【Java学习笔记】操作JAR文件

JAR文件是一种具有特定构造的zip文件

1.JAR文件的创建：

import java.util.jar.JarEntry; 
import java.util.jar.JarOutputStream; 
import java.util.jar.Manifest; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.FileInputStream; 
import java.io.IOException; 
public class JarCreate { 
    public static void main(String arg[]) { 
        JarCreate zc = new JarCreate(); 
        zc.create("testfile.jar",arg); 
    } 
    public void create(String jarfilename,String filename[]) { 
        byte block[] = new byte[256]; 
        int length; 
        try {

            //FileInputStream->Manifest->JarOutputStream

     //                                                                ^

     //                                                                 |

     //                                                    FileOutputStream

            FileInputStream fis = new FileInputStream("manifest"); 
            Manifest man = new Manifest(fis);//创建manifest文件 
            FileOutputStream fos = new FileOutputStream(jarfilename); 
            JarOutputStream out = new JarOutputStream(fos,man); 
            for(int i=0; i<filename.length; i++) { 
                FileInputStream in = new FileInputStream(filename[i]); 
                String name = filename[i].replace(File.separatorChar,'/');

                JarEntry jarentry = new JarEntry(name); 
                out.putNextEntry(jarentry);

                //FileInputStream->FileOutputStream 
                while((length = in.read(block)) > 0) 
                    out.write(block,0,length);

                out.closeEntry(); 
                in.close(); 
            } 
            out.close(); 
        } catch(IOException e) { 
            System.out.println(e); 
        } 
    } 
}

2.JAR文件的读取

import java.util.jar.JarFile; 
import java.util.jar.JarEntry; 
import java.util.Enumeration; 
import java.io.IOException; 
public class JarList { 
    public static void main(String arg[]) { 
        JarList zl = new JarList(); 
        zl.list("testfile.jar"); 
    } 
    public void list(String filename) { 
        try { 
            JarFile jarfile = new JarFile(filename); 
Enumeration entrylist = jarfile.entries(); 
            while(entrylist.hasMoreElements()) { 
                JarEntry jarentry = (JarEntry)entrylist.nextElement(); 
                System.out.println(jarentry.getName()); 
            } 
            jarfile.close(); 
        } catch(IOException e) { 
            System.out.println(e); 
        } 
    } 
}

3.JAR文件的解压

import java.util.jar.JarFile; 
import java.util.jar.JarEntry; 
import java.util.Enumeration; 
import java.io.InputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
public class JarExtract { 
    public static void main(String arg[]) { 
        JarExtract ze = new JarExtract(); 
        ze.extract("testfile.jar"); 
    } 
    public void extract(String jarfilename) { 
        byte block[] = new byte[256]; 
        int length; 
        try { 
            JarFile jarfile = new JarFile(jarfilename); 
            Enumeration entrylist = jarfile.entries(); 
            while(entrylist.hasMoreElements()) { 
                JarEntry jarentry = (JarEntry)entrylist.nextElement(); 
                InputStream in = jarfile.getInputStream(jarentry); 
                String newfilename = jarentry.getName(); 
                FileOutputStream out = new FileOutputStream(newfilename); 
                while((length = in.read(block)) > 0) 
                    out.write(block,0,length); 
                in.close(); 
                out.close(); 
            } 
        } catch(IOException e) { 
            System.out.println(e); 
        } 
    } 
}

本文转自gnuhpc博客园博客，原文链接：http://www.cnblogs.com/gnuhpc/archive/2012/12/17/2822265.html，如需转载请自行联系原作者