High concurrency Java network programming (b) BIO

 First, obstruction

Service-Terminal

public  class BIOServer { 

    public  static  void main (String [] args) throws Exception { 
        the ServerSocket SC = new new the ServerSocket (9093 ); 
        System.out.println ( "Server started successfully!" );
         the while (! sc.isClosed ()) { 
            Request the Socket = sc.accept (); // blocking 
            System.out.println ( "receive new connection:" + request.toString ());
             the try { 
                the InputStream IS = request.getInputStream (); // NET + I / o
                Reader = the BufferedReader new new the BufferedReader ( new new the InputStreamReader (IS, "UTF-. 8" )); 
                String MSG; 
                the while (! (MSG = reader.readLine ()) = null ) { // No data will block 
                    IF (msg.length ( ) == 0 ) {
                         BREAK ; 
                    } 
                    System.out.println (MSG); 
                } 
                System.out.println ( "data is received from the:" + request.toString ()); 
            } the catch (Exception E) {
                 // TODO: handle exception
            } finally {
                try {
                    request.close();
                } catch (Exception e2) {
                    // TODO: handle exception
                }
            }

        }
    }
}

sc.accept () causes the server block until the connection is created

InputStream is blocked

Client

public class BIOClient {

    public static void main(String[] args) throws IOException {
        Socket s = new Socket("localhost", 9093);
        OutputStream out = s.getOutputStream();

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入");
        String msg = scanner.nextLine();
        out.write(msg.getBytes());
        scanner.close();
        s.close();
    }

}

OutputStream is blocked, will not return after the completion of writing

 

When two clients simultaneously start

 Server only establishes a connection and wait for the client's input

We ended input 123 customers were waiting

 Server receives 123, and the establishment of a new connection

This does not meet our needs, following the introduction of multi-threaded, server-side upgrade

 

Second, the introduction of multi-threading

Thread Pool

public class BIOServer {

    private static ExecutorService threadPool = Executors.newCachedThreadPool();

    public static void main(String[] args) throws Exception {
        ServerSocket sc = new ServerSocket(9093);
        System.out.println("服务器启动成功！");
        while (!sc.isClosed()) {
            Socket request = sc.accept(); // 阻塞
            System.out.println("收到新连接:" + request.toString());
            threadPool.execute(() -> {
                try {
                    InputStream is = request.getInputStream(); // net+i/o
                    BufferedReader reader = new BufferedReader(new InputStreamReader(is, "utf-8"));
                    String msg;
                    while ((msg = reader.readLine()) != null) {
                        if (msg.length() == 0) {
                            break;
                        }
                        System.out.println(msg);
                    }
                    System.out.println("收到数据，来自：" + request.toString());
                } catch (Exception e) {
                    // TODO: handle exception
                } finally {
                    try {
                        request.close();
                    } catch (Exception e2) {
                        // TODO: handle exception
                    }
                }
            });
        }
    }

Started three clients, respectively input 123,456,789

 You do not have to wait for other clients

 

 Third, the service end interacting with the browser

The above simple C / S program does not meet the real scene, to interact with the server browser below.

Our address in the browser, enter the server's 127.0.0.1:9093

 

 

 

 We found the service side received the above information, but your browser does not have access to any content

 

 

 

 The reason: interactive use of the browser and the server is HTTP protocol

You must meet certain format:

1. The request packet

 

 

 FIG no upper third portion and a fourth portion

2. The response packet

 

 

 响应状态码

 

 

 

 因此，我们按照HTTP协议的格式，在服务端编写响应浏览器的内容，浏览器就可以收到我们的响应信息

public class BIOServer {

    private static ExecutorService threadPool = Executors.newCachedThreadPool();

    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9096);
        System.out.println("tomcat 服务器启动成功");
        while (!serverSocket.isClosed()) {
            Socket request = serverSocket.accept();
            System.out.println("收到新连接：" + request.toString());
            threadPool.execute(() -> {
                try {
                    InputStream inputStream = request.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"));
                    String msg;
                    while ((msg = reader.readLine()) != null) {
                        if (msg.length() == 0) {
                            break;
                        }
                        System.out.println(msg);
                    }
                    System.out.println("收到数据，来自：" + request.toString());
                    // 响应结果
                    OutputStream outputStream = request.getOutputStream();
                    outputStream.write("HTTP/1.1 200 ok\r\n".getBytes());
                    outputStream.write("Content-Length: 40\r\n\r\n".getBytes());
                    outputStream.write("<button type=\\\"button\\\">Click Me!</button>".getBytes());
                } catch (Exception e) {
                    // TODO: handle exception
                } finally {
                    try {
                        request.close();
                    } catch (Exception e) {
                        // TODO: handle exception
                    }
                }
            });

        }
        serverSocket.close();
    }
}

浏览器访问服务器

概念总结：

BIO：blocking IO，资源不可用时，IO请求一直阻塞，直到收到反馈结果（有数据或超时）。

NIO：non-blocking IO，资源不可用时，IO请求离开返回，返回数据标识资源不可用。

同步IO：synchronous IO，应用阻塞在发送或接收数据的状态，直到数据成功传输或返回失败。

异步IO：asynchronous IO，应用发送或接收数据后立刻返回，实际处理时异步执行的。

 

 

 

 阻塞带来的问题：阻塞导致在处理网络I/O时，一个线程只能处理一个网络连接。