JAVA BIO编程的一个应用示例

浅浅的花香味﹌ 2022-09-01 00:57 183阅读 0赞

*  服务端创建ServerSocket;
 *  客户端创建Socket用于和服务端进行通信；
 *  客户端发送链接请求，询问服务端是否有可用线程；
 *  客户端在收到服务端响应后，等待响应完成，继续执行后续操作；

package com.tech.netty.bio;
    
    import lombok.extern.slf4j.Slf4j;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.net.ServerSocket;
    import java.net.Socket;
    import java.nio.charset.StandardCharsets;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    /**
     * @author lw
     * @since 2021/7/26
     **/
    @Slf4j
    public class BioServer {
    
    
    
        public static void main(String[] args) throws IOException {
    
            ExecutorService executorService = Executors.newCachedThreadPool();
            ServerSocket serverSocket = new ServerSocket(6666);
            while(true){
                log.info("{}：等待客户端程序连接...",getThread());
                Socket accept = serverSocket.accept();
                log.info("{}：建立连接 {}",getThread(),accept.getInetAddress());
                executorService.execute(()-> handler(accept));
            }
        }
    
        private static void handler(Socket accept) {
            InputStream inputStream=null;
            try{
                inputStream = accept.getInputStream();
                byte[] bytes = new byte[1000];
                while(true){
                    log.info("{}：等待读取数据...",getThread());
                    int read = inputStream.read(bytes);
                    if(read!=-1){
                        log.info("{}：读取到：{},len={}",getThread(),new String(bytes,0,read, StandardCharsets.ISO_8859_1),read);
                    }else{
                        break;
                    }
                }
            }catch (Exception e){
                log.error("{}出错了，即将关闭连接",getThread());
            }finally {
                try {
                    if(inputStream!=null){
                        try {
                            inputStream.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    accept.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    
        private static String getThread(){
            return Thread.currentThread().getName()+"-"+Thread.currentThread().getId();
        }
    }

使用Telnet作为测试客户端程序，尝试与服务建立连接发送数据

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpYW5nd2VubWFpbA_size_16_color_FFFFFF_t_70][]

回车后， 按 ctr \] 组合键 ，send 客户端要发送的内容

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpYW5nd2VubWFpbA_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpYW5nd2VubWFpbA_size_16_color_FFFFFF_t_70 2][]

21:43:52.618 [main] INFO com.tech.netty.bio.BioServer - main-1：等待客户端程序连接...
    21:44:23.316 [main] INFO com.tech.netty.bio.BioServer - main-1：建立连接 /127.0.0.1
    21:44:23.356 [main] INFO com.tech.netty.bio.BioServer - main-1：等待客户端程序连接...
    21:44:23.356 [pool-1-thread-1] INFO com.tech.netty.bio.BioServer - pool-1-thread-1-12：等待读取数据...
    21:45:24.565 [pool-1-thread-1] INFO com.tech.netty.bio.BioServer - pool-1-thread-1-12：读取到：ok100,len=5
    21:45:24.565 [pool-1-thread-1] INFO com.tech.netty.bio.BioServer - pool-1-thread-1-12：等待读取数据...

BIO模型存在一定的弊端：

每一个客户端连接请求，服务端都需要启动一个线程进行处理，当并发较高时占用大量的线程资源；

当连接没有IO请求时，服务端启动的线程将会在read()方法上等待，产生没必要的线程资源开销；

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