java需要关注的知识点---I0之压缩

1.GZIP压缩：

public class GZIPPcompress {
	public static void main(String[] args) throws IOException {
		if (args.length == 0) {
			System.out.println("Usage: \n GZIPcompress file\n" +
					" \tUses GZIP compresion 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);
		}
	}
}

ZIP压缩文件：

package com.io;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.util.Enumeration;
import java.util.zip.Adler32;
import java.util.zip.CheckedInputStream;
import java.util.zip.CheckedOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

public class ZipCompress {
	public static void main(String[] args) throws IOException {
		FileOutputStream f = new FileOutputStream("test.zip");
		CheckedOutputStream cos = new CheckedOutputStream(f, new Adler32());
		ZipOutputStream zos = new ZipOutputStream(cos);
		BufferedOutputStream out = new BufferedOutputStream(zos);
		zos.setComment("A test of Java Zipping");
		for(String arg:args) {
			System.out.println("Writing file " + arg);
			zos.putNextEntry(new ZipEntry(arg));
			BufferedReader in = new BufferedReader(new FileReader(arg));
			int c;
			while((c = in.read()) != -1) {
				out.write(c);
			}
			out.flush();
			
		}
		out.close();
		System.out.println("Checksum:" + cos.getChecksum().getValue());
		System.out.println("Reading file!");
		FileInputStream fi = new FileInputStream("test.zip");
		CheckedInputStream cis = new CheckedInputStream(fi, new Adler32());
		ZipInputStream zis = new ZipInputStream(cis);
		BufferedInputStream bis = new BufferedInputStream(zis);
		ZipEntry ze;
		while((ze = zis.getNextEntry()) != null) {
			System.out.println("Read file:" +ze);
			int x;
			while((x = bis.read()) != -1) {
				System.out.write(x);
			}
			System.out.println();
		}
		if(args.length == 1) {
			System.out.println("Check Sum:" + cis.getChecksum().getValue());
			ZipFile zf = new ZipFile("test.zip");
			Enumeration e = zf.entries();
			while(e.hasMoreElements()) {
				ZipEntry ze2 = (ZipEntry) e.nextElement();
				System.out.println("File:" + ze2);
			}
		}
	}
	
}