Java.io.BufferedInputStream.available() 方法

描述

java.io.BufferedInputStream.available() 方法返回要从输入流中读取的剩余字节数，而不会被下一次调用此输入流的方法阻塞。

声明

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

public int available()

返回值

此方法返回 字节数 未阻塞地从此输入流中读取。

异常

IOException − 如果发生 I/O 错误。

示例

下面的例子展示了 java.io.BufferedInputStream.available() 方法的使用。

package com.tutorialspoint;

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。 该文件将用作我们示例程序的输入 −

ABCDE 

让我们编译并运行上面的程序，这将产生下面的结果 −

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