Java Java.io.BufferedInputStream.available() 方法

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  描述

  java.io.BufferedInputStream.available()方法返回要从输入流读取的剩余字节数，而不会因对该输入流的方法的下一次调用而阻塞。
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  声明

  以下是java.io.BufferedInputStream.available()方法的声明。

   public int available()

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  返回值

  此方法返回从该输入流读取的剩余number of bytes
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  异常

  IOException如果发生I / O错误。
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  例子

  以下示例显示java.io.BufferedInputStream.available（）方法的用法。

   package com.jc2182;
  
  import java.io.BufferedInputStream;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  
  public class BufferedInputStreamDemo {
     public static void main(String[] args) throws Exception {
        BufferedInputStream bis = null;
  
        try {
           // open input stream test.txt for reading purpose.
           inStream = new FileInputStream("c:/test.txt");
  
           // input stream is converted to buffered input stream
           bis = new BufferedInputStream(inStream);      
  
           // read until a single byte is available
           while( bis.available() > 0 ) {
              
              // get the number of bytes available
              Integer nBytes = bis.available();
              System.out.println("Available bytes = " + nBytes );
  
              // read next available character
              char ch =  (char)bis.read();
  
              // print the read character.
              System.out.println("The character read = " + ch );
           }
        } catch(Exception e) {
           e.printStackTrace();
        } finally {
           // releases any system resources associated with the stream
           if(inStream!=null)
              inStream.close();
           if(bis!=null)
              bis.close();
        }
     }
  }

  假设我们有一个文本文件c:/test.txt ，其内容如下。该文件将用作示例程序的输入-

   ABCDE

  让我们编译并运行以上程序，这将产生以下结果-

   Available bytes = 5
  The character read = A
  Available bytes = 4
  The character read = B
  Available bytes = 3
  The character read = C
  Available bytes = 2
  The character read = D
  Available bytes = 1
  The character read = E