AjaxSubmit+Servlet表单文件上传和下载

1、背景javascript

前段时间公司要求我作一个上传和下载固件的页面，以备硬件产品在线升级，如今我把这部分功能抽取出来做为一个Demo Project给你们分享。css

话很少说，先看项目演示 --> 演示源码html

2、源码前端

前端java

js库：jquery-3.2.1.min.js，jquery.form.js（异步表单提交）,jsviews.min.js（模板渲染）jquery

jsviews科普：jsviews是实现MVVM的js库，分为JsRender（渲染），JsViews（数据视图双向绑定），JsObservable （数据监听），有兴趣的同窗能够去官网了解，这里只用到了渲染的功能。web

一、下载页面 index.htmlajax

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>ajaxSubmit上传</title>
    <link rel="shortcut icon" href="images/favicon.ico">
    <link rel="Bookmark" href="images/favicon.ico">
    <link rel="stylesheet" href="css/index.css" />
    <script type="text/javascript" src="js/jquery-3.2.1.min.js"></script>
    <script type="text/javascript" src="js/jquery.form.js"></script>
    <script type="text/javascript" src="js/jsviews.min.js"></script>
    <script type="text/javascript" src="js/common.js"></script>
    
</head>
<body>
<h1>上传下载Demo</h1>
<h2>一、上传文件</h2>
<form id="addForm">
    <div>
        <span>选择类型：</span>
        <select name="code" id="code">
            <option value="0">普通开关</option>
            <option value="1">插座</option>
        </select>
    </div>
    <div>
        <span>选择文件（小于5k）：</span>
        <input type="file" id="file" name="file">
    </div>
    <div>
        <button type="button" id="addConfirm" name="addConfirm">肯定</button>
    </div>
</form>
<h2>二、测试上传结果</h2>
<table id="tbBody">
<thead>
<tr><td>类型</td><td>文件名</td><td>经过Servlet下载</td></tr>
</thead>
</table>
</body>
<script type="text/javascript" src="js/index.js"></script>
<!-- jsviews模板 -->
<script id="listTmpl" type="text/x-jsrender">
           <tr>
            <td> {^{if code=='0'}}普通开关 {{else code=='1'}}插座 {{else}}数据错误{{/if}}
            </td>
            <td>{{:fileName}}</td>
            <td><a href="fileDownload?fileName={{:fileName}}">urlServlet</a></td>
          </tr>
</script>
</html>

二、公共js js/common.jsjson

//获取连接参数
function getQueryString(name) { var reg = new RegExp("(^|&)"+ name +"=([^&]*)(&|$)"); var r = window.location.search.substr(1).match(reg); if(r!=null)return  unescape(r[2]); return null; }

三、 js/index.js后端

//提交表单
function addSubmit(){ var options={ 　 url: "fileUpload", type:'post', datatype:'json', 　　 success: function (data) { var result = JSON.parse(data); if(result.code == "0000"){ var pageBarTmpl = $.templates("#listTmpl"); var html = pageBarTmpl.render(result.content); $("#tbBody").append(html); }else{ alert(result.desc); }　　　　 　　} } $("#addForm").ajaxSubmit(options); } //提交前检查
function submitCheck(){ var code = $("#code").val(); if (!code) { alert("请选择类型"); return false; } var file = $("#file").val(); if (!file) { alert("请选择须要上传的固件"); return false; } return true; } //按钮触发
$("#addConfirm").click(function(){ if(submitCheck()) addSubmit(); });

四、css/index.css

table th,table td{ border:1px solid black; } form div{ margin:5px; }

后端

使用到了commons-fileupload-1.3.1.jar，commons-io-2.4.jar以及gson-2.6.2.jar

一、返回结果类 RspResult.java

/** * 返回结果类 * @author zhang * */
public class RspResult{ private String code; //返回码
    private String desc; //返回描述
    private Map<String,Object> content;  //返回内容
    public String getCode() { return code; } public void setCode(String code) { this.code = code; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } public Map<String, Object> getContent() { return content; } public void setContent(Map<String, Object> content) { this.content = content; } }

二、自定义异常类 MyException.java

/** * 自定义异常 * @author zhang * */
public class MyException extends Exception{ private static final long serialVersionUID = 3075956744530570774L; private String code;  //错误码
    private String desc;  //描述
    public MyException(String code, String desc) { super(); this.code = code; this.desc = desc; } public String getCode() { return code; } public void setCode(String code) { this.code = code; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } }

三、文件上传Servlet FileUpload.java

/** * 文件上传类 * 使用commons-fileupload工具包解析表单内容，捕获自定义异常 * @author zhang * */
public class FileUpload extends HttpServlet{ private static final long serialVersionUID = -4700695646596658600L; private static final String SAVE_LOCATION = "/home/www/download/blog/ajaxUpload/"; //保存地址
 @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException { resp.setCharacterEncoding("UTF-8"); RspResult result = new RspResult(); result.setCode("0000"); result.setDesc("success"); try { DiskFileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory); upload.setFileSizeMax( 5*1024 ); //单个文件最大上传大小为5k
            upload.setSizeMax( 5*1024 );     //设置所有文件最大上传总大小为5k
            upload.setHeaderEncoding("utf-8");  //设置编码
 List<FileItem> fileItems = upload.parseRequest(req); Iterator<FileItem> iterator = fileItems.iterator(); Map<String, Object> rspConent = new HashMap<>(); DiskFileItem fileItem = null; //循环读取表单数据
            while (iterator.hasNext()) { FileItem item = iterator.next(); if (!item.isFormField()) { //是否为文件类型，由于只有一个文件，因此单个引用就行
                    fileItem = (DiskFileItem) item; }else { rspConent.put(item.getFieldName(), item.getString()); } } if(fileItem == null) throw new MyException("0001","无选择文件"); String fileName = fileItem.getName(); fileItem.write(new File(SAVE_LOCATION + fileName)); rspConent.put("fileName", fileName); result.setContent(rspConent); } catch (FileUploadException e ) { result.setCode("0001"); result.setDesc("文件上传大小为5k"); e.printStackTrace(); } catch (MyException e ) {  //取得自定义异常结果
 result.setCode(e.getCode()); result.setDesc(e.getDesc()); } catch (Exception e) { result.setCode("0001"); result.setDesc("未知错误"); e.printStackTrace(); }finally { PrintWriter out = null; try { out = resp.getWriter(); } catch (IOException e) { e.printStackTrace(); } out.write(new Gson().toJson(result)); } } }

四、文件下载Servlet FileDownload.java

/** * 文件下载类，读取文件，以字节流形式写到response * @author admin * */
public class FileDownload extends HttpServlet { private static final long serialVersionUID = -9135576688701595777L; private final String SAVE_LOCATION = "/home/www/download/blog/ajaxUpload/"; @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException { InputStream in = null; try { String fileName = req.getParameter("fileName"); in = new FileInputStream(SAVE_LOCATION+fileName); // 设置输出格式
            resp.setCharacterEncoding("utf-8"); resp.addHeader("Content-Disposition", "attachment; filename=\"" + URLEncoder.encode(fileName, "UTF-8") + "\""); // 读取数据
            byte[] b = new byte[100]; int len = 0; while ((len = in.read(b)) > 0) resp.getOutputStream().write(b, 0, len); } catch (UnsupportedEncodingException e2) { e2.printStackTrace(); } catch (FileNotFoundException e1) { e1.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally { try { if(in != null) in.close(); } catch (IOException e) { e.printStackTrace(); } } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } }

配置

一、项目配置 web.xml

<?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:jsp="http://java.sun.com/xml/ns/javaee/jsp" 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>upload-download-demo</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>
   <servlet>
    <servlet-name>fileUpload</servlet-name>
    <servlet-class>com.yuejia.servlet.FileUpload</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>fileUpload</servlet-name>
    <url-pattern>/fileUpload</url-pattern>
  </servlet-mapping>
   <servlet>
    <servlet-name>fileDownload</servlet-name>
    <servlet-class>com.yuejia.servlet.FileDownload</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>fileDownload</servlet-name>
    <url-pattern>/fileDownload</url-pattern>
  </servlet-mapping>
</web-app>

二、tomcat配置url支持utf-8 server.xml

<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" URIEncoding="UTF-8" />

3、总结

本Demo适合一次性上传小文件，多数状况下须要先上传文件再进行表单提交，视需求而定。

在保存文件建议在文件名后面加上时间戳，保证同名文件不会被覆盖。

以上！