java[R3 Corda]找不到com的合同附件。样板IOUContractnull

Question

当我运行教程时：Hello, World!

Pt。2-合同约束有错误：

Cannot find contract attachments for com.template.IOUContractnull.

我从模板开始，然后完成helloword1。你好，我跑得很好

...build\nodes\PartyA\logs\node-clay-PC.log


--- Transition of flow [3d6b6d20-bc45-4e71-831a-b0cddd89b50d] ---
  Timestamp: 2019-07-02T11:57:54.562Z
  Event: Error(exception=net.corda.core.transactions.MissingContractAttachments: Cannot find contract attachments for com.template.IOUContractnull. See https://docs.corda.net/api-contract-constraints.html#debugging)
  Actions: 
    RollbackTransaction
    ScheduleEvent(event=DoRemainingWork)
  Continuation: ProcessEvents
  Diff between previous and next state:
checkpoint.errorState: 
    Clean
    Errored(errors=[FlowError(errorId=-9033011467502490789, exception=net.corda.core.transactions.MissingContractAttachments: Cannot find contract attachments for com.template.IOUContractnull. See https://docs.corda.net/api-contract-constraints.html#debugging)], propagatedIndex=0, propagating=false)
isFlowResumed: 
    true
    false

Answer 1

您可能需要将其更改为：

public class IOUContract implements Contract {
    public static final String ID = "com.template.contracts.IOUContract";

我在Kotlin中完成了教程，并发现以下内容也适用于设置合同ID：

companion object {
    val ID = IOUContract::class.qualifiedName!!
}

Answer 2

在我的例子中，我没有在我的契约类签名中添加implements Contract（它实现了一个extends Contract的接口）。我刚加了个符号，效果很好

Answer 3

请参阅以下文档的“调试”部分- https://docs.corda.net/api-contract-constraints.html

文件-

If an attachment constraint cannot be resolved, a MissingContractAttachments exception is thrown. There are three common sources of MissingContractAttachments exceptions:

1. You are running a test and have not specified the CorDapp packages to scan.
2. When running the Corda node ensure all CordDapp JARs are placed in cordapps directory of each node
3. You are specifying the fully-qualified name of the contract incorrectly

在日志中，合同名称记录为“com.template.IOUContractnull”而不是“com.template.IOUContract”

Event: Error(exception=net.corda.core.transactions.MissingContractAttachments: Cannot find contract attachments for com.template.IOUContractnull. See https://docs.corda.net/api-contract-constraints.html#debugging)

请检查IOUContract类中的ID值

public class IOUContract implements Contract {
    public static final String ID = "com.template.IOUContract";