Java中的InputStreamReader和OutputStreamWriter源码分析_动力节点Java学院整理

package java.io; import java.nio.charset.Charset; import java.nio.charset.CharsetDecoder; import sun.nio.cs.StreamDecoder; // 将“字节输入流”转换成“字符输入流” public class InputStreamReader extends Reader {  private final StreamDecoder sd;  // 根据in创建InputStreamReader，使用默认的编码  public InputStreamReader(InputStream in) {   super(in);   try {    sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object   } catch (UnsupportedEncodingException e) {    // The default encoding should always be available    throw new Error(e);   }  }  // 根据in创建InputStreamReader，使用编码charsetName(编码名)  public InputStreamReader(InputStream in, String charsetName)   throws UnsupportedEncodingException  {   super(in);   if (charsetName == null)    throw new NullPointerException("charsetName");   sd = StreamDecoder.forInputStreamReader(in, this, charsetName);  }  // 根据in创建InputStreamReader，使用编码cs  public InputStreamReader(InputStream in, Charset cs) {   super(in);   if (cs == null)    throw new NullPointerException("charset");   sd = StreamDecoder.forInputStreamReader(in, this, cs);  }  // 根据in创建InputStreamReader，使用解码器dec  public InputStreamReader(InputStream in, CharsetDecoder dec) {   super(in);   if (dec == null)    throw new NullPointerException("charset decoder");   sd = StreamDecoder.forInputStreamReader(in, this, dec);  }  // 获取解码器  public String getEncoding() {   return sd.getEncoding();  }  // 读取并返回一个字符  public int read() throws IOException {   return sd.read();  }  // 将InputStreamReader中的数据写入cbuf中，从cbuf的offset位置开始写入，写入长度是length  public int read(char cbuf[], int offset, int length) throws IOException {   return sd.read(cbuf, offset, length);  }  // 能否从InputStreamReader中读取数据  public boolean ready() throws IOException {   return sd.ready();  }  // 关闭InputStreamReader  public void close() throws IOException {   sd.close();  } }

package java.io; import java.nio.charset.Charset; import java.nio.charset.CharsetEncoder; import sun.nio.cs.StreamEncoder; // 将“字节输出流”转换成“字符输出流” public class OutputStreamWriter extends Writer {  private final StreamEncoder se;  // 根据out创建OutputStreamWriter，使用编码charsetName(编码名)  public OutputStreamWriter(OutputStream out, String charsetName)   throws UnsupportedEncodingException  {   super(out);   if (charsetName == null)    throw new NullPointerException("charsetName");   se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);  }  // 根据out创建OutputStreamWriter，使用默认的编码  public OutputStreamWriter(OutputStream out) {   super(out);   try {    se = StreamEncoder.forOutputStreamWriter(out, this, (String)null);   } catch (UnsupportedEncodingException e) {    throw new Error(e);   }  }  // 根据out创建OutputStreamWriter，使用编码cs  public OutputStreamWriter(OutputStream out, Charset cs) {   super(out);   if (cs == null)    throw new NullPointerException("charset");   se = StreamEncoder.forOutputStreamWriter(out, this, cs);  }  // 根据out创建OutputStreamWriter，使用编码器enc  public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {   super(out);   if (enc == null)    throw new NullPointerException("charset encoder");   se = StreamEncoder.forOutputStreamWriter(out, this, enc); }java io系列01之 "目录"  // 获取编码器enc  public String getEncoding() {   return se.getEncoding();  }  // 刷新缓冲区  void flushBuffer() throws IOException {   se.flushBuffer();  }  // 将单个字符写入到OutputStreamWriter中  public void write(int c) throws IOException {   se.write(c);  }  // 将字符数组cbuf从off开始的数据写入到OutputStreamWriter中，写入长度是len  public void write(char cbuf[], int off, int len) throws IOException {   se.write(cbuf, off, len);  }  // 将字符串str从off开始的数据写入到OutputStreamWriter中，写入长度是len  public void write(String str, int off, int len) throws IOException {   se.write(str, off, len); }java io系列01之 "目录"  // 刷新“输出流”  // 它与flushBuffer()的区别是：flushBuffer()只会刷新缓冲，而flush()是刷新流，flush()包括了flushBuffer。  public void flush() throws IOException {   se.flush();  }  // 关闭“输出流”  public void close() throws IOException {   se.close();  } }

 import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.OutputStreamWriter;; import java.io.InputStreamReader; import java.io.IOException; /** * InputStreamReader 和 OutputStreamWriter 测试程序 * *  */ public class StreamConverter {  private static final String FileName = "file.txt";  private static final String CharsetName = "utf-8";  //private static final String CharsetName = "gb2312";  public static void main(String[] args) {   testWrite();   testRead();  }  /**  * OutputStreamWriter 演示函数  *  */  private static void testWrite() {   try {    // 创建文件“file.txt”对应File对象    File file = new File(FileName);    // 创建FileOutputStream对应OutputStreamWriter：将字节流转换为字符流，即写入out的数据会自动由字节转换为字符。    OutputStreamWriter out1 = new OutputStreamWriter(new FileOutputStream(file), CharsetName);   // 写入10个汉字   out.write("字节流转为字符流示例");   // 向“文件中”写入"0123456789"+换行符    out1.write("0123456789/n");    out1.close();   } catch(IOException e) {    e.printStackTrace();   }  }  /**  * InputStreamReader 演示程序  */  private static void testRead() {   try {    // 方法1：新建FileInputStream对象   // 新建文件“file.txt”对应File对象    File file = new File(FileName);    InputStreamReader in = new InputStreamReader(new FileInputStream(file), CharsetName);    // 测试read()，从中读取一个字符   char c1 = (char)in1.read();    System.out.println("c1="+c1);   // 测试skip(long byteCount)，跳过4个字符   in1.skip(6);    // 测试read(char[] cbuf, int off, int len)    char[] buf = new char[10];   in1.read(buf, 0, buf.length);    System.out.println("buf="+(new String(buf)));    in.close();   } catch(IOException e) {    e.printStackTrace();   }  } }

c1=字buf=流示例0123456