浙江省建设厅官方网站,网站开发笔记,微信开发者文档官网,wordpress 繁体转简文章目录 一、NIO-Selector1.处理accept2.cancel3.处理read4.处理客户端断开5. 处理消息的边界6. 写入内容过多的问题7. 处理可写事件 一、NIO-Selector
1.处理accept
//1.创建selector,管理多个channel
Selector selector Selector.open();
ByteBuffer buffer ByteBuffer.… 文章目录 一、NIO-Selector1.处理accept2.cancel3.处理read4.处理客户端断开5. 处理消息的边界6. 写入内容过多的问题7. 处理可写事件 一、NIO-Selector
1.处理accept
//1.创建selector,管理多个channel
Selector selector Selector.open();
ByteBuffer buffer ByteBuffer.allocate(16);
ServerSocketChannel ssc ServerSocketChannel.open();
ssc.configureBlocking(false);
//2.建立selector和channel的联系注册
//SelectionKey就是将来事件发生后通过它可以知道事件和哪个channel的事件
//四个事件
//accept 会在有连接请求时触发
//connect 是客户端连接建立后触发
//read 可读事件
//write 可写事件
SelectionKey sscKey ssc.register(selector, 0, null);
sscKey.interestOps(SelectionKey.OP_ACCEPT);
ssc.bind(new InetSocketAddress(8080));
while(true){//3.select方法没有事件发生线程阻塞有事件线程才会恢复运行selector.select();//4.处理事件selectedKeys内部包含了所有发生的事件IteratorSelectionKey iter selector.selectedKeys.iterator();while(iter.next()){SelectionKey key iter.next();ServerSocketChannel channel (ServerSocketChannel)key.channel();SocketChannel sc channel.accept();}
}2.cancel
//1.创建selector,管理多个channel
Selector selector Selector.open();
ByteBuffer buffer ByteBuffer.allocate(16);
ServerSocketChannel ssc ServerSocketChannel.open();
ssc.configureBlocking(false);
//2.建立selector和channel的联系注册
SelectionKey sscKey ssc.register(selector, 0, null);
sscKey.interestOps(SelectionKey.OP_ACCEPT);
ssc.bind(new InetSocketAddress(8080));
while(true){//3.select方法没有事件发生线程阻塞有事件线程才会恢复运行//select在事件未处理时它不会阻塞事件发生后要么处理要么取消不能置之不理selector.select();//4.处理事件selectedKeys内部包含了所有发生的事件IteratorSelectionKey iter selector.selectedKeys.iterator();while(iter.next()){SelectionKey key iter.next();key.cancel();}
}3.处理read
用完key必须要remove
//1.创建selector,管理多个channel
Selector selector Selector.open();
ByteBuffer buffer ByteBuffer.allocate(16);
ServerSocketChannel ssc ServerSocketChannel.open();
ssc.configureBlocking(false);
//2.建立selector和channel的联系注册
SelectionKey sscKey ssc.register(selector, 0, null);
sscKey.interestOps(SelectionKey.OP_ACCEPT);
ssc.bind(new InetSocketAddress(8080));
while(true){//3.select方法没有事件发生线程阻塞有事件线程才会恢复运行selector.select();//4.处理事件selectedKeys内部包含了所有发生的事件//selector会在发生事件后向集合中加入key,但不会删除IteratorSelectionKey iter selector.selectedKeys.iterator();while(iter.next()){SelectionKey key iter.next();//处理key时要从selectedKeys集合中删除否则下次处理就会有问题iter.remove();//5.区分事件类型if(key.isAcceptable()){ //如果是acceptServerSocketChannel channel (ServerSocketChannel)key.channel();SocketChannel sc channel.accept();sc.configureBlocking(false);SelectionKey sckey sc.register(selector, 0, null);scKey.interestOps(SelectionKey.OP_READ);}elseif(key.isReadable()){//拿到触发事件的channelServerSocketChannel channel (ServerSocketChannel)key.channel();ByteBuffer buffer ByteBuffer.allocate(16);channel.read(buffer);buffer.flip();debugRead(buffer);}}
}4.处理客户端断开
//1.创建selector,管理多个channel
Selector selector Selector.open();
ByteBuffer buffer ByteBuffer.allocate(16);
ServerSocketChannel ssc ServerSocketChannel.open();
ssc.configureBlocking(false);
//2.建立selector和channel的联系注册
SelectionKey sscKey ssc.register(selector, 0, null); sscKey.interestOps(SelectionKey.OP_ACCEPT);
ssc.bind(new InetSocketAddress(8080));
while(true){ //3.select方法没有事件发生线程阻塞有事件线程才会恢复运行 selector.select(); //4.处理事件selectedKeys内部包含了所有发生的事件 //selector会在发生事件后向集合中加入key,但不会删除 IteratorSelectionKey iter selector.selectedKeys.iterator(); while(iter.next()){ SelectionKey key iter.next(); //处理key时要从selectedKeys集合中删除否则下次处理就会有问题 iter.remove(); //5.区分事件类型 if(key.isAcceptable()){ //如果是accept ServerSocketChannel channel (ServerSocketChannel)key.channel(); SocketChannel sc channel.accept();sc.configureBlocking(false); SelectionKey sckey sc.register(selector, 0, null); scKey.interestOps(SelectionKey.OP_READ); }elseif(key.isReadable()){ try{ //拿到触发事件的channel ServerSocketChannel channel (ServerSocketChannel)key.channel(); ByteBuffer buffer ByteBuffer.allocate(16); int read channel.read(buffer);//如果是正常断开read的方法的返回值是-1 ifread -1){ key.cancel(); }else{ buffer.flip(); debugRead(buffer); } }catch(IOException e){ e.printStackTrace();//因为客户端断开了因此需要将key取消从selector 的keys集合中真正删除key) key.cancel();}}}
}5. 处理消息的边界
固定消息长度数据包大小一样服务器按预定长度读取缺点是浪费带宽按分隔符拆分缺点是效率低TLV格式Type类型,Length长度Value数据可以方便获取消息大小分配合适的buffer缺点是buffer需要提前分配如果内容过大影响server吞吐量 Http1.1是TLV格式Http2.0是LTV格式
private static void split(ByteBuffer source){source.flip();for(int i 0; i source.limit(); i){//找到一条完整消息if(source.get(i) \n){int length i 1 -source.position();//把这条完整消息存入新的ByteBufferByteBuffer target ByteBuffer.allocate(length);//从source读向target写for(int j 0; j length; j){target.put(source.get());}debugAll(target);}}source.compact();
}public static void main(){//1.创建selector,管理多个channelSelector selector Selector.open(); ByteBuffer buffer ByteBuffer.allocate(16); ServerSocketChannel ssc ServerSocketChannel.open(); ssc.configureBlocking(false);//2.建立selector和channel的联系注册SelectionKey sscKey ssc.register(selector, 0, null); sscKey.interestOps(SelectionKey.OP_ACCEPT); ssc.bind(new InetSocketAddress(8080)); while(true){ //3.select方法没有事件发生线程阻塞有事件线程才会恢复运行 selector.select(); //4.处理事件selectedKeys内部包含了所有发生的事件 //selector会在发生事件后向集合中加入key,但不会删除 IteratorSelectionKey iter selector.selectedKeys.iterator(); while(iter.next()){ SelectionKey key iter.next(); //处理key时要从selectedKeys集合中删除否则下次处理就会有问题 iter.remove(); //5.区分事件类型 if(key.isAcceptable()){ //如果是accept ServerSocketChannel channel (ServerSocketChannel)key.channel(); SocketChannel sc channel.accept();sc.configureBlocking(false); ByteBuffer buffer ByteBuffer.allocate(16); //attachment附件//将一个byteBuffer作为附件关联到selectionKey上SelectionKey sckey sc.register(selector, 0, buffer); scKey.interestOps(SelectionKey.OP_READ); }elseif(key.isReadable()){ try{ //拿到触发事件的channel ServerSocketChannel channel (ServerSocketChannel)key.channel(); //获取selectionKey上关联的附件ByteBuffer buffer (ByteBuffer)key.attatchment();int read channel.read(buffer);//如果是正常断开read的方法的返回值是-1 ifread -1){ key.cancel(); }else{ split(buffer);if(buffer.position() buffer.limit()){//扩容ByteBuffer newBuffer ByteBuffer.allocate(buffer.capacity()*2);buffer.flip();newBuffer.put(buffer);//复制key.attach(newbuffer);//替换掉key上原有的buffer}} }catch(IOException e){ e.printStackTrace();//因为客户端断开了因此需要将key取消从selector 的keys集合中真正删除key) key.cancel();}}}}
}6. 写入内容过多的问题
//服务器
public static void main(){ServerSocketChannel ssc ServerSocketChannrl.open();ssc.configureBlocking(false);Selector selector Selector.open();ssc.register(selector, SelectionKey.OP_ACCEPT);ssc.bind(new InetSocketAddress(8080));while(trye){selector.select();IteratorSelectionKey iter selector.selectedKeys.iterator();while(iter.hasNext()){SelectionKey key iter.next();iter.remove();if(key.isAcceptable()){SocketChannel sc ssc.accept();sc.configureBlocking(false);//1.向客户端发送大量数据StringBuilder sb new StringBuilder();for(int i 0; i 3000000; i){sb.append(a);}BytrBuffer buffer Charset.defaultCharset().encode(sb.toString());//不符合非阻塞模式while(buffer.hasRemaining()){//2.返回值代表实际写入的字节数//不能一次性写完//write 0 缓冲区满写不了int write sc.write(buffer);System.out.println(write):}}}}
}//客户端
public static void main(){SocketChannel sc SocketChannel.open();sc.connect(new InetSocketAddress(localhost,8080));//3.接收数据int count 0;while(true){ByteBuffer buffer ByteBuffer.allocate(1024*1024);count sc.read(buffer);System.out.println(count);buffer.clear();}
}7. 处理可写事件
//服务器
public static void main(){ServerSocketChannel ssc ServerSocketChannrl.open();ssc.configureBlocking(false);Selector selector Selector.open();ssc.register(selector, SelectionKey.OP_ACCEPT);ssc.bind(new InetSocketAddress(8080));while(trye){selector.select();IteratorSelectionKey iter selector.selectedKeys.iterator();while(iter.hasNext()){SelectionKey key iter.next();iter.remove();if(key.isAcceptable()){SocketChannel sc ssc.accept();sc.configureBlocking(false);SelectionKey sckey sc.register(selector, 0, null);sckey.interestOps(SelectionKey.OP_READ);//1.向客户端发送大量数据StringBuilder sb new StringBuilder();for(int i 0; i 3000000; i){sb.append(a);}BytrBuffer buffer Charset.defaultCharset().encode(sb.toString());//2.返回值代表实际写入的字节数//不能一次性写完//先写一次int write sc.write(buffer);System.out.println(write)://3.判断是否有剩余内容while(buffer.hasRemaining()){//4.关注可写事件sckey.interestOps(sckey.interestOps() SelectionKey.OP_WRITE);//sckey.interestOps(sckey.interestOps() | SelectionKey.OP_WRITE);//5.把未写完的数据挂到sckey上sckey.attach(buffer);}}elseif(key.isWritable())[ByteBuffer buffer (ByteBuffer) key.attachment();SocketChannel sc (SocketChannel)key.channel();int write sc.write(buffer);System.out.println(write)://6.清理操作内存释放if!buffer.haeRemaining()){key.attach(null);//需要清除bufferkey.interestOps(key.interestOps() - SelectionKey.OP_WRITE);//不需关注可写事件}}}}
}
