0

我正在使用 Java Hector API 从 Cassandra 数据库中检索数据，如下所示：

public static void retrieveData() {
    try {
        //Create a cluster object from your existing Cassandra cluster
        Cluster cluster = HFactory.getOrCreateCluster("Test Cluster", "localhost:9160");

        //Create a keyspace object from the existing keyspace we created using CLI
        Keyspace keyspace = HFactory.createKeyspace("TestDB", cluster);

        SliceQuery<String, String, String> sliceQuery = HFactory.createSliceQuery(keyspace, stringSerializer, stringSerializer, stringSerializer);
        sliceQuery.setColumnFamily("ClientHeaders").setKey("1234");
        sliceQuery.setRange("", "", false, 10);
        sliceQuery.setColumnNames("ip_address","uuid");
        QueryResult<ColumnSlice<String, String>> result = sliceQuery.execute();                 
        System.out.println("\nInserted data is as follows:\n" + result.get());   
    } catch (Exception ex) {
        System.out.println("Error encountered while retrieving data!!");
        ex.printStackTrace() ;
    }

因此，我按以下顺序根据查询获取检索到的值：

ColumnSlice([HColumn(ip_address=203.110.85.171), HColumn(uuid=a3363400-abfd-0130-e2cf-07b5c765964c)])

但是我想在一些字符串变量（字符串 ip=ip_address 等）中提取结果并使用。但我不知道该怎么做？请帮忙。谢谢。

4

2 回答 2

1

基于 Hector 的 JavaDoc（QueryResult、ColumnSlice和HColumn），您应该能够做到这一点：

ColumnSlice columnSlice = result.get();
HColumn<String, String> column = columnSlice.getColumnByName("ip_address");
System.out.println("The value of ip_address is " + column.getValue());

或者

for (HColumn<String, String> column : result.get().getColumns()) {
    System.out.println("The value of " + column.getName() + " is " + column.getValue());
}
于 2013-06-11T06:28:35.480 回答
1

尝试这样做：

 if (result != null && result.get() != null) {
            List<HColumn<String, String>> resultCols = result.get().getColumns();
            for (HColumn<String, String> col : resultCols)
            {
               System.out.println(col.getValue());
            }
于 2013-06-11T06:33:50.270 回答