IO编程基础(四)
属性信息导入/导出
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SaveProperties
package org.wp.io;import java.io.FileWriter;import java.io.IOException;import java.util.Properties;/** * 属性信息的导出 * * @author wp * */public class SaveProperties {public static void main(String args[]) {try {// 当前系统属性集合作为 Properties对象返回// Properties ps = System.getProperties();Properties ps = new Properties();ps.setProperty("name", "Scott");ps.setProperty("password", "Tiger");FileWriter fw = new FileWriter("F:\\temp\\props.txt");/* * 以适合使用 load(Reader) 方法的格式，将此 Properties 表中的属性列表（键和元素对）写入输出字符 * writer - 输出字符流writer * comments - 属性列表的描述 */ps.store(fw, "loginfo");fw.close();} catch (IOException e) {e.printStackTrace();}}}?
LoadProperties
package org.wp.io;import java.io.FileReader;import java.io.IOException;import java.util.Properties;/** * 属性信息的导入 * * @author wp * */public class LoadProperties {public static void main(String args[]) {try {Properties ps = new Properties();FileReader fr = new FileReader("F:/temp/props.txt");// 按简单的面向行的格式从输入字符流中读取属性列表（键和元素对）ps.load(fr);fr.close();// 将属性列表输出到指定的输出流ps.list(System.out);} catch (IOException e) {e.printStackTrace();}}}?
随机存取文件
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RandomAccessFileTest
package org.wp.io;import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;/** * 随机访问文件的读取和写入 * * @author wp * */public class RandomAccessFileTest {private File file;public static void main(String args[]) {RandomAccessFileTest raft = new RandomAccessFileTest();raft.init();raft.record("张三", 21);raft.record("李四", 33);raft.record("王五", 18);raft.record("张三", 36);raft.listAllRecords();}public void init() {if (file == null) {file = new File("F:/temp/record.txt");try {// 检查文件是否存在，若不存在则创建该文件file.createNewFile();} catch (IOException e) {e.printStackTrace();}}}public void record(String record_breaker, int times) {try {RandomAccessFile raf = new RandomAccessFile(file, "rw");boolean flag = false;// getFilePointer// 返回此文件中的当前偏移量while (raf.getFilePointer() < raf.length()) {String name = raf.readUTF();if (record_breaker.equals(name)) {raf.writeInt(times);flag = true;break;} else {// 尝试跳过输入的 n个字节以丢弃跳过的字节raf.skipBytes(4);}}if (!flag) {raf.writeUTF(record_breaker);raf.writeInt(times);}raf.close();} catch (IOException e) {e.printStackTrace();}}public void listAllRecords() {try {RandomAccessFile raf = new RandomAccessFile(file, "r");while (raf.getFilePointer() < raf.length()) {String name = raf.readUTF();int times = raf.readInt();System.out.println("name:" + name + "\trecord:" + times);}raf.close();} catch (IOException e) {e.printStackTrace();}}}?
临时文件
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TempFileTest
package org.wp.io;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.io.PrintWriter;import javax.swing.JButton;import javax.swing.JFrame;public class TempFileTest implements ActionListener {private File tempPath;public static void main(String args[]) {TempFileTest tft = new TempFileTest();tft.init();tft.createUI();}public void init() {tempPath = new File("F:/temp/temp");// exists()// 测试此抽象路径名表示的文件或目录是否存在// isDirectory()// 测试此抽象路径名表示的文件是否是一个目录if (!tempPath.exists() || !tempPath.isDirectory()) {// mkdir()// 创建此抽象路径名指定的目录tempPath.mkdir();}}public void createUI() {JFrame frame = new JFrame();JButton jb = new JButton("创建临时文件");jb.addActionListener(this);frame.add(jb, "North");frame.setSize(350, 150);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.setVisible(true);}@Overridepublic void actionPerformed(ActionEvent e) {try {// 在tempPath路径下创建临时文件"mytempfileXXXX.txt"// XXXX 是系统自动产生的随机数, tempPath对应的路径应事先存在File tempFile = File.createTempFile("mytempfile", ".txt", tempPath);System.out.println(tempFile.getAbsolutePath());FileWriter fw = new FileWriter(tempFile);PrintWriter pw = new PrintWriter(fw);pw.println("some info!");pw.close();// delete()// 删除此抽象路径名表示的文件或目录// tempFile.delete();// deleteOnExit()// 在虚拟机终止时，请求删除此抽象路径名表示的文件或目录tempFile.deleteOnExit();} catch (IOException e1) {e1.printStackTrace();}}}?
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