压缩文件

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class FileCompress
{

	// 压缩
	public static void gz(String fromFilePath, String toFilePath) throws IOException
	{
		//读取文件
		InputStream fileIn = new FileInputStream(fromFilePath);
		byte[] b = new byte[fileIn.available()];
		fileIn.read(b);

		
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		GZIPOutputStream gzip = new GZIPOutputStream(out);
		//将文件内容压缩写入ByteArrayOutputStream
		gzip.write(b);
		gzip.close();

		
		//将压缩内容写入新文件
		byte[] ob = out.toByteArray();
		OutputStream fileOut = new FileOutputStream(toFilePath);
		fileOut.write(ob);
		fileOut.flush();
		fileOut.close();
	}

	// 解压缩
	public static void ungz(String fromFilePath, String toFilePath) throws IOException
	{
		//读取文件
		InputStream fileIn = new FileInputStream(fromFilePath);
		byte[] b = new byte[fileIn.available()];
		fileIn.read(b);
		
		//准备写入解压文件中
		OutputStream fileOut = new FileOutputStream(toFilePath);
		
		//将读取文件解压
		ByteArrayInputStream in = new ByteArrayInputStream(b);
		GZIPInputStream gunzip = new GZIPInputStream(in);
		byte[] buffer = new byte[256];
		
		//将压缩内容写入新文件
		int n;
		while ((n = gunzip.read(buffer)) >= 0)
		{
			fileOut.write(buffer, 0, n);
		}
		in.close();
		gunzip.close();
		fileOut.flush();
		fileOut.close();
		
	}
	
	
	public static void main(String[] args) throws IOException
	{
		String fromFile = "c:/1.xml";
		String toFile = "c:/1.gz";
		
		gz(fromFile, toFile);
		//ungz(toFile, fromFile);
	}

}