JAVA 的两种流 字节流 InputStream OutputStream 字符流 Reader Writer

IO分两种流 

字节流 InputStream OutputStream 

字符流 Reader  Writer 

他们都是抽象类 

具体实现 
字节流 FileInputStream  FileOutputStream 
字符流 FileReader    FileWriter 


字节流转换成字符流可以用 InputSteamReader  OutputStreamWriter 

转换成BufferdReader  BufferedWriter 他们具有缓冲区 

例如：读取文件 从字节流输入到字符流输入 
定义一个字节流： 
Java代码
FileInputStream fileInputStream = new FileInputStream("d:/text.txt");  // 定义一个指向D:/TEXT.TXT 的字节流   
   
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);   
//字节流转换成InputStreamReader   
   
BufferedReader bufferedReader = new BufferedReader(inputSteamReader);   
//InputStreamReader 转换成带缓存的bufferedReader   

FileInputStream fileInputStream = new FileInputStream("d:/text.txt");  // 定义一个指向D:/TEXT.TXT 的字节流  InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream); //字节流转换成InputStreamReader  BufferedReader bufferedReader = new BufferedReader(inputSteamReader); //InputStreamReader 转换成带缓存的bufferedReader


可以把读出来的内容赋值给字符 
Java代码
String ss = new String();   
String s;   
while((s = bufferedReader.readLine())!=null){   
    ss += s;   
}   

String ss = new String(); String s; while((s = bufferedReader.readLine())!=null){  ss += s; }

例如：写入文件  从字节流输出到字符流输出 
Java代码
FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt"); //定义一个   
   
指向D:/TEXT.TXT文件    
   
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);   
   
BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);   
   
bufferedWriter.write(s);   
   
bufferedWriter.close();   
outputStreamWriter.close();   
fileOutputStream.close();  


------------------------------------------------------------
字节流和字符流      如果数据流中最小的数据单元是字节，那么称这种流为字节流；如果数据流中最小的数据单元是字符，那么称这种流为字符流。在Java的IO系统 中，java.io.InputStream和java.io.OutputStream分别表示字节输入流和字节输出流，java.io.Reader 和java.io.Writer分别表示字符输入流和字符输出流。I/O流的层次
1．字节流：
从InputStream和OutputStream派生出来的一系列类。这类流以字节(byte)为基本处理单位。
◇ InputStream、OutputStream
◇ FileInputStream、FileOutputStream
◇ PipedInputStream、PipedOutputStream
◇ ByteArrayInputStream、ByteArrayOutputStream
◇ FilterInputStream、FilterOutputStream
◇ DataInputStream、DataOutputStream
◇ BufferedInputStream、BufferedOutputStream
2．字符流：
从Reader和Writer派生出的一系列类，这类流以16位的Unicode码表示的字符为基本处理单位。
◇ Reader、Writer
◇ InputStreamReader、OutputStreamWriter
◇ FileReader、FileWriter
◇ CharArrayReader、CharArrayWriter
◇ PipedReader、PipedWriter
◇ FilterReader、FilterWriter
◇ BufferedReader、BufferedWriter
◇ StringReader、StringWriter
3．对象流
◇ ObjectInputStream、ObjectOutputStream
4．其它
◇ 文件处理：
File、RandomAccessFile；
◇ 接口
DataInput、DataOutput、ObjectInput、ObjectOutput----------------------------------------------------------------------------------------

IO分两种流 

字节流 InputStream OutputStream 

字符流 Reader Writer 

他们都是抽象类 

具体实现 
字节流 FileInputStream FileOutputStream 
字符流 FileReader FileWriter  

       字符流处理的单元为2个字节的Unicode字符，分别操作字符、字符数组或字符串，而字节流处理单元为1个字节， 操作字节和字节数组。所以字符流是由Java虚拟机将字节转化为2个字节的Unicode字符为单位的字符而成的，所以它对多国语言支持性比较好！如果是 音频文件、图片、歌曲，就用字节流好点，如果是关系到中文（文本）的，用字符流好点.
所有文件的储存是都是字节（byte）的储存，在磁盘上保留的并不是文件的字符而是先把字符编码成字节，再储存这些字节到磁盘。在读取文件（特别是文本文件）时，也是一个字节一个字节地读取以形成字节序列.
字节流可用于任何类型的对象，包括二进制对象，而字符流只能处理字符或者字符串； 2. 字节流提供了处理任何类型的IO操作的功能，但它不能直接处理Unicode字符，而字符流就可以。

 

字节流转换成字符流可以用 InputSteamReader OutputStreamWriter 

转换成BufferdReader BufferedWriter 他们具有缓冲区 

例如：读取文件 从字节流输入到字符流输入 
定义一个字节流：

Java代码 <embed height="15" width="14" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" allowscriptaccess="always" quality="high" flashvars="clipboard=FileInputStream%20fileInputStream%20%3D%20new%20FileInputStream(%22d%3A%2Ftext.txt%22)%3B%0A%2F%2F%20%E5%AE%9A%E4%B9%89%E4%B8%80%E4%B8%AA%E6%8C%87%E5%90%91D%3A%2FTEXT.TXT%20%E7%9A%84%E5%AD%97%E8%8A%82%E6%B5%81%20%0A%0AInputStreamReader%20inputStreamReader%20%3D%20new%20InputStreamReader(fileInputStream)%3B%20%0A%2F%2F%E5%AD%97%E8%8A%82%E6%B5%81%E8%BD%AC%E6%8D%A2%E6%88%90InputStreamReader%20%0A%0ABufferedReader%20bufferedReader%20%3D%20new%20BufferedReader(inputSteamReader)%3B%20%0A%2F%2FInputStreamReader%20%E8%BD%AC%E6%8D%A2%E6%88%90%E5%B8%A6%E7%BC%93%E5%AD%98%E7%9A%84bufferedReader%0A%0A%E5%8F%AF%E4%BB%A5%E6%8A%8A%E8%AF%BB%E5%87%BA%E6%9D%A5%E7%9A%84%E5%86%85%E5%AE%B9%E8%B5%8B%E5%80%BC%E7%BB%99%E5%AD%97%E7%AC%A6%20%0AString%20ss%20%3D%20new%20String()%3B%20%0AString%20s%3B%20%0Awhile((s%20%3D%20bufferedReader.readLine())!%3Dnull)%7B%20%0A%20%20%20%20%20%20%20%20ss%20%2B%3D%20s%3B%20%0A%7D%20" src="http://suan2046.iteye.com/javascripts/syntaxhighlighter/clipboard_new.swf">
FileInputStream fileInputStream = new FileInputStream("d:/text.txt");   
// 定义一个指向D:/TEXT.TXT 的字节流    
   
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);    
//字节流转换成InputStreamReader    
   
BufferedReader bufferedReader = new BufferedReader(inputSteamReader);    
//InputStreamReader 转换成带缓存的bufferedReader   
   
可以把读出来的内容赋值给字符    
String ss = new String();    
String s;    
while((s = bufferedReader.readLine())!=null){    
        ss += s;    
}    

FileInputStream fileInputStream = new FileInputStream("d:/text.txt"); // 定义一个指向D:/TEXT.TXT 的字节流   InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);  //字节流转换成InputStreamReader   BufferedReader bufferedReader = new BufferedReader(inputSteamReader);  //InputStreamReader 转换成带缓存的bufferedReader  可以把读出来的内容赋值给字符  String ss = new String();  String s;  while((s = bufferedReader.readLine())!=null){          ss += s;  }

例如：写入文件 从字节流输出到字符流输出

Java代码 
FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt");   
   
//定义一个指向D:/TEXT.TXT文件   
   
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);   
   
BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);   
   
bufferedWriter.write(s);   
   
bufferedWriter.close();   
outputStreamWriter.close();   
fileOutputStream.close();    

FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt");  //定义一个指向D:/TEXT.TXT文件  OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);  BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);  bufferedWriter.write(s);  bufferedWriter.close(); outputStreamWriter.close(); fileOutputStream.close();



例程：
将字符串转化为字节流 #region  将字符串转化为字节流 
           /**/ ///   <summary> 
          ///  将字符串转化为字节流
          ///   </summary> 
          ///   <param name="_Source"> 字串 </param> 
          ///   <returns> 字节流 </returns> 
          public   static   byte [] String2Bytes( string  strSource)
            {
             System.IO.MemoryStream   memoryStream = new    System.IO.MemoryStream();   
             System.IO.BinaryWriter   binaryWriter = new    System.IO.BinaryWriter(memoryStream);   
             binaryWriter.Write( strSource );
              byte []   buffer = memoryStream.GetBuffer();
              return  buffer;    
         } 
          #endregion 
 
         
           将字节流转化为字符串 #region  将字节流转化为字符串 
           /**/ ///   <summary> 
          ///  将字节流转化为字符串
          ///   </summary> 
          ///   <param name="bytData"> 字节流 </param> 
          ///   <returns> 字串 </returns> 
          public   static   string  Bytes2String( byte [] bytData)
            {
              // 字节流->字符串    
             System.IO.MemoryStream   memoryStream2  =   new    System.IO.MemoryStream(bytData);   
             System.IO.BinaryReader   binaryReader  =   new    System.IO.BinaryReader(memoryStream2);   
              string    s2 = binaryReader.ReadString();   
              return  s2;
         } 
          #endregion 

FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt"); //定义一个  指向D:/TEXT.TXT文件   OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);  BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);  bufferedWriter.write(s);  bufferedWriter.close(); outputStreamWriter.close(); fileOutputStream.close();
 

评论

1 楼 cydiaone 2012-11-26  

不错喔，虽然经常用，但就是分不清谁是谁。