我使用的CUPS4J用於我的項目,該項目取決於http-client,http-core和slf4j。Websphere上的java.lang.LinkageError嘗試加載HttpUriRequest
要解決我們使用Maven的依賴,和我已經定義的依賴關係如下:
<dependency>
<groupId>cups4j</groupId>
<artifactId>cups4j</artifactId>
<version>0.6.4</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.0.3</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpcore</artifactId>
<version>4.1</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.7</version>
</dependency>
的cups4j依賴是我們artifactory的服務器上(我不能在網上找到它)。
如果我創建一個樣本main
方法來打印某些文檔並將其作爲Java應用程序啓動,那麼所有內容都可以作爲魅力使用。
當我發表我的班到WebSphere服務器,並調用該方法從一個網頁,它會生成一個java.lang.LinkageError
。
這是堆棧跟蹤的相關部分:
Caused by: java.lang.LinkageError: loader constraint violation: loader "org/eclipse/osgi/internal/baseadaptor/[email protected]" previously initiated loading for a different type with name "org/apache/http/client/methods/HttpUriRequest" defined by loader "com/ibm/ws/classloader/[email protected]"
at java.lang.ClassLoader.defineClassImpl(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:260)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.defineClass(DefaultClassLoader.java:188)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.defineClass(ClasspathManager.java:580)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findClassImpl(ClasspathManager.java:550)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClassImpl(ClasspathManager.java:481)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass_LockClassName(ClasspathManager.java:460)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:447)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:393)
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:469)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:422)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(ClassLoader.java:612)
at org.apache.http.impl.client.AbstractHttpClient.determineTarget(AbstractHttpClient.java:584)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:708)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:700)
at org.cups4j.operations.IppOperation.sendRequest(IppOperation.java:207)
at org.cups4j.operations.IppOperation.request(IppOperation.java:76)
at org.cups4j.CupsPrinter.print(CupsPrinter.java:113)
at it.dropcomp.tasks.print.PrinterService.printPDF(PrinterService.java:160)
這是打印PDF(內部it.dropcomp.tasks.print.PrinterService
)的方法:
public void printPDF() throws RemoteServiceException {
/*
* generatedPDF is defined as File, and it's properly initialized
* before calling this method.
*/
if(generatedPDF == null) {
throw new RemoteServiceException("You must generate a file first!");
}
try {
CupsPrinter selectedPrinter = new CupsPrinter(
new URL(Constants.PRINTER_FULL_URL),
Constants.PRINTER_NAME, true
);
InputStream is = new FileInputStream(generatedPDF);
PrintJob pj = new PrintJob.Builder(is).build();
selectedPrinter.print(pj); //this is line 160
} catch (Exception e) {
LOG.error("Exception", e);
throw new RemoteServiceException(e);
}
}
似乎HttpUriRequest
已經存在,使得衝突一個由Apache的httpclient
庫提供,但如果我嘗試從pom.xml
去除依賴,我得到了NoClassDefFoundException
該類。
如果很重要,我的IDE是Eclipse Luna。
我該如何解決這個異常?
不幸的是,我不能。我必須使用Maven來解決依賴關係,我在一個團隊中工作,團隊領導希望這樣做。我讀過,我可以告訴Maven該庫已提供,以便在應用程序部署到服務器上時不包含jar。我會嘗試這種方法,也許它解決了這個問題。謝謝! – BackSlash 2014-11-07 08:26:45
@BackSlash您仍然可以'build'與Maven,有與沒有問題,但你寫的,你需要標記這些依賴關係,並提供在應用程序中不包括,但不幸的是,應用服務器庫上對其進行配置。您可以嘗試改變只是類加載器的應用程序設置於母公司最後,但它,而不是要去解決您的問題。 – Gas 2014-11-07 08:57:30