引入pom支持，此处使用mysql数据库

<!-- MYSQL -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- Spring Boot JDBC -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

配置文件增加数据库链接

#Mysql
spring.datasource.url=jdbc:mysql://localhost:3306/duck
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=org.gjt.mm.mysql.Driver

添加实体类SysUser

package com.duck.bean;

public class SysUser {
    public Integer id;
    public String realName;
    public String loginName;
    public String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getRealName() {
        return realName;
    }

    public void setRealName(String realName) {
        this.realName = realName;
    }

    public String getLoginName() {
        return loginName;
    }

    public void setLoginName(String loginName) {
        this.loginName = loginName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

添加Service接口，SysUserService

package com.duck.service;

import com.duck.bean.SysUser;

import java.util.List;
import java.util.Map;

public interface SysUserService {

    List<SysUser> querySysUser(Map map);

}

添加实现类SysUserServiceImpl，并引入JdbcTemplate模板，实现SysUserService接口

package com.duck.service;

import com.duck.bean.SysUser;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Service;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

@Service
public class SysUserServiceImpl implements SysUserService{

    @Autowired
    JdbcTemplate jdbcTemplate;

    public List<SysUser> querySysUser(Map map){
        String sql = "select * from sys_user ";
        return jdbcTemplate.query(sql, new RowMapper<SysUser>() {
            @Override
            public SysUser mapRow(ResultSet resultSet, int i) throws SQLException {
                SysUser sysUser = new SysUser();
                sysUser.setId(resultSet.getInt("id"));
                sysUser.setLoginName(resultSet.getString("login_name"));
                sysUser.setRealName(resultSet.getString("real_name"));
                sysUser.setPassword(resultSet.getString("password"));
                return sysUser;
            }
        });
    }

}

Controller增加访问入口方法，并访问

@RequestMapping("querySysUser")
    public @ResponseBody List<SysUser> querySysUser(){
        logger.info("查询用户");
        List<SysUser> sysUserList = sysUserService.querySysUser(new HashMap());
        return sysUserList;
    }

image.png

项目结构如下

image.png