迭代從put接收到的參數ArrayList時獲取ClassCastException

Question

使用Restlet，我試圖通過PUT方法接收類Foo的列表

    class Foo {
        public String name;
        public int age;
    }

 public class Bar extends ServerResource  {   
    @Put
    public String update(ArrayList<Foo> foos) { 
        String names = "";        
        try {
            for (Foo foo : foos ) {
                names += ","+foo.name;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return names;
    }
}

但是在發送此JSON時

[
    {
        "name":"bar",
        "age":1
    },
    {
        "age":27,
        "name":"baz"
    }
]

我在for循環第一行收到此異常

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to Foo
    at Bar.update(Bar.java:55)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.restlet.resource.ServerResource.doHandle(ServerResource.java:503)
    at org.restlet.resource.ServerResource.put(ServerResource.java:1275)
    at org.restlet.resource.ServerResource.doHandle(ServerResource.java:583)
    at org.restlet.resource.ServerResource.doNegotiatedHandle(ServerResource.java:649)
    at org.restlet.resource.ServerResource.doConditionalHandle(ServerResource.java:348)
    at org.restlet.resource.ServerResource.handle(ServerResource.java:952)
    at org.restlet.resource.Finder.handle(Finder.java:246)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Router.doHandle(Router.java:431)
    at org.restlet.routing.Router.handle(Router.java:648)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:155)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:211)
    at org.restlet.engine.application.ApplicationHelper.handle(ApplicationHelper.java:84)
    at org.restlet.Application.handle(Application.java:381)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Router.doHandle(Router.java:431)
    at org.restlet.routing.Router.handle(Router.java:648)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.routing.Router.doHandle(Router.java:431)
    at org.restlet.routing.Router.handle(Router.java:648)
    at org.restlet.routing.Filter.doHandle(Filter.java:159)
    at org.restlet.routing.Filter.handle(Filter.java:206)
    at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:211)
    at org.restlet.Component.handle(Component.java:392)
    at org.restlet.Server.handle(Server.java:516)
    at org.restlet.engine.ServerHelper.handle(ServerHelper.java:72)
    at org.restlet.engine.adapter.HttpServerHelper.handle(HttpServerHelper.java:152)
    at org.restlet.ext.servlet.ServerServlet.service(ServerServlet.java:1089)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:501)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255)
    at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
    at org.eclipse.jetty.server.Server.handle(Server.java:370)
    at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)
    at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:982)
    at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1043)
    at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)
    at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)
    at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)
    at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
    at java.lang.Thread.run(Thread.java:744)

任何想法如何遍歷列表並獲取Foo項目屬性？

Answer 1

使用@XmlRootElement注釋您的Foo 。 否則，JSON序列化器將不知道您要反序列化到哪個類。

Answer 2

解決了-希望找到更簡單的解決方案，但這是我到目前為止找到的解決方案

 @Put
    @Trace(dispatcher = true)
    public String update(String args) {
        try {

            Gson gson = new Gson();
            TypeToken<List<Foo>> token = new TypeToken<List<Foo>>() {
            };
            List<Foo> fooz = gson.fromJson(args, token.getType());
            String names = "";
            for (Foo foo : fooz) {
                //do something foo.name;
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return "Success";
    }

Answer 3

根據我對先前答案的評論，這是一個更合適的答案：

使用Restlet轉換器，您需要使用JsonRepresentation對象，並告訴資源使用JSON：

@Put("json")
public String update(JsonRepresentation foos) {
    JSONArray fooArray = foos.getJsonArray();
    // ...
}