思路：
1：根据xml配置文件（全局配置文件）创建一个SqlSessionFactory对象 有数据源一些运行环境信息
2：sql映射文件；配置了每一个sql，以及sql的封装规则等。，并写一个接口与它对应
3：将sql映射文件注册在全局配置文件中
4：写代码：
1）、根据全局配置文件得到SqlSessionFactory；
2）、使用sqlSession工厂，获取到sqlSession对象使用他来执行增删改查一个 sqlSession就是代表和数据库的一次会话，用完关闭
3）、使用sql的唯一标志来告诉MyBatis执行哪个sql。sql都是保存在sql映射文件中的。
创建employee表
CREATE TABLE Employee(
id INTEGER PRIMARY KEY auto_increment,
lastName VARCHAR(20) NOT NULL,
email VARCHAR(20) NOT NULL,
gendar VARCHAR(20) NOT NULL
)
Employee表
package com.atstudying.mybatis.bean;
import org.apache.ibatis.type.Alias;
public class Employee {
private Integer id;
private String lastName;
private String email;
private String gendar;
private Department dept;
public Employee() {
super();
}
public Employee(Integer id, String lastName, String email, String gender) {
super();
this.id = id;
this.lastName = lastName;
this.email = email;
this.gendar = gender;
}
public Department getDept() {
return dept;
}
public void setDept(Department dept) {
this.dept = dept;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getGender() {
return gendar;
}
public void setGender(String gender) {
this.gendar = gender;
}
@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email="
+ email + ", gender=" + gendar + "]";
}
}
1：根据xml配置文件（全局配置文件）创建一个SqlSessionFactory对象 有数据源一些运行环境信息
mybatis-config.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>
<properties resource="dbconfig.properties"></properties>
<settings>
<!-- <setting name="mapUnderscoreToCamelCase" value="true"/> -->
<setting name="jdbcTypeForNull" value="NULL"/>
<!--显示的指定每个我们需要更改的配置的值，即使他是默认的。防止版本更新带来的问题 -->
<!-- 延迟加载 -->
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="aggressiveLazyLoading" value="false"/>
</settings>
<typeAliases>
<package name="com.atguigu.mybatis.bean"/>
</typeAliases>
<environments default="dev_mysql">
<environment id="dev_mysql">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</dataSource>
</environment>
</environments>
<databaseIdProvider type="DB_VENDOR">
<!-- 为不同的数据库厂商起别名 -->
<property name="MySQL" value="mysql"/>
<property name="Oracle" value="oracle"/>
<property name="SQL Server" value="sqlserver"/>
</databaseIdProvider>
<mappers>
<package name="com.atguigu.mybatis.dao"/>
</mappers>
</configuration>
MyBatisTest.java
public SqlSessionFactory getSqlSessionFactory() throws IOException {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
return new SqlSessionFactoryBuilder().build(inputStream);
}
2：sql映射文件；配置了每一个sql，以及sql的封装规则等。，并写一个接口与它对应
EmployeeMapper.java
package com.atstudying.mybatis.dao;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.annotations.Param;
import com.atguigu.mybatis.bean.Employee;
public interface EmployeeMapper {
public Employee getEmpById(Integer id);
public Long addEmp(Employee employee);
public boolean updateEmp(Employee employee);
public Integer deleteEmpById(Integer id);
}
EmployeeMapper.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">
<mapper namespace="com.atstudying.mybatis.dao.EmployeeMapper">
<!--
namespace:名称空间;指定为接口的全类名
id：唯一标识
resultType：返回值类型
#{id}：从传递过来的参数中取出id值
public Employee getEmpById(Integer id);
-->
<insert id="addEmp" parameterType="com.atstudying.mybatis.bean.Employee"
useGeneratedKeys="true" keyProperty="id" databaseId="mysql">
insert into employee(lastName,email,gendar)
values(#{lastName},#{email},#{gendar})
</insert>
<!-- public void updateEmp(Employee employee); -->
<update id="updateEmp">
update employee
set lastName=#{lastName},email=#{email},gendar=#{gendar}
where id=#{id}
</update>
<!-- public void deleteEmpById(Integer id); -->
<delete id="deleteEmpById">
delete from employee where id=#{id}
</delete>
<select id="getEmpById" resultType="com.atstudying.mybatis.bean.Employee"
databaseId="mysql">
select * from employee where id = #{id}
</select>
</mapper>
3：将sql映射文件注册在全局配置文件中
4：写代码：
1）、根据全局配置文件得到SqlSessionFactory；
2）、使用sqlSession工厂，获取到sqlSession对象使用他来执行增删改查一个 sqlSession就是代表和数据库的一次会话，用完关闭
3）、使用sql的唯一标志来告诉MyBatis执行哪个sql。sql都是保存在sql映射文件中的。
MyBatisTest.java
public class MyBatisTest {
public SqlSessionFactory getSqlSessionFactory() throws IOException {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
return new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void test03() throws IOException{
SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
//1、获取到的SqlSession不会自动提交数据
SqlSession openSession = sqlSessionFactory.openSession();
try{
EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
//测试添加
Employee employee = new Employee(null, "jerry4","[email protected]", "1");
mapper.addEmp(employee);
System.out.println(employee.getId());
//测试修改
Employee employee = new Employee(2, "Tom", "[email protected]", "0");
boolean updateEmp = mapper.updateEmp(employee);
System.out.println(updateEmp);
//测试删除
Integer num=mapper.deleteEmpById(3);
System.out.println(num);
//2、手动提交数据
openSession.commit();
}finally{
openSession.close();
}
}
结果：
测试增删改查这一个过程中，我们可以得到如下结论
1、mybatis允许增删改直接定义以下类型返回值
Integer、Long、Boolean、void
2、我们需要手动提交数据
sqlSessionFactory.openSession();——》手动提交
sqlSessionFactory.openSession(true);——》自动提交
3，主键必须
< insert id=“addEmp” parameterType=“com.atstudying.mybatis.bean.Employee”
useGeneratedKeys=“true” keyProperty=“id” databaseId=“mysql”>
insert into employee(lastName,email,gendar)
values(#{lastName},#{email},#{gendar})
< /insert >
获取自增主键的值：
useGeneratedKeys=“true”；使用自增主键获取主键值策略
keyProperty；指定对应的主键属性，也就是mybatis获取到主键值以后，将这个值封装给javaBean的哪个属性
