MyBatis - DAO接口不需要实现类分析(上)

/**  
 * 类UserMapper.java的实现描述：TODO 类实现描述  
 * @author yuezhihua 2015年7月9日 上午11:18:30 
 */  
public interface UserMapper {      
    /** 
     * 根据用户id查询用户角色 
     * @param userId 
     * @return 
     */  
    @Select("select * from role_main a INNER JOIN user_role b ON a.id = b.role_id WHERE b.user_id=#{userId}")  
    public List<RolePO> getRolesByUserId(@Param("userId")Integer userId);  
    /** 
     * 根据用户id查询用户角色名 
     * @param userId 
     * @return 
     */  
    @Select("select a.role_name from role_main a INNER JOIN user_role b ON a.id = b.role_id WHERE b.user_id=#{userId}")  
    public Set<String> getRoleNamesByUserId(@Param("userId")Integer userId);  
    /** 
     * 根据userid查询用户的所有权限 
     * @param userId 
     * @return 
     */  
    @Select("SELECT a.permission_name FROM permission_main a INNER JOIN role_permission b ON a.id=b.permission_id WHERE b.role_id IN (SELECT d.role_id from user_main c INNER JOIN user_role d ON c.id = d.user_id WHERE c.id=#{userId})")  
    public Set<String> getPermissionsByUserId(@Param("userId")Integer userId);  
    /** 
     * 通过用户名查询用户信息 
     * @param username 
     * @return 
     */  
    @Select("select * from user_main where username=#{username}")  
    @Results({  
          @Result(property = "roleNames", column = "id", many = @Many(fetchType=FetchType.LAZY,select = "getRoleNamesByUserId")),  
          @Result(property = "permissionNames", column = "id", many = @Many(fetchType=FetchType.LAZY,select = "getPermissionsByUserId"))  
      })  
    public UserPO getUserByUsername(@Param("username")String username);  
    @Select("select username from user_main")  
    public List<String> getRoleMain();  
}

/**   
 * 类SqlTemplateTest.java的实现描述：TODO 类实现描述  
 * @author yuezhihua 2015年7月29日 下午2:07:44 
 */  
@RunWith(SpringJUnit4ClassRunner.class)  
@ContextConfiguration(locations = {  
        "classpath*:spring/demo-locator.xml"  
})  
public class SqlTemplateTest {  
    @Autowired  
    private SqlSessionTemplate sqlSessionTemplate;  
    @Autowired  
    private SqlSessionFactory sqlSessionFactory;  
    /** 
     * 初始化datasource 
     */  
    @Before  
    public void init(){  
        DataSource ds = null;  
        try {  
            ds = BaseDataTest.createUnpooledDataSource(BaseDataTest.DERBY_PROPERTIES);  
            BaseDataTest.runScript(ds, "com/mybatis/demo/databases/lazyloader/lazyloader-schema.sql");  
            BaseDataTest.runScript(ds, "com/mybatis/demo/databases/lazyloader/lazyloader-dataload.sql");  
        } catch (IOException e) {  
            e.printStackTrace();  
        } catch (SQLException e) {  
            e.printStackTrace();  
        }  
    }       
    /** 
     * 测试mybatis自身的查询 
     */  
    @Test  
    public void testMybatisSelect(){  
        SqlSession session = sqlSessionFactory.openSession();  
        UserMapper mapper = session.getMapper(UserMapper.class);  
        UserPO userPo = mapper.getUserByUsername("zhangsan");  
        System.out.println("-----testMybatisSelect:"+userPo.getUsername());  
    }           
}

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {  
    if (Object.class.equals(method.getDeclaringClass())) {  
      try {  
        return method.invoke(this, args);  
      } catch (Throwable t) {  
        throw ExceptionUtil.unwrapThrowable(t);  
      }  
    }  
    final MapperMethod mapperMethod = cachedMapperMethod(method);  
    return mapperMethod.execute(sqlSession, args);  
}

public Object execute(SqlSession sqlSession, Object[] args) {  
    Object result;  
    if (SqlCommandType.INSERT == command.getType()) {  
      Object param = method.convertArgsToSqlCommandParam(args);  
      result = rowCountResult(sqlSession.insert(command.getName(), param));  
    } 
    else if (SqlCommandType.UPDATE == command.getType()) {  
      Object param = method.convertArgsToSqlCommandParam(args);  
      result = rowCountResult(sqlSession.update(command.getName(), param));  
    } 
    else if (SqlCommandType.DELETE == command.getType()) {  
      Object param = method.convertArgsToSqlCommandParam(args);  
      result = rowCountResult(sqlSession.delete(command.getName(), param));  
    } 
    else if (SqlCommandType.SELECT == command.getType()) {  
      if (method.returnsVoid() && method.hasResultHandler()) {  
        executeWithResultHandler(sqlSession, args);  
        result = null;  
      } else if (method.returnsMany()) {  
        result = executeForMany(sqlSession, args);  
      } else if (method.returnsMap()) {  
        result = executeForMap(sqlSession, args);  
      } else {  
        Object param = method.convertArgsToSqlCommandParam(args);  
        result = sqlSession.selectOne(command.getName(), param);  
      }  
    } 
    else {  
      throw new BindingException("Unknown execution method for: " + command.getName());  
    }  
    if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {  
      throw new BindingException("Mapper method '" + command.getName()   
          + " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");  
    }  
    return result;  
  }