org.apache.ibatis.exceptions.TooManyResultsException Java Examples

@Override
public void deleteBy(final String fieldName, final Object value) throws TooManyResultsException {
  try {
    final T entity = this.getEntity(fieldName, value);
    this.assertBy(entity);
    this.assertDelete(this.mapper.delete(entity) == 1);
  } catch (final Exception e) {
    throw new ServiceException(e.getMessage(), e);
  }
}
 

@Override
public T getBy(final String fieldName, final Object value) throws TooManyResultsException {
  try {
    final T entity = this.getEntity(fieldName, value);
    return this.mapper.selectOne(entity);
  } catch (final Exception e) {
    throw new ServiceException(e.getMessage(), e);
  }
}
 

/**
 * 获取List中最多只有一个的数据
 *
 * @param list
 *            List结果
 * @param <T>
 *            泛型类型
 * @return
 */
private <T> T getOne(List<T> list) {
	if (list.size() == 1) {
		return list.get(0);
	} else if (list.size() > 1) {
           throw new TooManyResultsException(
                   "Expected one result (or null) to be returned by selectOne(), but found: " + list.size());
	} else {
		return null;
	}
}
 

@Test(expected=TooManyResultsException.class)
public void shouldFailWithTooManyResultsException() throws Exception {
  SqlSession session = sqlMapper.openSession(TransactionIsolationLevel.SERIALIZABLE);
  try {
    session.selectOne("org.apache.ibatis.domain.blog.mappers.AuthorMapper.selectAllAuthors");
  } finally {
    session.close();
  }
}
 

@Override
public T selectBy(String fieldName, Object value) throws TooManyResultsException {
	try {
		T model = modelClass.newInstance();
		Field field = modelClass.getDeclaredField(fieldName);
		field.setAccessible(true);
		field.set(model, value);
		return mapper.selectOne(model);
	} catch (ReflectiveOperationException e) {
		throw new ServiceException(e.getMessage(), e);
	}
}
 

@Override
public <T> T selectOne(String statement, Object parameter) {
  // Popular vote was to return null on 0 results and throw exception on too many.
  //转而去调用selectList,很简单的，如果得到0条则返回null，得到1条则返回1条，得到多条报TooManyResultsException错
  // 特别需要主要的是当没有查询到结果的时候就会返回null。因此一般建议在mapper中编写resultType的时候使用包装类型
  //而不是基本类型，比如推荐使用Integer而不是int。这样就可以避免NPE
  List<T> list = this.<T>selectList(statement, parameter);
  if (list.size() == 1) {
    return list.get(0);
  } else if (list.size() > 1) {
    throw new TooManyResultsException("Expected one result (or null) to be returned by selectOne(), but found: " + list.size());
  } else {
    return null;
  }
}
 

/**
 * 查询全部
 */
@Test(expected = TooManyResultsException.class)
public void testDynamicSelectAll() {
    SqlSession sqlSession = MybatisHelper.getSqlSession();
    try {
        CountryMapper mapper = sqlSession.getMapper(CountryMapper.class);
        Country country = mapper.selectOne(new Country());
    } finally {
        sqlSession.close();
    }
}
 

/**
 * 入参为null时查询全部
 */
@Test(expected = TooManyResultsException.class)
public void testDynamicSelectAllByNull() {
    SqlSession sqlSession = MybatisHelper.getSqlSession();
    try {
        CountryMapper mapper = sqlSession.getMapper(CountryMapper.class);
        mapper.selectOne(null);
    } finally {
        sqlSession.close();
    }
}
 

@Override
public T findBy(String property, Object value) throws TooManyResultsException {
  try {
    T model = modelClass.newInstance();
    Field field = modelClass.getDeclaredField(property);
    field.setAccessible(true);
    field.set(model, value);
    return mapper.selectOne(model);
  } catch (ReflectiveOperationException e) {
    // TODO: 17-10-29 更换为一个自定义异常
    throw new RuntimeException(e.getMessage(), e);
  }
}
 

/**
 * 入参为null时查询全部
 */
@Test(expected = TooManyResultsException.class)
public void testDynamicSelectAllByNull() {
    SqlSession sqlSession = MybatisHelper.getSqlSession();
    try {
        CountryMapper mapper = sqlSession.getMapper(CountryMapper.class);
        mapper.selectOne(null);
    } finally {
        sqlSession.close();
    }
}
 

@Override
public <T> T selectOne(String statement, Object parameter) {
  // Popular vote was to return null on 0 results and throw exception on too many.
  //转而去调用selectList,很简单的，如果得到0条则返回null，得到1条则返回1条，得到多条报TooManyResultsException错
  List<T> list = this.<T>selectList(statement, parameter);
  if (list.size() == 1) {
    return list.get(0);
  } else if (list.size() > 1) {
    throw new TooManyResultsException("Expected one result (or null) to be returned by selectOne(), but found: " + list.size());
  } else {
    return null;
  }
}
 

@Test(expected=TooManyResultsException.class)
public void shouldFailWithTooManyResultsException() throws Exception {
  SqlSession session = sqlMapper.openSession(TransactionIsolationLevel.SERIALIZABLE);
  try {
    session.selectOne("org.apache.ibatis.domain.blog.mappers.AuthorMapper.selectAllAuthors");
  } finally {
    session.close();
  }
}
 

@Test(expected = TooManyResultsException.class)
public void testSelectOneByExampleException() {
    SqlSession sqlSession = MybatisHelper.getSqlSession();
    try {
        CountryMapper mapper = sqlSession.getMapper(CountryMapper.class);
        Example example = new Example(Country.class);
        example.createCriteria().andGreaterThan("id", 100).andLessThan("id", 151);
        example.or().andLessThan("id", 41);
        mapper.selectOneByExample(example);
    } finally {
        sqlSession.close();
    }
}
 

/**
 * 查询全部
 */
@Test(expected = TooManyResultsException.class)
public void testDynamicSelectAll() {
    SqlSession sqlSession = MybatisHelper.getSqlSession();
    try {
        CountryMapper mapper = sqlSession.getMapper(CountryMapper.class);
        Country country = mapper.selectOne(new Country());
    } finally {
        sqlSession.close();
    }
}
 

/**
 *	mybatis自带的条件查询返回的是一个list, 但是某些时候我们需要的是返回单条记录. <br/>
 *	该方法从mybatis的查询结果list中,取出为一个的第一条记录	
 * @author Hongbin.Yuan
 * @param list		
 * @return	list 为空或者size为0,返回空; 
 * 			list 元素超过一个.
 * 			list 只包含单独一个元素, 返回该元素
 * @throws Exception	list 元素超过一个.
 */
public static <T> T getOneFromList(List<T> list) throws Exception{
	if(list == null || list.isEmpty()){
		return null;
	}
	if(list.size() > 1){
		 throw new TooManyResultsException("Expected one result (or null) to be returned, but found: " + list.size());
	}
	return list.get(0);
}
 

/**
 *	mybatis自带的条件查询返回的是一个list, 但是某些时候我们需要的是返回单条记录. <br/>
 *	该方法从mybatis的查询结果list中,取出为一个的第一条记录	
 * @author Hongbin Yuan
 * @param list		
 * @return	list 为空或者size为0,返回空; 
 * 			list 元素超过一个.
 * 			list 只包含单独一个元素, 返回该元素
 * @throws Exception	list 元素超过一个.
 */
public static <T> T getOneFromList(List<T> list) throws Exception{
	if(list == null || list.isEmpty()){
		return null;
	}
	if(list.size() > 1){
		 throw new TooManyResultsException("Expected one result (or null) to be returned, but found: " + list.size());
	}
	return list.get(0);
}
 

/**
 * 通过某个成员属性查找,value 需符合 unique 约束
 *
 * @param property 属性名
 * @param value    属性值
 *
 * @return 实体
 *
 * @throws TooManyResultsException 结果集过大
 */
T findBy(String property, Object value) throws TooManyResultsException;
 

/**
 * 通过Model中某个成员变量名称（非数据表中column的名称）查找,value需符合unique约束
 * @param fieldName
 * @param value
 * @return
 * @throws TooManyResultsException
 */
T findBy(String fieldName, Object value) throws TooManyResultsException;
 

/**
 * @param fieldName
 * @param value
 * @throws TooManyResultsException
 * @Description: 通过Model中某个成员变量名称（非数据表中column的名称）查找,value需符合unique约束
 * @Reutrn T
 */
T selectBy(String fieldName, Object value) throws TooManyResultsException;
 

/**
 * 通过实体中某个成员变量名称查找 value 需符合 unique 约束
 *
 * @param fieldName 字段名
 * @param value 字段值
 * @return 实体
 * @throws TooManyResultsException 多条结果异常
 */
T getBy(String fieldName, Object value) throws TooManyResultsException;
 

/**
 * 通过实体中某个成员变量名称（非数据表中 column 的名称）刪除
 *
 * @param fieldName 字段名
 * @param value 字段值
 * @throws TooManyResultsException 多条结果异常
 */
void deleteBy(String fieldName, Object value) throws TooManyResultsException;