原始数据库表信息
创建一个maven项目 导入依赖，包括mysql驱动，mybatis依赖还有junit测试 <!--导入依赖--> <dependencies> <!--mysql驱动--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.49</version> </dependency> <!--mybatis--> <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.6</version> </dependency> <!--junit--> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> </dependency> </dependencies> 添加build标签设置，防止maven资源导入失败 <build> <resources> <resource> <directory>src/main/resources</directory> <filtering>true</filtering> <includes> <include>**/*.xml</include> <include>**/*.properties</include> </includes> </resource> <resource> <directory>src/main/java</directory> <filtering>true</filtering> <includes> <include>**/*.xml</include> <include>**/*.properties</include> </includes> </resource> </resources> </build> 创建bean类：User。bean类的属性最好和数据库表的字段一致，不然需要使用resultMap结果集映射 public class User { private int id; private String name; private String pwd; @Override public String toString() { return "User{" + "id=" + id + ", name='" + name + '\'' + ", pwd='" + pwd + '\'' + '}'; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } public User() { } public User(int id, String name, String pwd) { this.id = id; this.name = name; this.pwd = pwd; } } 创建一个接口，定义一个通过id查询用户的方法 public interface UserMapper { User getUserById(int id); } 编写对应的实现接口的配置文件UserMapper.xml，这里的文件名需要与对应的接口的名字一致。 <?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.test.dao.UserMapper"> <select id="getUserById" resultType="com.test.pojo.User"> select * from mybatis.user where id = #{id}; </select> </mapper> 编写一个properties文件，存储用于数据库连接的相关信息，比如用户名，密码，驱动类全限定名，数据库连接url db.properties driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis username=root password=root 编写Mybatis的核心配置文件 mybatis-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> <properties resource="db.properties"/> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <!--use the information of properties with $--> <property name="driver" value="${driver}"/> <property name="url" value="${url}"/> <property name="username" value="${username}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/test/dao/UserMapper.xml"/> </mappers> </configuration> 编写核心工具类 public class MybatisUtils { private static SqlSessionFactory sqlSessionFactory; static { try { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static SqlSession getSqlSession(){ SqlSession sqlSession = sqlSessionFactory.openSession(); return sqlSession; } } 测试 @Test public void getUserById(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); User user = mapper.getUserById(1); System.out.println(user); sqlSession.close(); }结果：
User{id=3, name='a3', pwd='123456'}