Mybatis框架 使用接口Mapper实现数据库的crud操作
2024-09-26 21:00:35
Mybatis的Mapper接口方式实现简单crud操作:
1.创建实体类 与数据库对应
我的实体类是《Student》
package com.hxzy.mybatis.pojo; import lombok.Data; @Data
public class Student {
private Integer s_id;
private String s_name;
private String s_address; /**
* 有参构造方法
* @param s_id
* @param s_name
* @param s_address
*/
public Student(Integer s_id, String s_name, String s_address) {
this.s_id = s_id;
this.s_name = s_name;
this.s_address = s_address;
} /**
* 无参构造
*/
public Student() { } @Override
public String toString() {
return "Student{" +
"s_id=" + s_id +
", s_name='" + s_name + '\'' +
", s_address='" + s_address + '\'' +
'}';
}
}
2.我的数据库表是student 《注意表字段要和实体类对应!!》
3.创建配置文件 (一般放在接口包中 ,名字为 接口名+Mapper.xml)
我的名字是 Student_Mapper.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">
<!--
配置namespace 这个路径就是接口所在的路径
-->
<mapper namespace="com.hxzy.mybatis.pojo.Student_Mapper"> <select id="select_student" parameterType="int" resultType="com.hxzy.mybatis.pojo.Student">
select * from student where s_id = #{id}
</select> <select id="select_all_student" resultType="com.hxzy.mybatis.pojo.Student" >
select * from student;
</select> <select id="du_student" resultType="com.hxzy.mybatis.pojo.Student" parameterType="String">
select * from student where student.s_name like "${value}%"
</select> <select id="insert_student" parameterType="com.hxzy.mybatis.pojo.Student">
insert into student values(#{s_id},#{s_name},#{s_address})
</select> <delete id="delete_student" parameterType="String">
delete from student where student.s_name = #{name}
</delete> <update id="update_student" parameterType="com.hxzy.mybatis.pojo.Student">
update student set student.s_name = #{s_name} where student.s_id = #{s_id}
</update> </mapper>
4.创建核心配置文件 (这个时候mybatis的配置文件 一般都叫 Mybatis_cfg.xml)
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="test1"> <!--配置数据库的信息-->
<environment id="test1">
<!--开启JDBC的事务-->
<transactionManager type="JDBC"></transactionManager>
<!--配置一些必要的信息-->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://127.0.0.1:3306/stu"></property>
<property name="username" value="root" ></property>
<property name="password" value="gubin"></property>
</dataSource>
</environment>
</environments>
<!--p配置核心配置文件-->
<mappers>
<mapper resource="student_Mapper.xml"></mapper>
</mappers>
</configuration>
5. 创建接口 (接口里面的方法名 就是Student_Mapper.xml的id)
package com.hxzy.mybatis.pojo; import java.util.List; public interface Student_Mapper {
/**
* 查询单个学生
* @param i
* @return
*/
Student select_student(int i);
/**
* 查询全部的学生
*/
List<Student> select_all_student();
/**
* 查询姓杜的学生
*/
List<Student> du_student(String str);
/**
* 添加学生
*/
void insert_student(Student student);
/**
* 删除学生
*/
void delete_student(String str);
/**
* 修改学生
*/
void update_student(Student student);
}
编写测试类:
package com.hxzy.mybatis.test; import com.hxzy.mybatis.entity.SqlSession_entity;
import com.hxzy.mybatis.pojo.Student;
import com.hxzy.mybatis.pojo.Student_Mapper;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test; import java.util.List; public class Test_mybatis {
/**
* 查询单个学生
*/
@Test
public void select_student(){
//得到SqlSession 对象
SqlSession session = SqlSession_entity.getSession();
//此处省略了Statement语句的编写
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
//加载interface中的方法
Student student = student_mapper.select_student(1);
session.close();
System.out.println(student);
}
/**
* 查询多个学生
*/
@Test
public void select_all_student(){
//获得Session对象
SqlSession session = SqlSession_entity.getSession();
//反射技术 将接口加载到内存
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
//将返回结果存入集合中
List<Student> list = student_mapper.select_all_student();
//增强for遍历
for (Student student : list) {
System.out.println(student);
}
session.close();
}
/**
* 查询所有姓杜的学生
*/
@Test
public void test_du(){
//获得Session
SqlSession session = SqlSession_entity.getSession();
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
List<Student> list = student_mapper.du_student("杜");
System.out.println(list);
session.close();
}
/**
* 添加学生
*/
@Test
public void tst_add(){
//获得Session
SqlSession session = SqlSession_entity.getSession();
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
//添加值
student_mapper.insert_student(new Student(5,"黄小斌","石家庄"));
//提交
session.commit();
//关闭
session.close();
}
/**
* 删除学生
*/
@Test
public void delete_student()
{
SqlSession session = SqlSession_entity.getSession();
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
student_mapper.delete_student("刘啊文");
session.commit();
session.close();
}
/**
* 修改学生
*/
@Test
public void update_student()
{
SqlSession session = SqlSession_entity.getSession();
System.out.println();
Student_Mapper student_mapper = session.getMapper(Student_Mapper.class);
student_mapper.update_student(new Student(4,"小阿六","避暑山庄")); session.commit();
session.close();
} }
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