一、背景
前段时间公司要求我做一个上传和下载固件的页面，以备硬件产品在线升级，现在我把这部分功能抽取出来作为一个Demo Project给大家分享。
二、源码
前端
js库：jquery-3.2.1.min.js，jquery.form.js（异步表单提交）,jsviews.min.js（模板渲染）
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），有兴趣的同学可以去官网了解，这里只用到了渲染的功能。
1、下载页面 index.html
<!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>1、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">确定</button>
</div>
</form>
<h2>2、测试上传结果</h2>
<table id="tbBody">
<thead>
<tr><td>类型</td><td>文件名</td><td>通过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>
2、公共js js/common.js
//获取链接参数
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;
}
3、 js/index.js
//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("请选择需要上传的固件");
return false;
}
return true; }
//按钮触发
$("#addConfirm").click(function(){
if(submitCheck())
addSubmit();
});
4、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
1、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;
} }
2、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;
}
}
3、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 ); //设置全部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，因为只有一个文件，所以单个引用就行
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));
}
}
}
4、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
1、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>
2、tomcat配置url支持utf-8 server.xml
<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" URIEncoding="UTF-8" />
三、总结
本Demo适合一次性上传小文件，多数情况下需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！