1.在src/main/java文件中新建一个包存放mapper接口，包名要符合命名规范

2.新建一个接口，接口名字要语义化，eg：UserMapper

public interface UserMapper {
    @Select("select * from t_user where id=#{id}")
    public User findById(int id);
    @Insert("insert into t_user (name,pwd,birthday,age) values(#{name},#{pwd},#{birthday},#{age})")
    public int save(User user);
    @Update("update t_user set name=#{name},pwd=#{pwd},birthday=#{birthday},age=#{age} where id=#{id}")
    public int update(User user);
    @Delete("delete from t_user where id=#{id}")
    public int del(int id);
}

3.在src/main/java文件中新建一个包存放实体类，包名要符合命名规范

4.类名为数据库中表名，属性为表的列

public class User {
    private int id;
    private String name;
    private String pwd;
    private Date birthday;
    private String age;
    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 getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    public User(String name, String pwd, Date birthday, String age) {
        super();
        this.name = name;
        this.pwd = pwd;
        this.birthday = birthday;
        this.age = age;
    }
    @Override
    public String toString() {
        return "用户id=" + id + ", 用户名=" + name + ", 用户密码=" + pwd + ", 生日=" + birthday + ", 
　　　　　　　　　年龄=" + age;
    }
    
}