1. 开发步骤
①添加MyBatis的坐标 ②创建user数据表 ③编写User实体类 ④编写映射⽂件UserMapper.xml ⑤编写核⼼⽂件SqlMapConfig.xml ⑥编写测试类 2. 环境搭建 1)导⼊MyBatis的坐标和其他相关坐标<properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.encoding>UTF-8</maven.compiler.encoding> <java.version>1.8</java.version> <maven.compiler.source>1.8</maven.compiler.source> <maven.compiler.target>1.8</maven.compiler.target> </properties> <!--mybatis坐标--> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <!--mysql驱动坐标--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.6</version> <scope>runtime</scope> </dependency> <!--单元测试坐标--> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <!--⽇志坐标--> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.12</version> </dependency>2) 创建user数据表
3) 编写User实体
public class User { private int id; private String username; private String password; //省略get个set⽅法 }4)编写UserMapper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="userMapper"> <select id="findAll" resultType="com.lagou.domain.User"> select * from User </select> </mapper>5) 编写MyBatis核⼼⽂件
<!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"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql:///test"/> <property name="username" value="root"/> <property name="password" value="root"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/lagou/mapper/UserMapper.xml"/> </mappers> </configuration>6) 编写测试代码
//加载核⼼配置⽂件 InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml"); //获得sqlSession⼯⼚对象 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream); //获得sqlSession对象 SqlSession sqlSession = sqlSessionFactory.openSession(); //执⾏sql语句 List<User> userList = sqlSession.selectList("userMapper.findAll"); //打印结果 System.out.println(userList); //释放资源 sqlSession.close();
3. MyBatis的增删改查操作
MyBatis的插⼊数据操作 1)编写UserMapper映射⽂件 <mapper namespace="userMapper"> <insert id="add" parameterType="com.lagou.domain.User"> insert into user values(#{id},#{username},#{password}) </insert> </mapper> 2)编写插⼊实体User的代码 InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream); SqlSession sqlSession = sqlSessionFactory.openSession(); int insert = sqlSession.insert("userMapper.add", user); System.out.println(insert); //提交事务 sqlSession.commit(); sqlSession.close(); 3)插⼊操作注意问题 • 插⼊语句使⽤insert标签 • 在映射⽂件中使⽤parameterType属性指定要插⼊的数据类型 •Sql语句中使⽤#{实体属性名}⽅式引⽤实体中的属性值•插⼊操作使⽤的API是sqlSession.insert(“命名空间.id”,实体对象); •插⼊操作涉及数据库数据变化,所以要使⽤sqlSession对象显示的提交事务,即sqlSession.commit() MyBatis的修改数据操作 1)编写UserMapper映射⽂件 <mapper namespace="userMapper"> <update id="update" parameterType="com.lagou.domain.User"> update user set username=#{username},password=#{password} where id=# {id} </update> </mapper> 2)编写修改实体User的代码 InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream); SqlSession sqlSession = sqlSessionFactory.openSession(); int update = sqlSession.update("userMapper.update", user); System.out.println(update); sqlSession.commit(); sqlSession.close(); 3)修改操作注意问题 • 修改语句使⽤update标签 • 修改操作使⽤的API是sqlSession.update(“命名空间.id”,实体对象); MyBatis的删除数据操作 1)编写UserMapper映射⽂件 <mapper namespace="userMapper"> <delete id="delete" parameterType="java.lang.Integer"> delete from user where id=#{id} </delete> </mapper> 2)编写删除数据的代码InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream); SqlSession sqlSession = sqlSessionFactory.openSession(); int delete = sqlSession.delete("userMapper.delete",3); System.out.println(delete); sqlSession.commit(); sqlSession.close(); 3)删除操作注意问题 • 删除语句使⽤delete标签 •Sql语句中使⽤#{任意字符串}⽅式引⽤传递的单个参数 •删除操作使⽤的API是sqlSession.delete(“命名空间.id”,Object);