2

更新：

现在我发现了一些非常奇怪的东西，当我将编译的测试类直接放入“super-csv-dozer-2.1.0.jar”中时，它的工作原理与svn repo中的结构相同。但是一旦我使用我自己的包，它就不起作用了。我总是像这样使用整个路径：myPackage.csv.SurveyResponse.class 我错过了什么？为什么它可以在普通的 Java 项目中工作，但不能在 Play 项目中工作？我还在 eclipse 之外的不同目录中尝试了它，并且没有任何来自 svn repo 的签出可能会混淆路径。我尝试的另一件事是将 Writing.class 放入不同的包中，但没有帮助。

原始问题：

我试图在 Play 项目中将 SuperCSV 与 Dozer 一起使用。官方的 supercsv 示例在单独的 Java 项目中运行良好。但是，当我将代码和所需的 SuperCSV Jars 放入新创建的 Play 项目中时，我总是在这行代码中得到 SurveyResponse.class 的 ClassNotfoundException： beanWriter.configureBeanMapping(myPackage.csv.SurveyResponse.class, FIELD_MAPPING);

这是我的项目结构的截图：http: //oi44.tinypic.com/mrqp7s.jpg

我确保所有 JARS 都可用，我将它们非托管放入 /lib 文件夹，它们在 eclipse 中可用，并且在编译过程中没有出现错误。我调试了代码，找到了 SurveyResponse.class 并且初始化了 beanWriter。所以不知何故，Play 必须在后台做一些魔法来触发这个错误。在后台播放什么可能会触发这种奇怪的行为？我能做些什么来解决这个问题？

我对示例所做的更改使其适用于 Play：我使用了与官方 supercsv 示例完全相同的代码。我所做的唯一更改是删除 Writing.main(..) 方法并将方法 Writing.writeWithDozerCsvBeanWriter() 和 Writing.partialWriteWithCsvDozerBeanWriter() 设置为公共，以便可以从应用程序控制器访问它。当然，我将所有类中的包名更改为 package myPackage.test；

示例链接：见评论，由于声誉低，我不能添加超过 2 个链接。

控制器：

public class Application extends Controller {
    public static Result index() throws Exception  {
        Writing.writeWithDozerCsvBeanWriter();
        Writing.partialWriteWithCsvDozerBeanWriter();
        return ok(index.render("Your new application is ready."));
    } 
}

在写作类中触发错误的代码：

ICsvDozerBeanWriter beanWriter = null;
    try {
        beanWriter = new CsvDozerBeanWriter(new FileWriter("target/writeWithCsvDozerBeanWriter.csv"),
            CsvPreference.STANDARD_PREFERENCE);
        
        // configure the mapping from the fields to the CSV columns
        //Here the exception occures:
        beanWriter.configureBeanMapping(myPackage.csv.SurveyResponse.class, FIELD_MAPPING);

堆栈跟踪：

play.api.Application$$anon$1: Execution exception[[MappingException: java.lang.ClassNotFoundException: myPackage.test.SurveyResponse]]
    at play.api.Application$class.handleError(Application.scala:289) ~[play_2.10.jar:2.1.1]
    at play.api.DefaultApplication.handleError(Application.scala:383) [play_2.10.jar:2.1.1]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anon$2$$anonfun$handle$1.apply(PlayDefaultUpstreamHandler.scala:144) [play_2.10.jar:2.1.1]
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anon$2$$anonfun$handle$1.apply(PlayDefaultUpstreamHandler.scala:140) [play_2.10.jar:2.1.1]
    at play.api.libs.concurrent.PlayPromise$$anonfun$extend1$1.apply(Promise.scala:113) [play_2.10.jar:2.1.1]
    at play.api.libs.concurrent.PlayPromise$$anonfun$extend1$1.apply(Promise.scala:113) [play_2.10.jar:2.1.1]
    at play.api.libs.concurrent.PlayPromise$$anonfun$extend$1$$anonfun$apply$1.apply(Promise.scala:104) [play_2.10.jar:2.1.1]
    at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24) [scala-library.jar:na]
    at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24) [scala-library.jar:na]
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source) [na:1.6.0_37]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.6.0_37]
    at java.lang.Thread.run(Unknown Source) [na:1.6.0_37]
org.dozer.MappingException: java.lang.ClassNotFoundException: myPackage.test.SurveyResponse
    at org.dozer.util.MappingUtils.throwMappingException(MappingUtils.java:82) ~[dozer-5.4.0.jar:na]
    at org.dozer.util.DefaultClassLoader.loadClass(DefaultClassLoader.java:38) ~[dozer-5.4.0.jar:na]
    at org.dozer.util.MappingUtils.loadClass(MappingUtils.java:224) ~[dozer-5.4.0.jar:na]
    at org.dozer.loader.DozerBuilder$MappingBuilder.classA(DozerBuilder.java:129) ~[dozer-5.4.0.jar:na]
    at org.dozer.loader.api.BeanMappingBuilder.mapping(BeanMappingBuilder.java:72) ~[dozer-5.4.0.jar:na]
    at org.dozer.loader.api.BeanMappingBuilder.mapping(BeanMappingBuilder.java:67) ~[dozer-5.4.0.jar:na]
    at org.supercsv.io.dozer.CsvDozerBeanWriter$MappingBuilder.configure(CsvDozerBeanWriter.java:178) ~[super-csv-dozer-2.1.0.jar:na]
    at org.dozer.loader.api.BeanMappingBuilder.build(BeanMappingBuilder.java:42) ~[dozer-5.4.0.jar:na]
    at org.dozer.DozerBeanMapper.addMapping(DozerBeanMapper.java:258) ~[dozer-5.4.0.jar:na]
    at org.supercsv.io.dozer.CsvDozerBeanWriter.configureBeanMapping(CsvDozerBeanWriter.java:91) ~[super-csv-dozer-2.1.0.jar:na]
    at myPackage.test.Writing.writeWithDozerCsvBeanWriter(Writing.java:88) ~[na:na]
    at controllers.Application.index(Application.java:12) ~[na:na]
    at Routes$$anonfun$routes$1$$anonfun$applyOrElse$1$$anonfun$apply$1.apply(routes_routing.scala:49) ~[na:na]
    at Routes$$anonfun$routes$1$$anonfun$applyOrElse$1$$anonfun$apply$1.apply(routes_routing.scala:49) ~[na:na]
    at play.core.Router$HandlerInvoker$$anon$6$$anon$2.invocation(Router.scala:164) ~[play_2.10.jar:2.1.1]
    at play.core.Router$Routes$$anon$1.invocation(Router.scala:345) ~[play_2.10.jar:2.1.1]
    at play.core.j.JavaAction$$anon$1.call(JavaAction.scala:31) ~[play_2.10.jar:2.1.1]
    at play.core.j.JavaAction$$anon$2.apply(JavaAction.scala:74) ~[play_2.10.jar:2.1.1]
    at play.core.j.JavaAction$$anon$2.apply(JavaAction.scala:73) ~[play_2.10.jar:2.1.1]
    at play.libs.F$Promise$PromiseActor.onReceive(F.java:420) ~[play_2.10.jar:2.1.1]
    at akka.actor.UntypedActor$$anonfun$receive$1.applyOrElse(UntypedActor.scala:159) ~[akka-actor_2.10.jar:na]
    at akka.actor.ActorCell.receiveMessage(ActorCell.scala:425) ~[akka-actor_2.10.jar:na]
    at akka.actor.ActorCell.invoke(ActorCell.scala:386) ~[akka-actor_2.10.jar:na]
    at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:230) ~[akka-actor_2.10.jar:na]
    at akka.dispatch.Mailbox.run(Mailbox.scala:212) ~[akka-actor_2.10.jar:na]
    at akka.dispatch.ForkJoinExecutorConfigurator$MailboxExecutionTask.exec(AbstractDispatcher.scala:502) ~[akka-actor_2.10.jar:na]
    at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:262) ~[scala-library.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:975) ~[scala-library.jar:na]
    at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1478) ~[scala-library.jar:na]
    at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:104) ~[scala-library.jar:na]
Caused by: java.lang.ClassNotFoundException: myPackage.test.SurveyResponse
    at java.net.URLClassLoader$1.run(Unknown Source) ~[na:1.6.0_37]
    at java.security.AccessController.doPrivileged(Native Method) ~[na:1.6.0_37]
    at java.net.URLClassLoader.findClass(Unknown Source) ~[na:1.6.0_37]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.6.0_37]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.6.0_37]
    at sbt.PlayCommands$$anonfun$53$$anonfun$55$$anon$2.loadClass(PlayCommands.scala:535) ~[na:na]
    at java.lang.Class.forName0(Native Method) ~[na:1.6.0_37]
    at java.lang.Class.forName(Unknown Source) ~[na:1.6.0_37]
    at org.apache.commons.lang3.ClassUtils.getClass(ClassUtils.java:823) ~[commons-lang3.jar:3.1]
    at org.apache.commons.lang3.ClassUtils.getClass(ClassUtils.java:889) ~[commons-lang3.jar:3.1]
    at org.apache.commons.lang3.ClassUtils.getClass(ClassUtils.java:872) ~[commons-lang3.jar:3.1]
    at org.dozer.util.DefaultClassLoader.loadClass(DefaultClassLoader.java:36) ~[dozer-5.4.0.jar:na]
    ... 28 common frames omitted

额外信息： 我仍然无法解决问题，但这里有一些额外信息来缩小问题范围：当我删除 configureBeanMapping 方法调用时，csv 标头已成功写入文件（请参见下面的代码）。当我对填充的 SurveyResponse 对象执行 System.out.println() 时，SurveyResponse 类也在工作（参见下面的代码）。所以它不是包或类名的问题。

仅写入标头的修改后的代码：

//...more code
myPackage.csv.SurveyResponse response3 = new myPackage.csv.SurveyResponse(42, false, Arrays.asList(new Answer(1, null), new Answer(2,
    "Carl Sagan"), new Answer(3, "Star Wars")));
final List<myPackage.csv.SurveyResponse> surveyResponses = Arrays.asList(response1, response2, response3);

ICsvDozerBeanWriter beanWriter = null;
try {
    beanWriter = new CsvDozerBeanWriter(new FileWriter("target/writeWithCsvDozerBeanWriter.csv"),
        CsvPreference.STANDARD_PREFERENCE);
    
    // configure the mapping from the fields to the CSV columns
    //beanWriter.configureBeanMapping(myPackage.csv.SurveyResponse.class, FIELD_MAPPING);
    
    //Prints the value 42 successfully
    System.out.println(response3.getAge());
    
    // write the header
    beanWriter.writeHeader("age", "consentGiven", "questionNo1", "answer1", "questionNo2", "answer2","questionNo3", "answer3");

//...more code
4

2 回答 2

0

From what I understand from the error, Play is trying to load the wrong class. Look at this line :

java.lang.ClassNotFoundException: org.supercsv.mock.dozer.SurveyResponse

I think that SurverResponse is one of your own project classes and not part of SuperCSV. Try to prefix it with the full path such as : 

beanWriter.configureBeanMapping(whateverpackage.models.SurveyResponse.class, FIELD_MAPPING);
于 2013-09-06T09:32:44.853 回答
0

SurveyResponse并且Answer是工件的测试类super-csv-dozer- 所以它们没有打包在发行版中（即它们不在 Maven 中或 SourceForge 上的 zip 文件中）。

您可以在线查看测试源或签出SVN 存储库（听起来您已经完成了），然后将它们复制到您的 Play 项目中。

这两个文件都在以下目录中：

supercsv/super-csv-dozer/src/test/java/org/supercsv/mock/dozer/

我有点好奇为什么在尝试SurveyResponse在代码中使用时没有出现编译错误。我的猜测是您已super-csv-dozer签出该项目并在您的 IDE 中打开，并且您的项目正在找到它。

于 2013-09-07T06:06:20.637 回答