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: \nGZIPcompress file\n" +
"\tUses 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();
}
}
}