字符串压缩（java&node.js)

编程时，遇到一个字节数组太长，需要压缩存储的需求，想找一个通用的压缩算法，然后搜到了zlib，试了一下，果真是个好东西，分享如下：

Java 参考 Java压缩技术（一） ZLib
Node.js 参考 nodejs 压缩和解压

Java代码：

import java.io.ByteArrayOutputStream;  
import java.io.IOException;  
import java.io.InputStream;  
import java.io.OutputStream;  
import java.util.zip.Deflater;  
import java.util.zip.DeflaterOutputStream;  
import java.util.zip.Inflater;  
import java.util.zip.InflaterInputStream;  
  
/** 
 * ZLib压缩工具 
 *  
 * @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a> 
 * @version 1.0 
 * @since 1.0 
 */  
public abstract class ZLibUtils {  
  
    /** 
     * 压缩 
     *  
     * @param data 
     *            待压缩数据 
     * @return byte[] 压缩后的数据 
     */  
    public static byte[] compress(byte[] data) {  
        byte[] output = new byte[0];  
  
        Deflater compresser = new Deflater();  
  
        compresser.reset();  
        compresser.setInput(data);  
        compresser.finish();  
        ByteArrayOutputStream bos = new ByteArrayOutputStream(data.length);  
        try {  
            byte[] buf = new byte[1024];  
            while (!compresser.finished()) {  
                int i = compresser.deflate(buf);  
                bos.write(buf, 0, i);  
            }  
            output = bos.toByteArray();  
        } catch (Exception e) {  
            output = data;  
            e.printStackTrace();  
        } finally {  
            try {  
                bos.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
        compresser.end();  
        return output;  
    }  
  
    /** 
     * 压缩 
     *  
     * @param data 
     *            待压缩数据 
     *  
     * @param os 
     *            输出流 
     */  
    public static void compress(byte[] data, OutputStream os) {  
        DeflaterOutputStream dos = new DeflaterOutputStream(os);  
  
        try {  
            dos.write(data, 0, data.length);  
  
            dos.finish();  
  
            dos.flush();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
  
    /** 
     * 解压缩 
     *  
     * @param data 
     *            待压缩的数据 
     * @return byte[] 解压缩后的数据 
     */  
    public static byte[] decompress(byte[] data) {  
        byte[] output = new byte[0];  
  
        Inflater decompresser = new Inflater();  
        decompresser.reset();  
        decompresser.setInput(data);  
  
        ByteArrayOutputStream o = new ByteArrayOutputStream(data.length);  
        try {  
            byte[] buf = new byte[1024];  
            while (!decompresser.finished()) {  
                int i = decompresser.inflate(buf);  
                o.write(buf, 0, i);  
            }
            output = o.toByteArray();  
        } catch (Exception e) {  
            output = data;  
            e.printStackTrace();  
        } finally {  
            try {  
                o.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
  
        decompresser.end();  
        return output;  
    }  
  
    /** 
     * 解压缩 
     *  
     * @param is 
     *            输入流 
     * @return byte[] 解压缩后的数据 
     */  
    public static byte[] decompress(InputStream is) {  
        InflaterInputStream iis = new InflaterInputStream(is);  
        ByteArrayOutputStream o = new ByteArrayOutputStream(1024);  
        try {  
            int i = 1024;  
            byte[] buf = new byte[i];  
  
            while ((i = iis.read(buf, 0, i)) > 0) {  
                o.write(buf, 0, i);  
            }  
  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
        return o.toByteArray();  
    }  
}  

public final void testBytes2() {  
        System.err.println("字节压缩／解压缩测试");  
        String inputStr = "zjw";  
        System.err.println("输入字符串:\t" + inputStr);  
        byte[] input = inputStr.getBytes();  
        System.err.println("输入字节长度:\t" + input.length);  
  
        
        byte[] data = ZLibUtils.compress(input);  
        System.err.println("压缩后字节长度:\t" + data.length);  
        for(byte bt: data) {
            System.err.print(Integer.toHexString((int)bt & 0xff) + ",");
        }
        for(byte bt: input) {
            System.out.print(bt + ",");
        }
        byte[] output = ZLibUtils.decompress(data);  
        System.err.println("解压缩后字节长度:\t" + output.length);  
        String outputStr = new String(output);  
        System.err.println("输出字符串:\t" + outputStr);
}

输出如下：

字节压缩／解压缩测试
输入字符串:  zjw
输入字节长度: 3
压缩后字节长度:    11
78,9c,ab,ca,2a,7,0,2,bc,1,5c
解压缩后字节长度:   3
输出字符串:  zjw

Node.js

var zlib = require('zlib');  
var async = require('async');  
  
function gzip(text){  
    var buf = new Buffer(text);  
  
    var zipRes = null;  
  
    async.auto({  
        zip:function(cb){  
            zlib.gzip(buf,function(err,res){  
                zipRes = res;  
                cb(err,res);  
            })  
        },  
        unzip:['zip',function(cb,res){  
            var zipRes = res.zip;  
  
            zlib.unzip(zipRes,function(err,res){  
                cb(err,res.toString());  
            })  
        }]  
  
    },function(err,res){  
  
        console.log(zipRes);  
        console.log(res.unzip);  
    })  
}  
  
  
function deflate(text){  
    var buf = new Buffer(text);  
  
    var deflateRes = null;  
  
    async.auto({  
        zip:function(cb){  
            zlib.deflate(buf,function(err,res){  
                deflateRes = res;  
                cb(err,res);  
            })  
        },  
        unzip:['zip',function(cb,res){  
            var zipRes = res.zip;  
  
            zlib.unzip(zipRes,function(err,res){  
                cb(err,res.toString());  
            })  
        }]  
  
    },function(err,res){  
  
        console.log(deflateRes);  
        console.log(res.unzip);  
    })  
}  
  
  
gzip('zjw');  
deflate('zjw'); 

node .\compressString.js
<Buffer 1f 8b 08 00 00 00 00 00 00 0a ab ca 2a 07 00 26 53 54 f7 03 00 00 00>
zjw
<Buffer 78 9c ab ca 2a 07 00 02 bc 01 5c>
zjw

可以看到，用deflate压缩的结果与java 是一致的