为什么我没有得到我的原始字符串后，COM pression和DECOM pression？ [英] Why am I not getting my original string after compression and decompression?

问题描述

我目前正在使用的 java.util.zip。* 包进行无损COM pression / DECOM pression。

I am currently trying to use the java.util.zip.* package to perform lossless compression/Decompression.

和我使用的 Apache的罐子EN code和德code用作Base64编码字符集的参数字符串。

And I have used apache's jar to encode and decode the String used as an argument in Base64 charset.

在我的code在与两个静态方法，分别用于COM pression，一个用于DECOM pression。

Following in my code with two static methods one each for compression and one for decompression.

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.zip.*;

import org.apache.commons.codec.binary.Base64;

public class main {

    public String compress(String stringToCompress) throws UnsupportedEncodingException
    {       
        //System.out.println("String to Be Compressed :: " + stringToCompress);
        byte[] input = Base64.decodeBase64(stringToCompress);

        Deflater compressor = new Deflater();
        compressor.setInput(input);
        compressor.finish();

        byte[] output = new byte[100];
        compressor.deflate(output);
        return Base64.encodeBase64String(output);
    }

    public String decompressToString(String stringToDecompress) throws UnsupportedEncodingException, DataFormatException
    {   
        //System.out.println("String to be Decompressed :: " + stringToDecompress);
        byte[] input = Base64.decodeBase64(stringToDecompress);

        Inflater deCompressor = new Inflater();
        deCompressor.setInput(input,0,input.length);

        byte[] output = new byte[100];
        deCompressor.inflate(output);
        deCompressor.end();

        return Base64.encodeBase64String(output);
    }


    public static void main(String[] args) throws UnsupportedEncodingException, DataFormatException {
        main m = new main();
        String strToBeCompressed  = "jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla";
        String compressedString  = m.compress(strToBeCompressed) ;
        String deCompressedString = m.decompressToString(compressedString);

        System.out.println("Original :: " + strToBeCompressed);
        System.out.println("Compressed :: " + compressedString);
        System.out.println("decompressed :: " + deCompressedString);
    }
}

下面是输出。

Original :: jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla
Compressed :: eJwBPQDC/44Y5LHYYH5I3bH4ZI4Y725ZGo55ZHX5r5ZLI33aL242ornYb2nY72o4L6IoGr4oKIGroLor2nX4Yo245JXcvx/9AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==
decompressed :: jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhvadjvajgvoigavigogauguivadfhijbjklQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==

如果您看到的输出原件及DECOM pressed字符串不匹配。我不知道为什么？任何一个可以告诉我原因。

If you see the output the original and decompressed string are not matching. I don't know why? Can any one tell me the reason.

推荐答案

我认为你应该分开的关注和治疗融为一体pression，uncom pression，基地64 EN code和的base64德code作为单独的方法，分离关注。我不能够推断出你为什么都涉及Base64的 - 也许有一个很好的理由。也许你想pssed字符串COM $ P $是Base64的EN codeD？

I think that you should separate concerns and treat compression, uncompression, base 64 encode and base64 decode as separate concerns in separate methods. I am not able to deduce why you have involved Base64 - perhaps there is a good reason. Maybe you want the compressed string to be Base64 encoded?

总之，这里是你的code的版本，可以融为一体preSS和uncom preSS没有任何损失的字符串（但不涉及Base64编码）：

Anyway, here is a version of your code that can compress and uncompress the string without any loss (but no Base64 involved):

package dk.tbsalling.stackoverflow;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.zip.*;

import org.apache.commons.codec.binary.Base64;

public class App
{
    private byte[] compress(String stringToCompress) throws UnsupportedEncodingException
    {
        byte[] compressedData = new byte[1024];
        byte[] stringAsBytes = stringToCompress.getBytes("UTF-8");

        Deflater compressor = new Deflater();
        compressor.setInput(stringAsBytes);
        compressor.finish();
        int compressedDataLength = compressor.deflate(compressedData);

        return Arrays.copyOf(compressedData, compressedDataLength);
    }

    private String decompressToString(byte[] compressedData) throws UnsupportedEncodingException, DataFormatException
    {   
        Inflater deCompressor = new Inflater();
        deCompressor.setInput(compressedData, 0, compressedData.length);
        byte[] output = new byte[1024];
        int decompressedDataLength = deCompressor.inflate(output);
        deCompressor.end();

        return new String(output, 0, decompressedDataLength, "UTF-8");
    }

    public static void main(String[] args) throws UnsupportedEncodingException, DataFormatException {
        App m = new App();
        String strToBeCompressed  = "jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla";
        byte[] compressedData  = m.compress(strToBeCompressed);
        String deCompressedString = m.decompressToString(compressedData);

        System.out.println("Original     :: " + strToBeCompressed.length() + " " + strToBeCompressed);
        System.out.println("Compressed   :: " + compressedData.toString());
        System.out.println("decompressed :: " + deCompressedString.length() + " " + deCompressedString);
    }
}

这将产生输出：

Original     :: 85 jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla
Compressed   :: [B@3ced0338
decompressed :: 85 jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla

Process finished with exit code 0

更新

下面是code生产的Base64-CN codeD重新$ P $的COM pressed字符串psentation：

UPDATE

Here is the code for producing Base64-encoded representation of the compressed string:

package dk.tbsalling.stackoverflow;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.zip.*;

import org.apache.commons.codec.binary.Base64;

public class App
{
    private String compress(String stringToCompress) throws UnsupportedEncodingException
    {
        byte[] compressedData = new byte[1024];
        byte[] stringAsBytes = stringToCompress.getBytes("UTF-8");

        Deflater compressor = new Deflater();
        compressor.setInput(stringAsBytes);
        compressor.finish();
        int compressedDataLength = compressor.deflate(compressedData);

        byte[] bytes = Arrays.copyOf(compressedData, compressedDataLength);
        return Base64.encodeBase64String(bytes);
    }

    private String decompressToString(String base64String) throws UnsupportedEncodingException, DataFormatException
    {
        byte[] compressedData = Base64.decodeBase64(base64String);

        Inflater deCompressor = new Inflater();
        deCompressor.setInput(compressedData, 0, compressedData.length);
        byte[] output = new byte[1024];
        int decompressedDataLength = deCompressor.inflate(output);
        deCompressor.end();

        return new String(output, 0, decompressedDataLength, "UTF-8");
    }

    public static void main(String[] args) throws UnsupportedEncodingException, DataFormatException {
        App m = new App();
        String strToBeCompressed  = "jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla";
        String compressedData  = m.compress(strToBeCompressed);
        String deCompressedString = m.decompressToString(compressedData);

        System.out.println("Original     :: " + strToBeCompressed.length() + " " + strToBeCompressed);
        System.out.println("Compressed   :: " + compressedData.toString());
        System.out.println("decompressed :: " + deCompressedString.length() + " " + deCompressedString);
    }
}

这将产生输出：

Original     :: 85 jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla
Compressed   :: eJwNxMkNwDAIBMBW3BoW4lhI/LDY+pN5DAJ1NdwKei0KAe4uwdul9rDrwvRwQ3I0uETxB+dJX8L04zI+SVGLxEa1fNDSIlU=
decompressed :: 85 jhjksdhgfkjdsfhkjhjvblkajnlkdfmvlksjfdovbjaiudhv adjv ajgvoig avigogauguivadfhijbjkla

Process finished with exit code 0

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