Java根据前端返回的字段名进行查询数据的实现方法

package com.example.demo.entity;
 
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
 
    // Getters and Setters
    public Long getId() {
        return id;
    }
 
    public void setId(Long id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public Integer getAge() {
        return age;
    }
 
    public void setAge(Integer age) {
        this.age = age;
    }
 
    public String getEmail() {
        return email;
    }
 
    public void setEmail(String email) {
        this.email = email;
    }
}

package com.example.demo.mapper;
 
import com.example.demo.entity.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.SelectProvider;
import org.apache.ibatis.jdbc.SQL;
 
import java.util.List;
import java.util.Map;
 
public interface UserMapper {
 
    @SelectProvider(type = UserSqlProvider.class, method = "dynamicSelect")
    List<User> dynamicSelect(@Param("params") Map<String, Object> params);
 
    class UserSqlProvider {
        public String dynamicSelect(@Param("params") Map<String, Object> params) {
            return new SQL() {{
                SELECT("*");
                FROM("user");
                if (params != null && !params.isEmpty()) {
                    for (Map.Entry<String, Object> entry : params.entrySet()) {
                        WHERE(entry.getKey() + " = #{params." + entry.getKey() + "}");
                        // 注意：这里为了简单起见，只考虑了单个字段的等值查询，
                        // 实际应用中可以扩展为支持多个字段、多种条件的查询
                        break; // 如果有多个字段，需要修改这里的逻辑，比如使用 AND 连接多个条件
                    }
                }
            }}.toString();
        }
    }
}

package com.example.demo.service;
 
import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
@Service
public class UserService {
 
    @Autowired
    private UserMapper userMapper;
 
    public List<User> queryByField(String fieldName, Object value) {
        Map<String, Object> params = new HashMap<>();
        params.put(fieldName, value);
        return userMapper.dynamicSelect(params);
    }
}

package com.example.demo.controller;
 
import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
 
import java.util.List;
 
@RestController
@RequestMapping("/users")
public class UserController {
 
    @Autowired
    private UserService userService;
 
    @GetMapping("/query")
    public List<User> queryByField(@RequestParam String fieldName, @RequestParam Object value) {
        return userService.queryByField(fieldName, value);
    }
}

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/your_database?useSSL=false&serverTimezone=UTC
    username: your_username
    password: your_password
    driver-class-name: com.mysql.cj.jdbc.Driver
 
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.example.demo.entity

CREATE TABLE user (
    id BIGINT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    age INT,
    email VARCHAR(100)
);

复制代码

http://localhost:8080/users/query?fieldName=name&value=John