mybatis配置

矫情吗；* 2022-06-02 03:26 121阅读 0赞

使用maven进行项目的创建

pom.xml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>first</groupId> <artifactId>com.xm</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>com.xm</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>4.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.4</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.37</version> </dependency> </dependencies> <build> <sourceDirectory>src</sourceDirectory> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> </project>

在使用mybatis时需要一个配置文件，如下为一个最基本的配置文件config.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> <settings>  <setting name="logImpl" value="STDOUT_LOGGING" /> </settings> <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" /> <property name="username" value="root" /> <property name="password" value="52005200" /> </dataSource> </environment> </environments> <mappers> <mapper resource="com/xm/mapper/usermapper.xml" /> </mappers> </configuration>

在conf.xml中dataSource中的property分别对应了jdbc的驱动类、数据库路径、数据库用户名、数据库密码

mappers 中是持久化类对应操作接口的配置文件(mapper 标签的resource 似乎是不区分大小写的)

数据库sql脚本：

CREATE TABLE IF NOT EXISTS `user` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(50) DEFAULT NULL, `age` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8; INSERT INTO `user` (`id`, `name`, `age`) VALUES (1, 'Neo', 35), (2, 'Jerry', 36);

持久化类User:

package com.xm.bean; /** * * @author liu * */ public class User { private String id; private String name; private int age; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "User [id=" + id + ", name=" + name + ", age=" + age + "]"; } }

UserMapping接口：

package com.xm.mapper; import com.xm.bean.User; /** * * @author liu * */ public interface UserMapping { /** * this method return a User by user_id * @param id * @return User */ public User getUser(Integer id); /** * this method return a User by user_age * @param age * @return User */ public User getUserByAge(Integer age); }

UserMappper.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.xm.mapper.UserMapping"> <select id="getUser" parameterType="Integer" resultType="com.xm.bean.User"> select * from user where id=#{id} </select> <select id="getUserByAge" parameterType="Integer" resultType="com.xm.bean.User"> select * from user where age=#{age} </select> </mapper>

测试用例：

package com.xm.test; import java.io.IOException; import java.io.InputStream; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import org.junit.Test; import com.xm.bean.User; import com.xm.mapper.UserMapping; public class MyBatisTest { @Test public void test() throws IOException { String resource = "conf.xml"; InputStream is = MyBatisTest.class.getClassLoader().getResourceAsStream(resource); SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is); SqlSession session = sessionFactory.openSession(); //法1 String statement = "com.xm.mapper.UserMapping.getUser";// 映射sql的标识字符串 User user = session.selectOne(statement, 1); System.out.println(user.toString()); //法2 UserMapping map = session.getMapper(UserMapping.class); User u1 = map.getUserByAge(35); System.out.println(u1); } }

结果：

![SouthEast][]

在测试中，采取了两种方式

法1为直接使用SqlSession对象中的selectOne方法传入的为配置文件中的方法id和参数

法2为使用getMapper获取接口，通过接口来执行数据库操作。

相对于法1来说，法2通过接口来执行语句，更加的便捷，省去了使用字符串的繁琐。

[SouthEast]: /images/20220602/c112101ddfc747d7a090b80cb03d04fe.png