压缩和解压缩java中的字符串数据 [英] compression and decompression of string data in java

问题描述

我使用以下代码来压缩和解压缩字符串数据，但我遇到的问题是，它很容易被压缩而没有错误，但是解压缩方法会引发跟随错误。

I am using the following code to compress and decompress string data, but the problem which I am facing is, it is easily getting compressed without error, but decompress method throws following error.

线程main中的异常java.io.IOException：不是GZIP格式

Exception in thread "main" java.io.IOException: Not in GZIP format

public static void main(String[] args) throws Exception {
        String string = "I am what I am hhhhhhhhhhhhhhhhhhhhhhhhhhhhh"
                + "bjggujhhhhhhhhh"
                + "rggggggggggggggggggggggggg"
                + "esfffffffffffffffffffffffffffffff"
                + "esffffffffffffffffffffffffffffffff"
                + "esfekfgy enter code here`etd`enter code here wdd"
                + "heljwidgutwdbwdq8d"
                + "skdfgysrdsdnjsvfyekbdsgcu"
                +"jbujsbjvugsduddbdj";

       System.out.println("after compress:");
        String compressed = compress(string);
        System.out.println(compressed);
        System.out.println("after decompress:");
        String decomp = decompress(compressed);
        System.out.println(decomp);
    }


     public static String compress(String str) throws Exception {
        if (str == null || str.length() == 0) {
            return str;
        }
        System.out.println("String length : " + str.length());
        ByteArrayOutputStream obj=new ByteArrayOutputStream();
        GZIPOutputStream gzip = new GZIPOutputStream(obj);
        gzip.write(str.getBytes("UTF-8"));
        gzip.close();
        String outStr = obj.toString("UTF-8");
        System.out.println("Output String length : " + outStr.length());
        return outStr;
     }

      public static String decompress(String str) throws Exception {
        if (str == null || str.length() == 0) {
            return str;
        }
        System.out.println("Input String length : " + str.length());
        GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(str.getBytes("UTF-8")));
        BufferedReader bf = new BufferedReader(new InputStreamReader(gis, "UTF-8"));
        String outStr = "";
        String line;
        while ((line=bf.readLine())!=null) {
          outStr += line;
        }
        System.out.println("Output String lenght : " + outStr.length());
        return outStr;
     }

仍然无法弄清楚如何解决这个问题!!!

Still couldn't figure out how to fix this issue!!!

推荐答案

这是因为

String outStr = obj.toString("UTF-8");

发送 byte [] 你可以从 ByteArrayOutputStream 获取和在 ByteArrayInputStream的来构建你的 GZIPInputStream 。以下是您的代码中需要进行的更改。

Send the byte[] which you can get from your ByteArrayOutputStream and use it as such in your ByteArrayInputStream to construct your GZIPInputStream. Following are the changes which need to be done in your code.

byte[] compressed = compress(string); //In the main method

public static byte[] compress(String str) throws Exception {
    ...
    ...
    return obj.toByteArray();
}

public static String decompress(byte[] bytes) throws Exception {
    ...
    GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(bytes));
    ...
}

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