java实现文件读写与压缩实例

本文通过实例讲述了Java对文件读写与压缩的实现方法，具体代码如下：

package com.toone.iform.action.common;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Random;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
public class TestFileIO {
  static String s = File.separator;

  private static void testInput() {
    // D盘下有个Welcome.java文件，现在按字节读入：
   int a = 0;
    // int counter=0;
   FileInputStream f11;
    // 输入流
   try {
      f11 = new FileInputStream("D:" + s + "Welcome.java");
      while ((a = f11.read()) != -1)
        System.out.print((char) a); // 这里是按字节输出，中文字符无法正常输出，因为一个中文字符时两个字节。
       System.out.println("\n\n--------------------------------------------------\n");

      FileReader f12 = new FileReader("D:" + s + "Welcome.java");
      while ((a = f12.read()) != -1)
        System.out.print((char) a);// 这里是按字符输出，中文字符都可以正常输出
       System.out.println("\n\n--------------------------------------------------\n");

      f11.close();// 读完之后要关闭文件
      f12.close();// 读完之后要关闭文件
      } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
       e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block
     e.printStackTrace();
    }
  }

  private static void testOutput() {
    // D盘下有个Welcome.java文件，现在按字节读入：
   int a = 0;
    // 输出流
   File f21 = new File("D:" + s + "testFile" + s + "test1.txt");
   // 定义一个新的文件f21，然后判断在这一目录下是否存在，如果不存在，则创建之。
   if (!f21.exists()) {
      f21.getParentFile().mkdirs();
      try {
        f21.createNewFile();
        // 将“Welcome.java”的内容复制到f21
        FileOutputStream fos = new FileOutputStream(f21);
        FileInputStream fis = new FileInputStream("D:" + s + "Welcome.java");// 读入“Welcome.java”文件
        while ((a = fis.read()) != -1)
          fos.write(a);// 将读入的内存写到fos中，现在得到的test1.txt就是复制Welcome.java的
        // writer类
        FileWriter f22 = new FileWriter("D:" + s + "testFile" + s + "test2.txt");
        for (int i = 0; i < 65535; i++)
          f22.write(i);//写入到test2.txt中。由这里也可以看出，上面35-38行判断文件是否存在的语句也可以不要。
        // 向文件中写入字符串
        FileWriter f23 = new FileWriter("D:" + s + "testFile" + s + "test3.txt");
        f23.write("Hello, world!");

        fos.close();
        fis.close();
        f22.close();
        f23.close();
      } catch (IOException e) {
        // TODO Auto-generated catch block
         e.printStackTrace();
      }
    }
  }

  private static void testBufferring() {
    // D盘下有个Welcome.java文件，现在按字节读入：
   int a = 0, counter = 0;
    // 缓冲字符，实现高效写入
   // BufferedWriter f31=new BufferedWriter(newFileWriter("D"+s+"testFile"+s+"test4.txt"));
   BufferedWriter f31;
    try {
      f31 = new BufferedWriter(new FileWriter("D:" + s + "testFile" + s
          + "test4.txt"));
      for (int i = 1; i <= 100; i++) {
        f31.write(String.valueOf(new Random().nextInt(100)) + " ");
        if (i % 10 == 0)
          f31.newLine();
      }
      f31.flush();// 刷新缓冲
      f31.close();

      BufferedReader f32 = new BufferedReader(new FileReader("D:" + s
          + "testFile" + s + "test4.txt"));
      String s32;
      System.out.println("输出文件f32的内容：");
      while ((s32 = f32.readLine()) != null)
        System.out.println(s32);
      f32.close();
      System.out.println("\n--------------------------------------------------\n");
    } catch (IOException e) {
      // TODO Auto-generated catch block
     e.printStackTrace();
    }
  }

  private static void testZip() {
    try {
      File f1 = new File("D:/test.zip");
      File f2 = new File("D:/testFile/testzip");
      ZipFile zf = new ZipFile(f1);
      testZipToUnzip(zf, f2);

    } catch (IOException e) {
      // TODO Auto-generated catch block
       e.printStackTrace();
    }
  }

  // 将压缩包zipfile解压到file中
  public static void testZipToUnzip(ZipFile zipfile, File file) {
    ZipEntry zentry = null;
    File zipout;
    InputStream zis = null;
    FileOutputStream fos = null;
    Enumeration e = zipfile.entries();// zipfile的目录
    while (e.hasMoreElements()) {
      zentry = (ZipEntry) e.nextElement();
      System.out.println(zentry.getName());// zipfile下有哪些文件？可是为什么不按顺序输出？？
      // 将解压后的文件放到file文件夹下：
      zipout = new File(file + s + zentry.getName());

      if (!zentry.isDirectory()) {
        try {
          zis = zipfile.getInputStream(zentry);
          if (!zipout.exists())
            zipout.getParentFile().mkdirs();
          fos = new FileOutputStream(zipout);
          byte[] b = new byte[1024];
          int length;
          while ((length = zis.read(b)) > 0) {
            fos.write(b, 0, length);
          }
          fos.close();
          zis.close();
        } catch (ZipException e1) {
          // TODO Auto-generated catch block
         e1.printStackTrace();
        } catch (IOException e1) {
          // TODO Auto-generated catch block
         e1.printStackTrace();
        }
      }
    }
  }

  public static void main(String[] args) throws ZipException {
    // TODO Auto-generated method stub
    testInput();
    testOutput();
    testBufferring();
    testZip();
  }
}