题目
使用IDEA 创建 MAVEN JAVA 项目
根据下图 在mysql数据库中创建员工表(t_employee)
创建实体类 Employee 并创建mapper映射文件(使用mybatis中的mapper映射文件)
以及测试类 对创建的mapper映射文件进行增删改查以及测试
项目目录结构
1.在数据库中创建表T_Employee(大小写无所谓)
DROP TABLE IF EXISTS t_employee;
CREATE TABLE t_employee (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(30) DEFAULT NULL,
age int(11) DEFAULT NULL,
birthday date DEFAULT NULL,
salary decimal(10,0) DEFAULT NULL,
PRIMARY KEY (id)
)
2.创建实体类Employee
package com.xiongluoluo.bean;
import lombok.*;
import java.math.BigDecimal;
import java.util.Date;
/**
* Created by Administrator on 2019/12/21 0021.
*/
@Getter
@Setter
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class Employee {
private int id;
private String name;
private int age;
private Date birthday;
private BigDecimal salary;
}
2.要使用mybatis的mapper映射文件,就必须先导入mybatis依赖,由于要和数据库进行交互,所以还要导入mysql连接数据库也就是JDBC的依赖.
2.1 pom.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.xiongluoluo</groupId>
<artifactId>mybatis1</artifactId>
<version>1.0.0</version>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.8</version>
<scope>provided</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.6</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<!--JDBC的依赖(在https://mvnrepository.com中搜索mysql,点击第一个即可)-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
</dependencies>
</project>
2.2 mybatis-config.xml文件
<?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="db.properties"/>
<typeAliases>
<package name="com.xiongluoluo.bean"/>
</typeAliases>
<environments default="mysql">
<environment id="mysql">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driverClassName}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/xiongluoluo/mapper/EmployeeMapper.xml"/>
</mappers>
</configuration>
2.3 EmployeeMapper.xml文件
<?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="test">
<resultMap id="employeeResultMap" type="Employee">
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="age" column="age"/>
<result property="birthday" column="birthday"/>
<result property="salary" column="salary"/>
</resultMap>
<select id="selectAllEmployee" resultMap="employeeResultMap">
/*查询全部*/
select id,name,age,birthday,salary from t_employee
</select>
<select id="selectEmployeeById" resultMap="employeeResultMap">
/* 根据id查询Employee*/
select id,name,age,birthday,salary from t_employee where id = #{id}
</select>
<insert id="insertEmployee" parameterType="Employee">
/*添加员工*/
insert into t_employee values(null,#{name},#{age},#{birthday},#{salary})
</insert>
<delete id="deleteEmployee" parameterType="int">
/*根据id删除员工*/
delete from t_employee where id = #{id}
</delete>
<update id="updateEmployee" parameterType="Employee">
/*更新员工信息*/
update t_employee set name = #{name},age=#{age},birthday=#{birthday},salary=#{salary} where id=#{id}
</update>
</mapper>
2.4 db.properties文件
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///test2
username=root
password=1234
4 测试类
package com.xiongluoluo.test;
import com.xiongluoluo.bean.Employee;
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.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.util.Date;
import java.util.List;
/**
* Created by Administrator on 2019/12/21 0021.
*/
public class MybatisTest {
//查询全部
@Test
public void testSelectAllEmployee(){
String resource = "mybatis-config.xml";
try {
InputStream is = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
List<Employee> list = sqlSession.selectList("selectAllEmployee");
for(Employee employee : list){
System.out.println(employee);
}
} catch (IOException e) {
e.printStackTrace();
}
}
//通过id查询Employee
@Test
public void testSelectEmployeeById(){
String resource = "mybatis-config.xml";
try {
InputStream is = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
Employee employee = sqlSession.selectOne("test.selectEmployeeById",7);
//namespace+id,参数
System.out.println(employee);
} catch (Exception e) {
e.printStackTrace();
}
}
//添加员工
@Test
public void testInsertEmployee(){
String resource = "mybatis-config.xml";
try {
InputStream is = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
Employee employee = new Employee();
employee.setName("熊落落");
employee.setAge(26);
employee.setBirthday(new Date());
employee.setSalary(new BigDecimal(5000));
int result = sqlSession.insert("test.insertEmployee", employee);
sqlSession.commit();
if(result>0){
System.out.println("插入成功!");
}else{
System.out.println("插入失败!");
}
sqlSession.commit();
sqlSession.close();
//增删改的时候一定要记得提交事务,不然数据库是不会更新的,这个跟之前不太一样,切记切记
} catch (Exception e) {
e.printStackTrace();
}
}
//删除员工
@Test
public void testDeleteEmployee(){
String resource = "mybatis-config.xml";
try {
InputStream is = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
int result = sqlSession.delete("test.deleteEmployee",20);
if(result>0){
System.out.println("删除成功!");
}else{
System.out.println("删除失败!");
}
sqlSession.commit();
sqlSession.close();
//提交事务,提交事务,提交事务!!!!
} catch (IOException e) {
e.printStackTrace();
}
}
//更新员工信息
@Test
public void testUpdateEmployee(){
String resource = "mybatis-config.xml";
try {
InputStream is = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
Employee employee = sqlSession.selectOne("test.selectEmployeeById", 7);
int result = sqlSession.update("test.updateEmployee", employee);
if(result>0){
System.out.println("更新成功!");
}else{
System.out.println("更新失败!");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
注释1:由于想多熟悉一下生成SqlSession那部分的代码,所以测试类的时候没有封装工具类.
注释2:有一个点需要注意,就是增删改的时候一定要提交事务,查询可以不提交,增删改一定不能忘,不然数据库中的值是不会改变的.
