Jersey RESTful 服务，错误 500答案

【问题标题】：Jersey RESTful Service, Error 500Jersey RESTful 服务，错误 500
【发布时间】：2013-11-03 03:29:17
【问题描述】：

我是 Restful Web 服务的新手。我想通过 Jersey 客户端访问服务器。但我收到 500 错误。我想要做的是通过客户端提交一个表名并将表内容作为 JSON 检索。谁能在这里找到错误？

这是我的客户端

 public JSONObject loadTable(String tablename) throws ClientProtocolException, IOException {
    pathParams.add("tablename", tablename);
    JSONObject jsontable = service.path("access").path("loadtable").queryParams(pathParams).get(JSONObject.class);
    return jsontable;
}

这是我的服务器端

@Path("/loadtable")
@GET
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.TEXT_PLAIN)
public JSONObject loadTable(@QueryParam("tablename") String tablename) throws Exception {
    List<Pricing> pricing = new ArrayList<Pricing>();
    try {
        query = c.prepareStatement("select * from '" + tablename + "'");
        ResultSet ets_rs = query.executeQuery();

        while (ets_rs.next()) {
            pricing.add(new Pricing(ets_rs.getString(1), ets_rs.getString(2),  ets_rs.getString(3), ets_rs.getString(4), ets_rs.getString(5), ets_rs.getString(6)));
        }
        query.close();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (c != null) {
            c.close();
        }
    }
    JSONObject jsonTable = JsonConvert.getJsonFromPricing(pricing);
    System.out.println(jsonTable);
    return jsonTable;
}

Server 端的 Pricing 类将 Result 集转换为 JSON。

这是 StackTrace：

Exception in thread "AWT-EventQueue-0" com.sun.jersey.api.client.UniformInterfaceException: GET http://localhost:8080/ServerETS/resources/access/loadtable?tablename=prices returned a response status of 500
    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:563)
    at com.sun.jersey.api.client.WebResource.get(WebResource.java:179)
    at Link.ClientLink.loadTable(ClientLink.java:60)
    at Interfaces.Pricing.loadTable(Pricing.java:112)
    at Interfaces.Pricing.<init>(Pricing.java:32)
    at Interfaces.MainMenu.panelPricing(MainMenu.java:1026)
    at Interfaces.AdminData.btnAdminDataOKActionPerformed(AdminData.java:150)
    at Interfaces.AdminData.access$000(AdminData.java:26)
    at Interfaces.AdminData$1.actionPerformed(AdminData.java:70)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6288)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6053)
    at java.awt.Container.processEvent(Container.java:2041)
    at java.awt.Component.dispatchEventImpl(Component.java:4651)
    at java.awt.Container.dispatchEventImpl(Container.java:2099)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
    at java.awt.Container.dispatchEventImpl(Container.java:2085)
    at java.awt.Window.dispatchEventImpl(Window.java:2478)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:643)
    at java.awt.EventQueue.access$000(EventQueue.java:84)
    at java.awt.EventQueue$1.run(EventQueue.java:602)
    at java.awt.EventQueue$1.run(EventQueue.java:600)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:616)
    at java.awt.EventQueue$2.run(EventQueue.java:614)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:613)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

这是 GlassFish 服务器日志

Caused by: com.sun.jersey.api.MessageException: A message body writer for Java class org.json.simple.JSONObject, and Java type class org.json.simple.JSONObject, and MIME media type application/json was not found
    ... 33 more

【问题讨论】：

请提供更多详细信息。什么是堆栈跟踪？
你能否提供服务器日志（应该还有一个异常解释导致 HTTP 500 的原因）？
@LutzHorn 我已经包含了 Stacktrace。
@MichalGajdos 我已经包含了服务器日志。

标签： java json rest jersey netbeans-6.9

【解决方案1】：

Jersey 无法将您对 JSON 的 JSONObject 响应序列化。把你的方法改成这样：

@GET
@Produces(MediaType.APPLICATION_JSON)
public Response loadTable(@QueryParam("tablename") String tablename) throws Exception {
  // ...
  Pricing pricing = ...
  return Response.ok(pricing).build();
}

用 JAXB @XmlRootElement 注释 Pricing 并让 JAXB 转换为 JSON。

【讨论】：

感谢您的快速回复。但我仍然遇到同样的错误。当我在“loadtable”方法标题下方添加一个 s.out 时，它不会给出任何结果。所以我猜错误出在客户端方法调用或服务器端“loadtable”方法头中。

【解决方案2】：

由于您尝试以 JSON 格式发送请求数据，您可以将服务器消费数据类型的 MIME 类型修改为 JSON 类型：

@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)

【讨论】：

@tonga... 实际上我的输入不是 JSON 格式。是纯文本。只有我的输出是 JSON。

【解决方案3】：

如下更改客户端

public String loadTable(String tablename) throws ClientProtocolException, IOException {
    pathParams.add("tablename", tablename);
    ClientResponse response = service.path("access").path("loadtable").queryParams(pathParams).type(MediaType.APPLICATION_JSON).get(ClientResponse.class);
    String responseString = response.getEntity(String.class);
    return responseString;
}

和服务器端如下，

@Path("/loadtable")
@GET
@Produces(MediaType.APPLICATION_JSON)
public List<Pricing> loadTable(@QueryParam("tablename") String tablename) throws Exception {
    List<Pricing> pricing = new ArrayList<Pricing>();
    try {
        query = c.prepareStatement("select * from " + tablename);
        ResultSet ets_rs = query.executeQuery();

        while (ets_rs.next()) {
            pricing.add(new Pricing(ets_rs.getString(1), ets_rs.getString(2),  ets_rs.getString(3), ets_rs.getString(4), ets_rs.getString(5), ets_rs.getString(6)));
        }
        query.close();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (c != null) {
            c.close();
        }
    }
    return pricing;
}

并使用 JAXB @XmlRootElement 进行注释定价... 像魔术一样工作！感谢@LutzHorn 的 cmets！

【讨论】：