要解壓縮 zip 文件，我們需要讀取 zip 文件，ZipInputStream然后ZipEntry一一讀取。然后使用FileOutputStream將它們寫入文件系統。如果輸出目錄不存在并且 zip 文件中存在任何嵌套目錄，我們還需要創建它。這是解壓之前創建tmp.zip的輸出目錄的java解壓縮文件程序。

package com.journaldev.files;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
public class UnzipFiles {
    public static void main(String[] args) {
        String zipFilePath = "/Users/pankaj/tmp.zip";        
        String destDir = "/Users/pankaj/output";        
        unzip(zipFilePath, destDir);
    }
    private static void unzip(String zipFilePath, String destDir) {
        File dir = new File(destDir);
        // create output directory if it doesn't exist
        if(!dir.exists()) dir.mkdirs();
        FileInputStream fis;
        //buffer for read and write data to file
        byte[] buffer = new byte[1024];
        try {
            fis = new FileInputStream(zipFilePath);
            ZipInputStream zis = new ZipInputStream(fis);
            ZipEntry ze = zis.getNextEntry();
            while(ze != null){
                String fileName = ze.getName();
                File newFile = new File(destDir + File.separator + fileName);
                System.out.println("Unzipping to "+newFile.getAbsolutePath());
                //create directories for sub directories in zip
                new File(newFile.getParent()).mkdirs();
                FileOutputStream fos = new FileOutputStream(newFile);
                int len;
                while ((len = zis.read(buffer)) > 0) {
                fos.write(buffer, 0, len);
                }
                fos.close();
                //close this ZipEntry
                zis.closeEntry();
                ze = zis.getNextEntry();
            }
            //close last ZipEntry
            zis.closeEntry();
            zis.close();
            fis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }        
    }
}

程序完成后，我們在具有相同目錄層次結構的輸出文件夾中擁有所有 zip 文件內容。上述程序的輸出是：

Unzipping to /Users/pankaj/output/.DS_Store
Unzipping to /Users/pankaj/output/data/data.dat
Unzipping to /Users/pankaj/output/data/data.xml
Unzipping to /Users/pankaj/output/data/xmls/project.xml
Unzipping to /Users/pankaj/output/data/xmls/web.xml
Unzipping to /Users/pankaj/output/data.Xml
Unzipping to /Users/pankaj/output/DB.xml
Unzipping to /Users/pankaj/output/item.XML
Unzipping to /Users/pankaj/output/item.xsd
Unzipping to /Users/pankaj/output/ms/data.txt
Unzipping to /Users/pankaj/output/ms/project.doc