如何处理使用 servlet 上传的 java 进程中的文件

Question

我开发了一个 Java servlet (tomcat 6.0) 来处理从客户端上传到服务器的文件。到目前为止，我的 javaapp 现在所能做的就是上传文件。我编写了另一个 java 应用程序，它扫描文件（excel 文档，apachi POI），并从中解析特定信息，然后打印出信息。

目标基本上是使用上传的文件，然后调用java程序处理文件。然后将数据从 java 控制台（结果）吐出到 HTML 页面。

这是我的 servlet 代码。我按照this 教程制作了这个。

小服务程序：

package net.codejava.upload;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * A Java servlet that handles file upload from client.
 * @author www.codejava.net
 */
public class UploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private static final String UPLOAD_DIRECTORY = "upload";
    private static final int THRESHOLD_SIZE     = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB

    /**
     * handles file upload via HTTP POST method
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // checks if the request actually contains upload file
        if (!ServletFileUpload.isMultipartContent(request)) {
            PrintWriter writer = response.getWriter();
            writer.println("Request does not contain upload data");
            writer.flush();
            return;
        }

        // configures upload settings
        DiskFileItemFactory factory = new DiskFileItemFactory();
        factory.setSizeThreshold(THRESHOLD_SIZE);
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

        ServletFileUpload upload = new ServletFileUpload(factory);
        upload.setFileSizeMax(MAX_FILE_SIZE);
        upload.setSizeMax(MAX_REQUEST_SIZE);

        // constructs the directory path to store upload file
        String uploadPath = getServletContext().getRealPath("")
            + File.separator + UPLOAD_DIRECTORY;
        // creates the directory if it does not exist
        File uploadDir = new File(uploadPath);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }

        try {
            // parses the request's content to extract file data
            List formItems = upload.parseRequest(request);
            Iterator iter = formItems.iterator();

            // iterates over form's fields
            while (iter.hasNext()) {
                FileItem item = (FileItem) iter.next();
                // processes only fields that are not form fields
                if (!item.isFormField()) {
                    String fileName = new File(item.getName()).getName();
                    String filePath = uploadPath + File.separator + fileName;
                    File storeFile = new File(filePath);

                    // saves the file on disk
                    item.write(storeFile);
                }
            }
            request.setAttribute("message", "Upload has been done successfully!");
        } catch (Exception ex) {
            request.setAttribute("message", "There was an error: " + ex.getMessage());
        }
        getServletContext().getRequestDispatcher("/message.jsp").forward(request, response);
    }
}

Web XML 文件：

<?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"
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    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">
  <display-name>UploadServletApp</display-name>

  <servlet>
    <description></description>
    <display-name>UploadServlet</display-name>
    <servlet-name>UploadServlet</servlet-name>
    <servlet-class>net.codejava.upload.UploadServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>UploadServlet</servlet-name>
    <url-pattern>/UploadServlet</url-pattern>
  </servlet-mapping>
</web-app>

我的上传JSP页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>File Upload</title>
</head>
<body>
    <center>
        <form method="post" action="UploadServlet" enctype="multipart/form-data">
            Select file to upload: <input type="file" name="uploadFile" />
            <br/><br/>
            <input type="submit" value="Upload" />
        </form>
    </center>
</body>
</html>

我的消息jsp页面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Upload</title>
</head>
<body>
    <center>
        <h2>${requestScope.message}</h2>
    </center>
</body>
</html>

有人可以告诉我现在要做什么，如何调用我制作的单独的java程序（代码未在此处发布）来处理文件，然后让它从java控制台吐出数据（结果) 到“消息”HTML jsp 页面？我到处找，找不到解决这个问题的方法。这让我疯狂。

Answer 1

首先，您需要创建一个返回 String 并将 String 作为参数的方法。

public String getContent(String filePath) {
    // logic goes here
}

你已经为里面创建了一个类，你需要创建这个方法。 然后你需要更改 servlet 的某些部分：

在doPost方法中声明一个变量String fileName = "";并改变

if (!item.isFormField()) {
    String fileName = new File(item.getName()).getName();

到

if (!item.isFormField()) {
    fileName = new File(item.getName()).getName(); // remove String 

在while循环之后调用你的类（假设FilterData是你的类名）

while (iter.hasNext()) {
    // Code
}
FilterData fd = new FilterData();
String data = fd.getData(uploadPath + "//" + fileName);
request.setAttribute("message", data);          

并删除

request.setAttribute("message", "Upload has been done successfully!");

希望对你有帮助！！！

Answer 2

如果您编写了其他 java 代码，只需在项目中包含该类：实例化该类并将其传递给文件。在您将文件写入磁盘的 servlet 中

  // saves the file on disk
  item.write(storeFile);

您可以实例化您的类并将文件对象或文件路径传递给它。