PipedReader与PipedWriter有哪些不同的地方-创新互联

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PipedWriter与PipedReader的区别

1. PipedWriter 源码

package java.io;
 public class PipedWriter extends Writer {
   // 与PipedWriter通信的PipedReader对象
   private PipedReader sink;
   // PipedWriter的关闭标记
   private boolean closed = false;
   // 构造函数，指定配对的PipedReader
   public PipedWriter(PipedReader snk) throws IOException {
     connect(snk);
   }
   // 构造函数
   public PipedWriter() {
   }
   // 将“PipedWriter” 和 “PipedReader”连接。
   public synchronized void connect(PipedReader snk) throws IOException {
     if (snk == null) {
       throw new NullPointerException();
     } else if (sink != null || snk.connected) {
       throw new IOException("Already connected");
     } else if (snk.closedByReader || closed) {
       throw new IOException("Pipe closed");
     }
     sink = snk;
     snk.in = -1;
     snk.out = 0;
     // 设置“PipedReader”和“PipedWriter”为已连接状态
     // connected是PipedReader中定义的，用于表示“PipedReader和PipedWriter”是否已经连接
     snk.connected = true;
   }
   // 将一个字符c写入“PipedWriter”中。
   // 将c写入“PipedWriter”之后，它会将c传输给“PipedReader”
   public void write(int c) throws IOException {
     if (sink == null) {
       throw new IOException("Pipe not connected");
     }
     sink.receive(c);
   }
   // 将字符数组b写入“PipedWriter”中。
   // 将数组b写入“PipedWriter”之后，它会将其传输给“PipedReader”
   public void write(char cbuf[], int off, int len) throws IOException {
     if (sink == null) {
       throw new IOException("Pipe not connected");
     } else if ((off | len | (off + len) | (cbuf.length - (off + len))) < ) {
       throw new IndexOutOfBoundsException();
     }
     sink.receive(cbuf, off, len);
   }
   // 清空“PipedWriter”。
   // 这里会调用“PipedReader”的notifyAll()；
   // 目的是让“PipedReader”放弃对当前资源的占有，让其它的等待线程(等待读取PipedWriter的线程)读取“PipedWriter”的值。
   public synchronized void flush() throws IOException {
     if (sink != null) {
       if (sink.closedByReader || closed) {
         throw new IOException("Pipe closed");
       }
       synchronized (sink) {
         sink.notifyAll();
       }
     }
   }
   // 关闭“PipedWriter”。
   // 关闭之后，会调用receivedLast()通知“PipedReader”它已经关闭。
   public void close() throws IOException {
     closed = true;
     if (sink != null) {
       sink.receivedLast();
     }
   }
 }