Can't Deserialize JSON in Java Servlet

2019-04-28 05:50发布

站内文章 / Java
33 0 0

问题:

My endpoint can't make sense of incoming JSON.

Here's the endpoint:

import javax.ws.rs.Consumes;
import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import org.hibernate.Query;
import org.hibernate.Session;
import org.json.JSONObject;
...

@POST
@Path("/{department}/{team}")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response handleJSON(JSONObject json , @PathParam("department") String department, @PathParam("team") String team){ 

    MyObj myObj = new MyObj();

    myObj.setDepartment(department);
    myObj.setTeam(team);
    myObj.setPlatform(json.optString("platform"));

    saveObj(myObj);

  return Response.ok(true).build();

}

I'm posting JSON containing the key/value for "platform" using Postman, with header: Content-Type as application/json

But I get this exception: com.owlike.genson.JsonBindingException: Could not deserialize to type class org.json.JSONObject

Looks like the problem has to do with: Illegal character at row 0 and column 1 expected { but read '-' !

But I'm pretty sure Postman should be sending valid JSON...

Here's more of the stacktrace:

09-Jul-2014 10:30:00.017 SEVERE [http-nio-8080-exec-4] com.sun.jersey.spi.container.ContainerResponse.logException Mapped exception to response: 500 (Internal Server Error)
 javax.ws.rs.WebApplicationException: com.owlike.genson.JsonBindingException: Could not deserialize to type class org.json.JSONObject
    at com.owlike.genson.ext.jaxrs.GensonJsonConverter.readFrom(GensonJsonConverter.java:127)
    at com.sun.jersey.spi.container.ContainerRequest.getEntity(ContainerRequest.java:474)
    at com.sun.jersey.server.impl.model.method.dispatch.EntityParamDispatchProvider$EntityInjectable.getValue(EntityParamDispatchProvider.java:123)
    at com.sun.jersey.server.impl.inject.InjectableValuesProvider.getInjectableValues(InjectableValuesProvider.java:46)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$EntityParamInInvoker.getParams(AbstractResourceMethodDispatchProvider.java:153)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:203)
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400)
    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:699)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:744)
Caused by: com.owlike.genson.JsonBindingException: Could not deserialize to type class org.json.JSONObject
    at com.owlike.genson.Genson.deserialize(Genson.java:391)
    at com.owlike.genson.ext.jaxrs.GensonJsonConverter.readFrom(GensonJsonConverter.java:125)
    ... 41 more
Caused by: com.owlike.genson.stream.JsonStreamException: Illegal character at row 0 and column 1 expected { but read '-' !
    at com.owlike.genson.stream.JsonReader.newWrongTokenException(JsonReader.java:949)
    at com.owlike.genson.stream.JsonReader.begin(JsonReader.java:425)
    at com.owlike.genson.stream.JsonReader.beginObject(JsonReader.java:157)
    at com.owlike.genson.reflect.BeanDescriptor.deserialize(BeanDescriptor.java:101)
    at com.owlike.genson.reflect.BeanDescriptor.deserialize(BeanDescriptor.java:90)
    at com.owlike.genson.convert.BeanViewConverter.deserialize(BeanViewConverter.java:102)
    at com.owlike.genson.convert.NullConverter$NullConverterWrapper.deserialize(NullConverter.java:56)
    at com.owlike.genson.Genson.deserialize(Genson.java:389)
    ... 42 more

回答1:

This might not be an ideal solution, but i do think it could work.

Hopefully you have the Jackson JSON dependency already...

you can find it here: http://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core

I would try the following code:

@POST
@Path("/{department}/{team}")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response handleJSON(String json, @PathParam("department") String department,       @PathParam("team") String team){ 

    ObjectMapper mapper = new ObjectMapper();
    JsonNode node = mapper.readValue(json, JsonNode.class);

    MyObj myObj = new MyObj();

    myObj.setDepartment(department);
    myObj.setTeam(team);

    if (node.get("platform") != null) {
        myObj.setPlatform(node.get("platform").textValue());
    }

    saveObj(myObj);

    return Response.ok(true).build();

}

Notice that I am asking your WS Framework to just pass me the JSON as a String and just handling it myself. Maybe its not ideal, but should work.

Cheers!



回答2:

I don't know which JSON Serializer you are using but most probably this will be Jettison or Jackson. As far as I know they don't support converting an instance of org.json.JSONObject directly. The more common way is to simply use custom Java Beans:

public class Foo implements Serializable {

    private String platform;

    // getters + setters

}

@POST
@Path("/{department}/{team}")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response handleJson(Foo foo, @PathParam("department") String department, @PathParam("team") String team) {
    ...
    myObj.setPlatform(foo.getPlatform());
    ...
}

Foo should be annotated with @XmlRootElement if you are using Jettison.

If you don't want to create a custom Bean for every Entity you are expecting you can use Object, Map or String as parameter and serialize on your own:

@POST
@Path("/{department}/{team}")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response handleJson(String json, @PathParam("department") String department, @PathParam("team") String team) {
    ...
    JSONObject jsonObject = new JSONObject(json);
    myObj.setPlatform(json.optString("platform"));
    ...
}

Last solution is implementing a MessageBodyReader which handles JSONObject. Simple example:

@Provider
public class JsonObjectReader implements MessageBodyReader<JSONObject> {

    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return type == JSONObject.class && MediaType.APPLICATION_JSON_TYPE.equals(mediaType);
    }

    @Override
    public JSONObject readFrom(Class<JSONObject> type, Type genericType,
            Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
            throws IOException, WebApplicationException {
        return new JSONObject(IOUtils.toString(entityStream));
    }

}


标签： java json rest servlets jersey
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