使用MyBatis必要配置如下：
(1) MyBatis配置信息，mybatis.xml
- mybatis.xml中配置数据库必须的基本信息：驱动，url，用户名，密码等必须信息，最大连接数，超时等非必须信息。
- 配置实体类映射配置文件（mapper标签下配置实体类配置文件路径）
- IDEA文件目录中的位置src/resource/mybatis.xml
(2) 实体类映射及数据库表操作方法配置 xxxMapper.xml
- xxxMapper.xml用于配置数据中表与实体类的映射关系，拼接数据库CRUD字符串。
- 配置文件位置和配置方式可参考 https://blog.csdn.net/bestcxx/article/details/72966768 本例配置文件放在resource下原路径
MyBatis使用案例
用例简介：对学生信息进行管理，数据库字段包括 s_id,s_name,s_height
1.项目中导入MyBatis依赖（maven或直接下载jar导入）
2.添加mybatis配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd" >
<configuration>
<!--默认连接环境信息-->
<environments default="mysql_developer">
<!--连接环境信息 取任意一个-->
<environment id="mysql_developer">
<!--表示mybatis使用什么方式管理（jdbc）-->
<transactionManager type="JDBC"></transactionManager>
<!--表示mybatis使连接池获取连接-->
<dataSource type="POOLED">
<!--配置数据库必要的4个属性-->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&useSSL=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
<environment id="oracle_developer">
<!--表示mybatis使用什么方式管理（jdbc）-->
<transactionManager type="JDBC"></transactionManager>
<!--表示mybatis使连接池获取连接-->
<dataSource type="POOLED">
<!--配置数据库必要的4个属性-->
<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:@localhost:1521:mybatis"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mybatis/StudentMapper.xml"/>
</mappers>
</configuration>
3.封装MyBatis工具类
package utils;
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 java.io.IOException;
import java.io.Reader;
public class MyBatisUtil {
private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<>();
private static SqlSessionFactory sqlSessionFactory;
private MyBatisUtil() {
}
static {
try {
Reader reader = Resources.getResourceAsReader("mybatis.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 获取SqlSession
*/
public static SqlSession getSqlSesson() {
//从当前线程获取sqlSession对象
SqlSession sqlSession = threadLocal.get();
if (sqlSession == null && sqlSessionFactory != null) {
sqlSession = sqlSessionFactory.openSession();
//将sqlsession与当前线程绑定起来
threadLocal.set(sqlSession);
}
return sqlSession;
}
/**
* 关闭 SqlSession
*/
public static void closeSqlSesson() {
SqlSession sqlSession = threadLocal.get();
if (sqlSession != null) {
//关闭sqlSession
sqlSession.close();
//分开当前线程与 SqlSession，目的让GC尽早回收
threadLocal.remove();
}
}
}
4.编写Student实体类，StudentDao，StudentDaoImpl
Student实体类
package com.test.mybatis;
public class Student {
private Integer id;
private String name;
private Float height;
public Student(Integer id, String name, Float height) {
this.id = id;
this.name = name;
this.height = height;
}
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 Float getHeight() {
return height;
}
public void setHeight(Float height) {
this.height = height;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", height=" + height +
'}';
}
}
StudentDao接口
package com.test.mybatis;
import java.util.List;
interface StudentDao {
void add(Student student);
boolean deleteById(int id);
boolean deleteAll();
Student findById(int id);
List<Student> findAll();
void update(Student student);
}
StudentDaoImpl接口实现类
package com.test.mybatis;
import org.apache.ibatis.session.SqlSession;
import utils.MyBatisUtil ;
import java.util.List;
/**
* @author 45000460
*/
public class StudentDaoImpl implements StudentDao{
/**
* 增加
*/
@Override
public void add(Student student) {
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil .getSqlSesson();
sqlSession.insert(Student.class.getName() + ".addBean", student);
sqlSession.commit();
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
/**
* 根据ID删除
*/
@Override
public boolean deleteById(int id) {
SqlSession sqlSession = null;
boolean isSuccess = false;
try {
sqlSession = MyBatisUtil .getSqlSesson();
int count = sqlSession.delete(Student.class.getName() + ".deleteById", id);
sqlSession.commit();
isSuccess = count != 0;
return isSuccess;
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
/**
* 删除所有
*/
@Override
public boolean deleteAll() {
SqlSession sqlSession = null;
boolean isSuccess = false;
try {
sqlSession = MyBatisUtil .getSqlSesson();
int count = sqlSession.delete(Student.class.getName() + ".deleteAll");
sqlSession.commit();
isSuccess = count != 0;
return isSuccess;
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
/**
* 通过id查询
*/
@Override
public Student findById(int id) {
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil .getSqlSesson();
Student student = sqlSession.selectOne(Student.class.getName() + ".findBeanById", id);
sqlSession.commit();
return student;
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
/**
* 查询所有
*/
@Override
public List<Student> findAll() {
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil .getSqlSesson();
List<Student> studentList = sqlSession.selectList(Student.class.getName() + ".findAll");
sqlSession.commit();
return studentList;
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
/**
* 更新（修改）
*/
@Override
public void update(Student student) {
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtil .getSqlSesson();
sqlSession.update(Student.class.getName() + ".update", student);
sqlSession.commit();
} catch (Exception e) {
sqlSession.rollback();
System.out.println(e.getMessage());
throw e;
} finally {
MyBatisUtil .closeSqlSesson();
}
}
//测试
public static void main(String[] strings) {
StudentDaoImpl studentDaoImpl = new StudentDaoImpl();
studentDaoImpl.add(new Student(null, "小明", 180.0f));
//根据ID查询
// Student student = studentDaoImpl.findById(16);
// System.out.println(student.toString());
////查询所有学生
// List<Student> list = studentDaoImpl.findAll();
// for (Student student : list) {
// System.out.println(student.toString());
// }
//修改学生信息
// Student student = studentDaoImpl.findById(15);
// System.out.println("原数据：\n" + student.toString());
// student.setName("修改后名字2");
// studentDaoImpl.update(student);
// Student student2 = studentDaoImpl.findById(15);
// System.out.println("修改后数据：\n" + student2.toString());
// 根据ID删除学生数据
// studentDaoImpl.deleteById(14);
// 删除所有数据
// studentDaoImpl.deleteAll();
}
}
5.配置Student实体类与数据库的对应关系（否则程序无法找到实体类属性与数据库字段之间的对应关系），需要依赖配置文件StudentMapper.xml(在mybatis配置文件中mapper标签中配置)
配置 StudentMapper.xml:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- 映射文件，解决数据库表和实体类的关系 -->
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<!-- namespace属性 名称空间，必须唯一 -->
<mapper namespace="com.test.mybatis.Student">
<!-- resultMap 映射实体与表-->
<!-- id 表示实体与表的映射去一个唯一名字-->
<!-- type 表示实体全路径名-->
<!--当实体属性与表字段不相同的时候必须配置一下代码 ，且查询返回值类型使用resultMap=resultMap的ID-->
<!--当实体属性与表字段相同的时候可选 查询返回值使用 resultType -->
<resultMap id="studentMap" type="com.test.mybatis.Student">
<!-- id 标签：映射主键属性-->
<!-- result 标签：映射非主键属性-->
<!-- property 属性： 实体的属性名 -->
<!--column 属性 表的字段名 -->
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="height" column="height"/>
</resultMap>
<!-- insert 属性 ：要书写insert sql语句-->
<!-- id 属性： 表示insert为sql语句取唯一的名字 -->
<!-- parameterType 属性 要执行dao 中方法的参数 ，如果是类的话，必须使用全路径类-->
<insert id="add">
insert into students(id,name,height)values (1,"小明",180)
</insert>
<insert id="addBean" parameterType="com.test.mybatis.Student">
insert into students(id,name,height)values (#{id},#{name},#{height})
</insert>
<!--根据ID删除-->
<delete id="deleteById" parameterType="int">
delete from students where id=#{id}
</delete>
<!--删除所有-->
<delete id="deleteAll" >
delete from students
</delete>
<!--根据id查询学生-->
<select id="findBeanById" parameterType="int" resultType="com.test.mybatis.Student">
select * from students where id=#{id}
</select>
<!--查询所有学生，结果保存在集合中 配置时只需要写出返回值集合中的数据类型即可 即Student的全路径名即可-->
<select id="findAll" resultType="com.test.mybatis.Student">
select * from students
</select>
<!--更新-->
<update id="update" parameterType="com.test.mybatis.Student">
update students set name=#{name},height = #{height} where id=#{id}
</update>
</mapper>
指定StudentMapper.xml配置文件路径
...
<mappers>
<mapper resource="com.test.mybatis/StudentMapper.xml"/>
</mappers>
测试用例结构目录：
测试用例结构目录.png
网友评论