要点

有另一种方法来完成语句映射。 它们映射的语句可以不用 XML 来配置，而可以使用 Java 注解来配置。

使用注解来映射简单语句会使代码显得更加简洁，但对于稍微复杂一点的语句，Java 注解不仅力不从心，还会让你本就复杂的 SQL 语句更加混乱不堪。

如果你需要做一些很复杂的操作，最好用 XML 来映射语句。

需要在config.xml中注册Java接口

<mappers> <mapper class="com.mybatis.DAO.PeopleMapper"/></mappers>

要用class=

查

public interface PeopleMapper { @Select("select * from people") List<People> getPeopleList();}

增
可以先开启事务自动提交

public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(true); }}

Mapper.java

public interface PeopleMapper { @Select("select * from people") List<People> getPeopleList(); @Insert("insert into people(id, name, age, address) VALUES (#{id},#{name},#{age},#{address})") int addPeople(People people);}

test

public class PeopleDAOtest { @Test public void print() { SqlSession sqlSession = MybatisUtils.getSqlSession(); PeopleMapper peopleMapper = sqlSession.getMapper(PeopleMapper.class); List<People> people = peopleMapper.getPeopleList(); for (People p :people){ System.out.println(p); } sqlSession.close(); } @Test public void add(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); PeopleMapper peopleMapper = sqlSession.getMapper(PeopleMapper.class); peopleMapper.addPeople(new People(6,"圣迭戈",456,"啥地方")); print(); }}

因为已经自动提交了，所以不需要sqlSession.commit();

删

注解@Param

只能用于基本数据类型

传入的参数只能和sql语句中参数一样

多个参数

样例

public interface PeopleMapper { @Delete("delete people from people where id=#{uid}") int delPeople(@Param("uid") int i);}

test

public class PeopleDAOtest { @Test public void del(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); PeopleMapper peopleMapper = sqlSession.getMapper(PeopleMapper.class); peopleMapper.delPeople(6); print(); }}

改

Mapper.java

public interface PeopleMapper { @Update("update mybatis.people set name=#{name} ,age=#{age} ,address=#{address} where id=#{id}") int updateP(People people);}

test

public class PeopleDAOtest { @Test public void update(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); PeopleMapper peopleMapper = sqlSession.getMapper(PeopleMapper.class); peopleMapper.updateP(new People(5,"圣迭戈",456,"啥地方")); print(); }}

总结

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