Java java.util.zip.Deflater.setInput()用法及代碼示例

描述

這個java.util.zip.Deflater.setInput(byte[] b, int off, int len)方法設置用於壓縮的輸入數據。每當 needsInput() 返回 true 表示需要更多輸入數據時，就應該調用它。

聲明

以下是聲明java.util.zip.Deflater.setInput(byte[] b, int off, int len)方法。

public void setInput(byte[] b, int off, int len)

參數

• b− 輸入數據字節。

• off- 他開始數據的偏移量。

• len- 數據的長度。

示例

下麵的例子展示了 java.util.zip.Deflater.setInput(byte[] b, int off, int len) 方法的用法。

package com.tutorialspoint;

import java.io.UnsupportedEncodingException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;

public class DeflaterDemo {
   public static void main(String[] args) 
      throws DataFormatException, UnsupportedEncodingException {
      String message = "Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;"
         +"Welcome to TutorialsPoint.com;";
      System.out.println("Original Message length:" + message.length());
      byte[] input = message.getBytes("UTF-8");
      // Compress the bytes
      byte[] output = new byte[1024];

      Deflater deflater = new Deflater();
      int inCount = input.length;  
      int inPosition = 0;
      int outPosition = 0;

      int MAX_BUFFER_SIZE = 10;
      while(!deflater.finished()){
         int want = -1;
         int got;
         if (deflater.needsInput() && inCount != 0) {
            want = (inCount < MAX_BUFFER_SIZE) ? inCount:MAX_BUFFER_SIZE;

            deflater.setInput(input, inPosition, want);

            inCount -= want;
            inPosition += want;
            if (inCount == 0) {
               deflater.finish();
            }
         }
         // deflate to current position in output buffer
         int compCount;

         compCount = deflater.deflate(output, outPosition, MAX_BUFFER_SIZE);
         outPosition += compCount;
      }

      System.out.println("Total uncompressed bytes output:" + deflater.getTotalOut());     
      System.out.println("Compressed Message Checksum:" + deflater.getAdler());     
      deflater.finished();

      System.out.println("Compressed Message length:" + outPosition);

      // Decompress the bytes
      Inflater inflater = new Inflater();
      inflater.setInput(output, 0, outPosition);
      byte[] result = new byte[1024];
      int resultLength = inflater.inflate(result);
      inflater.finished();

      // Decode the bytes into a String
      message = new String(result, 0, resultLength, "UTF-8");
      System.out.println("UnCompressed Message Checksum:" + inflater.getAdler());  
      System.out.println("UnCompressed Message length:" + message.length());
   }
}

讓我們編譯並運行上麵的程序，這將產生以下結果 -

Original Message length:300
Total uncompressed bytes output:42
Compressed Message Checksum:368538129
Compressed Message length:42
UnCompressed Message Checksum:368538129
UnCompressed Message length:300