JSP 异常错误：已为此响应调用getWriter()

hiz5n14c 于 2022-12-07 发布在其他

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我使用GlassFish作为服务器，使用Netbeans IDE 8.0。下面是我的项目结构。

我的程序如何工作：
1.客户端打开本地主机：8080/Beer
1.她/他选择啤酒（在index.html中）

it will POST to BeerSelect.java (BS for short)
BS will call BeerExpert.java and then call result.jsp for finally send Test.jar to client
下面是BS中的重要代码。

/* Result.jsp */
    String c = request.getParameter("color");
    BeerExpert be = new BeerExpert();
    List result = be.getBrands(c);

    request.setAttribute("styles", result);
    RequestDispatcher view = request.getRequestDispatcher("result.jsp");
    view.forward(request, response);

    /* Test Client Download */
    response.setContentType("application/jar");

    ServletContext ctx = getServletContext();
    InputStream is = ctx.getResourceAsStream("/Test.jar");

    int read = 0;
    byte[] bytes = new byte[1024];

    OutputStream os = response.getOutputStream();
    while ((read = is.read(bytes)) != -1){
        os.write(bytes, 0, read);
    }
    os.flush();

错误代码：