JAVA 缓存数组之----ByteArrayInputStream类详解

素颜马尾好姑娘i 2022-06-14 01:20 289阅读 0赞

## Java ByteArrayInputStream类 ##

字节数组输入流在内存中创建一个字节数组缓冲区，从输入流读取的数据保存在该字节数组缓冲区中。创建字节数组输入流对象有以下几种方式。

接收字节数组作为参数创建：

ByteArrayInputStream bArray = new ByteArrayInputStream(byte [] a);

另一种创建方式是接收一个字节数组，和两个整形变量 off、len，off表示第一个读取的字节，len表示读取字节的长度。

ByteArrayInputStream bArray = new ByteArrayInputStream(byte []a, 
                                                           int off, 
                                                           int len)

成功创建字节数组输入流对象后，可以参见以下列表中的方法，对流进行读操作或其他操作。

<table style="margin:4px 0px; padding:0px; width:818px; table-layout:fixed; border-collapse:collapse; border-spacing:0px; color:rgb(0,0,0); font-family:Verdana,Arial,Helvetica,sans-serif; font-size:13px; line-height:22.1px"> 
 <tbody style="margin:0px; padding:0px"> 
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   <th style="margin:0px; padding:3px; border-top-width:1px; border-right-width:1px; border-left-width:1px; border-style:solid solid none; border-top-color:rgb(189,189,189); border-right-color:rgb(189,189,189); border-left-color:rgb(189,189,189); color:rgb(255,255,255); font-size:14px; vertical-align:top; background-color:rgb(189,189,189)"> 序号</th> 
   <th style="margin:0px; padding:3px; border-top-width:1px; border-right-width:1px; border-left-width:1px; border-style:solid solid none; border-top-color:rgb(189,189,189); border-right-color:rgb(189,189,189); border-left-color:rgb(189,189,189); color:rgb(255,255,255); font-size:14px; vertical-align:top; background-color:rgb(189,189,189)"> 方法描述</th> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> 1</td> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> <span style="margin:0px; padding:0px">public int read()&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><br style="margin:0px; padding:0px"> 从此输入流中读取下一个数据字节。</td> 
  </tr> 
  <tr style="margin:0px; padding:0px; background-color:rgb(239,239,239)"> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> 2</td> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> <span style="margin:0px; padding:0px">public int read(byte[] r, int off, int len)</span><br style="margin:0px; padding:0px"> 将最多&nbsp;<code style="margin:0px 5px; padding:0px 4px; display:inline-block; font-size:13px; color:rgb(199,37,78); font-family:Consolas,'Courier New',Courier,monospace; background-color:rgb(249,242,244)">len</code>&nbsp;个数据字节从此输入流读入字节数组。</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> 3</td> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> <span style="margin:0px; padding:0px">public int available()</span><br style="margin:0px; padding:0px"> 返回可不发生阻塞地从此输入流读取的字节数。</td> 
  </tr> 
  <tr style="margin:0px; padding:0px; background-color:rgb(239,239,239)"> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> 4</td> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> <span style="margin:0px; padding:0px">public void mark(int read)</span><br style="margin:0px; padding:0px"> 设置流中的当前标记位置。</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> 5</td> 
   <td style="margin:0px; padding:7px 5px; min-width:40px; height:30px; border:1px solid rgb(221,221,221); vertical-align:top; font-size:14px"> <span style="margin:0px; padding:0px">public long skip(long n)</span><br style="margin:0px; padding:0px"> 从此输入流中跳过&nbsp;<code style="margin:0px 5px; padding:0px 4px; display:inline-block; font-size:13px; color:rgb(199,37,78); font-family:Consolas,'Courier New',Courier,monospace; background-color:rgb(249,242,244)">n</code>&nbsp;个输入字节。</td> 
  </tr> 
 </tbody> 
</table>

### 实例 ###

下面的例子演示了ByteArrayInputStream 和 ByteArrayOutputStream的使用：

import java.io.*;
    
    public class ByteStreamTest {
    
       public static void main(String args[])throws IOException {
    
          ByteArrayOutputStream bOutput = new ByteArrayOutputStream(12);
    
          while( bOutput.size()!= 10 ) {
             // 获取用户输入值
             bOutput.write(System.in.read());
          }
    
          byte b [] = bOutput.toByteArray();
          System.out.println("Print the content");
          for(int x= 0 ; x < b.length; x++) {          // 打印字符          System.out.print((char)b[x]  + "   ");       }       System.out.println("   ");        int c;        ByteArrayInputStream bInput = new ByteArrayInputStream(b);        System.out.println("Converting characters to Upper case " );       for(int y = 0 ; y < 1; y++ ) {          while(( c= bInput.read())!= -1) {             System.out.println(Character.toUpperCase((char)c));          }          bInput.reset();       }    } }

以上实例编译运行结果如下：

asdfghjkly
    Print the content
    a   s   d   f   g   h   j   k   l   y
    Converting characters to Upper case
    A
    S
    D
    F
    G
    H
    J
    K
    L
    Y