在程序处理过程中我们一般都需要和数据库进行交互，从数据库获取结果之后需要将相应的结果转换为程序对应实体对象，基于JDBC底层的需要我们进行手动的设置，比较繁琐，为此诞生了例如：hibernate。Mybatis等orm框架（Object Relational Mapping，对象关系映射模型）。 一般我们在程序中如果需要使用mybatis一般需要进行如下配置：
首先是pom配置： <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.6</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.36</version> </dependency> 基于xml配置mybatis-config.xml配置： <?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="jdbc.properties"/> <typeAliases> <typeAlias type="com.leo.test.mybatis.entity.Person" alias="person"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <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/leo/test/mybatis/mapper/PersonMapper.xml"/> <!--或者使用 <package name="com.leo.test.mybatis.mapper"/> --> </mappers> </configuration> 编写mapper配置文件和mapper接口： <!--- PersonMapper.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.leo.test.mybatis.mapper.PersonMapper"> <select id="selectPerson" resultType="person"> select * from person where id = #{id} </select> </mapper> public interface PersonMapper { public Person selectPerson(int id); } 启动类： public class Bootstrap { private static SqlSessionFactory sqlSessionFactory; static { String config = "mybatis-config.xml"; try (InputStream inputStream = Resources.getResourceAsStream(config)) { sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) { SqlSession sqlSession = null; try{ sqlSession = getSqlSession(); PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class); Person person = personMapper.selectPerson(1); System.out.println(person.getName()); }finally { close(sqlSession); } } public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(); } public static void close(SqlSession sqlSession){ if(sqlSession != null){ try{ sqlSession.close(); }catch(Exception e){ e.printStackTrace(); } } } }完全基于代码的处理如下：
// PersonMapperByAnnotation.java public interface PersonMapperByAnnotation { @Select(value = "select * from person where id = #{id}") public Person selectPerson(int id); } // Bootstrap .java public class Bootstrap { public static void main(String[] args) { PooledDataSource dataSource = new PooledDataSource(); dataSource.setDriver("com.mysql.jdbc.Driver"); dataSource.setUrl("jdbc:mysql://10.201.83.207:3306/test"); dataSource.setUsername("root"); dataSource.setPassword("123456"); TransactionFactory transactionFactory = new JdbcTransactionFactory(); Environment environment = new Environment("test",transactionFactory,dataSource); Configuration configuration = new Configuration(environment); configuration.getTypeAliasRegistry().registerAlias("person", Person.class); configuration.addMapper(PersonMapperByAnnotation.class); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration); SqlSession sqlSession = sqlSessionFactory.openSession(); PersonMapperByAnnotation mapper = sqlSession.getMapper(PersonMapperByAnnotation.class); Person p = mapper.selectPerson(1); System.out.println(p.getName()); } }