先分析一下上傳文件的流程
1-先通過前段頁面中的選擇文件選擇要上傳的圖片
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8" contentType="text/html; charset=UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="content-type" content="text/html;charset=utf-8"> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <script type="text/javascript" src="js/jquery.min.js"></script> <script type="text/javascript" src="js/common.js"></script> <script type="text/javascript" src="js/ajaxfileupload.js"></script> </head> <body> <input type="file" value="上傳" name="inputImage" id="inputImage"> <input type="button" value="上傳" id="upload"> <a id="downLoad">下載</a> </body></html>
2-點擊提交按鈕，通過ajax的文件上傳訪問服務(wù)器端
common.js
var path = (function() { //獲取當(dāng)前網(wǎng)址 var curWwwPath = window.document.location.href; //獲取主機地址之后的目錄 var pathName = window.document.location.pathname; var pos = curWwwPath.indexOf(pathName); //獲取主機地址 var localhostPath = curWwwPath.substring(0, pos); //獲取帶"/"的項目名 var projectName = pathName.substring(0, pathName.substr(1).indexOf('/') + 1); return { curWwwPath: curWwwPath, pathName: pathName, localhostPath: localhostPath, projectName: projectName, //部署路徑 deployPath: localhostPath + projectName };})();// 文件下載$("a[id=downLoad]").click(function(){ window.location.href=path.deployPath+"/fileDown";});// 文件上傳$("input[id=upload]").click(function() { $.ajaxFileUpload( { url : path.deployPath + "/fileUp", // 處理頁面的絕對路徑 fileElementId : "inputImage", //file空間的id屬性 dataType : "json", success : function(data) { alert("上傳成功"); } });});3-服務(wù)器端響應(yīng)保存或者下載
保存上傳文件的FileUpload.java
import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import java.util.List;import java.util.UUID;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import net.sf.json.JSONArray;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;import com.stu.util.HttpUtil;/** * 文件名稱： com.stu.fileupload.FileUpload.java<br/> * 初始作者： Administrator<br/> * 創(chuàng)建日期： 2018-1-31<br/> * 功能說明： 文件上傳 <br/> * =================================================<br/> * 修改記錄：<br/> * 修改作者 日期 修改內(nèi)容<br/> * ================================================<br/> * Copyright (c) 2010-2011 .All rights reserved.<br/> */public class FileUpload extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { // 獲取到當(dāng)前服務(wù)器所在的路徑 String serverPath = req.getSession().getServletContext().getRealPath("/"); // 設(shè)置保存上傳文件的路徑 String saveDirPath = serverPath + "img"; File saveDirPathFileObj = new File(saveDirPath); // 如果當(dāng)用來存放文件的目錄不存在時，要創(chuàng)建該目錄 if (!saveDirPathFileObj.exists()) { saveDirPathFileObj.mkdirs(); } // 創(chuàng)建一個解析器工廠 DiskFileItemFactory factory = new DiskFileItemFactory(); // 設(shè)置工廠的緩存區(qū)大小 factory.setSizeThreshold(5 * 1024); // 文件上傳的解析器(文件上傳對象) ServletFileUpload upload = new ServletFileUpload(factory); // 設(shè)置上傳文件的最大值 upload.setSizeMax(3 * 1024 * 1024); // 設(shè)置編碼格式 upload.setHeaderEncoding("UTF-8"); try { // 上傳以后的文件名 List<String> uploadFileNames = new ArrayList<String>(); List<FileItem> fileItems = upload.parseRequest(req); System.out.println(fileItems); for (FileItem file : fileItems) { // 新的文件名 String saveFileName = UUID.randomUUID().toString().replace("-", ""); // 文件的后綴 String oldFileName = new String(file.getName().getBytes(), "UTF-8"); System.out.println("oldFileName" + oldFileName); String fileType = oldFileName.substring(oldFileName.lastIndexOf(".")); // 新的文件路徑 String saveFilePath = saveDirPath + File.separator + saveFileName + fileType; uploadFileNames.add(saveFileName + fileType); // 保存上傳的文件 file.write(new File(saveFilePath)); } System.out.println(uploadFileNames); HttpUtil.setAttribute(req, "urls", uploadFileNames); res.setContentType("application/json;charset=utf-8"); PrintWriter pw = res.getWriter(); pw.print(JSONArray.fromObject(uploadFileNames)); } catch (FileUploadException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } }}下載文件的FileDownload.java
import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import java.util.List;import java.util.UUID;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import net.sf.json.JSONArray;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;import com.stu.util.HttpUtil;/** * 文件名稱： com.stu.fileupload.FileUpload.java<br/> * 初始作者： Administrator<br/> * 創(chuàng)建日期： 2018-1-31<br/> * 功能說明： 文件上傳 <br/> * =================================================<br/> * 修改記錄：<br/> * 修改作者 日期 修改內(nèi)容<br/> * ================================================<br/> * Copyright (c) 2010-2011 .All rights reserved.<br/> */public class FileUpload extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { // 獲取到當(dāng)前服務(wù)器所在的路徑 String serverPath = req.getSession().getServletContext().getRealPath("/"); // 設(shè)置保存上傳文件的路徑 String saveDirPath = serverPath + "img"; File saveDirPathFileObj = new File(saveDirPath); // 如果當(dāng)用來存放文件的目錄不存在時，要創(chuàng)建該目錄 if (!saveDirPathFileObj.exists()) { saveDirPathFileObj.mkdirs(); } // 創(chuàng)建一個解析器工廠 DiskFileItemFactory factory = new DiskFileItemFactory(); // 設(shè)置工廠的緩存區(qū)大小 factory.setSizeThreshold(5 * 1024); // 文件上傳的解析器(文件上傳對象) ServletFileUpload upload = new ServletFileUpload(factory); // 設(shè)置上傳文件的最大值 upload.setSizeMax(3 * 1024 * 1024); // 設(shè)置編碼格式 upload.setHeaderEncoding("UTF-8"); try { // 上傳以后的文件名 List<String> uploadFileNames = new ArrayList<String>(); List<FileItem> fileItems = upload.parseRequest(req); System.out.println(fileItems); for (FileItem file : fileItems) { // 新的文件名 String saveFileName = UUID.randomUUID().toString().replace("-", ""); // 文件的后綴 String oldFileName = new String(file.getName().getBytes(), "UTF-8"); System.out.println("oldFileName" + oldFileName); String fileType = oldFileName.substring(oldFileName.lastIndexOf(".")); // 新的文件路徑 String saveFilePath = saveDirPath + File.separator + saveFileName + fileType; uploadFileNames.add(saveFileName + fileType); // 保存上傳的文件 file.write(new File(saveFilePath)); } System.out.println(uploadFileNames); HttpUtil.setAttribute(req, "urls", uploadFileNames); res.setContentType("application/json;charset=utf-8"); PrintWriter pw = res.getWriter(); pw.print(JSONArray.fromObject(uploadFileNames)); } catch (FileUploadException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); } }}這里面用到了一個HttpUtil類，代碼如下：
import javax.servlet.FilterConfig;import javax.servlet.ServletConfig;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpSession;/** * 文件名稱＿com.niit.model2.util.Httputil.java</br> * 初始作逯?Administrator</br> * 創(chuàng)建日期＿2018-1-23</br> * 功能說明＿這里用一句話描述這個類的作用--此句話需刪除 <br/> * =================================================<br/> * 修改記錄＿br/> * 修改作迠日期 修改內(nèi)容<br/> * ================================================<br/> * Copyright (c) 2010-2011 .All rights reserved.<br/> */public class HttpUtil { private HttpUtil() { } /** * 方法描述: [用于向不同的作用域存放屬性]</br> * 初始作迺 Administrator<br/> * 創(chuàng)建日期: 2018-1-23-上午11:24:45<br/> * 弿?版本: 2.0.0<br/> * =================================================<br/> * 修改記錄＿br/> * 修改作迠日期 修改內(nèi)容<br/> * ================================================<br/> * void */ public static void setAttribute(Object scopeObj, String name, Object value) { if (scopeObj instanceof HttpServletRequest) { ((HttpServletRequest) scopeObj).setAttribute(name, value); } if (scopeObj instanceof HttpSession) { ((HttpSession) scopeObj).setAttribute(name, value); } if (scopeObj instanceof ServletContext) { ((ServletContext) scopeObj).setAttribute(name, value); } } /** * 方法描述: [獲取作用域中指定名稱的屬性思</br> * 初始作迺 Administrator<br/> * 創(chuàng)建日期: 2018-1-23-上午11:29:17<br/> * 弿?版本: 2.0.0<br/> * =================================================<br/> * 修改記錄＿br/> * 修改作迠日期 修改內(nèi)容<br/> * ================================================<br/> * * @param scopeObj * @param name * @return * Object */ public static Object getAttribute(Object scopeObj, String name) { if (scopeObj instanceof HttpServletRequest) { return ((HttpServletRequest) scopeObj).getAttribute(name); } if (scopeObj instanceof HttpSession) { return ((HttpSession) scopeObj).getAttribute(name); } if (scopeObj instanceof ServletContext) { return ((ServletContext) scopeObj).getAttribute(name); } return null; } /** * 方法描述: [獲取上下文對象的方法]</br> * 初始作迺 Administrator<br/> * 創(chuàng)建日期: 2018-1-23-上午11:31:26<br/> * 弿?版本: 2.0.0<br/> * =================================================<br/> * 修改記錄＿br/> * 修改作迠日期 修改內(nèi)容<br/> * ================================================<br/> * * @return * ServletContext */ public static ServletContext getServletContext(Object sourceObj) { if (sourceObj instanceof HttpServletRequest) { return ((HttpServletRequest) sourceObj).getSession().getServletContext(); } if (sourceObj instanceof ServletConfig) { return ((ServletConfig) sourceObj).getServletContext(); } if (sourceObj instanceof FilterConfig) { return ((FilterConfig) sourceObj).getServletContext(); } return null; } /** * 方法描述: [獲取項目的實際路徑]</br> * 初始作迺 Administrator<br/> * 創(chuàng)建日期: 2018-1-23-上午11:45:47<br/> * 弿?版本: 2.0.0<br/> * =================================================<br/> * 修改記錄＿br/> * 修改作迠日期 修改內(nèi)容<br/> * ================================================<br/> * * @param req * @return * String */ public static String getContextPath(HttpServletRequest req) { return req.getContextPath(); }}當(dāng)然，代碼編輯好了也不要忘了在 WebRoot/WEB-INF/web.xml 中添加新建的Servlet，就是剛剛的兩個Java文件啦
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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_2_5.xsd"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <!-- 文件上傳 --> <servlet> <servlet-name>fileUpload</servlet-name> <servlet-class>com.stu.fileupload.FileUpload</servlet-class> </servlet> <servlet-mapping> <servlet-name>fileUpload</servlet-name> <url-pattern>/fileUp</url-pattern> </servlet-mapping> <!-- 文件下載 --> <servlet> <servlet-name>fileDownload</servlet-name> <servlet-class>com.stu.fileupload.FileDownload</servlet-class> </servlet> <servlet-mapping> <servlet-name>fileDownload</servlet-name> <url-pattern>/fileDown</url-pattern> </servlet-mapping></web-app>
這樣的話就可以運行啦。
TIP： 不要忘記相關(guān)的jar包和 js 包哦
在 WebRoot / WEB-INF / lib 下，有 commons-fileupload.jar 和 commons-io.jar ，另外 json-lib-x.x.x-jdkxx.jar 包是用來把上傳的返回數(shù)據(jù)修改為JSON格式的
在 WebRoot / js 下，導(dǎo)入 jquery.js , common.js , ajaxfileupload.js
以上這篇JavaServlet的文件上傳和下載實現(xiàn)方法就是小編分享給大家的全部內(nèi)容了，希望能給大家一個參考，也希望大家多多支持VeVb武林網(wǎng)。
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