黑马程序员___IO流
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IO流(概述)：
IO流用来处理设备之间的数据传输Java对数据的操作是通过流的方式Java用于操作流的对象都在IO包中流按操作数据分为两种：字节流与字符流 。流按流向分为：输入流，输出流。
IO流常用基类：字节流的抽象基类：InputStream ，OutputStream。字符流的抽象基类：Reader ，Writer。注：由这四个类派生出来的子类名称都是 以其父类名作为子类名的后缀。如：InputStream的子类FileInputStream。如：Reader的子类FileReader。
IO流(FileWriter):
字符流和字节流：
字节流两个基类：InputStream ? OutputStream
字符流两个基类：Reader Writer
先学习一下字符流的特点。
既然IO流是用于操作数据的，那么数据的最常见体现形式是：文件。
那么先以操作文件为主来演示。
需求:在硬盘上，创建一个文件并写入一些文字数据。
找到一个专门用于操作文件的Writer子类对象。FileWriter。 ?后缀名是父类名。 前缀名是该流对象的功能。
示例：
import java.io.*;class FileWriterDemo{public static void main(String[] args) throws IOException{//创建一个FileWriter对象。该对象一被初始化就必须要明确被操作的文件。//而且该文件会被创建到指定目录下。如果该目录下已有同名文件，将被覆盖。//其实该步就是在明确数据要存放的目的地。FileWriter fw = new FileWriter("demo.txt");//调用write方法，将字符串写入到流中。fw.write("abcde");//刷新流对象中的缓冲中的数据。//将数据刷到目的地中。//fw.flush();//关闭流资源，但是关闭之前会刷新一次内部的缓冲中的数据。//将数据刷到目的地中。//和flush区别：flush刷新后，流可以继续使用，close刷新后，会将流关闭。fw.close();}}?IO流(IO异常处理方式)：示例：/*IO异常的处理方式。*/import java.io.*;class FileWriterDemo2{public static void main(String[] args) {FileWriter fw = null;try{fw = new FileWriter("demo.txt");fw.write("abcdefg");}catch (IOException e){System.out.println("catch:"+e.toString());}finally{try{if(fw!=null)fw.close();}catch (IOException e){System.out.println(e.toString());}}}}?IO流(文件的续写)：示例：/*演示对已有文件的数据续写。*/import java.io.*;class FileWriterDemo3{public static void main(String[] args) throws IOException{//传递一个true参数，代表不覆盖已有的文件。并在已有文件的末尾处进行数据续写。FileWriter fw = new FileWriter("demo.txt",true);fw.write("nihao\r\nxiexie");fw.close();}}?import java.io.*;class FileReaderDemo{public static void main(String[] args) throws IOException{//创建一个文件读取流对象，和指定名称的文件相关联。//要保证该文件是已经存在的，如果不存在，会发生异常FileNotFoundExceptionFileReader fr = new FileReader("demo.txt");//调用读取流对象的read方法。//read():一次读一个字符。而且会自动往下读。int ch = 0;while((ch=fr.read())!=-1){System.out.println(}/*while(true){int ch = fr.read();if(ch==-1)break;System.out.println("ch="+(char)ch);}*/fr.close();}}?/*第二种方式：通过字符数组进行读取。*/import java.io.*;class FileReaderDemo2 {public static void main(String[] args) throws IOException{FileReader fr = new FileReader("demo.txt");//定义一个字符数组。用于存储读到字符。//该read(char[])返回的是读到字符个数。char[] buf = new char[1024];int num = 0;while((num=fr.read(buf))!=-1){System.out.println(new String(buf,0,num));}fr.close();}}?//读取一个.java文件，并打印在控制台上。import java.io.*;class FileReaderTest {public static void main(String[] args) throws IOException{FileReader fr = new FileReader("DateDemo.java");char[] buf = new char[1024];int num = 0;while((num=fr.read(buf))!=-1){System.out.print(new String(buf,0,num));}fr.close();}}?IO流(拷贝文本文件、拷贝文本文件图例)：import java.io.*;class CopyText {public static void main(String[] args) throws IOException{copy_2();}public static void copy_2(){FileWriter fw = null;FileReader fr = null;try{fw = new FileWriter("SystemDemo_copy.txt");fr = new FileReader("SystemDemo.java");char[] buf = new char[1024];int len = 0;while((len=fr.read(buf))!=-1){fw.write(buf,0,len);}}catch (IOException e){throw new RuntimeException("读写失败");}finally{if(fr!=null)try{fr.close();}catch (IOException e){}if(fw!=null)try{fw.close();}catch (IOException e){}}}//从C盘读一个字符，就往D盘写一个字符。public static void copy_1()throws IOException{//创建目的地。FileWriter fw = new FileWriter("RuntimeDemo_copy.txt");//与已有文件关联。FileReader fr = new FileReader("RuntimeDemo.java");int ch = 0;while((ch=fr.read())!=-1){fw.write(ch);}fw.close();fr.close();}}?
import java.io.*;class BufferedWriterDemo{public static void main(String[] args) throws IOException{//创建一个字符写入流对象。FileWriter fw = new FileWriter("buf.txt");//为了提高字符写入流效率。加入了缓冲技术。//只要将需要被提高效率的流对象作为参数传递给缓冲区的构造函数即可。BufferedWriter bufw = new BufferedWriter(fw);for(int x=1; x<5; x++){bufw.write("abcd"+x);bufw.newLine();bufw.flush();}//记住，只要用到缓冲区，就要记得刷新。//bufw.flush();//其实关闭缓冲区，就是在关闭缓冲区中的流对象。bufw.close();}}?IO流(BufferedReader)：import java.io.*;class BufferedReaderDemo{public static void main(String[] args) throws IOException{//创建一个读取流对象和文件相关联。FileReader fr = new FileReader("buf.txt");//为了提高效率。加入缓冲技术。将字符读取流对象作为参数传递给缓冲对象的构造函数。BufferedReader bufr = new BufferedReader(fr);String line = null;while((line=bufr.readLine())!=null){System.out.print(line);}bufr.close();}}?IO流(通过缓冲区复制文本文件)：/*通过缓冲区复制一个.java文件。*/import java.io.*;class CopyTextByBuf{public static void main(String[] args) {BufferedReader bufr = null;BufferedWriter bufw = null;try{bufr = new BufferedReader(new FileReader("BufferedWriterDemo.java"));bufw = new BufferedWriter(new FileWriter("bufWriter_Copy.txt"));String line = null;while((line=bufr.readLine())!=null){bufw.write(line);bufw.newLine();bufw.flush();}}catch (IOException e){throw new RuntimeException("读写失败");}finally{try{if(bufr!=null)bufr.close();}catch (IOException e){throw new RuntimeException("读取关闭失败");}try{if(bufw!=null)bufw.close();}catch (IOException e){throw new RuntimeException("写入关闭失败");}}}}?
/*明白了BufferedReader类中特有方法readLine的原理后，可以自定义一个类中包含一个功能和readLine一致的方法。来模拟一下BufferedReader*/import java.io.*;class MyBufferedReader extends Reader{private Reader r;MyBufferedReader(Reader r){this.r = r;}//可以一次读一行数据的方法。public String myReadLine()throws IOException{//定义一个临时容器。原BufferReader封装的是字符数组。//为了演示方便。定义一个StringBuilder容器。因为最终还是要将数据变成字符串。StringBuilder sb = new StringBuilder();int ch = 0;while((ch=r.read())!=-1){if(ch=='\r')continue;if(ch=='\n')return sb.toString();elsesb.append((char)ch);}if(sb.length()!=0)return sb.toString();return null;}/*覆盖Reader类中的抽象方法。*/public int read(char[] cbuf, int off, int len) throws IOException{return r.read(cbuf,off,len) ;}public void close()throws IOException{r.close();}public void myClose()throws IOException{r.close();}}class MyBufferedReaderDemo{public static void main(String[] args) throws IOException{FileReader fr = new FileReader("buf.txt");MyBufferedReader myBuf = new MyBufferedReader(fr);String line = null;while((line=myBuf.myReadLine())!=null){System.out.println(line);}myBuf.myClose();}}???class Person{public void chifan(){System.out.println("吃饭");}}class SuperPerson {private Person p ;SuperPerson(Person p){this.p = p;}public void superChifan(){System.out.println("开胃酒");p.chifan();System.out.println("甜点");System.out.println("来一根");}}class PersonDemo{public static void main(String[] args) {Person p = new Person();//p.chifan();SuperPerson sp = new SuperPerson(p);sp.superChifan();}}?/*明白了BufferedReader类中特有方法readLine的原理后，可以自定义一个类中包含一个功能和readLine一致的方法。来模拟一下BufferedReader*/import java.io.*;class MyBufferedReader extends Reader{private Reader r;MyBufferedReader(Reader r){this.r = r;}//可以一次读一行数据的方法。public String myReadLine()throws IOException{//定义一个临时容器。原BufferReader封装的是字符数组。//为了演示方便。定义一个StringBuilder容器。因为最终还是要将数据变成字符串。StringBuilder sb = new StringBuilder();int ch = 0;while((ch=r.read())!=-1){if(ch=='\r')continue;if(ch=='\n')return sb.toString();elsesb.append((char)ch);}if(sb.length()!=0)return sb.toString();return null;}/*覆盖Reader类中的抽象方法。*/public int read(char[] cbuf, int off, int len) throws IOException{return r.read(cbuf,off,len) ;}public void close()throws IOException{r.close();}public void myClose()throws IOException{r.close();}}class MyBufferedReaderDemo{public static void main(String[] args) throws IOException{FileReader fr = new FileReader("buf.txt");MyBufferedReader myBuf = new MyBufferedReader(fr);String line = null;while((line=myBuf.myReadLine())!=null){System.out.println(line);}myBuf.myClose();}}?/*字符读取流缓冲区：该缓冲区提供了一个一次读一行的方法 readLine，方便于对文本数据的获取。当返回null时，表示读到文件末尾。readLine方法返回的时候只返回回车符之前的数据内容。并不返回回车符。*/import java.io.*;class BufferedReaderDemo{public static void main(String[] args) throws IOException{//创建一个读取流对象和文件相关联。FileReader fr = new FileReader("buf.txt");//为了提高效率。加入缓冲技术。将字符读取流对象作为参数传递给缓冲对象的构造函数。BufferedReader bufr = new BufferedReader(fr);String line = null;while((line=bufr.readLine())!=null){System.out.print(line);}bufr.close();}}?import java.io.*;class LineNumberReaderDemo {public static void main(String[] args)throws IOException {FileReader fr = new FileReader("PersonDemo.java");LineNumberReader lnr = new LineNumberReader(fr);String line = null;lnr.setLineNumber(100);while((line=lnr.readLine())!=null){System.out.println(lnr.getLineNumber()+":"+line);}lnr.close();}}//练习：模拟一个带行号的缓冲区对象。?import java.io.*;class MyLineNumberReader extends MyBufferedReader{private int lineNumber;MyLineNumberReader(Reader r){super(r);}public String myReadLine()throws IOException{lineNumber++;return super.myReadLine();}public void setLineNumber(int lineNumber){this.lineNumber = lineNumber;}public int getLineNumber(){return lineNumber;}}/*class MyLineNumberReader {private Reader r;private int lineNumber;MyLineNumberReader(Reader r){this.r = r;}public String myReadLine()throws IOException{lineNumber++;StringBuilder sb = new StringBuilder();int ch = 0;while((ch=r.read())!=-1){if(ch=='\r')continue;if(ch=='\n')return sb.toString();elsesb.append((char)ch);}if(sb.length()!=0)return sb.toString();return null;}public void setLineNumber(int lineNumber){this.lineNumber = lineNumber;}public int getLineNumber(){return lineNumber;}public void myClose()throws IOException{r.close();}}*/class MyLineNumberReaderDemo{public static void main(String[] args) throws IOException{FileReader fr = new FileReader("copyTextByBuf.java");MyLineNumberReader mylnr = new MyLineNumberReader(fr);String line = null;mylnr.setLineNumber(100);while((line=mylnr.myReadLine())!=null){System.out.println(mylnr.getLineNumber()+"::"+line);}mylnr.myClose();}}?import java.io.*;class FileStream{public static void main(String[] args) throws IOException{readFile_3();}public static void readFile_3()throws IOException{FileInputStream fis = new FileInputStream("fos.txt");//int num = fis.available();byte[] buf = new byte[fis.available()];//定义一个刚刚好的缓冲区。不用在循环了。fis.read(buf);System.out.println(new String(buf));fis.close();}public static void readFile_2()throws IOException{FileInputStream fis = new FileInputStream("fos.txt");byte[] buf = new byte[1024];int len = 0;while((len=fis.read(buf))!=-1){System.out.println(new String(buf,0,len));}fis.close();}public static void readFile_1()throws IOException{FileInputStream fis = new FileInputStream("fos.txt");int ch = 0;while((ch=fis.read())!=-1){System.out.println((char)ch);}fis.close();}public static void writeFile()throws IOException{FileOutputStream fos = new FileOutputStream("fos.txt");fos.write("abcde".getBytes());fos.close();}}?/*复制一个图片思路：1，用字节读取流对象和图片关联。2，用字节写入流对象创建一个图片文件。用于存储获取到的图片数据。3，通过循环读写，完成数据的存储。4，关闭资源。*/import java.io.*;class CopyPic{public static void main(String[] args) {FileOutputStream fos = null;FileInputStream fis = null;try{fos = new FileOutputStream("c:\\2.bmp");fis = new FileInputStream("c:\\1.bmp");byte[] buf = new byte[1024];int len = 0;while((len=fis.read(buf))!=-1){fos.write(buf,0,len);}}catch (IOException e){throw new RuntimeException("复制文件失败");}finally{try{if(fis!=null)fis.close();}catch (IOException e){throw new RuntimeException("读取关闭失败");}try{if(fos!=null)fos.close();}catch (IOException e){throw new RuntimeException("写入关闭失败");}}}}?IO流(字节流的缓冲区)：示例：/*演示mp3的复制。通过缓冲区。BufferedOutputStreamBufferedInputStream*/import java.io.*;class CopyMp3{public static void main(String[] args) throws IOException{long start = System.currentTimeMillis();copy_2();long end = System.currentTimeMillis();System.out.println((end-start)+"毫秒");}public static void copy_2()throws IOException{MyBufferedInputStream bufis = new MyBufferedInputStream(new FileInputStream("c:\\9.mp3"));BufferedOutputStream bufos = new BufferedOutputStream(new FileOutputStream("c:\\3.mp3"));int by = 0;//System.out.println("第一个字节:"+bufis.myRead());while((by=bufis.myRead())!=-1){bufos.write(by);}bufos.close();bufis.myClose();}//通过字节流的缓冲区完成复制。public static void copy_1()throws IOException{BufferedInputStream bufis = new BufferedInputStream(new FileInputStream("c:\\0.mp3"));BufferedOutputStream bufos = new BufferedOutputStream(new FileOutputStream("c:\\1.mp3"));int by = 0;while((by=bufis.read())!=-1){bufos.write(by);}bufos.close();bufis.close();}}?IO流(自定义字节流的缓冲区-read和write的特点)：示例：import java.io.*;class MyBufferedInputStream{private InputStream in;private byte[] buf = new byte[1024*4];private int pos = 0,count = 0;MyBufferedInputStream(InputStream in){this.in = in;}//一次读一个字节，从缓冲区(字节数组)获取。public int myRead()throws IOException{//通过in对象读取硬盘上数据，并存储buf中。if(count==0){count = in.read(buf);if(count<0)return -1;pos = 0;byte b = buf[pos];count--;pos++;return b&255;}else if(count>0){byte b = buf[pos];count--;pos++;return b&0xff;}return -1;}public void myClose()throws IOException{in.close();}}/*11111111-111111110000000000101001001010100101010010101001010byte: -1 ---> int : -1;00000000 00000000 00000000 11111111 25511111111 11111111 11111111 1111111111111111 -->提升了一个int类型 那不还是-1吗？是-1的原因是因为在8个1前面补的是1导致的。那么我只要在前面补0，即可以保留原字节数据不变，又可以避免-1的出现。怎么补0呢？ 11111111 11111111 11111111 11111111 &00000000 00000000 00000000 11111111 ------------------------------------ 00000000 00000000 00000000 11111111 0000-00011111-11100000000011111-1111 -1结论：字节流的读一个字节的read方法为什么返回值类型不是byte，而是int。因为有可能会读到连续8个二进制1的情况，8个二进制1对应的十进制是-1.那么就会数据还没有读完，就结束的情况。因为我们判断读取结束是通过结尾标记-1来确定的。所以，为了避免这种情况将读到的字节进行int类型的提升。并在保留原字节数据的情况前面了补了24个0，变成了int类型的数值。而在写入数据时，只写该int类型数据的最低8位。*/?IO流(读取键盘录入)：读取键盘录入。System.out:对应的是标准输出设备，控制台。System.in:对应的标准输入设备：键盘。import java.io.*;class ReadIn{public static void main(String[] args) throws IOException{InputStream in = System.in;StringBuilder sb = new StringBuilder();while(true){int ch = in.read();if(ch=='\r')continue;if(ch=='\n'){String s = sb.toString();if("over".equals(s))break;System.out.println(s.toUpperCase());sb.delete(0,sb.length());}elsesb.append((char)ch);}}}?IO流(读取转换流、写入转换流)：import java.io.*;class TransStreamDemo{public static void main(String[] args) throws IOException{//获取键盘录入对象。//InputStream in = System.in;//将字节流对象转成字符流对象，使用转换流。InputStreamReader//InputStreamReader isr = new InputStreamReader(in);//为了提高效率，将字符串进行缓冲区技术高效操作。使用BufferedReader//BufferedReader bufr = new BufferedReader(isr);//键盘的最常见写法。BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));//OutputStream out = System.out;//OutputStreamWriter osw = new OutputStreamWriter(out);//BufferedWriter bufw = new BufferedWriter(osw);BufferedWriter bufw = new BufferedWriter(new OutputStreamWriter(System.out));String line = null;while((line=bufr.readLine())!=null){if("over".equals(line))break;bufw.write(line.toUpperCase());bufw.newLine();bufw.flush();}bufr.close();}}?import java.io.*;class TransStreamDemo2{public static void main(String[] args) throws IOException{System.setIn(new FileInputStream("PersonDemo.java"));System.setOut(new PrintStream("zzz.txt"));//键盘的最常见写法。BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));BufferedWriter bufw = new BufferedWriter(new OutputStreamWriter(System.out));String line = null;while((line=bufr.readLine())!=null){if("over".equals(line))break;bufw.write(line.toUpperCase());bufw.newLine();bufw.flush();}bufr.close();}}IO流(异常的日志信息)：示例：import java.io.*;import java.util.*;import java.text.*;class ExceptionInfo{public static void main(String[] args)throws IOException {try{int[] arr = new int[2];System.out.println(arr[3]);}catch (Exception e){try{Date d = new Date();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String s = sdf.format(d);PrintStream ps = new PrintStream("exeception.log");ps.println(s);System.setOut(ps);}catch (IOException ex){throw new RuntimeException("日志文件创建失败");}e.printStackTrace(System.out);}}}//log4j?IO流(系统信息)：示例：import java.util.*;import java.io.*;class SystemInfo{public static void main(String[] args) throws IOException{Properties prop = System.getProperties();//System.out.println(prop);prop.list(new PrintStream("sysinfo.txt"));}}?IO流(File概述、File对象功能-创建和删除、File对象功能-判断、File对象功能-获取)：import java.io.*;/*File类常见方法：1，创建。boolean createNewFile():在指定位置创建文件，如果该文件已经存在，则不创建，返回false。和输出流不一样，输出流对象一建立创建文件。而且文件已经存在，会覆盖。boolean mkdir():创建文件夹。boolean mkdirs():创建多级文件夹。2，删除。boolean delete()：删除失败返回false。如果文件正在被使用，则删除不了返回falsel。void deleteOnExit();在程序退出时删除指定文件。3，判断。boolean exists() :文件是否存在.isFile():isDirectory();isHidden();isAbsolute();4，获取信息。getName():getPath():getParent():getAbsolutePath() long lastModified() long length() */class FileDemo {public static void main(String[] args) throws IOException{method_5();}public static void method_5(){File f1 = new File("c:\\Test.java");File f2 = new File("d:\\hahah.java");sop("rename:"+f2.renameTo(f1));}public static void method_4(){File f = new File("file.txt");sop("path:"+f.getPath());sop("abspath:"+f.getAbsolutePath());sop("parent:"+f.getParent());//该方法返回的是绝对路径中的父目录。如果获取的是相对路径，返回null。//如果相对路径中有上一层目录那么该目录就是返回结果。}public static void method_3()throws IOException{File f = new File("d:\\java1223\\day20\\file2.txt");//f.createNewFile();//f.mkdir();//记住在判断文件对象是否是文件或者目的时，必须要先判断该文件对象封装的内容是否存在。//通过exists判断。sop("dir:"+f.isDirectory());sop("file:"+f.isFile());sop(f.isAbsolute());}public static void method_2(){File f = new File("file.txt");//sop("exists:"+f.exists());//sop("execute:"+f.canExecute());//创建文件夹File dir = new File("abc\\kkk\\a\\a\\dd\\ee\\qq\\aaa");sop("mkdir:"+dir.mkdirs());}public static void method_1()throws IOException{File f = new File("file.txt");//sop("create:"+f.createNewFile());//sop("delete:"+f.delete());}//创建File对象public static void consMethod(){//将a.txt封装成file对象。可以将已有的和为出现的文件或者文件夹封装成对象。File f1 = new File("a.txt");//File f2 = new File("c:\\abc","b.txt");File d = new File("c:\\abc");File f3 = new File(d,"c.txt");sop("f1:"+f1);sop("f2:"+f2);sop("f3:"+f3);File f4 = new File("c:"+File.separator+"abc"+File.separator+"zzz"+File.separator+"a.txt");}public static void sop(Object obj){System.out.println(obj);}}?IO流(File对象功能-文件列表)：示例：import java.io.*;class FileDemo2{public static void main(String[] args) {File dir = new File("c:\");File[] files = dir.listFiles();for(File f : files){System.out.println(f.getName()+"::"+f.length());}}public static void listDemo_2(){File dir = new File("d:\\java1223\\day18");String[] arr = dir.list(new FilenameFilter(){public boolean accept(File dir,String name){///System.out.println("dir:"+dir+"....name::"+name);/*if(name.endsWith(".bmp"))return true;elsereturn false;*/return name.endsWith(".bmp");}});System.out.println("len:"+arr.length);for(String name : arr){System.out.println(name);}}public static void listDemo(){File f = new File("c:\\abc.txt");String[] names = f.list();//调用list方法的file对象必须是封装了一个目录。该目录还必须存在。for(String name : names){System.out.println(name);}}public static void listRootsDemo(){File[] files = File.listRoots();for(File f : files){System.out.println(f);}}}?IO流(列出目录下所有内容-递归、列出目录下所有内容-带层次)：/*列出指定目录下文件或者文件夹，包含子目录中的内容。也就是列出指定目录下所有内容。因为目录中还有目录，只要使用同一个列出目录功能的函数完成即可。在列出过程中出现的还是目录的话，还可以再次调用本功能。也就是函数自身调用自身。这种表现形式，或者编程手法，称为递归。递归要注意：1，限定条件。2，要注意递归的次数。尽量避免内存溢出。*/import java.io.*;class FileDemo3 {public static void main(String[] args) {File dir = new File("d:\\testdir");//showDir(dir,0);//toBin(6);//int n = getSum(8000);//System.out.println("n="+n);System.out.println(dir.delete());}public static String getLevel(int level){StringBuilder sb = new StringBuilder();sb.append("|--");for(int x=0; x<level; x++){//sb.append("|--");sb.insert(0,"| ");}return sb.toString();}public static void showDir(File dir,int level){System.out.println(getLevel(level)+dir.getName());level++;File[] files = dir.listFiles();for(int x=0; x<files.length; x++){if(files[x].isDirectory())showDir(files[x],level);elseSystem.out.println(getLevel(level)+files[x]);}}public static int getSum(int n){if(n==1)return 1;return n+getSum(n-1);}public static void toBin(int num){if(num>0){toBin(num/2);System.out.println(num%2);}}public static void method(){method();}}?IO流(删除带内容的目录)：/*删除一个带内容的目录。删除原理：在window中，删除目录从里面往外删除的。既然是从里往外删除。就需要用到递归。*/import java.io.*;class RemoveDir{public static void main(String[] args) {File dir = new File("d:\\testdir");removeDir(dir);}public static void removeDir(File dir){File[] files = dir.listFiles();for(int x=0; x<files.length; x++){if(files[x].isDirectory())removeDir(files[x]);elseSystem.out.println(files[x].toString()+":-file-:"+files[x].delete());}System.out.println(dir+"::dir::"+dir.delete());}}?IO流(创建java文件列表)：/*练习将一个指定目录下的java文件的绝对路径，存储到一个文本文件中。建立一个java文件列表文件。思路：1，对指定的目录进行递归。2，获取递归过程所以的java文件的路径。3，将这些路径存储到集合中。4，将集合中的数据写入到一个文件中。*/import java.io.*;import java.util.*;class JavaFileList{public static void main(String[] args) throws IOException{File dir = new File("d:\\java1223");List<File> list = new ArrayList<File>();fileToList(dir,list);//System.out.println(list.size());File file = new File(dir,"javalist.txt");writeToFile(list,file.toString());}public static void fileToList(File dir,List<File> list){File[] files = dir.listFiles();for(File file : files){if(file.isDirectory())fileToList(file,list);else{if(file.getName().endsWith(".java"))list.add(file);}}}public static void writeToFile(List<File> list,String javaListFile)throws IOException{BufferedWriter bufw = null;try{bufw = new BufferedWriter(new FileWriter(javaListFile));for(File f : list){String path = f.getAbsolutePath();bufw.write(path);bufw.newLine();bufw.flush();}}catch (IOException e){throw e;}finally{try{if(bufw!=null)bufw.close();}catch (IOException e){throw e;}}}}?IO流(Properties简述、Properties存取、Properties存取配置文件)：示例：/*Properties是hashtable的子类。也就是说它具备map集合的特点。而且它里面存储的键值对都是字符串。是集合中和IO技术相结合的集合容器。该对象的特点：可以用于键值对形式的配置文件。那么在加载数据时，需要数据有固定格式：键=值。练习：限制程序运行次数。当运行次数到达5次时，给出，请您注册的提示。并不再让该程序执行。*/import java.io.*;import java.util.*;class PropertiesDemo {public static void main(String[] args) throws IOException{//method_1();loadDemo();}public static void loadDemo()throws IOException{Properties prop = new Properties();FileInputStream fis = new FileInputStream("info.txt");//将流中的数据加载进集合。prop.load(fis);prop.setProperty("wangwu","39");FileOutputStream fos = new FileOutputStream("info.txt");prop.store(fos,"haha");//System.out.println(prop);prop.list(System.out);fos.close();fis.close();}//演示，如何将流中的数据存储到集合中。//想要将info.txt中键值数据存到集合中进行操作。/*1,用一个流和info.txt文件关联。2，读取一行数据，将该行数据用"="进行切割。3，等号左边作为键，右边作为值。存入到Properties集合中即可。*/public static void method_1()throws IOException{BufferedReader bufr = new BufferedReader(new FileReader("info.txt"));String line = null;Properties prop = new Properties();while((line=bufr.readLine())!=null){String[] arr = line.split("=");///System.out.println(arr[0]+"...."+arr[1]);prop.setProperty(arr[0],arr[1]);}bufr.close();System.out.println(prop);}//设置和获取元素。public static void setAndGet(){Properties prop = new Properties();prop.setProperty("zhangsan","30");prop.setProperty("lisi","39");//System.out.println(prop);String value = prop.getProperty("lisi");//System.out.println(value);prop.setProperty("lisi",89+"");Set<String> names = prop.stringPropertyNames();for(String s : names){System.out.println(s+":"+prop.getProperty(s));}}}?IO流(Properties练习)：示例：/*用于记录应用程序运行次数。如果使用次数已到，那么给出注册提示。很容易想到的是:计数器。可是该计数器定义在程序中，随着程序的运行而在内存中存在，并进行自增。可是随着该应用程序的退出，该计数器也在内存中消失了。下一次在启动该程序，又重新开始从0计数。这样不是我们想要的。程序即使结束，该计数器的值也存在。下次程序启动在会先加载该计数器的值并加1后在重新存储起来。所以要建立一个配置文件。用于记录该软件的使用次数。该配置文件使用键值对的形式。这样便于阅读数据，并操作数据。键值对数据是map集合。数据是以文件形式存储，使用io技术。那么map+io -->properties.配置文件可以实现应用程序数据的共享。*/import java.io.*;import java.util.*;class RunCount{public static void main(String[] args) throws IOException{Properties prop = new Properties();File file = new File("count.ini");if(!file.exists())file.createNewFile();FileInputStream fis = new FileInputStream(file);prop.load(fis);int count = 0;String value = prop.getProperty("time");if(value!=null){count = Integer.parseInt(value);if(count>=5){System.out.println("您好，使用次数已到，拿钱!");return ;}}count++;prop.setProperty("time",count+"");FileOutputStream fos = new FileOutputStream(file);prop.store(fos,"");fos.close();fis.close();}}/*name=zhangsanage=20<persons><person id="001"><name>zhagnsan</name><age>30</age><address>bj</address></person><person><name</person></persons>*/?IO流(PrintWriter)：示例：/*打印流：该流提供了打印方法，可以将各种数据类型的数据都原样打印。字节打印流：PrintStream构造函数可以接收的参数类型：1，file对象。File2，字符串路径。String3，字节输出流。OutputStream字符打印流：PrintWriter构造函数可以接收的参数类型：1，file对象。File2，字符串路径。String3，字节输出流。OutputStream4，字符输出流，Writer。*/import java.io.*;class PrintStreamDemo{public static void main(String[] args) throws IOException{BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));PrintWriter out = new PrintWriter(new FileWriter("a.txt"),true);String line = null;while((line=bufr.readLine())!=null){if("over".equals(line))break;out.println(line.toUpperCase());//out.flush();}out.close();bufr.close();}}?IO流(合并流)：示例：import java.io.*;import java.util.*;class SequenceDemo {public static void main(String[] args) throws IOException{Vector<FileInputStream> v = new Vector<FileInputStream>();v.add(new FileInputStream("c:\\1.txt"));v.add(new FileInputStream("c:\\2.txt"));v.add(new FileInputStream("c:\\3.txt"));Enumeration<FileInputStream> en = v.elements();SequenceInputStream sis = new SequenceInputStream(en);FileOutputStream fos = new FileOutputStream("c:\\4.txt");byte[] buf = new byte[1024];int len =0;while((len=sis.read(buf))!=-1){fos.write(buf,0,len);}fos.close();sis.close();}}?IO流(切割文件)：示例：import java.io.*;import java.util.*;class SplitFile {public static void main(String[] args) throws IOException{//splitFile();merge();}public static void merge()throws IOException{ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();for(int x=1; x<=3; x++){al.add(new FileInputStream("c:\\splitfiles\"+x+".part"));}final Iterator<FileInputStream> it = al.iterator();Enumeration<FileInputStream> en = new Enumeration<FileInputStream>(){public boolean hasMoreElements(){return it.hasNext();}public FileInputStream nextElement(){return it.next();}};SequenceInputStream sis = new SequenceInputStream(en);FileOutputStream fos = new FileOutputStream("c:\\splitfiles\\0.bmp");byte[] buf = new byte[1024];int len = 0;while((len=sis.read(buf))!=-1){fos.write(buf,0,len);}fos.close();sis.close();}public static void splitFile()throws IOException{FileInputStream fis = new FileInputStream("c:\\1.bmp");FileOutputStream fos = null;byte[] buf = new byte[1024*1024];int len = 0;int count = 1;while((len=fis.read(buf))!=-1){fos = new FileOutputStream("c:\\splitfiles\"+(count++)+".part");fos.write(buf,0,len);fos.close();}fis.close();}}?IO流(对象的序列化)：示例：import java.io.*;class ObjectStreamDemo {public static void main(String[] args) throws Exception{//writeObj();readObj();}public static void readObj()throws Exception{ObjectInputStream ois = new ObjectInputStream(new FileInputStream("obj.txt"));Person p = (Person)ois.readObject();System.out.println(p);ois.close();}public static void writeObj()throws IOException{ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("obj.txt"));oos.writeObject(new Person("lisi0",399,"kr"));oos.close();}}?import java.io.*;class Person implements Serializable{public static final long serialVersionUID = 42L;private String name;transient int age;static String country = "cn";Person(String name,int age,String country){this.name = name;this.age = age;this.country = country;}public String toString(){return name+":"+age+":"+country;}}?IO流(管道流)：示例：import java.io.*;class Read implements Runnable{private PipedInputStream in;Read(PipedInputStream in){this.in = in;}public void run(){try{byte[] buf = new byte[1024];System.out.println("读取前。。没有数据阻塞");int len = in.read(buf);System.out.println("读到数据。。阻塞结束");String s= new String(buf,0,len);System.out.println(s);in.close();}catch (IOException e){throw new RuntimeException("管道读取流失败");}}}class Write implements Runnable{private PipedOutputStream out;Write(PipedOutputStream out){this.out = out;}public void run(){try{System.out.println("开始写入数据，等待6秒后。");Thread.sleep(6000);out.write("piped lai la".getBytes());out.close();}catch (Exception e){throw new RuntimeException("管道输出流失败");}}}class PipedStreamDemo{public static void main(String[] args) throws IOException{PipedInputStream in = new PipedInputStream();PipedOutputStream out = new PipedOutputStream();in.connect(out);Read r = new Read(in);Write w = new Write(out);new Thread(r).start();new Thread(w).start();}}?IO流(RandomAccessFile)：import java.io.*;/*RandomAccessFile该类不是算是IO体系中子类。而是直接继承自Object。但是它是IO包中成员。因为它具备读和写功能。内部封装了一个数组，而且通过指针对数组的元素进行操作。可以通过getFilePointer获取指针位置，同时可以通过seek改变指针的位置。其实完成读写的原理就是内部封装了字节输入流和输出流。通过构造函数可以看出，该类只能操作文件。而且操作文件还有模式：只读r，，读写rw等。如果模式为只读 r。不会创建文件。会去读取一个已存在文件，如果该文件不存在，则会出现异常。如果模式rw。操作的文件不存在，会自动创建。如果存则不会覆盖。*/class RandomAccessFileDemo {public static void main(String[] args) throws IOException{//writeFile_2();//readFile();//System.out.println(Integer.toBinaryString(258));}public static void readFile()throws IOException{RandomAccessFile raf = new RandomAccessFile("ran.txt","r");//调整对象中指针。//raf.seek(8*1);//跳过指定的字节数raf.skipBytes(8);byte[] buf = new byte[4];raf.read(buf);String name = new String(buf);int age = raf.readInt();System.out.println("name="+name);System.out.println("age="+age);raf.close();}public static void writeFile_2()throws IOException{RandomAccessFile raf = new RandomAccessFile("ran.txt","rw");raf.seek(8*0);raf.write("周期".getBytes());raf.writeInt(103);raf.close();}public static void writeFile()throws IOException{RandomAccessFile raf = new RandomAccessFile("ran.txt","rw");raf.write("李四".getBytes());raf.writeInt(97);raf.write("王五".getBytes());raf.writeInt(99);raf.close();}}?IO流(操作基本数据类型的流对象DataStream)：/*DataInputStream与DataOutputStream可以用于操作基本数据类型的数据的流对象。*/import java.io.*;class DataStreamDemo {public static void main(String[] args) throws IOException{//writeData();//readData();//writeUTFDemo();//OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("gbk.txt"),"gbk");////osw.write("你好");//osw.close();//readUTFDemo();}public static void readUTFDemo()throws IOException{DataInputStream dis = new DataInputStream(new FileInputStream("utf.txt"));String s = dis.readUTF();System.out.println(s);dis.close();}public static void writeUTFDemo()throws IOException{DataOutputStream dos = new DataOutputStream(new FileOutputStream("utfdate.txt"));dos.writeUTF("你好");dos.close();}public static void readData()throws IOException{DataInputStream dis = new DataInputStream(new FileInputStream("data.txt"));int num = dis.readInt();boolean b = dis.readBoolean();double d = dis.readDouble();System.out.println("num="+num);System.out.println("b="+b);System.out.println("d="+d);dis.close();}public static void writeData()throws IOException{DataOutputStream dos = new DataOutputStream(new FileOutputStream("data.txt"));dos.writeInt(234);dos.writeBoolean(true);dos.writeDouble(9887.543);dos.close();ObjectOutputStream oos = null;oos.writeObject(new O());}}?IO流(ByteArrayStream)：?/*用于操作字节数组的流对象。ByteArrayInputStream ：在构造的时候，需要接收数据源，。而且数据源是一个字节数组。ByteArrayOutputStream： 在构造的时候，不用定义数据目的，因为该对象中已经内部封装了可变长度的字节数组。这就是数据目的地。因为这两个流对象都操作的数组，并没有使用系统资源。所以，不用进行close关闭。在流操作规律讲解时：源设备，键盘 System.in，硬盘 FileStream，内存 ArrayStream。目的设备：控制台 System.out，硬盘FileStream，内存 ArrayStream。用流的读写思想来操作数据。*/import java.io.*;class ByteArrayStream {public static void main(String[] args) {//数据源。ByteArrayInputStream bis = new ByteArrayInputStream("ABCDEFD".getBytes());//数据目的ByteArrayOutputStream bos = new ByteArrayOutputStream();int by = 0;while((by=bis.read())!=-1){bos.write(by);}System.out.println(bos.size());System.out.println(bos.toString());//bos.writeTo(new FileOutputStream("a.txt"));}}?IO流(转换流的字符编码)：示例：import java.io.*;class EncodeStream {public static void main(String[] args) throws IOException {//writeText();readText();}public static void readText()throws IOException {InputStreamReader isr = new InputStreamReader(new FileInputStream("utf.txt"),"gbk");char[] buf = new char[10];int len = isr.read(buf);String str = new String(buf,0,len);System.out.println(str);isr.close();}public static void writeText()throws IOException {OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("utf.txt"),"UTF-8");osw.write("你好");osw.close();}}?字符编码：/*编码：字符串变成字节数组。解码：字节数组变成字符串。String-->byte[]; str.getBytes(charsetName);byte[] -->String: new String(byte[],charsetName);*/import java.util.*;class EncodeDemo{public static void main(String[] args)throws Exception {String s = "哈哈";byte[] b1 = s.getBytes("GBK");System.out.println(Arrays.toString(b1));String s1 = new String(b1,"utf-8");System.out.println("s1="+s1);//对s1进行iso8859-1编码。byte[] b2 = s1.getBytes("utf-8");System.out.println(Arrays.toString(b2));String s2 = new String(b2,"gbk");System.out.println("s2="+s2);}}?字符编码-联通：class EncodeDemo2 {public static void main(String[] args) throws Exception{String s = "?";byte[] by = s.getBytes("gbk");for(byte b : by){System.out.println(Integer.toBinaryString(b&255));}System.out.println("Hello World!");}}?练习：/*有五个学生，每个学生有3门课的成绩，从键盘输入以上数据（包括姓名，三门课成绩），输入的格式：如：zhagnsan，30，40，60计算出总成绩，并把学生的信息和计算出的总分数高低顺序存放在磁盘文件"stud.txt"中。1，描述学生对象。2，定义一个可操作学生对象的工具类。思想：1，通过获取键盘录入一行数据，并将该行中的信息取出封装成学生对象。2，因为学生有很多，那么就需要存储，使用到集合。因为要对学生的总分排序。所以可以使用TreeSet。3，将集合的信息写入到一个文件中。*/import java.io.*;import java.util.*;class Student implements Comparable<Student>{private String name;private int ma,cn,en;private int sum;Student(String name,int ma,int cn,int en){this.name = name;this.ma = ma;this.cn = cn;this.en = en;sum = ma + cn + en;}public int compareTo(Student s){int num = new Integer(this.sum).compareTo(new Integer(s.sum));if(num==0)return this.name.compareTo(s.name);return num;}public String getName(){return name;}public int getSum(){return sum;}public int hashCode(){return name.hashCode()+sum*78;}public boolean equals(Object obj){if(!(obj instanceof Student))throw new ClassCastException("类型不匹配");Student s = (Student)obj;return this.name.equals(s.name) && this.sum==s.sum;}public String toString(){return "student["+name+", "+ma+", "+cn+", "+en+"]";}}class StudentInfoTool{public static Set<Student> getStudents()throws IOException{return getStudents(null);}public static Set<Student> getStudents(Comparator<Student> cmp)throws IOException{BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));String line = null;Set<Student> stus = null;if(cmp==null)stus = new TreeSet<Student>();elsestus = new TreeSet<Student>(cmp);while((line=bufr.readLine())!=null){if("over".equals(line))break;String[] info = line.split(",");Student stu = new Student(info[0],Integer.parseInt(info[1]),Integer.parseInt(info[2]),Integer.parseInt(info[3]));stus.add(stu);}bufr.close();return stus;}public static void write2File(Set<Student> stus)throws IOException{BufferedWriter bufw = new BufferedWriter(new FileWriter("stuinfo.txt"));for(Student stu : stus){bufw.write(stu.toString()+"\t");bufw.write(stu.getSum()+"");bufw.newLine();bufw.flush();}bufw.close();}}class StudentInfoTest {public static void main(String[] args) throws IOException{Comparator<Student> cmp = Collections.reverseOrder();Set<Student> stus = StudentInfoTool.getStudents(cmp);StudentInfoTool.write2File(stus);}}??---------------------- android培训、java培训、期待与您交流！ ----------------------详细请查看：http://edu.csdn.net/heima