MyBatis案例四：基于注解的学生管理程序

在数据库中创建一个学生表s_student和班级表c_class

要求：

1.查询id为2的学生信息；

2.将id为4的学生姓名修改为李雷，年龄修改为21；

3.增加一条学生信息（5，赵六，19，1）；

4.删除id为1的学生信息；

5.查询姓名为赵六，年龄为20的学生信息；

6.一对多查询出二班所有学生的信息；

7.一对一查询出id=2的学生信息；

步骤：

1.创建表

2.创建持久化类Student、Class1

package com.xiao.pojo;


public class Student {
    private Integer id;
    private String name;
    private Integer age;
    private Integer cid;
    private Class1 classId;

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public Class1 getClassId() {
        return classId;
    }

    public void setClassId(Class1 classId) {
        this.classId = classId;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", age=" + age +
                ", cid=" + cid + "classId=" + classId +
                '}';
    }
}

package com.xiao.pojo;

import java.util.List;


public class Class1 {
    private Integer id;
    private String classname;
    private List studentList;

    public Integer getId() {
        return id;
    }

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

    public String getClassname() {
        return classname;
    }

    public void setClassname(String classname) {
        this.classname = classname;
    }

    public List getStudentList() {
        return studentList;
    }

    public void setStudentList(List studentList) {
        this.studentList = studentList;
    }

    @Override
    public String toString() {
        return "Class{" +
                "id=" + id +
                ", classname='" + classname + ''' + "studentList=" + studentList +
                '}';
    }
}

3.在src/main/java创建com.xiao.dao包，包下创建StudentMapper、ClassMapper接口

package com.xiao.dao;

import com.xiao.pojo.Student;
import org.apache.ibatis.annotations.*;

import java.util.List;


public interface StudentMapper {
    //(1)查询id=2的学生信息
    @Select("select * from s_student where id = #{id}")
    Student selectStudentById(int id);
    //(2)将id=4的学生姓名修改为李雷，年龄修改为21
    @Update("update s_student set name = #{name},age = #{age} " + "where id = #{id}")
    int updateStudent(Student student);
    //(3）增加一条学生信息（赵六，19，1）；
    @Insert("Insert into s_student(name,age,cid)" + "values(#{name},#{age},#{cid})")
    int insertStudent(Student student);
    //(4)删除id=1的学生信息
    @Delete("delete from s_student where id = #{id}")
    int deleteStudentById(int id);
    //(5)查询姓名为赵六，年龄为19的学生信息；
    @Select("select * from s_student where name = #{param01} and age = #{param02}")
    Student selectStudentByNameAndAge(@Param("param01") String name,@Param("param02") int age);
    //（6）一对多查询出二班所有学生的信息
    @Select("select * from s_student where cid = #{id}")
    @Results({@Result(id = true,column = "id",property = "id"),
            @Result(column = "name",property = "name"),
            @Result(column = "age",property = "age")})
    List selectStudentByCid(int cid);
    //(7)一对一查询出id=4的学生所有信息
    @Select("select * from s_student where id = #{id}")
    @Results({@Result(column = "cid",property = "classId",
    one = @One(select = "com.xiao.dao.ClassMapper.selectClassById"))})
    Student selectStudentWithClass(int id);
}

package com.xiao.dao;

import com.xiao.pojo.Class1;
import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;


public interface ClassMapper {
    //（6）一对多查询出二班所有学生的信息
    @Select("select * from c_class where id = #{id}")
    @Results({@Result(id = true,property = "id",column = "id"),
            @Result(property = "classname",column = "classname"),
            @Result(column = "id",property = "studentList",
            many = @Many(select = "com.xiao.dao.StudentMapper.selectStudentByCid"))})
    Class1 selectStudentByClass(int id);
    //(7)一对一查询出id=4的学生所有信息
    @Select("select * from c_class where id = #{id}")
    Class1 selectClassById(int id);
}

4.在mybatis-config.xml引入接口

5.创建测试类

package Test;

import com.xiao.dao.ClassMapper;
import com.xiao.dao.StudentMapper;
import com.xiao.pojo.Class1;
import com.xiao.pojo.Student;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import utils.MyBatisUtils;


public class mybatisTest {
    SqlSession sqlSession = MyBatisUtils.getSession();
    //(1)查询id=2的学生信息
    @Test
    public void findStudentById(){
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectStudentById(2);
        System.out.println(student.toString());
        sqlSession.close();
    }
    //(2)将id=4的学生姓名修改为李雷，年龄修改为21
    @Test
    public void updateStudent(){
        Student student = new Student();
        student.setId(4);
        student.setName("李雷");
        student.setAge(21);
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        int update = mapper.updateStudent(student);
        if (update > 0){
            System.out.println("成功修改了" + update + "条数据！");
        }else {
            System.out.println("修改失败！");
        }
        System.out.println(student.toString());
        sqlSession.commit();
        sqlSession.close();
    }
    //(3）增加一条学生信息（5,赵六，19，1）；
    @Test
    public void insertStudent(){
        Student student = new Student();
        student.setId(5);
        student.setName("赵六");
        student.setAge(19);
        student.setCid(1);
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        int insert = mapper.insertStudent(student);
        if (insert > 0){
            System.out.println("成功添加了" + insert + "条数据！");
        }else {
            System.out.println("添加失败！");
        }
        System.out.println(student.toString());
        sqlSession.commit();
        sqlSession.close();
    }
    //(4)删除id=1的学生信息
    @Test
    public void deleteStudentById(){
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        int delete = mapper.deleteStudentById(1);
        if (delete > 0){
            System.out.println("成功删除了" + delete + "条数据！");
        }else {
            System.out.println("删除失败！");
        }
        sqlSession.commit();
        sqlSession.close();
    }
    //(5)查询姓名为赵六，年龄为19的学生信息；
    @Test
    public void findStudentByNameAndAge(){
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectStudentByNameAndAge("赵六",19);
        System.out.println(student.toString());
        sqlSession.close();
    }
    //（6）一对多查询出二班所有学生的信息
    @Test
    public void selectStudentByClass(){
        ClassMapper mapper = sqlSession.getMapper(ClassMapper.class);
        Class1 class1 = mapper.selectStudentByClass(2);
        System.out.println(class1.toString());
        sqlSession.close();
    }
    //(7)一对一查询出id=4的学生所有信息
    @Test
    public void selectStudentWithClass(){
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectStudentWithClass(4);
        System.out.println(student.toString());
        sqlSession.close();
    }
}