Java Java类

实现一个输入流过滤器，用于以“deflate”压缩格式压缩数据。

构造函数和描述

• DeflaterInputStream(InputStream in) ：创建一个具有默认压缩器和缓冲区大小的新输入流。
• DeflaterInputStream(InputStream in, Deflater defl) ：使用指定的压缩器和默认缓冲区大小创建一个新的输入流。
• DeflaterInputStream(InputStream in, Deflater defl, int bufLen) ：使用指定的压缩器和缓冲区大小创建一个新的输入流。

方法：

• int available() ：到达 EOF 后返回 0，否则总是返回 1。

  Syntax :public int available()
                throws IOException
  Parameters:
  n - number of bytes to be skipped
  Returns:
  the actual number of bytes skipped
  Throws:
  IOException

• void close() ：关闭此输入流及其底层输入流，丢弃任何未决的未压缩数据。

  Syntax :public void close()
             throws IOException
  Overrides:
  close in class FilterInputStream
  Throws:
  IOException

• void mark(int limit) ：不支持此操作。

  Syntax :public void mark(int limit)
  Parameters:
  limit - maximum bytes that can be read before invalidating the position marker
  

• boolean markSupported() ：始终返回 false，因为此输入流不支持 mark() 和 reset() 方法。

  Syntax :public boolean markSupported()
  Returns:
  false, always

• int read() ：从输入流中读取单个字节的压缩数据。

  Syntax :public int read()
           throws IOException
  Returns:
  a single byte of compressed data, or -1 if the end of the uncompressed
  input stream is reached
  Throws:
  IOException

• int read(byte[] b, int off, int len) ：将压缩数据读入字节数组。

  Syntax :public int read(byte[] b,
         int off,
         int len)
           throws IOException
  Parameters:
  b - buffer into which the data is read
  off - starting offset of the data within b
  len - maximum number of compressed bytes to read into b
  Returns:
  the actual number of bytes read, or -1 if the end of the
  uncompressed input stream is reached
  Throws:
  IndexOutOfBoundsException 
  IOException 

• void reset() ：不支持此操作。

  Syntax :public void reset()
             throws IOException
  Throws:
  IOException

• long skip(long n) ：跳过并丢弃输入流中的数据。

  Syntax :public long skip(long n)
            throws IOException
  Parameters:
  n - number of bytes to be skipped
  Returns:
  the actual number of bytes skipped
  Throws:
  IOException

程序：

//Java program to illustrate DeflaterInputStream class
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.DeflaterInputStream;
  
class DeflaterInputStreamDemo
{
    public static void main(String[] args) throws IOException
    {
        byte b[] = new byte[10];
        for (byte i = 0; i <10 ; i++)
        {
            b[i] = i;
        }
        ByteArrayInputStream bin = new ByteArrayInputStream(b);
        DeflaterInputStream din = new DeflaterInputStream(bin);
  
        //illustrating markSupported() method
        System.out.println(din.markSupported());
          
        //illustrating skip() method
        din.skip(1);
  
        //illustrating available() method
        System.out.println(din.available());
  
        //illustrating read(byte[] b,int off,int len)
        byte c[] = new byte[10];
          
        din.read(c,0,9);
                for (int i = 0; i < 9; i++)
        {
            System.out.print(c[i]);
        }
        while(din.available() == 1)
        {
            //Reads a single byte of compressed data
            System.out.print(din.read());
        }
          
        System.out.println();
        System.out.println(din.available());
  
        // illustrating close() method
        din.close();
    }
}

输出 ：

false
1
-1009996100981029710199231224400175046-1
0

上面的输出代表压缩数据。

下一篇： Java Java类