环境测试

1.数据库建立ssm库，建立user表

2.user实体类

public class User {

    private int id;
    private String name;
    private String password;

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

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

3.UserDao

public interface UserDao {
    public User queryUserById(int id);
}

4.UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="org.example.ssm.dao.UserDao">
    <select id="queryUserById" parameterType="int" resultType="org.example.ssm.vo.User">
        select *
        from user
        where id=#{id}
    </select>
</mapper>

5.UserService

@Service
public class UserService {
    @Autowired
    private UserDao userDao;

    public User queryUserById(int id){
        return userDao.queryUserById(id);
    }
}

6.UserController

@Controller
public class UserController {

    @Resource
    private UserService userService;

    @RequestMapping("user")
    public String user(int id, Model model){
        User user=userService.queryUserById(id);
        model.addAttribute("user",user);
        return "hello";
    }
}