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();  } }