从 Corda 自定义表中获取数据时出错

Question

如何从 corda 自定义表中获取数据？ 我的示例代码如下：-

Api layer -- getIous() method 
{
    Field attributeValue=IOUSchemaV1.PersistentIOU.class.getDeclaredField("value");
    CriteriaExpression currencyIndex = Builder.equal(attributeValue, "12");
    QueryCriteria.VaultCustomQueryCriteria criteria = new 
    QueryCriteria.VaultCustomQueryCriteria(currencyIndex);
    vaultStates = services.vaultQueryByCriteria(criteria,IOUState.class);
}

1. 在 ExamplePlugin 中，我添加了下面的架构注册代码

   public class ExamplePlugin extends CordaPluginRegistry implements 
   WebServerPluginRegistry
   {
   @NotNull
   @Override
   public Set<MappedSchema> getRequiredSchemas()
   {
       Set<MappedSchema> requiredSchemas = new HashSet<>();
       requiredSchemas.add(new IOUSchemaV1());
       return requiredSchemas;
   }
   

   }

2. 我的 Schema 类是 ---

   public final class IOUSchema {
   
   }
   
   
   @CordaSerializable
   public class IOUSchemaV1 extends MappedSchema 
   {
   public IOUSchemaV1() {
       super(IOUSchema.class, 1, ImmutableList.of(PersistentIOU.class));
   }
   
   @Entity
   @Table(name = "iou_states")
   public static class PersistentIOU extends PersistentState {
   @Column(name = "sender_name") private final String senderName;
   @Column(name = "recipient_name") private final String recipientName;
   @Column(name = "value") private final int value;
   
   
   public PersistentIOU(String senderName, String recipientName, int value) {
       this.senderName = senderName;
       this.recipientName = recipientName;
       this.value = value;
   }
   
   public String getSenderName() {
       return senderName;
   }
   
   public String getRecipientName() {
       return recipientName;
   }
   
   public int getValue() {
       return value;
   }
   

   } }

3. 我的州有：-

   public class IOUState implements LinearState, QueryableState 
   {
   
   --- some code goes here and below methods as well.---
   @Override
   public PersistentState generateMappedObject(MappedSchema schema) {
   if (schema instanceof IOUSchemaV1) {
       return new IOUSchemaV1.PersistentIOU(
               this.sender.getName().toString(),
               this.recipient.getName().toString(),
               this.iou.getValue());
   } else {
       throw new IllegalArgumentException("Unrecognised schema $schema");
   }
   }
   
   @Override
   public Iterable<MappedSchema> supportedSchemas() {
   return ImmutableList.of(new IOUSchemaV1());
   }
   }
   

但我总是遇到异常。

引起：net.corda.core.node.services.VaultQueryException：

请在您的 CorDapp 的 CordaPluginRegistry 配置中注册实体 'com.example.schema.IOUSchemaV1' 类（requiredSchemas 属性） 并确保您已声明（在supportedSchemas（）中）并映射（在generateMappedObject（）中） 关联合约状态的 QueryableState 接口实现中的架构。

谁能帮忙解决这个问题。

Answer 1

尝试从插件声明中删除implements WebServerPluginRegistry。