java - 在 Struts 中将 JSON 字符串写入 Printwriter 时出现 ArrayIndexOutOfBoundsException

Question

我从数据库获取行的 List 并将其转换为 JSONstring 并将其写入 PrintWritter 以将输出作为 JSON 发送。

我能够写入一些行，直到现在它在下面代码中指向的行处给出了ArrayIndexOutOfBoundsException。

Gson gson = new Gson();
String jsonString = gson.toJson(subAreaCriteriaList);
response.setHeader("X-JSON", jsonString);

PrintWriter writer = response.getWriter();
writer = response.getWriter();
writer.write(jsonString);//exception at this line
writer.flush();

这是我的操作方法

public Object doGetSubAreasifExist(BaseActionMapping mapping,
        ActionForm form, HttpServletRequest request,
        HttpServletResponse response) throws Exception {
        try {
            CurrentRoute route = new CurrentRoute();
            String areaID = request.getParameter("areaID");
            LoginService bbcService = (LoginService) Context.getInstance()
                                                            .getBean("LoginService");

            DetachedCriteria subAreaCriteria = DetachedCriteria.forClass(CabArea.class);
            subAreaCriteria.add(Restrictions.ne(CabArea.PROP_ID, Long.parseLong(areaID)));

            List<CabArea> subAreaCriteriaList = bbcService.findAll(subAreaCriteria);

            Gson gson = new Gson();
            String jsonString = gson.toJson(subAreaCriteriaList);
            response.setHeader("X-JSON", jsonString);

            PrintWriter writer = response.getWriter();
            writer = response.getWriter();
            writer.write(jsonString);
            writer.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

这是我的strut-config xml部分

<action path="/admin/cabsharing/getSubAreasifExist"
            type="com.ihexa.common.admin.cabsharing.action.CabsharingAction"
            name="actionForm">              
</action>

这是我的堆栈跟踪

java.lang.ArrayIndexOutOfBoundsException
    at java.lang.System.arraycopy(Native Method)
    at org.apache.coyote.http11.InternalOutputBuffer.write(InternalOutputBuffer.java:701)
    at org.apache.coyote.http11.InternalOutputBuffer.sendStatus(InternalOutputBuffer.java:438)
    at org.apache.coyote.http11.Http11Processor.prepareResponse(Http11Processor.java:1626)
    at org.apache.coyote.http11.Http11Processor.action(Http11Processor.java:958)
    at org.apache.coyote.Response.action(Response.java:183)
    at org.apache.coyote.Response.sendHeaders(Response.java:379)
    at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
    at org.apache.catalina.connector.OutputBuffer.close(OutputBuffer.java:274)
    at org.apache.catalina.connector.Response.finishResponse(Response.java:493)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:317)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)

Answer 1

根据您添加的评论我可以发送一定数量的数据，但是当我超过时它会给我错误，它看起来像 header 大小(在您的情况下是 response.setHeader("X-JSON", jsonString);) 超出了最大限制(引用 Maximum on http header values? 可能会有所帮助)，并且问题似乎是特定于服务器的。

如果您使用的是 Apache Tomcat 那么您可以引用 maxHttpHeaderSize in Apache Tomcat Configuration Reference修改conf/server.xml。在 server.xml 中设置 maxHttpHeaderSize 将解决您的问题。这是sample server.xml maxHttpHeaderSize 使用的文件。

您还必须关闭writer对象，如下所示:

writer.flush();
writer.close();