1.1 Using Maven's quickstart framework
Note that the quickstart of w does not appear:
1.2 Add dependencies
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!--mybatis依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.1</version>
</dependency>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.9</version>
</dependency>
</dependencies>1.3 Introducing plugins
<build>
<!--资源插件：处理src/main/java目录中的xml-->
<resources>
<resource>
<directory> src/main/java</directory> <!--所在的目录-->
<includes><!--包括目录下的.properties,.xml文件都会扫描到-->
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>Note that the dao xml file can only be loaded into the target classes after the plug-in is added:
1.4 Create a Student entity class in the pojo package
package jiang.pojo;
public class Student {
private Integer id;
private String name;
private Integer age;
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 Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
'}';
}
public Student(Integer id, String name, Integer age) {
this.id = id;
this.name = name;
this.age = age;
}
public Student() {
}
}
1.5 Create the corresponding Student database
1.6 Create the StudentDao interface in the dao package
package jiang.dao;
import jiang.pojo.Student;
public interface StudentDao {
Student selectStudentById(Integer id);
}
1.7 Create a StudentDao.xml file in the dao package
Note: namespace, id, and resultType need to be modified; do not write semicolon after the sql statement;
<?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="jiang.dao.StudentDao"><!--namespace、id、resultType都需要修改-->
<select id="selectStudentById" resultType="jiang.pojo.Student">
<!--查询一个学生Student
<select>：表示查询操作，里面的select
id:要执行的sql语句的唯一表示。是一个自定义的字符串。
推荐使用dao接口中的方法名称
resultType:告诉mybatis，执行sql语句，把数据赋值给那个类型的java对象。
resultType的值现在使用的java对象的全限定名称,从java路径后开始写包路径
-->
SELECT * FROM student where id = 1
</select>
</mapper>1.8 Create resources resource package in main
1.9 Create mybatis.xml main configuration file in resources
Part to modify:
1. <property name="url" value="jdbc:mysql://localhost:3306/ study ?useUnicode=true&characterEncoding=utf-8"/> study is the name of the database!
2.<mapper resource="jiang/dao/StudentDao.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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<!--配置数据源:创建connection对象。-->
<dataSource type="POOLED">
<!--driver:驱动的内容-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<!--url:连接数据库的url-->
<property name="url" value="jdbc:mysql://localhost:3306/study?useUnicode=true&characterEncoding=utf-8"/>
<!--用户名-->
<property name="username" value="root"/>
<!--密码-->
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!--指定其他mapper文件的位置:找到其他文件的sql语句-->
<mappers>
<!--使用mapper的resource属性指定mapper文件路径
这个路径是从target/classes路径开启的
使用注意:
resoruce="mapper文件的路径，使用/分割路径"
一个mapper resource指定一个mapper文件
-->
<mapper resource="jiang/dao/StudentDao.xml"/>
</mappers>
</configuration>1.10 Create test content
package jiang;
import jiang.pojo.Student;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import org.apache.ibatis.io.Resources;
import java.io.IOException;
import java.io.InputStream;
public class MyTest {
@Test
public void test1() throws IOException {
//调用mybatis某个对象的方法，执行mapper文件中的sql语句
// mybatis核心类:sqlsessionFactory
//1.定义mybatis主配置文件的位置，从类路径开始的相对路径
String config = "mybatis.xml";
//2.读取主配置文件。使用mybatis框架中的Resources类
InputStream inputStream = Resources.getResourceAsStream(config);
//3.创建SqlSessionFactory对象，使用sqlSessionFactoryBuidler类
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
//4.获取SqlSession对象
SqlSession sqlSession = factory.openSession();
//5.指定要执行的sql语句的id
// sql的id = namespace+"."+ selectlupdate|insert |delete标签的id属性值(接口的方法名）
String sqlId = "jiang.dao.StudentDao"+"."+"selectStudentById";
//6.通过SqlSession方法，执行sql语句
Student student = sqlSession.selectOne(sqlId);
System.out.print("使用mybatis查询一个学生:"+student);
//7.关闭SqlSession对象
sqlSession.close();
}
}
The result of the operation is as follows:
1.11 Common Mistakes and Notes
a. The first line of the main configuration file cannot be empty, otherwise an error will be reported:
org.apache.ibatis.exceptions.PersistenceException:
### Error building SqlSession.
### Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: org.xml.sax.SAXParseException; lineNumber: 2 ; columnNumber: 6; Processing instruction targets matching "[xX][mM][lL]" are not allowed.
