Servlet異步上傳文件

時間 2019-11-21

原文原文鏈接

這裏須要用到插件ajaxfileupload.js，jar包：commons-fileupload-1.3.2.jar，commons-io-2.5.jarjavascript

注意紅色部分的字！！！！html

一、建立一個web工程，在配置web.xml前端

<!-- 文件上傳的servlet -->
    <servlet>
        <servlet-name>UploadServlet</servlet-name>
        <servlet-class>com.eviac.blog.restws.FileUpload</servlet-class>
      </servlet>
   
      <servlet-mapping>
        <servlet-name>UploadServlet</servlet-name>
        <url-pattern>/uploadFile</url-pattern>
      </servlet-mapping>

二、upload.jsp頁面java

<%@ 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>文件上傳實例——servlet 異步上傳文件（ajaxFileupload）</title>
</head>
   <script type="text/javascript" src="js/jquery.js"></script>
    <script type="text/javascript" src="js/ajaxfileupload.js"></script>
    <script type="text/javascript">
  function ajaxFileUpload()
  {
    
    
    
    $.ajaxFileUpload
    (
      {
        url:'/servleToRestful/uploadFile',//用於文件上傳的服務器端請求地址
        secureuri:false,//通常設置爲false
        fileElementId:'file',//文件上傳空間的id屬性 <input type="file" id="file" name="file" />
        dataType: 'text',//返回值類型 通常設置爲json
        success: function (data, status) //服務器成功響應處理函數
        {
             //方法一，用後臺返回值
             alert(data);//後臺out輸出的值
             //用ajaxFileUpload來判斷成功與否，設置值
              $('#myspan').html("上傳成功！");
         
        },
        error: function (data, status, e)//服務器響應失敗處理函數
        {
               //方法一，用後臺返回值
                 alert(data);//後臺out輸出的值
                 //用ajaxFileUpload來判斷成功與否，設置值
              $('#myspan').html("上傳失敗！");
        }
      }
    )
    
    return false;

  }
  </script>
<body>
<h1>文件上傳實例——servlet 異步上傳文件（ajaxFileupload）</h1>
<!-- <form method="post" action="/servleToRestful/uploadFile" enctype="multipart/form-data">
    選擇一個文件:
    <input type="file" name="uploadFile" />
    <br/><br/>
    <input type="submit" value="上傳" />
</form>
 -->

    <br/>
    <input type="file" id="file" name="file" />
    <br />
    <input type="button" value="上傳" onclick="return ajaxFileUpload();">
    
    <br>
    <p><span id="myspan"></span></p>
</body>
</html>

三、後臺代碼FileUpload類jquery

package com.eviac.blog.restws;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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;

public class FileUpload extends HttpServlet{
    private static final long serialVersionUID = 1L;
    
    // 上傳文件存儲目錄
    private static final String UPLOAD_DIRECTORY = "upload";
 
    // 上傳配置
    private static final int MEMORY_THRESHOLD   = 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
    
    public FileUpload(){
        super();
    }
    
    public void service(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
                PrintWriter writer = response.getWriter();
                // 檢測是否爲多媒體上傳
                if (!ServletFileUpload.isMultipartContent(request)) {
                    // 若是不是則中止
                    
                    writer.println("Error: 表單必須包含 enctype=multipart/form-data...");
                    writer.flush();
                    return;
                }
                
                //記住要寫這句話，上傳的文件名纔不會亂碼！！！！！！！！！
                request.setCharacterEncoding("utf-8");
                response.setContentType("text/html;charset=utf-8");
         
                // 配置上傳參數
                DiskFileItemFactory factory = new DiskFileItemFactory();
                // 設置內存臨界值 - 超事後將產生臨時文件並存儲於臨時目錄中
                factory.setSizeThreshold(MEMORY_THRESHOLD);
                // 設置臨時存儲目錄
                factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
         
                ServletFileUpload upload = new ServletFileUpload(factory);
                 
                // 設置最大文件上傳值
                upload.setFileSizeMax(MAX_FILE_SIZE);
                 
                // 設置最大請求值 (包含文件和表單數據)
                upload.setSizeMax(MAX_REQUEST_SIZE);
         
                // 構造臨時路徑來存儲上傳的文件
                // 這個路徑相對當前應用的目錄
                String uploadPath = request.getContextPath() + File.separator + UPLOAD_DIRECTORY;
                
                //獲取項目發佈路徑  下的upload文件夾
                uploadPath = request.getSession().getServletContext().getRealPath("/upload");
                
                           
                 
                // 若是目錄不存在則建立
                File uploadDir = new File(uploadPath);
                if (!uploadDir.exists()) {
                    uploadDir.mkdir();
                }
         
                try {
                    // 解析請求的內容提取文件數據
//                    @SuppressWarnings("unchecked")
                    List<FileItem> formItems = upload.parseRequest(request);
         
                    if (formItems != null && formItems.size() > 0) {
                        // 迭表明單數據
                        for (FileItem item : formItems) {
                            // 處理不在表單中的字段
                            if (!item.isFormField()) {
                                //這裏處理文件中文亂碼沒用。。。。。。。。。
                                System.out.println(new String(item.getName().getBytes("utf-8"),"iso-8859-1"));
                                String fileName = new File(item.getName()).getName();
                                String filePath = uploadPath + File.separator + fileName;
                                File storeFile = new File(filePath);
                                // 在控制檯輸出文件的上傳路徑
                                System.out.println(filePath);
                                // 保存文件到硬盤
                                item.write(storeFile);
                                //注意編碼，否則返回前端會亂碼！！！
                                writer.println(new String("上傳成功！".getBytes("utf-8"),"iso-8859-1"));
                            }
                        }
                    }
                    
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
                // 跳轉到 message.jsp,這裏使用了異步上傳，因此不用跳轉頁面
                    //request.getRequestDispatcher("/message.jsp").forward(request, response);
            }
}