Contents

• 数据交换格式
  • JSON数据编码和解码
    • 编码
    • 解码
  • 案例：聊天工具

21.4. 数据交换格式

21.4.1. JSON数据编码和解码

编码

package com.a51work.cn;

import com.a51work.cn.org.json.JSONArray;
import com.a51work.cn.org.json.JSONException;
import com.a51work.cn.org.json.JSONObject;

public class Json_encode {
    public static void main(String[] args) {
        try {
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("name", "hujianli");
            jsonObject.put("age", 30);

            JSONArray jsonArray = new JSONArray();
            jsonArray.put(1).put(3);
            jsonObject.put("a", jsonArray);
            // 编码完成
            System.out.println(jsonObject.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

解码

package com.a51work.cn;

import com.a51work.cn.org.json.JSONArray;
import com.a51work.cn.org.json.JSONException;
import com.a51work.cn.org.json.JSONObject;

public class JSON_decode {
    public static void main(String[] args) {
        String jsonString = "{\"name\":\"tony\", \"age\":30, \"a\":[1, 3]}";
        try {
            JSONObject jsonObject = new JSONObject(jsonString);
            String name = jsonObject.getString("name");
            System.out.println("name : " + name);
            int age = jsonObject.getInt("age");
            System.out.println("age : " + age);
            JSONArray jsonArray = jsonObject.getJSONArray("a");
            int n1 = jsonArray.getInt(0);
            System.out.println("数组a第一个元素 : " + n1);
            int n2 = jsonArray.getInt(1);
            System.out.println("数组a第二个元素 : " + n2);
        } catch (
                JSONException e) {
            e.printStackTrace();
        }
    }
}

21.4.2. 案例：聊天工具

JSON_chatServer.java

package com.a51work.cn;

import com.a51work.cn.org.json.JSONObject;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

public class JSON_ChatServer {
    public static void main(String[] args) {
        System.out.println("服务器运行...............");
        Thread t = new Thread(() -> {
            try (// 创建一个ServerSocket监听端口8080客户请求
                 ServerSocket server = new ServerSocket(8080);
                 // 使用accept()阻塞等待客户端请求
                 Socket socket = server.accept();
                 DataInputStream in = new DataInputStream(socket.getInputStream());
                 DataOutputStream out = new DataOutputStream(socket.getOutputStream());
                 BufferedReader keyboardIn = new BufferedReader(new InputStreamReader(System.in))) {
                while (true) {
                    /* 接收数据 */
                    String str = in.readUTF();
                    // JSON解码
                    JSONObject jsonObject = new JSONObject(str);
                    //打印接收的数据
                    System.out.printf("从客户端接收的数据：%s\n", jsonObject);

                    /* 发送数据 */
                    // 读取键盘输入的字符串
                    String keyboardInputString = keyboardIn.readLine();
                    // 结束聊天
                    if (keyboardInputString.equals("bye")) {
                        break;
                    }
                    // 编码
                    jsonObject = new JSONObject();
                    jsonObject.put("message",keyboardInputString);
                    jsonObject.put("userid","acid");
                    jsonObject.put("username","hujianli1");

                    //发送
                    out.writeUTF(jsonObject.toString());
                    out.flush();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        });

        t.start();

    }
}

JSON_chatClient.java

package com.a51work.cn;

import com.a51work.cn.org.json.JSONObject;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.Socket;

public class JSON_ChatClient {
    public static void main(String[] args) {
        System.out.println("客户端运行..............");
        Thread t = new Thread(() -> {
            try (//  向127.0.0.1主机8080端口发出连接请求
                 Socket socket = new Socket("127.0.0.1", 8080);
                 DataInputStream in = new DataInputStream(socket.getInputStream());
                 DataOutputStream out = new DataOutputStream(socket.getOutputStream());
                 BufferedReader keyboardIn = new BufferedReader(new InputStreamReader(System.in))) {
                while (true) {
                    /* 发送数据 */
                    // 读取键盘输入的字符串
                    String keyboardInputString = keyboardIn.readLine();
                    //结束聊天
                    if (keyboardInputString.equals("bye")) {
                        break;
                    }
                    JSONObject jsonObject = new JSONObject();
                    jsonObject.put("message", keyboardInputString);
                    jsonObject.put("userid", "javaee");
                    jsonObject.put("username", "胡建力2");

                    //发送
                    out.writeUTF(jsonObject.toString());
                    out.flush();
                    //接收数据
                    String str = in.readUTF();
                    jsonObject = new JSONObject(str);
                    //打印接收的数据
                    System.out.printf("从服务器接收的数据：【%s】\n", str);
                }
            } catch (Exception e) {
                System.out.println("服务器暂时未启动........");
            }
            System.out.println("客户端停止！");
        });
        t.start();
    }
}