使用REST JAX-RS实现满足特定条件时如何重定向用户? [英] How to redirect user when certain condition is met using REST JAX-RS implementation?

问题描述

我以前只使用可以执行查询的Tomcat和JSP页面，然后将查询结果分配给数组或对象，然后通过响应将数据传递到客户端.

I used to just use Tomcat and JSP pages which I can execute query, then assign query result into the array or object then pass that data onto client side via response.

request.setAttribute("errorMessage", "this is error!!");
request.getRequestDispatcher("report.jsp").forward(request, response);

在客户端jsp代码中，我可以做类似的事情:

In client jsp code, I could do something like:

$ {errorMessage}

然后这是错误！"消息将会显示.

Then the "this is error!!" message would show up.

我想对REST JAX-RS GlassFish v3做同样的事情.

I want to do the same thing with REST JAX-RS GlassFish v3.

    @Path("schedule/test")
    @POST
    @Consumes("application/x-www-form-urlencoded")
    @Produces("application/vnd.ms-excel")
    public Object tmpTest(String content) {
        try {

            //just my method to execute query and get result
            Vector out = (Vector)QueryManager.executeQuery;

            //if query result is empty, I want user to redirect to report.jsp page
            if(out.isEmpty()) {
                request.setAttribute("errorMessage", "This is error!!");
                request.getRequestDispatcher("report.jsp").forward(request, response);
                return null;
            }
        ....continue code......
   }

这会导致我从未见过的神秘异常.

This results in mysterious exception I've never seen.

java.lang.ClassCastException: $Proxy109 cannot be cast to org.apache.catalina.core.ApplicationHttpRequest
            at org.apache.catalina.core.ApplicationHttpRequest.getRequestFacade(ApplicationHttpRequest.java:1001)
            at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:472)
            at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:379)
            at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:336)
            at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:314)

那我该如何将用户重定向到report.jsp并传递诸如这是错误"之类的消息?

客户端jsp希望错误msg变量具有一个值:

The client jsp expects the error msg variable to have a value:

<b>${errorMessage}</b>

推荐答案

那不是RESTful的.您需要使用 WebApplicationException 特定的状态代码，以便客户了解到底出了什么问题.例如.当实际上是服务器的错误时:

That's not RESTful. You need to throw a WebApplicationException with a specific status code so that the client understands what exactly went wrong. E.g. when it's actually the server's mistake:

throw new WebApplicationException(Response.Status.INTERNAL_SERVER_ERROR);

或者是在所有客户的错误之后:

Or when it was after all client's mistake:

throw new WebApplicationException(Response.Status.BAD_REQUEST);

有关概述，另请参见 HTTP状态代码定义.

您正面临的ClassCastException之所以会发生，是因为分派的request实际上不是servlet容器提供的实现的实例(在这种情况下，是Tomcat或Tomcat-fork之一) .毕竟，您不应该这样做.您正在开发REST Web服务，而不是JSP/Servlet网站.这是两个不同的世界.

The ClassCastException which you're facing is by the way occurring because the dispatched request is actually not an instance of the servletcontainer-provided implementation (in this particular case, the one of Tomcat or a Tomcat-fork). After all, you shouldn't be doing it this way. You're developing a REST webservice, not a JSP/Servlet website. It are two distinct worlds.

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