RpcUtil

com.google.protobuf

Class RpcUtil

java.lang.Object
- com.google.protobuf.RpcUtil

```
public final class RpcUtil
extends Object
```
Grab-bag of utility functions useful when dealing with RPCs.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
`static class`	`RpcUtil.AlreadyCalledException` Exception thrown when a one-time callback is called more than once.

Method Summary

Methods

Modifier and Type	Method and Description
`static <Type extends Message> RpcCallback<Message>`	`generalizeCallback(RpcCallback<Type> originalCallback, Class<Type> originalClass, Type defaultInstance)` Take an `RpcCallback` accepting a specific message type and convert it to an `RpcCallback<Message>`.
`static <ParameterType> RpcCallback<ParameterType>`	`newOneTimeCallback(RpcCallback<ParameterType> originalCallback)` Creates a callback which can only be called once.
`static <Type extends Message> RpcCallback<Type>`	`specializeCallback(RpcCallback<Message> originalCallback)` Take an `RpcCallback<Message>` and convert it to an `RpcCallback` accepting a specific message type.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - specializeCallback
```
public static <Type extends Message> RpcCallback<Type> specializeCallback(RpcCallback<Message> originalCallback)
```
    Take an RpcCallback<Message> and convert it to an RpcCallback accepting a specific message type. This is always type-safe (parameter type contravariance).
  - generalizeCallback
```
public static <Type extends Message> RpcCallback<Message> generalizeCallback(RpcCallback<Type> originalCallback,
                                                                             Class<Type> originalClass,
                                                                             Type defaultInstance)
```
    Take an RpcCallback accepting a specific message type and convert it to an RpcCallback<Message>. The generalized callback will accept any message object which has the same descriptor, and will convert it to the correct class before calling the original callback. However, if the generalized callback is given a message with a different descriptor, an exception will be thrown.
  - newOneTimeCallback
```
public static <ParameterType> RpcCallback<ParameterType> newOneTimeCallback(RpcCallback<ParameterType> originalCallback)
```
    Creates a callback which can only be called once. This may be useful for security, when passing a callback to untrusted code: most callbacks do not expect to be called more than once, so doing so may expose bugs if it is not prevented.