MyBatis入門
最近入門了mybatis，怕以後忘記，做個入門筆記
mybatis的環境搭建
第一步：創建maven工程並導入座標
pom.xml
<?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>org.example</groupId>
<artifactId>MybatisTest</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.4</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.48</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
</project>
第二步：創建實體類和dao的接口
注意：實體類的列名應與實體類的成員變量一致
User.java
package com.itheima.test;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable {
private Integer id;
private String username;
private Date birthday;
private String sex;
private String address;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", birthday=" + birthday +
", sex='" + sex + '\'' +
", address='" + address + '\'' +
'}';
}
}
IUserDao.java
package com.itheima.dao;
import com.itheima.test.User;
import java.util.List;
public interface IUserDao {
/*
* 查詢所有操作
* @return
*
* */
List<User> findAll();
}
第三步：創建mybatis的主配置文件 SqlMapConifg.xml
SqlMapConifg.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">
<!--主配置文件-->
<configuration>
<!--配置環境 -->
<environments default="mysql">
<!--配置mysql的環境-->
<environment id="mysql">
<!--配置事物類型-->
<transactionManager type="JDBC"></transactionManager>
<!--配置數據源（連接池）-->
<dataSource type="POOLED">
<!--配置數據庫的基本信息-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/xscj?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="520China"/>
</dataSource>
</environment>
</environments>
<!--指定映射配置文件的位置，映射配置文件指的是每個dao獨立的配置文件-->
<mappers>
<mapper resource="com/itheima/dao/IUserDao.xml"/>
</mappers>
</configuration>
第四步：創建映射配置文件 IUserDao.xml
IUserDao.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.itheima.dao.IUserDao">
<!--配置查詢所有-->
<select id="findAll" resultType="com.itheima.test.User" >
select * from user
</select>
</mapper>
注意事項：
- mybatis的映射配置文件位置要與dao接口包結構相同
- 映射配置文件mapper標籤的spacename屬性的取值必須是dao接口的全限定類名
- 映射配置文件的操作配置（select），id的取值必須是dao接口的方法名
mybatis入門案例
1.在resources下寫一個配置文件 log4j.properties，如下：
#Set root category priority to INFO and its only appender to CONSOLE.
#Log4j.rootCategory=INFO,CONSOLE debug info warn error fatal
log4j.rootCategory=debug,CONSOLE,LOGFILE
#Set the enterprise logger category to FATAL and its only appender to CONSOLE.
log4j.logger.org.apache.axis.enterprise=FATAL,CONSOLE
#CONSOLE is set to be a ConsoleAppender using A PatternLayout.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
#LOGFILE is set to be a File appender using a PatternLayout.
log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:\axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
2.在test下寫個測試類 MyBatisTest.java 如下：
package com.itheima.test;
import com.itheima.dao.IUserDao;
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;
import java.util.List;
public class MyBatisTest {
/*
* 入門
* */
public static void main(String[] arg) throws IOException {
//1.讀取配置文件
InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2.創建SqlSessionFactory工廠
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//3.使用工廠生產SqlSession對象
SqlSession session = factory.openSession();
//4.使用SQLSession創建dao接口的代理對象
IUserDao userDao = session.getMapper(IUserDao.class);
//5.使用代理對象執行方法
List<User> users = userDao.findAll();
for(User user:users){
System.out.println(user);
}
//6.釋放資源
session.close();
in.close();
}
}
運行結果：
與數據庫一樣
自此就入門完成了。