如何在显示 jsp 页面之前触发 doGet

Question

我有一个名为export.jsp的网页，当用户访问domain/export.jsp时，我想让他通过servlet的doGet方法自动下载一个csv文件.之后我想显示实际的 jsp 文件，即 export.jsp

我的doGet方法如下：

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //RequestDispatcher rd = request.getRequestDispatcher("/export.jsp");
        //rd.forward(request, response);

        //getting and loading the property file
        Properties propConfig = new Properties();
        Properties propLog = new Properties();

        Statement stmt = null;
        Connection connection = null;

        try {
            //Loading the property files
            propConfig.load(getServletContext().getResourceAsStream("/WEB-INF/config.properties"));
            propLog.load(getServletContext().getResourceAsStream("/WEB-INF/log4j.properties"));
            PropertyConfigurator.configure(propLog);

            logger.info("loaded log4j properties From Path: /WEB-INF/log4j.properties");

            connection = DbTools.getConnection(propConfig.getProperty("db_hostname"), 
                    propConfig.getProperty("db_port"), propConfig.getProperty("db_serviceName"),
                    propConfig.getProperty("db_userName"),propConfig.getProperty("db_password"));

            stmt = connection.createStatement();
            ResultSet rset = stmt .executeQuery("SELECT * FROM QACOMPLETE_DEFECT");

            File csvfile = FileTools.generateCsvFile(rset);


            response.setContentType("text/csv");
            response.setHeader("Content-Disposition", "inline; filename=\""+csvfile.getName()+"\"");

            OutputStream outputStream = response.getOutputStream();
            outputStream.write(Files.readAllBytes(Paths.get(csvfile.getAbsolutePath())));
            outputStream.flush();
            outputStream.close();

        } catch (SQLException e) {
            logger.error("SQLException", e);

        }catch (IOException e) {
            logger.error("IOexception, The user may have cancel the download ", e);
        }
        finally
        {
            DbTools.closeQuietly(stmt);
            DbTools.closeQuietly(connection);
        }
    }

我的web.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <servlet>
    <description></description>
    <display-name>DefectExporter</display-name>
    <servlet-name>DefectExporter</servlet-name>
    <servlet-class>exporter.DefectExporter</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>DefectExporter</servlet-name>
    <url-pattern>/export.jsp</url-pattern>
  </servlet-mapping>
</web-app>

我做错了什么吗？因为当我在浏览器中输入url http://localhost:7001/DefectsExporter/export.jsp时，doGet方法被触发但是网页export.jsp没有出现。

Answer 1

你不能那样做，至少没有 Javascript。

ServletResponse 只能做一件事：return csv 数据，或 return HTML 页面。您绝对需要 2 个不同的请求（无论是简单的普通请求还是 javascript 一个请求）：第一个是下载 csv 文件，第二个是显示 JSP.

我能想到的满足这种要求的唯一方法是 servlet 通过 javascript 和客户端发送一个页面，首先下载（并保存）csv 文件，然后使用不同的 URL 发送对 JSP 页面的请求。但是 AFAIK，没有办法在服务器端执行此操作。

如何在显示 jsp 页面之前触发 doGet

How to trigger a doGet before displaying a jsp page

jsp

web.xml

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