Java Examples for org.apache.ibatis.exceptions.TooManyResultsException

@Override
public Object compileResults(ExitOperationsCollector exitOperationsCollector) {
    List<Object> list = exitOperationsCollector.apply(nonNullResult);
    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;
    }
}

/**
	 * 查询一条记录
	 * 
	 * @param arg0
	 * @param arg1
	 * @return
	 */
public <M extends BaseBean> M selectOne(String arg0, M param) {
    if (param == null) {
        return null;
    }
    SqlSession session = openSession();
    M bean = null;
    try {
        bean = session.selectOne(arg0, param);
    } catch (MyBatisSystemException e) {
        if (e != null && e.getCause() instanceof TooManyResultsException) {
        } else {
            throw e;
        }
    }
    return bean;
}

//核心selectOne
@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;
    }
}

@SuppressWarnings("unchecked")
private void queryCount(Invocation invocation, Connection connection) throws Throwable {
    Object[] queryArgs = invocation.getArgs();
    MappedStatement ms = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];
    Object parameter = queryArgs[PARAMETER_INDEX];
    RowBounds rowBounds = (RowBounds) queryArgs[ROWBOUNDS_INDEX];
    // 将需要执行的查询语句修改成 select count(*) 的形式
    MappedStatement queryCountMs = MyBatisConfig.getQueryCountStatement(ms);
    if (null == queryCountMs) {
        queryCountMs = createMappedStatement(ms);
        MyBatisConfig.registerQueryCountStatement(ms, queryCountMs);
    }
    Executor executor = (Executor) invocation.getTarget();
    SimpleExecutor s = new SimpleExecutor(ms.getConfiguration(), executor.getTransaction());
    List<Integer> list = (List<Integer>) s.doQuery(queryCountMs, parameter, RowBounds.DEFAULT, null);
    if (list.size() == 1) {
        int count = (Integer) list.get(0);
        MyBatisConfig.setRecordNum(connection, count);
        int offset = rowBounds.getOffset();
        if ((offset > count) && (offset != RowBounds.NO_ROW_OFFSET)) {
            PageHelper helper = new PageHelper(count, rowBounds.getLimit());
            helper.setCurrPage(helper.getMaxPage());
            queryArgs[ROWBOUNDS_INDEX] = helper.getRowBounds();
        }
    } else {
        throw new TooManyResultsException("Expected one result to be returned by PageQueryInterceptor.intercept()");
    }
}

public <T> T selectOne(String statement, Object parameter) {
    // Popular vote was to return null on 0 results and throw exception on too many.
    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;
    }
}

@Override
public <T> T selectOne(String statement, Object parameter) {
    // Popular vote was to return null on 0 results and throw exception on too many.
    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();
    }
}