java mysql查询中文乱码

-- 修改数据库字符集
ALTER DATABASE your_database_name CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 修改表字符集
ALTER TABLE your_table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

String url = "jdbc:mysql://localhost:3306/your_database_name?useUnicode=true&characterEncoding=utf8mb4";

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/your_database_name?useUnicode=true&characterEncoding=utf8mb4

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class MySQLExample {
    public static void main(String[] args) {
        try {
            // 加载JDBC驱动
            Class.forName("com.mysql.cj.jdbc.Driver");

            // 配置连接字符串，指定字符集为utf8mb4
            String url = "jdbc:mysql://localhost:3306/your_database_name?useUnicode=true&characterEncoding=utf8mb4";
            String user = "your_username";
            String password = "your_password";

            // 建立连接
            Connection conn = DriverManager.getConnection(url, user, password);

            // 创建Statement对象
            Statement stmt = conn.createStatement();

            // 执行查询
            ResultSet rs = stmt.executeQuery("SELECT * FROM your_table_name");

            // 处理结果集
            while (rs.next()) {
                System.out.println(rs.getString("your_column_name"));
            }

            // 关闭资源
            rs.close();
            stmt.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}