Java java.util.zip.DeflaterInputStream.read()用法及代码示例

描述

这个java.util.zip.DeflaterInputStream.read(byte[] b, int off, int len)方法从输入流中读取一个字节的压缩数据。此方法将阻塞，直到可以读取和压缩某些输入。

声明

以下是声明java.util.zip.DeflaterInputStream.read(byte[] b, int off, int len)方法。

public int read(byte[] b, int off, int len)
   throws IOException

参数

• b- 读取数据的缓冲区。

• off- b 内数据的起始偏移量。

• len- 要读入 b 的最大压缩字节数。

返回

读取的实际字节数，如果到达未压缩输入流的末尾，则为 -1。

异常

• IndexOutOfBoundsException - 如果 len > b.length - 关闭。

• IOException - 如果发生 I/O 错误或此流已关闭。

示例

下面的例子展示了 java.util.zip.DeflaterInputStream.read(byte[] b, int off, int len) 方法的用法。

package com.tutorialspoint;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.InflaterInputStream;

public class DeflaterInputStreamDemo {
   public static void main(String[] args) throws DataFormatException, IOException {
      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");
      int length = message.length();
      // Compress the bytes
      byte[] output = new byte[1024];
      Deflater deflater = new Deflater();
      deflater.setInput(input);
   
      deflater.finish();
      int compressedDataLength = deflater.deflate(output,0 , output.length, Deflater.NO_FLUSH);
      System.out.println("Total uncompressed bytes input:" + deflater.getTotalIn());
      System.out.println("Compressed Message Checksum:" + deflater.getAdler());     
      deflater.finished();

      System.out.println("Compressed Message length:" + compressedDataLength);
   
      ByteArrayInputStream bin = new ByteArrayInputStream(output);
      InflaterInputStream inflaterInputStream = new InflaterInputStream(bin);
      byte[] result = new byte[1024];

      inflaterInputStream.read(result,0,result.length);
      inflaterInputStream.close();
      // Decode the bytes into a String
      String message1 = new String(result,0, length,"UTF-8");
      System.out.println(message.equals(message1));
   }
}

让我们编译并运行上面的程序，这将产生以下结果 -

Original Message length:300
Total uncompressed bytes input:300
Compressed Message Checksum:368538129
Compressed Message length:42
true