Floodlight源码阅读之内存数据库(二)

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上一篇文章介绍内存数据的最基础结构但那远远不能满足需求，需要再次封装一下。首先看看一个创建数据库的方法

        Set<String> indexedColumnNames = new HashSet<String>();//初始化表列map
indexedColumnNames.add(PERSON_FIRST_NAME);
indexedColumnNames.add(PERSON_LAST_NAME);//添加表列
storageSource.setExceptionHandler(null);//添加异常处理方法
storageSource.setDebugCounterService(new MockDebugCounterService());
storageSource.createTable(PERSON_TABLE_NAME, indexedColumnNames);//创建表

上面的方法创建了一个table。然后就往表里面添加数据

  <span style="white-space:pre">	</span>Map<String,Object> rowValues = createPersonRowValues(personData);storageSource.insertRow(PERSON_TABLE_NAME, rowValues);//表添加行

每行都是一个map，插入数据过后就可以查询数据了

下面第一个是简单查询

String[] columnList = {PERSON_FIRST_NAME,PERSON_LAST_NAME};Object[][] expectedResults = {{"Lisa", "Jones"},{"Susan", "Jones"}};IPredicate predicate = new OperatorPredicate(PERSON_LAST_NAME, OperatorPredicate.Operator.EQ, "Jones");IQuery query = storageSource.createQuery(PERSON_TABLE_NAME, columnList, predicate, new RowOrdering(PERSON_SSN));IResultSet resultSet = storageSource.executeQuery(query);

当然也支持复杂查询

        String[] columnList = {PERSON_FIRST_NAME,PERSON_LAST_NAME};Object[][] expectedResults = {{"Lisa", "Jones"}};IResultSet resultSet = storageSource.executeQuery(PERSON_TABLE_NAME, columnList,new CompoundPredicate(CompoundPredicate.Operator.AND, false,new OperatorPredicate(PERSON_LAST_NAME, OperatorPredicate.Operator.EQ, "Jones"),new OperatorPredicate(PERSON_FIRST_NAME, OperatorPredicate.Operator.EQ, "Lisa")),new RowOrdering(PERSON_SSN));

查询支持AND查询和OR组合查询，上面的例子展示了AND查询，OR的就不演示了

如果查询需要传参

        String[] columnList = {PERSON_FIRST_NAME,PERSON_LAST_NAME, PERSON_AGE};        Object[][] expectedResults = {{"John", "Smith", 40},{"Bjorn", "Borg", 55},{"John", "McEnroe", 53}};IPredicate predicate = new OperatorPredicate(PERSON_AGE, OperatorPredicate.Operator.GTE, "?MinimumAge?");IQuery query = storageSource.createQuery(PERSON_TABLE_NAME, columnList, predicate, new RowOrdering(PERSON_SSN));query.setParameter("MinimumAge", 40);IResultSet resultSet = storageSource.executeQuery(query);

这样就可以实现参数传递了刚才创建的表是有主键的那么通过主机删除是很简单的

<span style="white-space:pre">	</span>storageSource.deleteRow(PERSON_TABLE_NAME, "111-11-1111");

简单高效，如果你想通过查询再删除也是可以的

        // Query once to delete the rowsIResultSet resultSet = storageSource.executeQuery(PERSON_TABLE_NAME, PERSON_COLUMN_LIST, null, new RowOrdering(PERSON_SSN));for (int i = 0; i < 4; i++) {resultSet.next();resultSet.deleteRow();}resultSet.save();resultSet.close();

还有更牛的是删除匹配行

storageSource.deleteMatchingRows(PERSON_TABLE_NAME, new OperatorPredicate(PERSON_AGE, OperatorPredicate.Operator.LT, 40));

实现删除年龄大于40岁的person删除，CURD剩下UPDATE了

 <span style="white-space:pre">	</span>Map<String,Object> updateValues = new HashMap<String,Object>();updateValues.put(PERSON_FIRST_NAME, "Tennis");updateValues.put(PERSON_AGE, 60);IPredicate predicate = new OperatorPredicate(PERSON_AGE, OperatorPredicate.Operator.GT, 50);IResultSet resultSet = storageSource.executeQuery(PERSON_TABLE_NAME, null, predicate, new RowOrdering(PERSON_SSN));while (resultSet.next()) {String key = resultSet.getString(PERSON_SSN);storageSource.updateRow(PERSON_TABLE_NAME, key, updateValues);}resultSet.close();

先构造一个更新对象，然后通过主键更新，和上面查询删除例子一样查询更新也可以

        IPredicate predicate = new OperatorPredicate(PERSON_AGE, OperatorPredicate.Operator.GT, 50);IResultSet resultSet = storageSource.executeQuery(PERSON_TABLE_NAME, null, predicate, null);while (resultSet.next()) {resultSet.setString(PERSON_FIRST_NAME, "Tennis");resultSet.setInt(PERSON_AGE, 60);}resultSet.save();resultSet.close();

ok，一个简单NQSQL数据的API封装就介绍到这里

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