Mybatis注解开发

1.注解的概述

常用注解：

@Select(“查询的 SQL 语句”)：执行查询操作注解

@Insert(“查询的 SQL 语句”)：执行新增操作注解

@Update(“查询的 SQL 语句”)：执行修改操作注解

@Delete(“查询的 SQL 语句”)：执行删除操作注解

2.注解实现查询的操作

1.创建接口和查询方法

2.在核心配置文件中配置映射关系

3.编写测试类

例：

bean.Student：

package Mybatis4.bean;
 
public class Student {
    private Integer id;
    private String name;
    private Integer age;
 
    public Student() {
    }
 
    public Student(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
 
    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;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

Mapper接口 ：

package Mybatis4.mapper;
 
import Mybatis4.bean.Student;
import org.apache.ibatis.annotations.Select;
 
import java.util.List;
 
public interface StudentMapper {
    //查询全部
    @Select("SELECT * FROM student")
    public abstract List selectAll();
}

MyBatisConfig.xml ：

<mappers>
        <package name="Mybatis4.mapper"/>
    mappers>
    

测试类：

package Mybatis4.test;
 
import Mybatis4.bean.Student;
import Mybatis4.mapper.StudentMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
 
import java.io.InputStream;
import java.util.List;
 
public class Test01 {
    @Test
    public void selectAll() throws Exception{
        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MybatisConfig.xml");
        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通过工厂对象获取SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.获取StudentMapper接口的实现类对象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.调用实现类的方法，接收结果
        List list = mapper.selectAll();
        //6.处理结果
        for (Student student : list) {
            System.out.println(student);
        }
        //7.释放资源
        sqlSession.close();
        is.close();
    }
}

3.注解实现新增的操作 

1.创建新增方法

2.编写测试类

Mapper接口：

//新增操作: sql的参数与之前的写法一致，从insert方法的参数中获取对应属性值
@Insert("INSERT INTO student VALUES (#{id},#{name},#{age})")
public abstract Integer insert(Student stu);

测试类：

@Test
    public void insert() throws Exception{
        //1.加载核心配置文件
        InputStream is = Resources.getResourceAsStream("MybatisConfig.xml");
        //2.获取SqlSession工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通过工厂对象获取SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.获取StudentMapper接口的实现类对象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.调用实现类的方法，接收结果
        Student stu = new Student(4,"赵六",26);
        Integer result = mapper.insert(stu);
        //6.处理结果
        System.out.println(result);
        //7.释放资源
        sqlSession.close();
        is.close();
    }

 4.注解实现修改的操作

1.创建修改方法

2.编写测试类

Mapper接口：

//修改操作
@Update("UPDATE student SET name=#{name},age=#{age} WHERE id=#{id}")
public abstract Integer update(Student stu);

测试类：

@Test
public void update() throws Exception{
    InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
    SqlSession sqlSession = sqlSessionFactory.openSession(true);
    StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 
    Student stu = new Student(4,"赵六",36);
    Integer result = mapper.update(stu);
    System.out.println(result);
 
    sqlSession.close();
    is.close();
}

5.注解实现删除操作

1.创建删除方法

2.编写测试类

Mapper接口：

//删除操作
    @Delete("DELETE FROM student WHERE id=#{id}")
    public abstract Integer delete(Integer id);

测试类：

@Test
public void delete() throws Exception{
    InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
    SqlSession sqlSession = sqlSessionFactory.openSession(true);
    StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
 
    Integer result = mapper.delete(4);
    System.out.println(result);
 
    sqlSession.close();
    is.close();
}

注：映射配置关系

<mappers> 
    <package name="接口所在包"/> 
mappers>