文件压缩

文件的压缩
    Java I/O类库中的类支持读写压缩格式的数据流。可以用它们对其他的I/O类进行封装，以提供压缩功能。
    这些类不是从Reader和Writer类派生而来的，而是属于InputStream和OutputStream继承层次结构的一部分，这样做是因为压缩类库是按字节的方式而不是按字符的方式处理的。

package solutions;

import java.io.*;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
 * Created by Administrator on 2016/3/14.
 */
public class GZIPcompress {
    public static void main(String[] args) throws IOException{
        if(args.length==0){
            System.out.println("Usage: 
GZIPcompress file
" +
                    "	Uses GZIP compression to compress " +
                    " the file to test.gz");
            System.exit(1);
        }
        BufferedReader in=new BufferedReader(new FileReader(args[0]));
        BufferedOutputStream out=new BufferedOutputStream(new GZIPOutputStream(new FileOutputStream("test.gz")));
        System.out.println("writing file");
        int c;
        while ((c=in.read())!=-1)
            out.write(c);
        in.close();
        out.close();
        System.out.println("reading file");
        BufferedReader in2=new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream("test.gz"))));
        String s;
        while ((s=in2.readLine())!=null)
            System.out.println(s);
    }
}

 用Zip进行多文件的保存
     支持Zip格式的Java库更加全面，利用该库可以方便地保存多个文件，它甚至有一个独立的类，使得读取Zip文件更加方便

package solutions;

import java.io.*;
import java.util.zip.*;

/**
 * Created by Administrator on 2016/3/14.
 */
public class ZipCompress
{
    public static void main(String[] args) throws IOException{
        //1.写文件（压缩文件）
        FileOutputStream f=new FileOutputStream("test.zip");
        /*
        *
        * */
        CheckedOutputStream csum=new CheckedOutputStream(f,new Adler32());
        ZipOutputStream zos=new ZipOutputStream(csum);
        BufferedOutputStream out=new BufferedOutputStream(zos);
        zos.setComment("A test of Java Zipping");
        for(String arg:args){
            System.out.print("writing file"+arg);
            BufferedReader in=new BufferedReader(new FileReader(arg));
            zos.putNextEntry(new ZipEntry(arg));
            int c;
            while ((c=in.read())!=-1)
                out.write(c);
            in.close();
            out.flush();
        }
        out.close();
        //2.读文件（解压文件）
        FileInputStream fi=new FileInputStream("tets.zip");
        CheckedInputStream csumi=new CheckedInputStream(fi,new Adler32());
        ZipInputStream in2=new ZipInputStream(csumi);
        BufferedInputStream bis=new BufferedInputStream(in2);
        ZipEntry ze;
        while ((ze=in2.getNextEntry())!=null){
            int x;
            while ((x=bis.read())!=-1){
                System.out.write(x);
            }
            bis.close();
        }
    }
}