问题描述。
此后,我使用immutables site中当前示例的简化版本。
所以我有一个要与MongoDB一起使用的项目。
@Value.Immutable
@Mongo.Repository("items")
public abstract class Item {
@Mongo.Id
public abstract long id();
public abstract String name();
}
为简单起见,我创建了一个Junit测试。就像例子一样。 我的问题是,尽管在immutables site的示例中展示了这个junit测试,但它抛出了一个异常:
public class ItemTest{
@Test
public void testRepository() {
try {
//Simple ItemRepository creation
ItemRepository items = new ItemRepository(
RepositorySetup.forUri("mongodb://localhost/test")
);
// Create item Item item = ImmutableItem.builder()
.id(1)
.name("one")
.build();
//Insert is async. Returns a Future.
FluentFuture<Integer> future=items.insert(item);
future.get(); // get the result (ensure it was saved)
}catch(Exception e){
e.printStackTrace();
Assert.fail(e.getMessage());
}
}//end test
}//end class
运行此测试将导致以下异常:
org.bson.codecs.configuration.CodecConfigurationException:找不到 接口spyros.stackoverflow.example.Item
的编解码器
下面提供了完整的堆栈跟踪。
java.lang.AssertionError: java.util.concurrent.ExecutionException: **org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for interface spyros.stackoverflow.example.Item.**
at com.google.common.util.concurrent.AbstractFuture.getDoneValue(AbstractFuture.java:552)
at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:533)
at com.google.common.util.concurrent.FluentFuture$TrustedFuture.get(FluentFuture.java:82)
at com.google.common.util.concurrent.ForwardingFuture.get(ForwardingFuture.java:62)
at spyros.stackoverflow.example.ItemTest.testRepository(ItemTest.java:78)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.bson.codecs.configuration.CodecConfigurationException: Can't find a codec for interface spyros.stackoverflow.example.Item.
at org.bson.codecs.configuration.CodecCache.getOrThrow(CodecCache.java:46)
at org.bson.codecs.configuration.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:63)
at org.bson.codecs.configuration.ProvidersCodecRegistry.get(ProvidersCodecRegistry.java:37)
at com.mongodb.MongoCollectionImpl.getCodec(MongoCollectionImpl.java:591)
at com.mongodb.MongoCollectionImpl.insertMany(MongoCollectionImpl.java:333)
at com.mongodb.MongoCollectionImpl.insertMany(MongoCollectionImpl.java:322)
at org.immutables.mongo.repository.Repositories$Repository$2.call(Repositories.java:130)
at org.immutables.mongo.repository.Repositories$Repository$2.call(Repositories.java:127)
at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:125)
at com.google.common.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:69)
at com.google.common.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:78)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
at org.junit.Assert.fail(Assert.java:88)
at spyros.stackoverflow.example.ItemTest.testRepository(ItemTest.java:84)
我使用gradle,下面是build.gradle
。
plugins {
id 'java'
id 'java-library'
}
sourceCompatibility = 1.8
targetCompatibility = 1.8
repositories {
mavenLocal()
mavenCentral()
jcenter()
}
dependencies {
implementation 'org.apache.logging.log4j:log4j-slf4j-impl:2.7'
implementation 'org.apache.logging.log4j:log4j-core:2.7'
implementation 'javax.persistence:javax.persistence-api:2.2'
implementation 'javax.xml.bind:jaxb-api:2.1'
implementation 'com.fasterxml.jackson.core:jackson-databind:2.9.8'
implementation 'com.google.guava:guava:27.1-jre'
annotationProcessor 'org.immutables:value:2.7.4'
implementation 'org.immutables:value:2.7.4'
implementation 'org.immutables:mongo:2.7.4'
implementation 'org.apache.commons:commons-lang3:3.4'
implementation 'org.apache.commons:commons-collections4:4.1'
implementation 'org.apache.commons:commons-configuration2:2.3'
testCompile group: 'junit', name: 'junit', version: '4.12'
}
已查明原因
Immutables JSON库需要能够找到自动生成的GsonAdaptersItem.class
implements com.google.gson.TypeAdapterFactory
。实际上,对于每个名为interface
的{{1}}或abstract class
,其注释都与“类项”中的注释类似(上面提供),不可变对象会生成与{{1 }}
为了能够自动找到这些类,XXX
使用GsonAdapterXXX
自动找到它们。
这是相关的代码部分:
implements com.google.gson.TypeAdapterFactory
引发异常的原因是由于某种原因该异常似乎不起作用,并且引发了以下异常。
更新
进一步的研究表明,该示例有效,但前提是该jar已编译。这是因为Immutables生成以下文件,该文件实际上将用于查找所有必需的RepositorySetup
类。
java.util.ServiceLoader
org.bson.codecs.configuration.CodecConfigurationException:找不到 接口spyros.stackoverflow.example.Item的编解码器 This is a permalink to the source code.
变通
直接的工作方式是将 GsonBuilder gsonBuilder = new GsonBuilder();
// there are no longer auto-registed from class-path, but from here or if added manually.
gsonBuilder.registerTypeAdapterFactory(new TypeAdapters());
for (TypeAdapterFactory factory : ServiceLoader.load(TypeAdapterFactory.class)) {
gsonBuilder.registerTypeAdapterFactory(factory);
}
return gsonBuilder.create();
专门注册到GsonAdapterXXX
。
以下Junit测试有效。
build\classes\java\main\META-INF\services\com.google.gson.TypeAdapterFactory
可以使用此替代方法来手动创建通用的api,程序员需要提供GsonAdaptersItem
。例如。 GsonBuilder
还可以创建更具体的 @Test
public void testItemVerbose() {
try {
//repeat what the RepositorySetup#createGson does
GsonBuilder gsonBuilder = new GsonBuilder();
//iterating in this loop
for (TypeAdapterFactory factory : ServiceLoader.load(TypeAdapterFactory.class)) {
//You can see that the ServiceLoader does not find the GsonAdaptersItem
//System.out.println("Factory:"+factory.getClass().getCanonicalName()+" "+factory.toString());
gsonBuilder.registerTypeAdapterFactory(factory);
}
//add the GsonAdaptersItem manually
gsonBuilder.registerTypeAdapterFactory(new GsonAdaptersItem());
Gson gson = gsonBuilder.create();
Item item = ImmutableItem.builder()
.id(1)
.name("one")
.build();
final MongoClient mongo = new MongoClient( "localhost" , 27017 );
final MongoDatabase mongoDatabase=mongo.getDatabase("test");
ItemRepository items =new ItemRepository(
RepositorySetup.builder()
.executor(MoreExecutors.newDirectExecutorService())
.database(mongoDatabase)
.gson(gson).build()
);
// Insert async and get
items.insert(item).get(); // returns future, works
}catch (final Exception e){
e.printStackTrace();
Assert.fail(e.getMessage());
}
}
提供者。
GsonAdapterXXX
但是,以上所有方面都需要维护,而且更容易出错,并且无论如何都需要编写样板代码,这是使用Immutables的人希望避免的事情。
问题
我希望该示例能够如immutables site所示工作。我最好的猜测是,由于我使用gradle而不是maven,也许我需要更改一些设置或依赖项。 问题是: 为了使简单的ItemRepository创建(如下所示)有效,需要更改什么?
ItemRepository itemRepository=reporitoryProvider.getRepositoryWithRegisteredGsonAdapter(new GsonAdaptersItem());
是否可以使用Immutables进行操作,而无需手动编写逐级注册或逐包注册编解码器的代码? 我真的很感谢一个解释,为什么它首先不起作用。
答案 0 :(得分:0)
我在一段时间后重新审视这个老问题。 目前建议的解决方案是使用不可变的 criteria 功能。
@Value.Immutable
@Criteria.Repository
public abstract class Item {
@Criteria.Id
public abstract long id();
public abstract String name();
}