Java REST API:返回ArrayList<;T>;作为JSON响应问题
我需要简单地返回一个对象的ArrayList作为Rest API响应,但我一直遇到以下错误: Java类的消息体编写器 Collections$SingletonList和MIME媒体类型 找不到application/json 我的代码:Java REST API:返回ArrayList<;T>;作为JSON响应问题,java,rest,google-app-engine,arraylist,jersey,Java,Rest,Google App Engine,Arraylist,Jersey,我需要简单地返回一个对象的ArrayList作为Rest API响应,但我一直遇到以下错误: Java类的消息体编写器 Collections$SingletonList和MIME媒体类型 找不到application/json 我的代码: @Path("/plans") public class PlanAPI { @GET @Produces(MediaType.APPLICATION_JSON) @Path("/getplans/{type}") publ
@Path("/plans")
public class PlanAPI {
@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/getplans/{type}")
public Response GetAllPlans(@PathParam("type") String type) {
PlanDAO dao = new PlanDAO();
ArrayList<UserPlan> plans = dao.GetAllPlans_ByType(type);
return Response.status(200).entity(plans).build();
}
}
com.sun.jersey.spi.container.ContainerResponse logException
SEVERE: Mapped exception to response: 500 (Internal Server Error)
javax.ws.rs.WebApplicationException: com.sun.jersey.api.MessageException: A message body writer for Java class java.util.Collections$SingletonList, and Java type java.util.List<java.util.ArrayList<com.dinuka.planapp.model.UserPlan>>, and MIME media type application/json was not found.
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:284)
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1510)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1419)
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1409)
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:409)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:558)
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:733)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:128)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:50)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:513)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: com.sun.jersey.api.MessageException: A message body writer for Java class java.util.Collections$SingletonList, and Java type java.util.List<java.util.ArrayList<com.dinuka.planapp.model.UserPlan>>, and MIME media type application/json was not found.
public class UserPlan {
String ID = "";
String Name = "";
String Description = "";
//Getter Setter and Constructors
}
当我调用API时,我得到了前面提到的错误。我做错了什么
@XmlRootElement
@XmlType(propOrder = {ID, Name, Description})
public class UserPlan {
String ID = "";
String Name = "";
String Description = "";
//Getter Setter and Constructors
}
尝试为UserPlan类添加@XmlRootElement@XmlType
String json = new Gson().toJson(plans);
@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/getplans/{type}")
public String GetAllPlans(@PathParam("type") String type) {
PlanDAO dao = new PlanDAO();
ArrayList<UserPlan> plans = dao.GetAllPlans_ByType(type);
return new Gson().toJson(plans);
}
String json=new Gson().toJson(计划);
@得到
@产生(MediaType.APPLICATION_JSON)
@路径(“/getplans/{type}”)
公共字符串GetAllPlans(@PathParam(“类型”)字符串类型){
PlanDAO=新的PlanDAO();
ArrayList plans=dao.GetAllPlans\u ByType(类型);
返回新的Gson().toJson(计划);
}
此代码有两个错误:
UserPlan
)不对应于任何支持。通常,提供者(或messagebodyreader/writer)将处理对象到相应MediaType的转换。因此,对于您定义的每个自定义类,或者将该类转换为预处理类型。为您的POJO添加@XmlRootElement
注释使其表示一个JAXBElement
,默认提供程序将对其起作用arraylistplans=dao.GetAllPlans\u按类型(type);
GenericEntity实体=新的GenericEntity(计划){};
返回Response.ok(entity.build()代码>如果您在项目中使用maven,请取消对pom.xml文件中以下行的注释,然后重新启动服务器。它会很好用的
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-moxy</artifactId>
</dependency>
org.glassfish.jersey.media
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