java中的流——缓冲流

朴灿烈づ我的快乐病毒、 2022-04-06 09:42 291阅读 0赞

# java中的流——缓冲流 #

缓冲流要套在相应的“节点流”之上，对读写的数据提供缓冲功能。

JDK提供了四种缓冲流：

java.io

## Class BufferedReader ##

### Constructor Summary ###

<table style="width:636px;border-left:1px solid #eeeeee;border-right:1px solid #eeeeee;border-bottom:1px solid #eeeeee;color:#353833;font-family:'DejaVu Sans', Arial, Helvetica, sans-serif;">  
 <span style="background-color:#f8981d;border:none;">Constructors</span>  
 <tbody> 
  <tr> 
   <th style="vertical-align:top;background:#dee3e9;font-size:13px;">Constructor and Description</th> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedReader</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">Reader</a>&nbsp;in)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a buffering character-input stream that uses a default-sized input buffer. 
    </div> </td> 
  </tr> 
  <tr style="background-color:#eeeeef;"> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedReader</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">Reader</a>&nbsp;in, int&nbsp;sz)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a buffering character-input stream that uses an input buffer of the specified size. 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

java.io

## Class BufferedWriter ##

### Constructor Summary ###

<table style="width:663px;border-left:1px solid #eeeeee;border-right:1px solid #eeeeee;border-bottom:1px solid #eeeeee;color:#353833;font-family:'DejaVu Sans', Arial, Helvetica, sans-serif;">  
 <span style="background-color:#f8981d;border:none;">Constructors</span>  
 <tbody> 
  <tr> 
   <th style="vertical-align:top;background:#dee3e9;font-size:13px;">Constructor and Description</th> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedWriter</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">Writer</a>&nbsp;out)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a buffered character-output stream that uses a default-sized output buffer. 
    </div> </td> 
  </tr> 
  <tr style="background-color:#eeeeef;"> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedWriter</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">Writer</a>&nbsp;out, int&nbsp;sz)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a new buffered character-output stream that uses an output buffer of the given size. 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

java.io

## Class BufferedInputStream ##

### Constructor Summary ###

<table style="width:662px;border-left:1px solid #eeeeee;border-right:1px solid #eeeeee;border-bottom:1px solid #eeeeee;color:#353833;font-family:'DejaVu Sans', Arial, Helvetica, sans-serif;">  
 <span style="background-color:#f8981d;border:none;">Constructors</span>  
 <tbody> 
  <tr> 
   <th style="vertical-align:top;background:#dee3e9;font-size:13px;">Constructor and Description</th> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedInputStream</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">InputStream</a>&nbsp;in)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a&nbsp; 
     <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;">BufferedInputStream</code>&nbsp;and saves its argument, the input stream&nbsp; 
     <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;">in</code>, for later use. 
    </div> </td> 
  </tr> 
  <tr style="background-color:#eeeeef;"> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedInputStream</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">InputStream</a>&nbsp;in, int&nbsp;size)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a&nbsp; 
     <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;">BufferedInputStream</code>&nbsp;with the specified buffer size, and saves its argument, the input stream&nbsp; 
     <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;">in</code>, for later use. 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

java.io

## Class BufferedOutputStream ##

### Constructor Summary ###

<table style="width:641px;border-left:1px solid #eeeeee;border-right:1px solid #eeeeee;border-bottom:1px solid #eeeeee;color:#353833;font-family:'DejaVu Sans', Arial, Helvetica, sans-serif;">  
 <span style="background-color:#f8981d;border:none;">Constructors</span>  
 <tbody> 
  <tr> 
   <th style="vertical-align:top;background:#dee3e9;font-size:13px;">Constructor and Description</th> 
  </tr> 
  <tr> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedOutputStream</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">OutputStream</a>&nbsp;out)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a new buffered output stream to write data to the specified underlying output stream. 
    </div> </td> 
  </tr> 
  <tr style="background-color:#eeeeef;"> 
   <td style="vertical-align:top;font-size:13px;"> <code style="font-family:'DejaVu Sans Mono', monospace;font-size:14px;line-height:1.4em;"><span style="font-weight:bold;"><a style="color:#4a6782;" rel="nofollow">BufferedOutputStream</a></span>(<a style="color:#4a6782;font-weight:bold;" title="class in java.io" rel="nofollow">OutputStream</a>&nbsp;out, int&nbsp;size)</code> 
    <div style="color:#474747;font-size:14px;font-family:'DejaVu Serif', Georgia, 'Times New Roman', Times, serif;">
      Creates a new buffered output stream to write data to the specified underlying output stream with the specified buffer size. 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

处理流类型：

![0dadc03d-f643-3519-a304-dd0e620fc0d5.png][]

java.io

## Class BufferedInputStream ##

TestBufferStream1.java

import java.io.*;
    
    /*
    	BufferedInputStream缓冲输入流
    	测试BufferStream，缓冲流
    */
    public class TestBufferStream1 {
      public static void main(String[] args) {
        try {
          FileInputStream fis = new FileInputStream("F:\\java\\io\\HelloWorld.java");
    			  
    	  //BufferedInputStream缓冲流
          BufferedInputStream bis = new BufferedInputStream(fis);
          int c = 0;
          System.out.println((char)bis.read());
          System.out.println(bis.read());
    	  
    	  //mark(100),标记，从第100个字符开始读
          bis.mark(100);
          for(int i=0;i<=10 && (c=bis.read())!=-1;i++){
            System.out.print((char)c+" ");
          }
          System.out.println(); 
    	  
    	  //reset()回到标记的点，即第100个字符
          bis.reset();
          for(int i=0;i<=10 && (c=bis.read())!=-1;i++){
            System.out.print((char)c+" ");
          }
          bis.close();
        } catch (IOException e) {e.printStackTrace();}
      }
    }

F:\java\io>javac TestBufferStream1.java
    
    F:\java\io>java TestBufferStream1
    p
    117
    b l i c   c l a s s
    b l i c   c l a s s
    F:\java\io>javac TestBufferStream2.java

java.io

## Class BufferedReader ##

java.io

## Class BufferedWriter ##

TestBufferStream2.java

import java.io.*;
    
    /*
    	BufferedWriter，BufferedReader 缓冲流
    */
    public class TestBufferStream2 {
      public static void main(String[] args) {
        try {
          BufferedWriter bw = new BufferedWriter(new FileWriter("F:\\java\\io\\dat2.txt"));
          BufferedReader br = new BufferedReader(new FileReader("F:\\java\\io\\dat2.txt"));
          String s = null;
          for(int i=1;i<=100;i++){
    		//随机数转成字符串
            s = String.valueOf(Math.random());
    		//写入缓冲流
            bw.write(s);
            //换行
    		bw.newLine();
          }
    	  //倒光数据
          bw.flush();
    	  
    	  //读取行
          while((s=br.readLine())!=null){
            System.out.println(s);
          }
          bw.close(); 
          br.close();
        } catch (IOException e) { 
    	  e.printStackTrace();
    	}
      }
    }

F:\java\io>java TestBufferStream2
    0.44605365873993197
    0.7172517110637919
    0.45266496240025944
    0.26441294566414975
    0.40643865442669536
    0.7307633218927724
    0.2641493131251609
    0.16215857289597668
    0.09546816530624025
    0.05250590007012379
    0.706305952265802
    0.7146685956709623
    0.12094533453441803
    0.41902835622438284
    0.716202475273043
    0.7838577652318317
    0.7729074867368703
    0.41414034677906597
    0.9838619363312414
    0.14519005797714812
    0.09659520188919035
    0.6194052270847193
    0.20280298200322233
    0.8644062694639841
    0.059035295760902495
    0.24494202492557415
    0.3453610863673868
    0.7162218991497389
    0.5663478287237094
    0.940274785183616
    0.7633587185037936
    0.15772118849521666
    0.7461146190378233
    0.9937553274103151
    0.8375434198068626
    0.7685868655604795
    0.34762266286039056
    0.6691255839665746
    0.10331487867637068
    9.70149639575757E-4
    0.3325232668934798
    0.9990736725881437
    0.2656129731949294
    0.5437184674341257
    0.7294229747248173
    0.958178159164025
    0.28244080752612866
    0.5988433149852124
    0.6081506107095568
    0.5714226965983857
    0.7443482366259503
    0.8925242801963478
    0.592919434086085
    0.17950368867556477
    0.10630276309040054
    0.2986093862407587
    0.6783319116914838
    0.7784411465205322
    0.938726461500579
    0.5394861049131998
    0.23814935074824095
    0.07854366352549125
    0.25607902421683426
    0.5473613826413953
    0.023976602180069806
    0.6865658312828175
    0.15421857525112181
    0.7184029694266285
    0.6394879002643735
    0.6049366977117457
    0.44187356561114777
    0.4728586447683065
    0.44554652206609735
    0.06322664824973623
    0.6869106357451145
    0.2461837005738483
    0.10254764456903398
    0.5495584892863888
    0.11468448059632808
    0.27937135694773985
    0.9885405636272356
    0.79345848200023
    0.09360825354076607
    0.35109483302822087
    0.5451623333244178
    0.3666817980972056
    0.5221833506515708
    0.8999336014991125
    0.19814206262263445
    0.5148354642313737
    0.29208016057346686
    0.8218706075012052
    0.875111660954438
    0.8101619682408246
    0.14346207744893114
    0.5964115429721846
    0.30068472586288386
    0.22463444345335803
    0.6515971969848199
    0.29409071208430937
    
    F:\java\io>

先生成文件dat2.txt，再读取文件

[0dadc03d-f643-3519-a304-dd0e620fc0d5.png]: /images/20220406/4147d30602ec483ea5efca35159c862f.png