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我有以下的Web服務:澤西島:如何返回列表<MyType<K,V>>作爲迴應?
@Path("/storage-dirs/{user}")
@GET
@Produces(MediaType.APPLICATION_XML)
public JResponse<List<MarshalledMapEntry<String, Integer>>> getStorageDirs(@PathParam("user") String user) {
//List<MarshalledMapEntry<String, Integer>>
List<MarshalledMapEntry<String, Integer>> myEntries = new ArrayList<MarshalledMapEntry<String, Integer>>();
Map<String, Integer> originalEntries = DBAccessor.getStorageDirsForUser(user);
for (Map.Entry<String, Integer> en : originalEntries.entrySet()) {
myEntries.add(new MarshalledMapEntry<String, Integer>(en.getKey(), en.getValue().intValue()));
}
//GenericEntity<List<MarshalledMapEntry<String, Integer>>> entity = new GenericEntity<List<MarshalledMapEntry<String, Integer>>> {};
return JResponse.ok(myEntries).build();
}
這是我MarshalledMapEntry:
@XmlRootElement
public class MarshalledMapEntry<K, V> {
@XmlElement
private K key;
@XmlElement
private V value;
MarshalledMapEntry() {} //JAXB requires it
public MarshalledMapEntry(K key, V value) {
this.key = key;
this.value = value;
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
}
因爲JAXB不支持集合作爲頂級元素我寫了一個簡單的類,它封裝了一個地圖。但我得到以下異常:
javax.ws.rs.WebApplicationException: com.sun.jersey.api.MessageException: A message body writer for Java class java.util.ArrayList, and Java type java.util.List<silverline.MarshalledMapEntry<java.lang.String, java.lang.Integer>>, and MIME media type application/xml was not found
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:285)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1437)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:708)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
可以明顯看出我曾嘗試使用JResponse避免列表<的類型擦除>但因爲我有我的鎧類仿製藥,我相信這會導致一個問題。那麼,如果我想能夠返回Generic Maps,我可以實現什麼解決方案。如果我更改MarshalledMapEntry,以便不使用泛型,而是將String,String作爲類型使用,但我可以使用多種不同的Map類型,並且不希望僅使用更改的類型創建此類的副本?