what is java socket programming

java socket programming refers to the process of using Java language for network communication, including operations such as establishing connections, transmitting data, and closing connections. Java provides two classes, java.net.Socket and java.net.ServerSocket, to support Socket programming.

Java Socket programming refers to the process of using Java language for network communication, including operations such as establishing connections, transmitting data, and closing connections. Java provides two classes, java.net.Socket and java.net.ServerSocket, to support Socket programming.

1. Basic knowledge of Socket

1.1 Overview of Socket

Socket refers to the "socket", which is the bridge between the application layer and the transport layer and is used on the network. Perform two-way communication. In Socket programming, the communication between the client and the server needs to be implemented through Socket. The client sends a request to the server through Socket, and the server returns a response after receiving the request, completing the entire communication process.

1.2 Socket communication model

Socket communication model is divided into two types: TCP and UDP. TCP is a reliable transmission protocol that guarantees the integrity and orderliness of data and is suitable for scenarios that require reliable transmission. UDP is a connectionless transmission protocol. It does not guarantee the integrity and orderliness of data. It is suitable for real-time communication, streaming media transmission and other scenarios.

1.3 Socket programming process

The Socket programming process generally includes the following steps

1. Create a Socket object (client) or ServerSocket object (server)
2. Bind Socket address.
3. Start the listening process (server) or connection process (client)
4. Send or receive data.
5. Close the connection.

2. Java Socket Programming Implementation

2.1 Create Socket Object

The client needs to create a Socket object to connect to the server, and the server needs to create a ServerSocket object to wait for the client connect. The method of creating Socket and ServerSocket is as follows

// 创建 Socket
Socket socket = new Socket(String host, int port);
// 创建 ServerSocket
ServerSocket serverSocket = new ServerSocket(int port);

where host represents the server address and port represents the port number.

2.2 Bind Socket address

Before establishing a connection, the Socket needs to be bound to a local address and port for data transmission. The method of binding the Socket address is as follows

// 绑定 Socket 地址
socket.bind(SocketAddress bindpoint);

where bindpoint is the address and port to be bound.

2.3 Start the listening process or connection process

After creating the ServerSocket object, you need to call the accept() method to start waiting for the client's connection request. After creating the Socket object, you need to call the connect() method to connect to the server. The connection process is as follows

// 服务器等待连接
Socket socket = serverSocket.accept();
// 客户端连接服务器
socket.connect(SocketAddress endpoint);

where endpoint is the server address and port.

2.4 Send or receive data

After the connection is established, the client can use the OutputStream in the Socket to send data to the server, and the server can use the InputStream in the Socket to receive the data sent by the client. . The client can use InputStream in Socket to receive data sent by the server, and the server can use OutputStream in Socket to send data to the client. The methods of sending and receiving data are as follows

// 客户端向服务器发送数据
OutputStream outputStream = socket.getOutputStream();
outputStream.write(byte[] b);
// 服务器向客户端发送数据
InputStream inputStream = socket.getInputStream();
inputStream.read(byte[] b);

where byte[] b represents the data to be sent or received.

2.5 Close the connection

After the communication ends, the connection needs to be closed to release resources. The method of closing the connection is as follows

socket.close();
serverSocket.close();

3. Precautions for Java Socket programming

3.1 Port number issue

The port number used in Socket programming must be a non-system Reserve the port, otherwise it will cause an error that the port is occupied.

3.2 Handling Abnormal Situations

In Socket programming, various abnormal situations may occur in network communication, such as connection timeout, connection interruption, etc. Therefore, when writing a Socket program, possible exceptions should be handled.

3.3 Network load

When programming Socket, you should consider the problem of network load. If the network load is too high, it may cause connection failure or data transmission failure.

4. Summary

Java Socket programming is a programming method based on network communication, which can realize two-way communication between the client and the server. In Socket programming, two classes, Socket and ServerSocket, need to be used to implement network communication. Issues such as network load and abnormal conditions also need to be considered.

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