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Java內建支援ZIP格式檔案的壓縮及解壓縮，透過使用java.util.zip套件，我們可以用來將網頁上傳的ZIP檔案加以解壓縮再做後續處理。這裡我們可以先將解壓縮的固定步驟寫成一個UnZipBean，後續要解壓縮zip時只要先將檔名及解壓縮的目錄傳進去，再呼叫unzip()函式即可。

程式碼：
UnZipBean.java:

/*

 * Copyright (c) 2005, Andowson Chang

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *  1. Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *  2. Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in

 *     the documentation and/or other materials provided with the

 *     distribution.

 *  3. Neither the name of the "Andowson Chang" nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.



 * This file creation date: 2005/01/31 18:33:36 

 * Reference:

 *      http://www.wakhok.ac.jp/~tatsuo/sen97/10shuu/UnZip.java.html

 */  

package com.andowson;



import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileOutputStream;

import java.io.FileNotFoundException;

import java.io.InputStream;

import java.io.IOException;

import java.util.Enumeration;

import java.util.zip.ZipEntry;

import java.util.zip.ZipException;

import java.util.zip.ZipFile;



public class UnZipBean {    

    public static final int EOF = -1;

    static final int BUFFER = 2048;



    private String zipFile;

    private String targetDirectory;

    private ZipFile zf;

    

    /** Constructor */

    public UnZipBean() {       

    }

    

    public UnZipBean(String zipFile, String targetDirectory) {

        this.zipFile = zipFile;

        this.targetDirectory = targetDirectory;

    }

    

    public void setZipFile(String zipFile) {

        this.zipFile = zipFile;

    }

    

    public String getZipFile() {

        return zipFile;

    }

    

    public void setTargetDirectory(String targetDirectory) {

    	this.targetDirectory = targetDirectory;

    }

    

    public String getTargetDirectory() {

        return targetDirectory;

    }

        

    public boolean unzip() {

    	boolean done = false;

    	if (zipFile != null) {    		

    		try {            

    			zf = new ZipFile(zipFile);

    			Enumeration enumeration = zf.entries();

    			while (enumeration.hasMoreElements()) {

    				ZipEntry target = (ZipEntry)enumeration.nextElement();

    				System.out.print(target.getName() + " .");

    				saveEntry(target);

    				System.out.println(". unpacked");

    			}

    			done = true;

    		}

    		catch (FileNotFoundException e){

    			System.out.println("zipfile not found"+e.getMessage());

    		}

    		catch (ZipException e){

    			System.out.println("zip error..."+e.getMessage());

    		}

    		catch (IOException e){

    			System.out.println("IO error..."+e.getMessage());

    		} 

    		finally {

    			try {

    				zf.close();

    			} catch (IOException e) {

    				System.out.println("IO error...Can't close zip file"+e.getMessage());

    			}

    		}

    	}

    	return done;

    }



    private void saveEntry(ZipEntry target)

                                   throws ZipException, IOException {

        try {

            File file = new File(targetDirectory + File.separator + target.getName());

            if (target.isDirectory()) {

                file.mkdirs();

            }

            else {

                InputStream is = zf.getInputStream(target);

                BufferedInputStream bis = new BufferedInputStream(is);

                File dir = new File(file.getParent());

                dir.mkdirs();

                FileOutputStream fos = new FileOutputStream(file);

                BufferedOutputStream bos = new BufferedOutputStream(fos);



                int c;

                byte[] data = new byte[BUFFER];

                while((c = bis.read(data, 0, BUFFER)) != EOF) {

                    bos.write(data, 0, c);

                }

                bos.flush();

                bos.close();

                fos.close();

            }

        }

        catch (ZipException e) {

            throw e;

        }

        catch (IOException e) {

            throw e;

        }

    }

}

unziptest.jsp:

<%@ page contentType="text/html; charset=Big5" errorPage="" %>

<%@ page import="com.andowson.UnZipBean" %>

<%

    String zipFile = "c:\\temp\\test.zip";

    String targetDirectory = application.getRealPath("/tmp");

    UnZipBean uzb = new UnZipBean(zipFile, targetDirectory);

    boolean succ = uzb.unzip();

    if (succ) out.println(uzb.getZipFile() + " UnZipped");

%>

參考資料：
http://java.sun.com/developer/technicalArticles/Programming/compression/
http://www.wakhok.ac.jp/~tatsuo/sen97/10shuu/UnZip.java.html