GSON 应为 BEGIN_ARRAY，但为 BEGIN_OBJECT

Posted 2023-02-26

【中文标题】GSON 应为 BEGIN_ARRAY，但为 BEGIN_OBJECT

【英文标题】：GSON Expected BEGIN_ARRAY but was BEGIN_OBJECT

【发布时间】：2013-05-15 06:40:22

【问题描述】：

当我只收到一个列表中的一项时，我收到了这个错误。我在服务器端 REST Web 服务中使用 Jersey，我只在 List 返回一个元素并且当它有 0 elements 我得到 java.lang.NullPointerException 时才收到错误但是当它有多个时它工作得很好，而且这个我就是这样做的：

@GET
@Path("getproject")
@Produces(MediaType.APPLICATION_JSON)
public List<Project> getPagedProjects(
       @QueryParam("offset") int offset,
       @QueryParam("limit") int limit,
       @QueryParam("searchKey") String searchKey) throws Exception 

  System.out.println("Returning Paged Project ");
  return projectService.getPagedProjects(offset, limit, searchKey);

为什么 Jersey 不发送包含单个项目的列表？这是球衣上的虫子吗？ 有没有办法让它总是序列化为数组？

这是我在 Web 服务返回 0 元素时的 JSON 数据：

null

当网络服务返回 1 个元素时，这是我的 JSON 数据：

    "project": 
        "abbreviation": "abc",
        "customer": "customer1",
        "description": "description3",
        "icon": "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",
        "name": "projectname3",
        "plannedEndDate": "2012-05-23T00:00:00+01:00",
        "plannedStartDate": "2012-05-23T00:00:00+01:00",
        "projectStatus": 
            "name": "In Progress"
        ,
        "realEndDate": "2012-05-23T00:00:00+01:00",
        "realStartDate": "2012-05-23T00:00:00+01:00"
    

当网络服务返回超过 1 个元素时，这是我的 JSON 数据：

    "project": [
        
            "abbreviation": "abd",
            "customer": "customer1",
            "description": "description1",
            "icon": "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",
            "name": "projectname1",
            "plannedEndDate": "2012-05-25T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": 
                "name": "Opened"
            ,
            "realEndDate": "2012-05-25T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        ,
        
            "abbreviation": "bd",
            "customer": "customer1",
            "description": "description2",
            "icon": "iVBORw0KGgoAAAANSUhEUgAAADAAAAAwCAYAAABXAvmHAAAN4UlEQVR42u2ZeXBUx53Hx8FgSAIWMiB0jO7RLRkwbFxxnC1ntyp/JXbh9TrmirEDOpA4JQQ6kdCBDiQOU65UjNdO2djYGLCzKRJjY841SJoZzaEZaTSjc0b3hST0JCH5u79fa54YCZLUZteurQpTfKq7X/f0+35//et+b4RC8fDz8PPw8/Dz8PMP/ykoKFBkZmY+evLkyR9//PHHr545c2azC6/9BUQ/jd/w4Ycf/uLNN9+M3r179w8AKNzd3b878eXl5QoSoXjnnXd+ZjAYmjo7Oye6uromme7u7m+coKenR+YbF3jcWHt7+2B9fX3r1atXP3777befW7du3aOpqanfjYGysjJFY2Oj4uzZszt6e3sxOjoqGBu/i7sTE8QkJia/EdC/aeRr3D9+9y7Gx8cxPDyM2tpaO821JysrayHP/Z0YuH37tuLcuXO7+vr6vpEN9LZa4DBcQ5vxGjpqrqOz5ga6TIT5Brpd6K27hZGBboyNjU2bdzgcdy5duvS7N954I4Ru8ciWLVu+XQMDAwO8AjvZAEe+v7kG2pyfQLvTG7rdSuj3+MKQ4gdjqr+gJtUPpr2+MKcoUZushP10CkZHhoV4SZIENNeEXq+vvnDhwqFTp05tfPfdd1+gNP3l/5a33nrrudLS0sePHj2qyMvLu9/A+N0J9JmvonE/CUtdBHvWUtgLvGEv9Ye9PHCKEj/Y871gz1wCe/IP0fnbtZAG+yCRgZGREdy5c0fAKUVpOUkrIrW0tAw3NzcPNzU1DTGUtoKGhgaBzWYTWK3WIdpPAovFIqirqxNQeg5TUPo+++yzQ+vXr3/0yJEjD1qBcYwO38bA1++g90IG+r7MRd+1QvTdLEFfVRn6Kg+j7+ti9F7JR+/FAzQmG0OWa9PiZQMsfmhoSDA4OCigVAXdC/39/bxCbG76cOCDgg4E0CGCjo4O0MGAtrY2AQUAdrsdra2tAjosqnJycpbyKggDNOE9A5TLY2Pj4JVgeJPOwHmdU43HjRLS6NgDxcui/y+E0wqCVlCUZKA6Pz/fY4aBTz75ZIdsQJxCVPLJwsyuy5tVzvm/FnlZPCOLlw3I4mUDLF42MDvqsgGGDdCz654BmlgY4HyVhbEgnpQFsWguuc3XnZtU3FjOd44ei2LhLJZvykK5zuMo70U/X+M+bsvCKfdFm8WzaLPZLIRynfYHjEaj6Je5cuXKzBWgSYUBfjDJpwgLoQ0khIpjlW7Mbb7OJnhyvrEccdp0QhhHncfyTVkQpw1HkzafEMwmeB7ul9NGp9Px80OM50hXVFSANrOYjzYvbt68KYzQpp82MGMF2AC9FmynJZ2cfYrIdYaF8jXXHJdLOU1cc9013zldZue7a86zSTlt2IQMrwQLl2ED96UQ3UAY4NcHWeBf4kEni2ueP0j87M06Y8O2dwgcbR2wOziF2tBqd6Cl1Y7mFjuamjndWtDohNtXrl6vziso9ig/emKmAZp4UhYoR9s10rNPFtfTZfYp8zcj39FJEaco27RoMFyETfsH2NTnYdUwn8Kq/RT1DLUtdN1SdQ6WyrOCa+fLrJ8XRT9/rXShlzBAk/ML3XaaeFKOLIvhvGMR3GYR3JbF8nLzcsqiuU/euCyWc5dTg+vyxmxra0dHZxds1lqYbpyC+VQsDAXPQLc3DLo9wdDvVUGfFgFdZjQMB1fBWLCG+ldDn7sC+uyYqb4UFbSJ3ner4xZ1VOW4nxcGSDgbSKIlnZRToaenl25ah86ubtweHBYRM1G7p7cf/QODtJzNqLNY0dvXT9f6YK6tQ0Njk6i3d3TRpjVSGjjQ1d0jlr1apyeDzWgyfgHd71+DencQtBuWQP1v7qhcuxhVa92p/oSg8kV3VHH9pSWinG47qXh+0V3184/2aNLddMIACVd89NFHSRTVSRFRoqeLNpXlKhymz+EwX4Sj9gviS7RZLqGt/is4rFO02S4L7PWXYLd8ida6L9BC45tr/oxm45/QpPsjGivPoP7yCZg/SKBIrkL15uXQvLwM6r8LD1SsdRtXvzi3uyp78Z+EARKuOH36dBIt9SSnQ09PJ6x/PggDLaU+OYSWNgyGfREwpkXBmBEDY9YKGA+sQk3uatQc/CdiDYw5q2EkcYbMJ2FIpxTYHwl9aji9CIZAtz0A1XG+0P7aE5pXSPwrntOo/w4qXnQf17w8r6Mid/F7wgAJFwYohyc4hzvsFtSc+DmqN3nTMiud+EC7/h6a+/B24vPXoXnU651scELfm0Luc23P6qPxFS8tGdNsmG+/ledWLAyQcAX9LEyiM3eim3Lf0aiFvuhpVLGgTX4UOX9RVrJ4Z1u9wRdVbIzqDPdVbfSdMVZNba5zWbFuai6mar1yqp/7Nk318VyuY+Xv8nW5rXZ+v/Jlj1H15gUtX+e77RAGSLgwQKfKBG+6ZvNXtPNXQcPiXg2EdnOQKDW/DqD6VFvj2nbWNa8GTI0n1C5t7lNv8hdtjbNPtHmMs6521me3Z49lKn7lOare8v2G64fc/n36J+UHH3yQSOUEnzoNmrPQZ0Sj+nU6sv6nvBY8jeZbQUWr5z1aFf8D49Vit58JA/ROo6BfTYlUTrTTOW258Radt+Go3hIm0DpxrT+Y0Jn8JhSab4HKjcrRyqQfVlwucVshDNCLkzBA5QQ/1msvlkK3KxTq35CorRGojo0UpZpFxnI7Apqt4dNthsdqtoSLcVrqq+KbbZ1q83Vua6fbYfRdaseGC9RbeSy146gdR31bQ0SpjXdp81jup3tVbvYbq9i98Ksvy9yUwgC9HQoD9EY50UpPzZrz+1C9IxwVr5OouChUJ0RDQyYq2BC346NRRaIq5TZR+TobplWLjSKRkah8LUQI1sWR+dgwMqCCjgTpt5GIeEq1eHrybqfjeTsJ3xZER60Khp2h0O8MgSYxELodITBQELnUJAZBv4P7wqgMhyaeDOxf9J8X3ljsJgzQY1/x/vvvJ1I50dLSBD094nU7oqFNeJLEuxAfQyKIuBgSGi3QTRMFPRkxxBMJkTAmhKMmkUgKg4lEmkiIeVcIancTe1SoTVahLoUJRt1eIvUetfuc7FcJzPuYEJgEZCTZ725F1qJ3Pz2xeIEwQO/iwgCVE42NFuh+9zJ0iSR020roElaQaOZJ6Jk4J7ExMJARI61GTUIUTImRMCdFoHZ7OOooUnUUPQs9xOpJaD0JtZJIa2oQbPuI/YGwpQWiIZ3ICLhHJpE1hc2JNStQUJ8VRATDkqWCKV05UZH7+OET/7FkjjBgMpkU7733XqLZXDthq9Oi+tgvaKnpBSqBnqxM/EoSuxJGhszU0GqYtsWQ4CgSHEmCI1C/KxzWPWGwJYfClhKCBnoxa6QoNu4PQhOJbc4gSGBLlj9ashk/tB4gchhftOZO0XJQxg/NTpoO+gsac8lcbiAsB7wnK/IeT7dnLVLcZ6C+5jp0Rf8qhGu30GtBHL0yJDwlhBson2uTYmCh9KrjSFNe2vaEoyGFhZPYvUFoSQtGC0W2Oc0PdhLrILGOA76wZ/ugPVeJ9jwl2g56E15oz/dGewHV870E7YU+aCv0hj3fEw4qHdS2Ey00rrWQDBb6oaXAH9Y8r7Fb+W6xhly3WQZq6ybqqj+HLucZyuHVlNcrKNKrSPRKijRHPBLW3VFoSI4kQtFI+duapoI9I4jwR1uWHzpz/NFJEezM9UF3vg96CggS013oid4iL/QVc7kcPUUe6C1Zjt5SqhcvQ0+JB3qo3k3XOoo90FniSZCpYi84DnmirYjMFSnhKPKFrdB79Ov8J16sOrj0fgO1t87QQ+xpEruGIvwULDtXoX73CopwDEU4Cs37wtGaHgpHpgrt2UEkOADdtLw9+X7oLfBDP0VqgG5yu1iJ2yVKDJb6YPAw442hMq8pyj2J5YQHBo8wy3BbsBQDRH/5MvQRvWUe6C7zRNdhL3SWeqOjhFaM5rQd8hq6nrfs2Ru5HorpTUwGktiA8dJJGPf/CJZdq1G/5ynK55VoTI1BC71d2jPC0J4VQqKDSXQgiQ5AHy3pwCF/EuyPwRJ/DJX6Y/iwP+6U+WOknDjiD4k56kf4QjrG+BDeGDnmhZHjywkP3Dm+DMOCpRg8thS3iYGjZISM9ZLZHjLeRYHopIBYCpWdFzO9Ij7P9FIo+M9zly9fZgNxJtoD2j8chyl1DazJT9FGXEkRj6aIR1DEQ9FxQIWu3CD05AWS8AAMFJLoogAMlQRguDQAI4cDIZUFYbQ8GGNHVEQIxo+GTnGM6sdURBDGjwcQfhg7riS8MXrcExKZGCEDd8gAM3RsCQaP8orwalC6lVF60SqyAWNOkPmjXdE+Z5IjFYpHHnmE/8Y7JyUl5blz5z81/fH3x6Qvdv5Y+q9tMdLNpCjp1vYIqXJnuKTeFSpp94RIumSVpE9RSYa9wVJNarBk2qeSzPtVUm1aiFSXHirVZ4RJ1swIyZYZKTVkRUkN2TFSoyCa6tyOIMIkW3aIZM0OluqzA4kAyZLlL9Vl+UrmTF/JlKmUTBlKyUgY0pWSPt1Xqk7zk7T7/aVbe4PunI6NPLlS5fME61bMmTPne4899pj7ggULVq9Zs+bVtS+8sO+lf3k67VfPhKczrzA/CUtf58L6Z++xQeanU2z8abhgE/PPMhEudSZMsJER3wkVbHCy/tmZrJsmLP35H4XuUXos+eW8x+ZHLJg/f6H4E/u8efPmzJ079/u0GnyBWeQs/18yd+68hRT0+aT7ew//g/Dh5x/989/YnyApxuVsjAAAAABJRU5ErkJggg==",
            "name": "projectname2",
            "plannedEndDate": "2012-05-23T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": 
                "name": "Closed"
            ,
            "realEndDate": "2012-05-23T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        ,
        
            "abbreviation": "abc",
            "customer": "customer1",
            "description": "description3",
            "icon": "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",
            "name": "projectname3",
            "plannedEndDate": "2012-05-23T00:00:00+01:00",
            "plannedStartDate": "2012-05-23T00:00:00+01:00",
            "projectStatus": 
                "name": "In Progress"
            ,
            "realEndDate": "2012-05-23T00:00:00+01:00",
            "realStartDate": "2012-05-23T00:00:00+01:00"
        
    ]

在 android 端，我像这样反序列化 JSON 响应：

Gson gson = new Gson();
final ProjectContainer container = gson.fromJson(resultat, ProjectContainer.class);
final ListView lv = (ListView) findViewById(R.id.list);
adaptateur = new ProjectAdapter(ProjectActivity.this, R.layout.ligne_project, container);
lv.setAdapter(adaptateur);

这是我的 ProjectContainer 类：

  public class ProjectContainer 
        @SerializedName("project")
        List<Project> projects ;

        public List<Project> getProjects() 
            return projects;
            
        public void setProjects(List<Project> projects) 
            this.projects = projects;
        
    

非常感谢您帮助解决这个问题。提前致谢

【问题讨论】：

这可能是相关的：How to make Jersey/Jackson serialize empty list; single element list as an array.

问题很不清楚......当返回List作为1个元素时你只会得到错误？当它有 0 或 >1 个元素时它可以工作吗？清除 JSON 响应也会很有用...

是的，我只在 List 返回一个元素并且它有 0 个元素时得到错误，但当它有多个元素时，它会完美运行。

您能否提供 Web 服务返回的实际 JSON 响应，如果可能的话，包括 3 个不同的响应（0、1 或 >1 个元素）

@MikO 我根据你的要求更新了我的问题

【参考方案1】：

你的问题结果对我来说真的很奇怪......看来泽西岛的单元素数组的 JSON 序列化肯定有问题......如果你谷歌“Jersey JSON 单元素数组”你'会发现同样的问题，例如here 或here。我对泽西岛了解不多，所以无法帮助您...

---

也就是说，我可以建议在 Gson 中使用手动解析的解决方法，以使您的解析适应 2 个不同的响应（对象或数组）。你可以这样做：

//manually parsing until get the "project" element...
JsonParser parser = new JsonParser();
JsonObject rootObejct = parser.parse(yourJsonString).getAsJsonObject();
JsonElement projectElement = rootObejct.get("project");

Gson gson = new Gson();
List<Project> projectList = new ArrayList<>();

//Check if "project" element is an array or an object and parse accordingly...
if (projectElement.isJsonObject()) 
    //The returned list has only 1 element
    Project project = gson.fromJson(projectElement, Project.class);
    projectList.add(project);

else if (projectElement.isJsonArray()) 
    //The returned list has >1 elements
    Type projectListType = new TypeToken<List<Project>>() .getType();
    projectList = gson.fromJson(projectElement, projectListType);


//Now you have a List<Project> projectList with one or many Project elements, 
//depending on the response...

请注意，您不需要您的班级ProjectContainer。

这样的东西应该对你有用，虽然显然最好的办法是解决序列化问题！

【讨论】：

Jersey 或 Gson 不存在“问题”……Web 服务基本上已损坏且无法持续返回。他的 Java 类有一个 List<Project>，如果它要正确映射，它必须在 JSON（一个数组）中。 Web 服务根据 Project 对象的数量以两种不同的方式响应

@Brian，显然 Web 服务没有正确响应，这是肯定的，但如果到 JSON 的映射是由 Jersey 自动生成的......我想确实存在一些“问题”（或奇怪行为）在泽西映射中......否则，如果他没有任何序列化代码，错误在哪里？！服务哪里坏了？！问题一定出在 Jersey 的序列化中……

哦，等等，我明白你的意思了——我看错了。我以为你的意思是在 Gson 方面。未知 - 这取决于 getPagedProjects 返回的内容。

@Brian，是的，在我的回答中，我明确表示问题出在泽西岛......并且查看 JSON 响应，方法 getPagedProjects 对我来说似乎是正确返回的，否则他不会无法获取该数据...并且它必须返回 List<Project> 或者甚至 IDE 都会抱怨...所以，泽西岛再次出现问题，在我提供的链接中它们似乎有相同的问题...

谢谢。我非常感谢您对@MikO 的帮助，您提供的链接非常有帮助，我更喜​​欢修复 Jersey 的序列化问题，而不是解决 Gson 中的解析问题。再次感谢您，非常感谢您的帮助。

【参考方案2】：

基本上，您的 Web 服务在响应方式方面存在问题。如果project 只有一个对象，则它只返回一个对象而不是数组。

MikO 的回答解决了这个问题，但另一种方法是将该逻辑封装在自定义反序列化器中：

class MyDeserializer implements JsonDeserializer<ProjectContainer> 

    @Override
    public ProjectContainer deserialize(JsonElement je, Type type, JsonDeserializationContext jdc) throws JsonParseException 

        JsonObject jo = je.getAsJsonObject().getAsJsonObject("project");
        if (jo.isJsonArray()) 
             return new Gson().fromJson(je, ProjectContainer.class);
         else 
             Project p = jdc.deserialize(jo, Project.class);
             List<Project> pList = new ArrayList<Project>(1);
             pList.add(p);
             ProjectContainer pc = new ProjectContainer();
             pc.setProjects(pList);
             return pc;
        
    

那么你可以使用：

Gson gson = new GsonBuilder()
                .registerTypeAdapter(ProjectContainer.class, new MyDeserializer())
                .build();
ProjectContainer pContainer = gson.fromJson(myJson, ProjectContainer.class);

【参考方案3】：

我最终使用Jackson library 而不是gson 来解析json 响应。它会自动将对象转换为ArrayList。就易用性而言，它与 gson 非常相似。希望对您有所帮助！