那些遇到过的问题

无法使用Jersey客户端解组JSON对象数组

Mat*_*all 26 java json jaxb jersey

我试图解组的单元素JSON数组:

[
   {
      "id":"42",
      "status":"Active",
      "name":"purple monkey dishwasher"
   }
]
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相应的Java类(为简洁省略了getter和setter):

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Badge
{
    @XmlElement(name="id")
    private String id;

    @XmlElement(name="status")
    private Status status;

    @XmlElement(name="name")
    private String name;

    public static enum Status
    {
        Active,
        NotActive
    }
}
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Jersey客户端代码发出HTTP请求并且应该将上述JSON解组为一个元素List<Foo>:

Client client = Client.create();
WebResource apiRoot = client.resource("http://localhost:9000/api");
List<Badge> badges = apiRoot.path("/badges").get(new GenericType<List<Badge>>(){});
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最后一行,特别是WebResource#get()调用,抛出以下异常:

javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"status"). Expected elements are <{}badge>
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:662)
    at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:258)
    at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:253)
    at com.sun.xml.bind.v2.runtime.unmarshaller.Loader.reportUnexpectedChildElement(Loader.java:120)
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext$DefaultRootLoader.childElement(UnmarshallingContext.java:1063)
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext._startElement(UnmarshallingContext.java:498)
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext.startElement(UnmarshallingContext.java:480)
    at com.sun.xml.bind.v2.runtime.unmarshaller.InterningXmlVisitor.startElement(InterningXmlVisitor.java:75)
    at com.sun.xml.bind.v2.runtime.unmarshaller.StAXStreamConnector.handleStartElement(StAXStreamConnector.java:247)
    at com.sun.xml.bind.v2.runtime.unmarshaller.StAXStreamConnector.bridge(StAXStreamConnector.java:181)
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:369)
    at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:341)
    at com.sun.jersey.core.provider.jaxb.AbstractListElementProvider.readFrom(AbstractListElementProvider.java:232)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:552)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:522)
    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:617)
    at com.sun.jersey.api.client.WebResource.get(WebResource.java:191)
    at com.redacted.badge.client.BadgerImpl.findAllBadges(BadgerImpl.java:105)
    at com.redacted.webapp.admin.BadgeAction.unspecified(BadgeAction.java:40)
    at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:245)
    at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
    at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
    at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
    at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
    at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.MemberFilter.doFilter(MemberFilter.java:83)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.AuthFilter.doFilter(AuthFilter.java:113)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.LanguageHandlingFilter.doFilter(LanguageHandlingFilter.java:151)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:146)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.PartnerFilter.doFilter(PartnerFilter.java:59)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.redacted.webapp.filter.SessionStatusFilter.doFilter(SessionStatusFilter.java:113)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at com.googlecode.psiprobe.Tomcat60AgentValve.invoke(Tomcat60AgentValve.java:30)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:680)
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我尝试了各种注释组合Badge,或使用数组而不是GenericType:

List<Badge> badges = Arrays.asList(apiRoot.path("/badges").get(Badge[].class));
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或使用中间体ClientResponse:

GenericType<List<Badge>> type = new GenericType<List<Badge>>(){};
ClientResponse clientResponse = apiRoot.path("/badges").get(ClientResponse.class);
List<Badge> badges = clientResponse.getEntity(type);
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但迄今为止都没有解决问题.

更令人困惑的是,我现有的设置在解组其他结构内部的JSON编码时没有问题Badge,如下所示:

{
   "userid":"123456789",
   "userbadges":[
      {
         "badge":{
              "id":"42",
              "status":"Active",
              "name":"purple monkey dishwasher"
         },
         "earned":"2012-03-06 18:16:18.172"
      }
   ]
}
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我究竟做错了什么？

Mat*_*all 23

通过使用Jersey Client实例JacksonJsonProvider的MessageBody(Reader|Writer)提供程序,我能够以最小的努力解决这个问题:

ClientConfig cfg = new DefaultClientConfig();
cfg.getClasses().add(JacksonJsonProvider.class);
Client client = Client.create(cfg);
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杰克逊的MessageBodyReader实施似乎比泽西JSON的表现更为出色.

感谢我如何自定义JAXB对象列表到JSON的序列化？指出我在杰克逊的方向.

bdo*_*han 14

注意: 我是EclipseLink JAXB(MOXy)的负责人,也是JAXB(JSR-222)专家组的成员.

您可以使用添加到EclipseLink 2.4中的MOXy组件的JSON Binding扩展来处理此用例:

演示

Jersey客户端API允许您从客户端的服务器端利用相同的MessageBodyReader/ MessageBodyWriter. 

package forum9627170;

import java.util.List;
import org.example.Customer;
import com.sun.jersey.api.client.*;
import com.sun.jersey.api.client.config.*;

public class Demo {

    public static void main(String[] args) {
        ClientConfig cc = new DefaultClientConfig();
        cc.getClasses().add(MOXyJSONProvider.class);
        Client client = Client.create(cc);
        WebResource apiRoot = client.resource("http://localhost:9000/api");
        List<Badge> badges = apiRoot.path("/badges").accept("application/json").get(new GenericType<List<Badge>>(){});

        for(Badge badge : badges) {
            System.out.println(badge.getId());
        }
    }

}
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MOXyJSONProvider

下面是一个通用MessageBodyReader/ MessageBodyWriter可以与任何服务器/客户端一起使用以启用MOXy作为JSON绑定提供程序.

package forum9627170;

import java.io.*;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import javax.xml.transform.stream.StreamSource;

import javax.ws.rs.*;
import javax.ws.rs.core.*;
import javax.ws.rs.ext.*;
import javax.xml.bind.*;

@Provider
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public class MOXyJSONProvider implements 
    MessageBodyReader<Object>, MessageBodyWriter<Object>{

    @Context
    protected Providers providers;

    public boolean isReadable(Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    public Object readFrom(Class<Object> type, Type genericType,
            Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
            throws IOException, WebApplicationException {
            try {
                Class domainClass = getDomainClass(genericType);
                Unmarshaller u = getJAXBContext(domainClass, mediaType).createUnmarshaller();
                u.setProperty("eclipselink.media-type", mediaType.toString());
                u.setProperty("eclipselink.json.include-root", false);
                return u.unmarshal(new StreamSource(entityStream), domainClass).getValue();
            } catch(JAXBException jaxbException) {
                throw new WebApplicationException(jaxbException);
            }
    }

    public boolean isWriteable(Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    public void writeTo(Object object, Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType,
        MultivaluedMap<String, Object> httpHeaders,
        OutputStream entityStream) throws IOException,
        WebApplicationException {
        try {
            Marshaller m = getJAXBContext(getDomainClass(genericType), mediaType).createMarshaller();
            m.setProperty("eclipselink.media-type", mediaType.toString());
            m.setProperty("eclipselink.json.include-root", false);
            m.marshal(object, entityStream);
        } catch(JAXBException jaxbException) {
            throw new WebApplicationException(jaxbException);
        }
    }

    public long getSize(Object t, Class<?> type, Type genericType,
        Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

    private JAXBContext getJAXBContext(Class<?> type, MediaType mediaType) 
        throws JAXBException {
        ContextResolver<JAXBContext> resolver 
            = providers.getContextResolver(JAXBContext.class, mediaType);
        JAXBContext jaxbContext;
        if(null == resolver || null == (jaxbContext = resolver.getContext(type))) {
            return JAXBContext.newInstance(type);
        } else {
            return jaxbContext;
        }
    }

    private Class<?> getDomainClass(Type genericType) {
        if(genericType instanceof Class) {
            return (Class) genericType;
        } else if(genericType instanceof ParameterizedType) {
            return (Class) ((ParameterizedType) genericType).getActualTypeArguments()[0];
        } else {
            return null;
        }
    }

}
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欲获得更多信息

UPDATE

在GlassFish 4中,EclipseLink JAXB(MOXy)是Jersey使用的默认JSON绑定提供程序:

  • 谢谢,我会试一试.我很想知道_Why_这不是开箱即用 - 你知道吗？而且,我知道你发布一个答案`:)`只是时间问题 (2认同)

yve*_*lem 11

默认情况下,Jersey使用JAXB进行(un)编组过程,遗憾的是,JAXB JSON处理器不是标准处理器(忽略单元素数组,将空数组转换为单元素空数组......).

所以,你有两个选择:

  1. 将JAXB配置为更标准(有关更多信息,请参见此处);
  2. 使用杰克逊代替JAXB - 我推荐.

使用Jackson客户端是通过以下方式完成的:

ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
Client client = Client.create(clientConfig);
List<Badge> badges = client.resource("/badges").getEntity(new GenericType<List<Badge>>() {});
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gur*_*eta 6

我有类似的问题,并通过以下解决

  1. 像这样制作一个JAXB上下文解析器

    import java.util.ArrayList;
import java.util.List;

import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;
import javax.xml.bind.JAXBContext;

import com.sun.jersey.api.json.JSONConfiguration;
import com.sun.jersey.api.json.JSONJAXBContext;

@Provider
public class JAXBContextResolver implements ContextResolver<JAXBContext> {

    private JAXBContext       context;

    private Class<?>[]        types    = { Badge.class };

    private List<Class<?>>    classes    = new ArrayList<Class<?>>();

    public JAXBContextResolver() throws Exception {
        this.context = new JSONJAXBContext(JSONConfiguration.natural().build(), types);

        for (Class<?> clazz : types) {
            classes.add(clazz);
        }
    }

    public JAXBContext getContext(Class<?> objectType) {
        return classes.contains(objectType) ? context : null;
    }

}
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  2. 为您的客户添加了上下文解析器

    ClientConfig config = new DefaultClientConfig();
config.getClasses().add(JAXBContextResolver.class);

Client client = Client.create(config);
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  3. 现在您可以获取对象数组

    WebResource apiRoot = client.resource("http://localhost:9000/api");
Badge[] badges = apiRoot.path("/badges").get(Badge[].class);
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如果你想要一个清单,只需使用

   Arrays.asList(badges)
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