java NIO 之 Pipe
Java NIO Pipe是2个线程之间的单向数据连接。Pipe有一个source通道和一个sink通道。数据会被写到sink通道,从source通道读取。
Pipe原理的图示:
Pipe的特点
Pipe 提供一种机制,可以按照写入的顺序读取数据。 Pipe.SinkChannel用来向管道写入数据,而Pipe.SourceChannel用来从管道读取数据
例子:
package cn.outofmemory.nio.channels; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.Pipe; public class PipeTest { public static void main(String[] args) throws IOException { //初始化Pipe实例 Pipe pipe = Pipe.open(); // 获取写通道 Pipe.SinkChannel skChannel = pipe.sink(); String testData = "Test Data to Check java NIO Channels Pipe."; ByteBuffer buffer = ByteBuffer.allocate(512); buffer.clear(); buffer.put(testData.getBytes()); buffer.flip(); //向写通道写入数据 while(buffer.hasRemaining()) { skChannel.write(buffer); } //获得读取数据通道 Pipe.SourceChannel sourceChannel = pipe.source(); buffer = ByteBuffer.allocate(512); //将读取数据写到控制台 while(sourceChannel.read(buffer) > 0){ //flip方法将当前读取位置设置为0, limit设置为写入数据的size buffer.flip(); while(buffer.hasRemaining()){ char ch = (char) buffer.get(); System.out.print(ch); } //clear方法将buffer的limit设置为其容量capacity, 将position设置为0 buffer.clear(); } } }
输出:
Test Data to Check java NIO Channels Pipe.
创建管道
Pipe pipe = Pipe.open();
向管道写数据
Pipe.SinkChannel sinkChannel = pipe.sink();
通过调用SinkChannel的write()方法,将数据写入SinkChannel:
String newData = "New String to write to file..." + System.currentTimeMillis(); ByteBuffer buf = ByteBuffer.allocate(48); buf.clear(); buf.put(newData.getBytes()); buf.flip(); while(buf.hasRemaining()) { sinkChannel.write(buf); }
从管道读取数据
Pipe.SourceChannel sourceChannel = pipe.source();
调用source通道的read()方法来读取数据:
ByteBuffer buf = ByteBuffer.allocate(48); int bytesRead = sourceChannel.read(buf);
read()方法返回的int值会告诉我们多少字节被读进了缓冲区。