google snapy 压缩文件

引入 google snappy 包

   github 上snappy地址 http://github.com/google/snappy

<dependency>
	<groupId>org.xerial.snappy</groupId>
	<artifactId>snappy-java</artifactId>
	<version>1.1.2.6</version>
</dependency>

 使用snappy压缩文件

import java.io.ByteArrayOutputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import org.xerial.snappy.Snappy;

public class SnappyDemo {

	public static void main(String[] args) throws Exception {
		// 待压缩的文件,可以是任意文件
		RandomAccessFile raf = new RandomAccessFile("c:/花好月圆夜.mp4", "r");
                //压缩后保存的文件
		RandomAccessFile w = new RandomAccessFile("c:/cas-server-3.5.2-master.snappy", "rw");
		FileChannel channel = raf.getChannel();
		ByteBuffer buffer = ByteBuffer.allocate(4096);
		ByteArrayOutputStream out = new ByteArrayOutputStream(1024); 
		while (channel.read(buffer) > -1) {
			buffer.flip() ;
			
			while(buffer.hasRemaining()){
				out.write( buffer.get() ); 
			}
			buffer.clear() ;
		}
                //压缩内容写入 文件，如果文件比较大 压缩后的文件可以分多个文件保存，
               // 例如hadoop 文件每个块自定义为128M
		w.write( Snappy.compress(out.toByteArray()) ); 
		raf.close();
		w.close();
		out.close(); 
	}
}

 

使用snappy解压缩

import java.io.ByteArrayOutputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import org.xerial.snappy.Snappy;

public class UnSnappyDemo {

	public static void main(String[] args) throws Exception {
		RandomAccessFile raf = new RandomAccessFile("c:/cas-server-3.5.2-master.snappy", "r");
		RandomAccessFile w = new RandomAccessFile("c:/cas-server-3.5.2-master.zip", "rw");
		FileChannel channel = raf.getChannel();
		ByteBuffer buffer = ByteBuffer.allocate(196);
		ByteArrayOutputStream out = new ByteArrayOutputStream(1024);  
		while (channel.read(buffer) > -1){
			buffer.flip() ;
			while(buffer.hasRemaining()){
				out.write( buffer.get() ); 
			}
			buffer.clear() ;
			buffer = ByteBuffer.allocate(196);
		}
		w.write( Snappy.uncompress(out.toByteArray()) );
		raf.close();
		w.close(); 
	}
}