Question

我正在使用Voldemort来存储我的数据。我的关键是一个单词，值是单词和URL的出现次数。例如：

key :question
value: 10, www.stackoverflow.com

我正在使用string[]传递值。但是当我尝试使用client.put ("xxxx", valuePair);时，我得到 java.lang.ClassCastException：[Ljava.lang.String;无法转换为java.lang.String。 我的代码看起来像这样

public class ClientExample { 
  public static void main (String [] args) { 
    String bootstrapUrl = "tcp://localhost:6666";

    ClientConfig cc = new ClientConfig (); 
    cc.setBootstrapUrls (bootstrapUrl); 
    String[] valuePair = new String[2];
    int val = 1;
    String value = new Integer(val).toString();
    valuePair[0]=value;
    valuePair[1] = "www.cnn.com";
    System.out.println("Executed one");
    StoreClientFactory factory = new SocketStoreClientFactory (cc); 
    StoreClient <String, String[]> client = factory.getStoreClient ("test"); 
    System.out.println("Executed two");

    client.put ("xxxx", valuePair); 
    System.out.println("Executed three");
    String[] ans = client.getValue("key");
    System.out.println("Executed four");
    System.out.println ("value " +ans[0] +ans[1]); 
    System.out.println("Executed 5");
  } 
}

Answer 1

您应该编辑store.xml以更改值序列化程序的设置。现在应该看起来像这样：

<stores>
  <store>
    <name>test</name>
    <persistence>bdb</persistence>
    <routing>client</routing>
    <replication-factor>1</replication-factor>
    <required-reads>1</required-reads>
    <required-writes>1</required-writes>
    <key-serializer>
      <type>string</type>
    </key-serializer>
    <value-serializer>
      <type>string</type>
    </value-serializer>
  </store>
</stores>

现在，您需要将value-serializer更改为：

<value-serializer>
      <type>json</type>
      <schema-info>["string"]</schema-info>
</value-serializer>

请注意，这不会映射到Java数组，而是映射到Java列表。如果这就是你真的那么就是我所知道的那么接近它。

但是，可能想要这样的内容：

<value-serializer>
      <type>json</type>
      <schema-info>{"occurences":"int32", "site":"string"}</schema-info>
</value-serializer>

然后，你可以（摘录）：

Map<String, Object> pair = new HashMap<String,Object>();
pair.put("occurences", 10);
pair.put("site", "www.stackoverflow.com");

client.put("question",pair);

System.out.println(client.get("question"));

希望这有用！您可以在以下位置查看相关文档：

http://project-voldemort.com/design.php

JSON序列化类型详细信息

如何在voldemort中传递字符串数组

1 个答案: