JSP+Servlet中使用jspsmartupload.jar进行图片上传下载

    <form action="FileServlet" method="post" enctype="multipart/form-data">
        <input type="file" name="myfile"> 
        <input type="text" name="cmt" value="example示例"> 
        <input type="submit">
    </form>

<a href="FileServlet?filename=1.xlsx">download</a>

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.jspsmart.upload.File;
import com.jspsmart.upload.Request;
import com.jspsmart.upload.SmartUpload;
import com.jspsmart.upload.SmartUploadException;

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        String strName = request.getParameter("filename");
        if (strName == null) {
            return;
        }
        // new一下
        SmartUpload su = new SmartUpload();
        // 初始化
        su.initialize(getServletConfig(), request, response);
        // 初始化
        su.setContentDisposition(null);
        try {
            su.downloadFile("up/" + strName);
        } catch (SmartUploadException e) {
            e.printStackTrace();
        }
        // 下载就不用重定向了，响应已经提交过了，会出错：
        // Cannot call sendRedirect() after the response has been committed
        //response.sendRedirect("upload.jsp");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // new一下
        SmartUpload su = new SmartUpload();
        // 初始化
        su.initialize(getServletConfig(), request, response);
        try {
            su.upload();
            File f = su.getFiles().getFile(0);

            // SAVE_PHYSICAL 操作系统根目录
            // SAVE_VIRTUAL Web应用根目录
            // SAVE_AUTO 组件自己选择
            f.saveAs("up/" + f.getFileName(), SmartUpload.SAVE_VIRTUAL);
        } catch (SmartUploadException e) {
            e.printStackTrace();
        }
        // ↓↓↓取参数
        String sevletP = request.getParameter("cmt");
        System.out.println("直接获取参数不可以:" + sevletP);

        Request request2 = su.getRequest();
        String suP = request2.getParameter("cmt");
        System.out.println("通过SmartUpload对象间接获取参数:" + suP);
        // ↑↑↑取参数

        // 转去下载页面
        response.sendRedirect("download.jsp");
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>FileServlet</servlet-name>
        <servlet-class>FileServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>FileServlet</servlet-name>
        <url-pattern>/FileServlet</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>upload.jsp</welcome-file>
    </welcome-file-list>
</web-app>