Java压缩/解压缩二进制文件

在Java中提供Deflater和Inflater工具类来压缩/解压缩数据。 这两个工具类采用zlib算法，下面给出一个封装好的工具。

package com.lifeiflong.io;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;


/**
 * util for compress/decompress data
 * Java压缩/解压缩二进制文件
 * 在Java中提供Deflater和Inflater工具类来压缩/解压缩数据。 这两个工具类采用zlib算法
 */
public final class CompressionUtil {
	
	/**
	 * Compression level
	 */
	private static enum Level {

		/**
		 * Compression level for no compression.
		 */
		NO_COMPRESSION(0),

		/**
		 * Compression level for fastest compression.
		 */
		BEST_SPEED(1),

		/**
		 * Compression level for best compression.
		 */
		BEST_COMPRESSION(9),

		/**
		 * Default compression level.
		 */
		DEFAULT_COMPRESSION(-1);

		private int level;

		Level(

		int level) {
			this.level = level;
		}

		public int getLevel() {
			return level;
		}
	}

	private static final int BUFFER_SIZE = 4 * 1024;

	public static byte[] compress(byte[] data, Level level) throws IOException {

		Deflater deflater = new Deflater();
		// set compression level
		deflater.setLevel(level.getLevel());
		deflater.setInput(data);

		ByteArrayOutputStream outputStream = new ByteArrayOutputStream(data.length);

		deflater.finish();
		byte[] buffer = new byte[BUFFER_SIZE];
		while (!deflater.finished()) {
			int count = deflater.deflate(buffer); // returns the generated code... index
			outputStream.write(buffer, 0, count);
		}
		byte[] output = outputStream.toByteArray();
		outputStream.close();
		return output;
	}

	public static byte[] decompress(byte[] data) throws IOException,
			DataFormatException {
		Inflater inflater = new Inflater();
		inflater.setInput(data);

		ByteArrayOutputStream outputStream = new ByteArrayOutputStream(
				data.length);
		byte[] buffer = new byte[BUFFER_SIZE];
		while (!inflater.finished()) {
			int count = inflater.inflate(buffer);
			outputStream.write(buffer, 0, count);
		}
		byte[] output = outputStream.toByteArray();
		outputStream.close();
		return output;
	}

	

	public static void testCompress() throws Exception {

		BufferedInputStream in = new BufferedInputStream(new FileInputStream(
				"E:\\myerp_error.log"));
		ByteArrayOutputStream out = new ByteArrayOutputStream(1024);

		byte[] temp = new byte[1024];
		int size = 0;
		while ((size = in.read(temp)) != -1) {
			out.write(temp, 0, size);
		}
		in.close();
		byte[] data = out.toByteArray();
		byte[] output = CompressionUtil.compress(data,
				CompressionUtil.Level.BEST_COMPRESSION);
		System.out.println("before : " + (data.length / 1024) + "k");
		System.out.println("after : " + (output.length / 1024) + "k");

		FileOutputStream fos = new FileOutputStream(
				"E:\\myerp_error_compress.log");
		fos.write(output);
		out.close();
		fos.close();
	}

	public static void testDecompress() throws Exception {

		BufferedInputStream in = new BufferedInputStream(new FileInputStream(
				"E:\\myerp_error_compress.log"));
		ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
		byte[] temp = new byte[1024];
		int size = 0;
		while ((size = in.read(temp)) != -1) {
			out.write(temp, 0, size);
		}
		in.close();
		byte[] data = out.toByteArray();
		byte[] output = CompressionUtil.decompress(data);
		System.out.println("before : " + (data.length / 1024) + "k");
		System.out.println("after : " + (output.length / 1024) + "k");

		FileOutputStream fos = new FileOutputStream(
				"E:\\myerp_error_decompress.log");
		fos.write(output);
		out.close();
		fos.close();
	}
	
	
	public static void main(String[] args) throws Exception {
//		testCompress();
		testDecompress();
	}
}

 

 

 关于OutOfMemoryError，请参考：http://www.devguli.com/blog/eng/java-deflater-and-outofmemoryerror/