mybatis01
Mybatis
一.创建一个项目的基本步骤
1.搭建环境
1.1使用sql语句创建一个数据库和表
CREATE DATABASE `jcl`;
USE `jcl`;
CREATE TABLE lei_xing (
id int NOT NULL auto_increment,
leixing varchar(100),
PRIMARY KEY (id)
);
CREATE TABLE dian_ying (
id int NOT NULL auto_increment,
leixing_id int DEFAULT NULL,
ming varchar(100) DEFAULT NULL,
yanyuan varchar(20) DEFAULT NULL,
daoyan varchar(20) DEFAULT NULL,
piaojia float DEFAULT NULL,
tupianlujing varchar(500) DEFAULT NULL,
PRIMARY KEY (id),
CONSTRAINT dian_ying_ibfk_1 FOREIGN KEY (leixing_id) REFERENCES lei_xing (id)
) ;
insert into lei_xing(id,leixing) values (1,'动画');
insert into lei_xing(id,leixing) values (2,'动作');
insert into lei_xing(id,leixing) values (3,'爱情');
insert into lei_xing(id,leixing) values (4,'喜剧');
insert into lei_xing(id,leixing) values (5,'惊悚');
insert into lei_xing(id,leixing) values (6,'3D');
insert into lei_xing(id,leixing) values (7,'其它');
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (1,1,'哪吒','哪吒','不知道',100);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (2,2,'复仇者联盟4','唐尼','我',20);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (3,3,'呵呵','哈哈','怀藏族',22);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (4,1,'魔童降世','申公豹','姜太公',10);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (5,4,'魔童降世2','申公豹','姜太公',20);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (6,3,'魔童降世3','姜子牙','菩提祖师',30);
insert into dian_ying(id,leixing_id,ming,yanyuan,daoyan,piaojia) values (7,3,'魔童降世4','姜子牙','菩提祖师他姐',40);
1.2创建maven项目
创建maven项目，删除src，导入maven jar包
<dependencies>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.11version>
<scope>testscope>
dependency>
<dependency>
<groupId>org.mybatisgroupId>
<artifactId>mybatisartifactId>
<version>3.5.9version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>8.0.25version>
dependency>
<dependency>
<groupId>org.slf4jgroupId>
<artifactId>slf4j-apiartifactId>
<version>1.7.5version>
dependency>
<dependency>
<groupId>log4jgroupId>
<artifactId>log4jartifactId>
<version>1.2.17version>
dependency>
dependencies>
1.3创建一个模块
编写mybatis的配置文件
<configuration>
<environments default="xxx">
<environment id="xxx">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/film?serverTimezone=Asia/Shanghai"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
dataSource>
environment>
environments>
<mappers>
<mapper resource="mapper/LeiXingMapper.xml">mapper>
mappers>
configuration>
编写mybitsUtils工具类
package com.jcl.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.InputStream;
//mybatis工具类
public class mybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try {
String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}catch(IOException e){
e.printStackTrace();
}
}
// 通过SqlSessionFactory的opensession（）方法来获取SqlSession
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
1.4编写代码
实体类
package com.study.entity;
public class LeiXing {
/*
* id
* leiXing
*/
private Integer id;//int 不可以表示null，而包装类可以
private String leiXing;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLeiXing() {
return leiXing;
}
public void setLeiXing(String leiXing) {
this.leiXing = leiXing;
}
@Override
public String toString() {
return "LeiXing{" +
"id=" + id +
", leiXing='" + leiXing + '\'' +
'}';
}
}
Dao接口
public interface LeiXingMapper {
List<LeiXing> getLeiXingList();
}
接口实现类 (由原来的UserDaoImpl转换为一个Mapper配置文件)
<mapper namespace="com.jcl.dao.LeiXingMapper">
<select id="getLeiXingList" resultType="com.jcl.pojo.LeiXing">
select * from lei_xing
select>
mapper>
1.5测试
junit测试
Q：
- build配置resource中存在资源导出失败的问题
- 配置文件的注册
- 方法名不同
- 返回类型不对
- maven导出资源问题
package com.jcl.dao;
import com.jcl.pojo.LeiXing;
import com.jcl.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class LeiXingMapperTest {
@Test
public void test(){
// z 1.获取sqlsession对象
SqlSession sqlSession = MybatisUtils.getSqlSession();
// 2.执行SQL
// sqlSession.getMapper从LeiXingMapper.class得到了leiXingMapper对象，在调用对象的方法
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
List<LeiXing> list = leiXingMapper.getLeiXingList();
for (LeiXing leiXing : list) {
System.out.println(leiXing);
}
// 3.关闭Session
sqlSession.close();
}
}
二.CRUD
接口，mapper.xml Test
1、namespace
namespace中的包名要和Dao/mapper接口的包名一致！
2、select
查询语句；
id：对应namespace中的方法名
resultType：Sql语句执行的返回值！
parameterType:参数类型
3、insert
useGeneratedKeys 取得自增的id值，返回到keyproperty所设置的属性中
public interface LeiXingMapper {
//获取全部的类型数据
List<LeiXing> getLeiXingList();
//根据id查询类型
LeiXing getLeiXingById(int id);
//插入一个类型
void addLeiXing(LeiXing leiXing);
//修改一个类型
void updateLeiXing(LeiXing leiXing);
//删除一个类型
void deleteLeiXing(int id);
}
<select id="getLeiXingById" resultType="com.jcl.pojo.LeiXing" parameterType="int">
select * from lei_xing where id = #{id}
select>
<insert id="addLeiXing" parameterType="com.jcl.pojo.LeiXing">
insert into lei_xing(id,leixing)values(#{id},#{leixing})
insert>
<update id="updateLeiXing" parameterType="com.jcl.pojo.LeiXing">
update lei_xing set leixing=#{leixing} where id=#{id};
update>
<delete id="deleteLeiXing" parameterType="int">
delete from lei_xing where id = #{id}
delete>
public class LeiXingMapperTest {
@Test
public void getLeiXingListTest(){
// 1.获取sqlsession对象
SqlSession sqlSession = MybatisUtils.getSqlSession();
// 2.执行SQL
// sqlSession.getMapper从LeiXingMapper.class得到了leiXingMapper对象，在调用对象的方法
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
List<LeiXing> list = leiXingMapper.getLeiXingList();
for (LeiXing leiXing : list) {
System.out.println(leiXing.toString());
}
// 3.关闭Session
sqlSession.close();
}
@Test
public void getLeiXingByIdTest(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
LeiXing leiXing = leiXingMapper.getLeiXingById(1);
System.out.println(leiXing);
sqlSession.close();
}
@Test
public void addLeiXingTest(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
leiXingMapper.addLeiXing(new LeiXing(666,"jcl"));
// 提交事物
sqlSession.commit();
sqlSession.close();
}
@Test
public void updateLeiXingTest(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
leiXingMapper.updateLeiXing(new LeiXing(666,"jclnb"));
sqlSession.commit();
sqlSession.close();
}
@Test
public void deleteLeiXingTest(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
LeiXingMapper leiXingMapper = sqlSession.getMapper(LeiXingMapper.class);
leiXingMapper.deleteLeiXing(666);
sqlSession.commit();
sqlSession.close();
}
}
3、增删查改是要提交事物
sqlSession.commit();
2.1Map
假设实体类参数过多，或者数据库中的表，字段，或者参数过多，要考虑使用map