无法将java.util.ArrayList的实例反序列化为START

无法将java.util.ArrayList的实例反序列化为START_OBJECT令牌(Can not deserialize instance of java.util.ArrayList out of START_OBJECT token)

我试图POST自定义对象List 。 我的JSON在请求正文中是这样的：

{ "collection": [ { "name": "Test order1", "detail": "ahk ks" }, { "name": "Test order2", "detail": "Fisteku" } ] }

处理请求的服务器端代码：

import java.util.Collection; import javax.ws.rs.Consumes; import javax.ws.rs.POST; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; @Path(value = "/rest/corder") public class COrderRestService { @POST @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response postOrder(Collection<COrder> orders) { StringBuilder stringBuilder = new StringBuilder(); for (COrder c : orders) { stringBuilder.append(c.toString()); } System.out.println(stringBuilder); return Response.ok(stringBuilder, MediaType.APPLICATION_JSON).build(); } }

实体COrder ：

import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class COrder { String name; String detail; @Override public String toString() { return "COrder [name=" + name + ", detail=" + detail + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]"; } }

但抛出异常：

SEVERE: Failed executing POST /rest/corder org.jboss.resteasy.spi.ReaderException: org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token at [Source: org.apache.catalina.connector.CoyoteInputStream@6de8c535; line: 1, column: 1] at org.jboss.resteasy.core.MessageBodyParameterInjector.inject(MessageBodyParameterInjector.java:183) at org.jboss.resteasy.core.MethodInjectorImpl.injectArguments(MethodInjectorImpl.java:88) at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:111) at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:280) at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:234) at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:221) at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356) at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179) at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220) at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56) at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) 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:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:724)

I'm trying to POST a List of custom objects. My JSON in request body is this:

{ "collection": [ { "name": "Test order1", "detail": "ahk ks" }, { "name": "Test order2", "detail": "Fisteku" } ] }

Server side code that handles the request:

import java.util.Collection; import javax.ws.rs.Consumes; import javax.ws.rs.POST; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; @Path(value = "/rest/corder") public class COrderRestService { @POST @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response postOrder(Collection<COrder> orders) { StringBuilder stringBuilder = new StringBuilder(); for (COrder c : orders) { stringBuilder.append(c.toString()); } System.out.println(stringBuilder); return Response.ok(stringBuilder, MediaType.APPLICATION_JSON).build(); } }

Entity COrder:

import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class COrder { String name; String detail; @Override public String toString() { return "COrder [name=" + name + ", detail=" + detail + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()=" + super.toString() + "]"; } }

But an exception is thrown:

SEVERE: Failed executing POST /rest/corder org.jboss.resteasy.spi.ReaderException: org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token at [Source: org.apache.catalina.connector.CoyoteInputStream@6de8c535; line: 1, column: 1] at org.jboss.resteasy.core.MessageBodyParameterInjector.inject(MessageBodyParameterInjector.java:183) at org.jboss.resteasy.core.MethodInjectorImpl.injectArguments(MethodInjectorImpl.java:88) at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:111) at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:280) at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:234) at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:221) at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356) at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179) at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220) at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56) at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) 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:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:724)

最满意答案

问题是JSON - 默认情况下，它不能反序列化到一个Collection因为它实际上并不是一个JSON数组 - 看起来像这样：

[ { "name": "Test order1", "detail": "ahk ks" }, { "name": "Test order2", "detail": "Fisteku" } ]

既然你没有控制反序列化的确切过程（RestEasy） - 第一个选择是简单地将JSON作为String注入，然后控制反序列化过程：

Collection<COrder> readValues = new ObjectMapper().readValue(jsonAsString, new TypeReference<Collection<COrder>>() { });

你会放松一点方便，不用自己做，但你可以很容易地解决问题。

另一个选项 - 如果您不能更改JSON - 将是构造一个包装器来适应JSON输入的结构，而不是使用Collection<COrder> 。

希望这可以帮助。

The problem is the JSON - this cannot, by default, be deserialized into a Collection because it's not actually a JSON Array - that would look like this:

[ { "name": "Test order1", "detail": "ahk ks" }, { "name": "Test order2", "detail": "Fisteku" } ]

Since you're not controlling the exact process of deserialization (RestEasy does) - a first option would be to simply inject the JSON as a String and then take control of the deserialization process:

Collection<COrder> readValues = new ObjectMapper().readValue( jsonAsString, new TypeReference<Collection<COrder>>() { } );

You would loose a bit of the convenience of not having to do that yourself, but you would easily sort out the problem.

Another option - if you cannot change the JSON - would be to construct a wrapper to fit the structure of your JSON input - and use that instead of Collection<COrder>.

Hope this helps.