // 等待Socket输入的等待时间public static int BUFSIZ = 1024; // 输入的缓冲大小public static boolean logging = false; // 是否要求代理服务器在日志中记录所有已传输的数据public static OutputStream log = null; // 默认日志例程将向该OutputStream对象输出日志信息public void run() { // 执行操作的线程String line;String host;int port = 80;Socket outbound = null;try {socket.setSoTimeout(TIMEOUT);// 设置超时时间InputStream is = socket.getInputStream(); // 创建输入流OutputStream os = null;try {line = ""; // 获取请求行的内容host = "";int state = 0;boolean space;while (true) { // 无限循环int c = is.read(); // 读取输入流的信息if (c == -1) // 没有读取信息break;if (logging)proxyLog(c, true); // 将信息写入日志space = Character.isWhitespace((char) c);// 判断是否为空白字符switch (state) { // 判断状态case 0:if (space)continue; // 跳过本次循环state = 1; // 更改状态case 1:if (space) {state = 2;continue; // 跳过本次循环}line = line + (char) c; // 添加读取的信息break;case 2:if (space)continue; // 跳过空白字符state = 3; // 更改状态case 3:if (space) { // 如果是空白字符state = 4; // 更改状态String host0 = host; // 取出网址int n;n = host.indexOf("//"); // 获取网址（不包括协议）if (n != -1) // 没有找到host = host.substring(n + 2);n = host.indexOf('/');if (n != -1) // 没有找到/host = host.substring(0, n);n = host.indexOf(":"); // 分析可能存在的端口号if (n != -1) { // 没有找到:port = Integer.parseInt(host.substring(n + 1));host = host.substring(0, n);}host = outLog(host0, host, port, socket);// 获得网站域名if (parent != null) {host = parent;port = parentPort;}int retry = RETRIES;while (retry-- != 0) {try { // 创建连接对象outbound = new Socket(host, port);break;} catch (Exception e) {System.out.println("无法创建连接："+ e.getMessage());}Thread.sleep(PAUSE); // 设置线程等待}if (outbound == null)break;outbound.setSoTimeout(TIMEOUT); // 设置超时时间os = outbound.getOutputStream(); // 获得输出流对象os.write(line.getBytes()); // 将信息写入流os.write(' ');os.write(host0.getBytes()); // 将信息写入流os.write(' ');outInfo(is, outbound.getInputStream(), os, socket.getOutputStream()); // 调用方法将信息写入日志break;}host = host + (char) c;break;}}} catch (IOException e) {}} catch (Exception e) {} finally {try {socket.close(); // 释放资源} catch (Exception e1) {}try {outbound.close();} catch (Exception e2) {}}}void outInfo(InputStream is0, InputStream is1, OutputStream os0,OutputStream os1) throws IOException { // 读取流中信息写入日志try {int ir;byte bytes[] = new byte[BUFSIZ]; // 创建字节数组，大小：1024while (true) {try {if ((ir = is0.read(bytes)) > 0) { // 判断读取输入流的信息os0.write(bytes, 0, ir); // 读取数据写入输出流对象中if (logging)proxyLog(bytes, 0, ir, true); // 写入日志} else if (ir < 0) // 读取完毕break;} catch (InterruptedIOException e) { // 捕获中断IO流异常}try {if ((ir = is1.read(bytes)) > 0) { // 判断读取输入流的信息os1.write(bytes, 0, ir); // 读取数据写入输出流对象中if (logging)proxyLog(bytes, 0, ir, false); // 写入日志} else if (ir < 0) // 读取完毕break;} catch (InterruptedIOException e) { // 捕获中断IO流异常}}} catch (Exception e0) { // 捕获异常}}// 用来把一个代理服务器链接到另一个代理服务器（需要指定另一个服务器的名称和端口）。public static void setProxy(String name, int port) {parent = name;parentPort = port;}public LANProxy(Socket s) { // 创建一个代理线程socket = s;start(); // 启动线程}public void proxyLog(int c, boolean browser) throws IOException {// 写日志log.write(c);}public void proxyLog(byte[] bytes, int offset, int len, boolean browser)throws IOException { // 循环写日志for (int i = 0; i < len; i++)proxyLog((int) bytes[offset + i], browser);}// 默认情况下，日志信息输出到控制台或文件public String outLog(String url, String host, int port, Socket sock) {java.text.DateFormat cal = java.text.DateFormat.getDateTimeInstance();System.out.println(cal.format(new java.util.Date()) + " - " + url + " "+ sock.getInetAddress() + "\n");return host;}public static void startProxy(int port, Class clobj) {ServerSocket serverSocket;try {serverSocket = new ServerSocket(port); // 根据端口创建服务器端Socket对象while (true) {Class[] objClass = new Class[1]; // 创建类数组，大小为1Object[] obj = new Object[1]; // 创建对象数组，大小为1objClass[0] = Socket.class;// 添加Socket类try { // 创建代理服务器实例Constructor cons = clobj.getDeclaredConstructor(objClass);obj[0] = serverSocket.accept(); // 挂起等待客户的请求cons.newInstance(obj); // 创建HttpProxy或其派生类的实例} catch (Exception e) {Socket socket = (Socket) obj[0];// 对象强制转换try {socket.close(); // 释放资源} catch (Exception ec) {}}}} catch (IOException e) {}}public static void main(String args[]) { // java程序主入口处System.out.println("LAN使用代理服务器连接成功......");LANProxy.log = System.out; // 日志信息输出到控制台LANProxy.logging = false;LANProxy.startProxy(8080, LANProxy.class);// 调用方法}}?
实例291 BBS论坛服务器端
package net;import java.awt.BorderLayout;import java.awt.Color;import java.awt.event.*;import java.io.*;import java.net.ServerSocket;import java.net.Socket;import java.util.StringTokenizer;import java.util.Vector;import javax.swing.*;import javax.swing.border.TitledBorder;/** * 聊天室的服务器端程序，GUI界面 */public class BBSServer extends JFrame {static JLabel statusBar = new JLabel(); // 状态栏标签// 显示客户端的连接信息的列表static java.awt.List connectInfoList = new java.awt.List(10);// 保存当前处理客户端请求的处理器线程static Vector clientProcessors = new Vector(10);// 当前的连接数static int activeConnects = 0;// 构造方法public BBSServer() {init();try {// 设置界面为系统默认外观UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());SwingUtilities.updateComponentTreeUI(this);} catch (Exception e) {e.printStackTrace();}}private void init() {this.setTitle("BBS论坛1号聊天室");statusBar.setText("");// 初始化菜单JMenu fileMenu = new JMenu();fileMenu.setText("文件");JMenuItem exitMenuItem = new JMenuItem();exitMenuItem.setText("退出");exitMenuItem.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {exitActionPerformed(e);}});fileMenu.add(exitMenuItem);JMenuBar menuBar = new JMenuBar();menuBar.add(fileMenu);this.setJMenuBar(menuBar);// 将组件进行布局JPanel jPanel1 = new JPanel();jPanel1.setLayout(new BorderLayout());JScrollPane pane = new JScrollPane(connectInfoList);pane.setBorder(new TitledBorder(BorderFactory.createEtchedBorder(Color.red, new Color(134, 134, 0)), "客户端IP一览表"));jPanel1.add(new JScrollPane(pane), BorderLayout.CENTER);this.getContentPane().setLayout(new BorderLayout());this.getContentPane().add(statusBar, BorderLayout.SOUTH);this.getContentPane().add(jPanel1, BorderLayout.CENTER);this.pack();}/** 退出菜单项事件 */public void exitActionPerformed(ActionEvent e) {// 向客户端发送断开连接信息sendMsgToClients(new StringBuffer(Message.QUIT_IDENTIFER));closeAll(); // 关闭所有的连接System.exit(0);}/** 处理窗口关闭事件 */protected void processWindowEvent(WindowEvent e) {super.processWindowEvent(e);if (e.getID() == WindowEvent.WINDOW_CLOSING) {exitActionPerformed(null);}}/** 刷新聊天室，不断刷新clientProcessors，制造最新的用户列表 */public static void RefreshRoom() {StringBuffer people = new StringBuffer(Message.PEOPLE_IDENTIFER);for (int i = 0; i < clientProcessors.size(); i++) {MessFromClient c = (MessFromClient) clientProcessors.elementAt(i);people.append(Message.SEPERATOR).append(c.clientName);}// 用sendClients方法向客户端发送用户列表的信息sendMsgToClients(people);}/** 向所有客户端群发消息 */public static synchronized void sendMsgToClients(StringBuffer msg) {for (int i = 0; i < clientProcessors.size(); i++) {MessFromClient c = (MessFromClient) clientProcessors.elementAt(i);System.out.println("send msg: " + msg);c.send(msg);}}/** 关闭所有连接 */public static void closeAll() {while (clientProcessors.size() > 0) {MessFromClient c = (MessFromClient) clientProcessors.firstElement();try {// 关闭socket连接和处理线程c.socket.close();c.toStop();} catch (IOException e) {System.out.println("Error:" + e);} finally {clientProcessors.removeElement(c);}}}/** * 判断客户端是否合法。 不允许同一客户端重复登陆，所谓同一客户端是指IP和名字都相同。 */public static boolean isCheck(MessFromClient newclient) {if (clientProcessors.contains(newclient)) {return false;} else {return true;}}/** * 断开某个连接，并且从连接列表中删除 */public static void disconnect(MessFromClient client) {disconnect(client, true);}/** * 断开某个连接，根据要求决定是否从连接列表中删除 */public static synchronized void disconnect(MessFromClient client,boolean toRemoveFromList) {try {// 在服务器端程序的list框中显示断开信息connectInfoList.add(client.clientIP + "断开连接");BBSServer.activeConnects--; // 将连接数减1String constr = "当前在线人数：" + BBSServer.activeConnects + "人";statusBar.setText(constr);// 向客户发送断开连接信息client.send(new StringBuffer(Message.QUIT_IDENTIFER));client.socket.close();} catch (IOException e) {System.out.println("Error:" + e);} finally {// 从clients数组中删除此客户的相关socket等信息， 并停止线程。if (toRemoveFromList) {clientProcessors.removeElement(client);client.toStop();}}}public static void main(String[] args) {BBSServer chatServer1 = new BBSServer();chatServer1.setVisible(true);System.out.println("Server starting ...");ServerSocket server = null;try {// 服务器端开始侦听server = new ServerSocket(Message.SERVER_PORT);} catch (IOException e) {System.out.println("Error:" + e);System.exit(1);}while (true) {// 如果当前客户端数小于MAX_CLIENT个时接受连接请求if (clientProcessors.size() < Message.MAX_CLIENT) {Socket socket = null;try {// 收到客户端的请求socket = server.accept();if (socket != null) {System.out.println(socket + "连接");}} catch (IOException e) {System.out.println("Error:" + e);}// 定义并实例化一个ClientProcessor线程类，用于处理客户端的消息MessFromClient c = new MessFromClient(socket);if (isCheck(c)) {clientProcessors.addElement(c); // 添加到列表int connum = ++BBSServer.activeConnects; // 如果客户端合法，则继续// 在状态栏里显示连接数String constr = "当前在线人数：" + connum + "人";BBSServer.statusBar.setText(constr);// 将客户socket信息写入list框BBSServer.connectInfoList.add(c.clientIP + "连接");c.start();RefreshRoom(); // 通知所有客户端用户列表发生变化} else {// 如果客户端不合法c.ps.println("不允许重复登陆");disconnect(c, false);}} else {// 如果客户端超过了MAX_CLIENT个，则等待一段时间再尝试接受请求try {Thread.sleep(200);} catch (InterruptedException e) {}}}}}/** * 处理客户端发送的请求的线程 */class MessFromClient extends Thread {Socket socket; // 存储一个连接客户端的socket信息String clientName; // 存储客户端的连接姓名String clientIP; // 存储客户端的ip信息BufferedReader br; // 用来实现接受从客户端发来的数据流PrintStream ps; // 用来实现向客户端发送信息的打印流boolean running = true;/** 构造方法 */public MessFromClient(Socket s) {socket = s;try {// 初始化输入输出流br = new BufferedReader(new InputStreamReader(socket.getInputStream()));ps = new PrintStream(socket.getOutputStream());// 读取收到的信息，第一条信息是客户端的名字、IP信息String clientInfo = br.readLine();// 读取信息，根据消息分隔符解析消息StringTokenizer stinfo = new StringTokenizer(clientInfo,Message.SEPERATOR);String head = stinfo.nextToken();if (head.equals(Message.CONNECT_IDENTIFER)) {if (stinfo.hasMoreTokens()) {// 关键字后的第二段数据是客户名信息clientName = stinfo.nextToken();}if (stinfo.hasMoreTokens()) {// 关键字后的第三段数据是客户ip信息clientIP = stinfo.nextToken();}System.out.println(head); // 在控制台打印头信息}} catch (IOException e) {System.out.println("Error:" + e);}}/** 向客户端发送消息 */public void send(StringBuffer msg) {ps.println(msg);ps.flush();}// 线程运行方法public void run() {while (running) {String line = null;try {// 读取客户端发来的数据流line = br.readLine();} catch (IOException e) {System.out.println("Error" + e);BBSServer.disconnect(this);BBSServer.RefreshRoom();return;}// 客户已离开if (line == null) {BBSServer.disconnect(this);BBSServer.RefreshRoom();return;}StringTokenizer st = new StringTokenizer(line, Message.SEPERATOR);String keyword = st.nextToken();// 如果关键字是MSG则是客户端发来的聊天信息if (keyword.equals(Message.MSG_IDENTIFER)) {StringBuffer msg = new StringBuffer(Message.MSG_IDENTIFER).append(Message.SEPERATOR);msg.append(clientName);msg.append(st.nextToken("\0"));// 再将某个客户发来的聊天信息发送到每个连接客户的聊天栏中BBSServer.sendMsgToClients(msg);} else if (keyword.equals(Message.QUIT_IDENTIFER)) {// 如果关键字是QUIT则是客户端发来断开连接的信息BBSServer.disconnect(this); // 服务器断开与这个客户的连接// 继续监听聊天室并刷新其他客户的聊天人名listBBSServer.RefreshRoom();running = false;}}}public void toStop() {running = false;}// 覆盖Object类的equals方法public boolean equals(Object obj) {if (obj instanceof MessFromClient) {MessFromClient obj1 = (MessFromClient) obj;if (obj1.clientIP.equals(this.clientIP)&& (obj1.clientName.equals(this.clientName))) {return true;}}return false;}// 覆盖Object类的hashCode方法public int hashCode() {return (this.clientIP + Message.SEPERATOR + this.clientName).hashCode();}}?
package net;import java.awt.*;import java.awt.event.*;import java.io.*;import java.net.InetAddress;import java.net.Socket;import java.util.StringTokenizer;import javax.swing.*;import javax.swing.border.TitledBorder;/** * 聊天室的客户端程序，GUI界面。 */public class BBSClient extends JFrame implements ActionListener {// 登陆聊天室的名字标签和输入框JLabel nameLabel = new JLabel();JTextField nameTextField = new JTextField(15);// 连接和断开连接的按钮JButton connectButton = new JButton();JButton disConnectButton = new JButton();JTextArea chatContentTextArea = new JTextArea(9, 30); // 聊天室内容的文本域JButton sendMsgButton = new JButton(); // 发送消息的按钮JTextField msgTextField = new JTextField(20); // 消息输入框JLabel msglabel = new JLabel();java.awt.List peopleList = new java.awt.List(10); // 聊天室用户列表/** 以下定义数据流和网络变量 */Socket soc = null;PrintStream ps = null;// 客户端侦听服务器消息的线程ListenClentThread listener = null;public BBSClient() {init();}// 初始化图形界面public void init() {this.setTitle("欢迎来到1号聊天室");// 初始化按钮和标签nameLabel.setText("姓名：");connectButton.setText("登 录");connectButton.addActionListener(this);disConnectButton.setText("退 出");disConnectButton.addActionListener(this);// 设置聊天内容不可编辑chatContentTextArea.setEditable(false);sendMsgButton.setText("发送信息");sendMsgButton.addActionListener(this);msgTextField.setText("");// panel1放置输入姓名和连接两个按钮JPanel panel1 = new JPanel();panel1.setLayout(new FlowLayout());panel1.add(nameLabel);panel1.add(nameTextField);panel1.add(connectButton);panel1.add(disConnectButton);// 用于放置聊天信息显示和聊天人员列表JPanel panel2 = new JPanel();panel2.setLayout(new FlowLayout());JScrollPane pane1 = new JScrollPane(chatContentTextArea);pane1.setBorder(new TitledBorder(BorderFactory.createEtchedBorder(Color.white, new Color(134, 134, 134)), "聊天内容"));panel2.add(pane1);JScrollPane pane2 = new JScrollPane(peopleList);pane2.setBorder(new TitledBorder(BorderFactory.createEtchedBorder(Color.white, new Color(134, 134, 134)), "在线用户"));panel2.add(pane2);// 用于放置发送信息区域JPanel panel3 = new JPanel();panel3.setLayout(new FlowLayout());panel3.add(msglabel);panel3.add(msgTextField);panel3.add(sendMsgButton);// 将组件添加到界面this.getContentPane().setLayout(new BorderLayout());this.getContentPane().add(panel1, BorderLayout.NORTH);this.getContentPane().add(panel2, BorderLayout.CENTER);this.getContentPane().add(panel3, BorderLayout.SOUTH);this.pack();try {UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());SwingUtilities.updateComponentTreeUI(this);} catch (Exception e) {e.printStackTrace();}}/** 关闭聊天室客户端事件 */protected void processWindowEvent(WindowEvent e) {super.processWindowEvent(e);if (e.getID() == WindowEvent.WINDOW_CLOSING) {// 如果是关闭聊天室客户端，则断开连接disconnect();dispose();System.exit(0);}}/** 处理按钮事件 */public void actionPerformed(ActionEvent event) {Object source = event.getSource();if (source == connectButton) {// 如果点击连接按钮if (soc == null) {try {// 使用端口2525实例化一个本地套接字soc = new Socket(InetAddress.getLocalHost(),Message.SERVER_PORT);System.out.println(soc); // 在控制台打印实例化的结果ps = new PrintStream(soc.getOutputStream());// 将ps指向soc的输出流// 定义一个字符缓冲存储发送信息StringBuffer info = new StringBuffer(Message.CONNECT_IDENTIFER).append(Message.SEPERATOR);// 其中INFO为关键字让服务器识别为连接信息// 并将name和ip用"："分开，在服务器端将用一个// StringTokenizer类来读取数据String userinfo = nameTextField.getText()+ Message.SEPERATOR+ InetAddress.getLocalHost().getHostAddress();ps.println(info.append(userinfo));ps.flush();// 将客户端线程实例化，并启动listener = new ListenClentThread(this, nameTextField.getText(), soc);listener.start();} catch (IOException e) {System.out.println("Error:" + e);disconnect();}}} else if (source == disConnectButton) {// 如果点击断开连接按钮disconnect();} else if (source == sendMsgButton) {// 如果点击发送按钮if (soc != null) {// 定义并实例化一个字符缓冲存储发送的聊天信息StringBuffer msg = new StringBuffer(Message.MSG_IDENTIFER).append(Message.SEPERATOR);// 用打印流发送聊天信息ps.println(msg.append(msgTextField.getText()));ps.flush();}}}/** 断开与服务器的连接 */public void disconnect() {if (soc != null) {try {// 用打印流发送QUIT信息通知服务器断开此次通信ps.println(Message.QUIT_IDENTIFER);ps.flush();soc.close(); // 关闭套接字listener.toStop();soc = null;} catch (IOException e) {System.out.println("Error:" + e);}}}public static void main(String[] args) {BBSClient client = new BBSClient();client.setVisible(true);}/** 客户端线程类用来监听服务器传来的信息 */class ListenClentThread extends Thread {String name = null; // 存储客户端连接后的name信息BufferedReader br = null; // 客户端接受服务器数据的输入流PrintStream ps = null; // 实现从客户端发送数据到服务器的打印流Socket socket = null; // 存储客户端的socket信息BBSClient parent = null; // 存储当前运行的ChatClient实例boolean running = true;// 构造方法public ListenClentThread(BBSClient p, String n, Socket s) {// 接受参数parent = p;name = n;socket = s;try {// 实例化两个数据流br = new BufferedReader(new InputStreamReader(s.getInputStream()));ps = new PrintStream(s.getOutputStream());} catch (IOException e) {System.out.println("Error:" + e);parent.disconnect();}}// 停止侦听public void toStop() {this.running = false;}// 线程运行方法public void run() {String msg = null;while (running) {msg = null;try {// 读取从服务器传来的信息msg = br.readLine();System.out.println("receive msg: " + msg);} catch (IOException e) {System.out.println("Error:" + e);parent.disconnect();}// 如果从服务器传来的信息为空则断开此次连接if (msg == null) {parent.listener = null;parent.soc = null;parent.peopleList.removeAll();running = false;return;}// 用StringTokenizer类来实现读取分段字符StringTokenizer st = new StringTokenizer(msg, Message.SEPERATOR);// 读取信息头即关键字用来识别是何种信息String keyword = st.nextToken();if (keyword.equals(Message.PEOPLE_IDENTIFER)) {// 如果是PEOPLE则是服务器发来的客户连接信息// 主要用来刷新客户端的用户列表parent.peopleList.removeAll();// 遍历st取得目前所连接的客户while (st.hasMoreTokens()) {String str = st.nextToken();parent.peopleList.add(str);}} else if (keyword.equals(Message.MSG_IDENTIFER)) {// 如果关键字是MSG则是服务器传来的聊天信息,// 主要用来刷新客户端聊天信息区将每个客户的聊天内容显示出来String usr = st.nextToken();parent.chatContentTextArea.append(usr);parent.chatContentTextArea.append(st.nextToken("\0"));parent.chatContentTextArea.append("\r\n");} else if (keyword.equals(Message.QUIT_IDENTIFER)) {// 如果关键字是QUIT则是服务器关闭的信息, 切断此次连接System.out.println("Quit");try {running = false;parent.listener = null;parent.soc.close();parent.soc = null;} catch (IOException e) {System.out.println("Error:" + e);} finally {parent.soc = null;parent.peopleList.removeAll();}break;}}// 清除用户列表parent.peopleList.removeAll();}}}?
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实例292 UDP报文的发送与接收
import java.io.File;import java.io.FileInputStream;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;/**--------文件名：UDPServer.java-------------*/public class UDPServer {public static void main(String args[]) {try {System.out.println("UDP服务端启动成功，等待接收消息...");if (args.length != 1) {throw new IllegalArgumentException("参数个数有误");}int port = Integer.parseInt(args[0]); // 从命令行中获取端口号参数// 创建一个socket，侦听这个端口。DatagramSocket dsocket = new DatagramSocket(port);byte[] buffer = new byte[2048]; // 保存接收到的UDP报文的字节数组// 创建一个DatagramPacket，将收到的报文写入buffer中。// 注意，这里指定了报文的长度，如果收到的UDP报文比2048大，// 多余的信息被舍弃DatagramPacket packet = new DatagramPacket(buffer, buffer.length);// 不断循环，接收数据while (true) {dsocket.receive(packet); // 等待收到一个数据包// 将收到的报文的字节数组封装成字符串。String msg = new String(buffer, 0, packet.getLength());// 从数据包中取得消息来源的地址System.out.println("Receive: "+ packet.getAddress().getHostAddress() + ": " + msg);// 如果收到QUIT指令，则退出循环。if (msg.equalsIgnoreCase("QUIT")) {System.out.println("退出UDP服务");break;}packet.setLength(buffer.length); // 重设数据包的长度}// 关闭socketdsocket.close();} catch (Exception e) {System.err.println(e);// System.err.println(usage);}}}/**--------文件名：UDPClient.java-------------*/class UDPClient {public static void main(String args[]) {try {// 检查参数个数if (args.length < 3) {throw new IllegalArgumentException("参数个数有误");}// 域名和端口String host = args[0];int port = Integer.parseInt(args[1]);// 下面构造待发送报文的字节数组byte[] message;if (args[2].equals("-f")) {// 如果第三个参数为 -f，则表示将文件的内容以UDP方式发送// 获得待发送的文件对象以及文件的长度File f = new File(args[3]);int len = (int) f.length();// 创建一个足够容纳文件内容的字节数组message = new byte[len];FileInputStream in = new FileInputStream(f);// 将文件内容以字节的方式读到字节数组中int bytes_read = 0, n;do {n = in.read(message, bytes_read, len - bytes_read);bytes_read += n;} while ((bytes_read < len) && (n != -1));} else {// 如果第三个参数不是 -f，则将后面的参数当作消息发送String msg = args[2];for (int i = 3; i < args.length; i++) {msg += " " + args[i];}message = msg.getBytes();}// 根据域名获取IP地址InetAddress address = InetAddress.getByName(host);// 初始化一个UDP包。// DatagramPacket的构造方法中必须使用InetAddress，而不能是IP地址或者域名DatagramPacket packet = new DatagramPacket(message, message.length,address, port);// 创建一个DatagramSocket，以发送UDP包DatagramSocket dsocket = new DatagramSocket();dsocket.send(packet);System.out.println("send: " + new String(message));dsocket.close();// 注意：如果在构造DatagramPacket时，不提供IP地址和端口号，// 则需要调用DatagramSocket的connect方法，否则无法发送UDP包packet = new DatagramPacket(message, message.length);dsocket = new DatagramSocket();dsocket.connect(address, port);dsocket.send(packet);System.out.println("Send: " + new String(message));dsocket.close();} catch (Exception e) {System.err.println(e);}}}?