MyBatis3-示例工程
一、准备工作：
0、新建QuitStart类型POM项目（即Application），Java Build Path为JDK1.8，Java Compiler为1.8，MySQL为5.5.38，数据库使用Test。MySQL驱动为5.1.38，MyBatis版本为3.4.4。由于不是Spring项目并且不使用数据库连接池，所以不引入Tomcat的DBCP连接池。
1、在MySQL中新建数据表及添加示例数据，脚本如下：
Create TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `userName` varchar(50) DEFAULT NULL, `userAge` int(11) DEFAULT NULL, `userAddress` varchar(200) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8; Insert INTO `user` VALUES ('1', 'jim', '100', 'guangdong,guangzhou');
注意：表类型应为InnoDB。
2、添加MyBatis3的依赖和MySQL的驱动依赖，POM配置如下：
<!-- mysql-connector-java --> <!-- http://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.38</version> </dependency> <!-- mybatis --> <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.4</version> </dependency>
二、实现步骤：
1、项目的整体结构如下所示：
2、配置POM，配置如下：
<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.jsoft.testmybatis</groupId> <artifactId>test1</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>test1</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <!-- mysql-connector-java --> <!-- http://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.38</version> </dependency> <!-- mybatis --> <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.4</version> </dependency> </dependencies> </project>
3、新建User.java的POJOs
package com.jsoft.testmybatis.models; public class User { private int id; private String userName; private String userAge; private String userAddress; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserAge() { return userAge; } public void setUserAge(String userAge) { this.userAge = userAge; } public String getUserAddress() { return userAddress; } public void setUserAddress(String userAddress) { this.userAddress = userAddress; } }
4、配置User.xml的SQL映射文件
<?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="com.jsoft.testmybatis.models.UserMapper"> <select id="selectUserByID" parameterType="int" resultType="User"> select * from user where id = #{id} </select> </mapper>
注意：这里的namespace只是做为一个名词不是真是存在的。
5、配置MyBatis对应的配置文件Configuration.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> <typeAliases> <typeAlias alias="User" type="com.jsoft.testmybatis.models.User" /> </typeAliases> <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://127.0.0.1:3306/Test?serverTimezone=UTC" /> <property name="username" value="root" /> <property name="password" value="root" /> </dataSource> </environment> </environments> <mappers> <mapper resource="com/jsoft/testmybatis/models/User.xml" /> </mappers> </configuration>
6、测试代码在App.java中
package com.jsoft.testmybatis.test1; import java.io.IOException; import java.io.InputStream; 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 com.jsoft.testmybatis.models.User; public class App { public static void main(String[] args) throws IOException { InputStream inputStream = Resources.getResourceAsStream("Configuration.xml"); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession session = sqlSessionFactory.openSession(); try { User user = (User) session.selectOne("com.jsoft.testmybatis.models.UserMapper.selectUserByID", 1); System.out.println(user.getUserAddress()); System.out.println(user.getUserName()); } finally { session.close(); } } }
7、测试结果如下：
三、解释说明：
1.Configuration.xml是MyBatis用来建立SessionFactory用的，里面主要包含了数据库连接相关东西，还有Java类所对应的别名，比如<typeAlias alias="User" type="com.jsoft.testmybatis.models.User"/>这个别名非常重要，在具体的类的映射中，比如User.xml中resultType就是对应这里的。要保持一致，当然这里的resultType还有另外单独的定义方式。
2. Configuration.xml里面的<mapper resource="com/jsoft/testmybatis/models/User.xml"/>是包含要映射的类的XML配置文件。
3. 在User.xml文件里面主要是定义各种SQL语句，以及这些语句的参数，以及要返回的类型等。
测试工程：https://github.com/easonjim/5_java_example/tree/master/mybatis/test1
参考：
http://www.yihaomen.com/article/java/303.htm（注意，这个例子里面用的版本是3.2.0-SNAOPSHOT，因此不会报错，如果按照这个例子使用3.2.0版本会报错，想要解决请参考：http://www.cnblogs.com/EasonJim/p/7050312.html）
