目录
1、 MyBatis是什么？
官网：mybatis – MyBatis 3 | 简介
2、Mybatis解决哪些问题？
3、开始创建工程
【1】创建Maven项目
【2】pom.xml依赖
<?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>
<!--自定义-->
<groupId>com.qinluyu</groupId>
<artifactId>Mybatis01</artifactId>
<version>1.0-SNAPSHOT</version>
<!--Mybatis-->
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.7</version>
</dependency>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<!--mysql版本5-6之间-->
<version>5.1.45</version>
</dependency>
<!--测试test-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<!--maven-->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<!--jdk-->
<target>1.8</target>
<source>1.8</source>
</configuration>
</plugin>
</plugins>
</build>
</project>【3】mybatis.xml依赖
<?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="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT"/>
<property name="username" value="${root}"/>
<property name="password" value="${123}"/>
</dataSource>
</environment>
</environments>
<!--映射文件-->
<mappers>
<mapper resource="com.qinluyu.Dao.Team.xml"/>
</mappers>
</configuration>
【4】实体类
public class Team {
private Integer teamId;
private String teamName;
private String location;
private Date createTime;
get/set方法
tostring方法【5】实体类的映射文件
【6】测试类
private String resource="mybatis.xml";
@Test
public void test02(){
SqlSession sqlSession=null;
try{
Reader reader=Resources.getResourceAsReader(resource);
SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(reader);//根据图纸创建出了工厂
sqlSession=factory.openSession();
//执行sql
List<Team> list=sqlSession.selectList("com.qinluyu.Dao.Team.queryAll");
//遍历结果
for(Team team:list){
System.out.println(team);
}
}catch(IOException e){
e.printStackTrace();
}finally{
//关闭资源
sqlSession.close();
}【7】发现一个BUG,Team.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.qinluyu.pojo.Team">
<!--查询,id为自定义名称，相当于dao-->
<select id="queryAll" resultType="com.qinluyu.pojo.Team">
<!--<select id="queryAll" resultMap="com.qinluyu.pojo.Team">-->此为BUG
select * from team;
</select>
</mapper>【8】结果
【9】改进，使用@Before@After
public class TestTeam {
private String resource="mybatis.xml";
private SqlSession sqlSession;
@Test
public void test02(){
System.out.println("改进————,查询单个");
Team team = sqlSession.selectOne("com.qinluyu.pojo.Team.queryOne", 1002);
System.out.println(team);
}
@Before
public void before(){
Reader reader=null;
try {
reader=Resources.getResourceAsReader(resource);
} catch (IOException e) {
e.printStackTrace();
}
SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(reader);
sqlSession=factory.openSession();
}
@After
public void after(){
sqlSession.close();
}
4、日志的使用
【1】pom.xml
<!--日志的使用-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>【2】log4j.properties
# Global logging configuration info warning error
log4j.rootLogger=DEBUG,stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n【3】mybatis.xml
<!--注意顺序
configuration (properties?, settings?, typeAliases?, typeHandlers?, objectFactory?, objectWrapperFactory?, reflectorFactory?, plugins?, environments?, databaseIdProvider?, mappers
-->
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>【4】结果
5、建造者设计模式介绍
6、#{} 和 ${}的区别
【1】#{}
【2】${}
7、动态SQL
更新
<update id="updateAuthorIfNecessary">
update Author
<set>
<if test="username != null">username=#{username},</if>
<if test="password != null">password=#{password},</if>
<if test="email != null">email=#{email},</if>
<if test="bio != null">bio=#{bio}</if>
</set>
where id=#{id}
</update>8、分页
【1】pom.xml
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>5.2.0</version>
</dependency>【2】mybatis.xml
<!--分页-->
<plugins>
<plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
<!--<property name="reasonable" value="true"/>-->
</plugins>【3】测试
public void test5() {
// PageHelper.startPage 必须紧邻查询语句，而且只对第一条查询语句生效
PageHelper.startPage(2, 5);
List<Team> teams = teamMapper.queryAll();//查询语句结尾不能有分号
teams.forEach(team -> System.out.println(team));
PageInfo<Team> info = new PageInfo<>(teams);
System.out.println("分页信息如下：");
System.out.println("当前页:" + info.getPageNum());
System.out.println("总页数:" + info.getPages());
System.out.println("前一页:" + info.getPrePage());
System.out.println("后一页:" + info.getNextPage());
System.out.println("navigatepageNums:" + info.getNavigatepageNums());
for (int num : info.getNavigatepageNums()) {
System.out.println(num);
}
