转自： https://blessht.iteye.com/blog/1405057
最近自己在做一个小系统玩的时候涉及到了文件的上传，于是在网上找到Java上传文件的方案，最后确定使用common-fileupload实现上传操作。
- 需求说明
用户添加页面有一个“上传”按钮，点击按钮弹出上传界面，上传完成后关闭上传界面。
- 所需Jar包
commons.fileupload-1.2.0.jar、commons.logging-1.1.1.jar、commons.beanutils-1.8.0.jar、commons.collections-3.2.0.jar、commons.io-1.4.0.jar、commons.lang-2.1.0.jar
- 实现效果
- 代码实现
首先编写核心代码，Javascript打开上传页面，并且从上传页获取返回参数，最后数据返回给回调函数callback：
<%@ 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>定义input type="file" 的样式</title>
<style type="text/css">
body {
font-size: 14px;
} input {
vertical-align: middle;
margin: 0;
padding: 0
} .file-box {
position: relative;
width: 340px
} .txt {
height: 22px;
border: 1px solid #cdcdcd;
width: 180px;
} .btn {
background-color: #FFF;
border: 1px solid #CDCDCD;
height: 24px;
width: 70px;
} .file {
position: absolute;
top: 0;
right: 80px;
height: 24px;
filter: alpha(opacity : 0);
opacity: 0;
width: 260px
}
</style>
<script>
/**
* 跳转到上传页
* functionId:功能ID
* fileType:文件类型
* maxSize:文件容量上限
* callback:回调函数，返回三个参数：文件真名、文件存放名和文件大小
用户添加页面相关代码，点击“上传”按钮时调用上面的核心js代码，并且获取返回值
*/
function openUpload(functionId, fileType, maxSize, callback) {
var url = root + "/CommonController.jhtml?method=goFileUpload&";
if (functionId != null) {
url = url + "functionId=" + functionId + "&";
}
if (fileType != null) {
url = url + "fileType=" + fileType + "&";
}
if (maxSize != null) {
url = url + "maxSize=" + maxSize;
}
var win = window.showModalDialog(url, "",
"dialogWidth:300px;dialogHeight:150px;scroll:no;status:no");
if (win != null) {
var arrWin = win.split(",");
callback(arrWin[0], arrWin[1], arrWin[2]);
}
}
<script>
....... function openUpload_(){
openUpload(null,'JPG,GIF,JPEG,PNG','5',callback);
} /**
* 回调函数,获取上传文件信息
* realName真实文件名
* saveName文件保存名
* maxSize文件实际大小
*/
function callback(realName,saveName,maxSize){
$("#photo_").val(saveName);
//回调后其它操作
}
</script>
</script>
</head>
<body> <div class="file-box">
<tr>
<td>头像：</td>
<td><input type="hidden" name="photo" id="photo_"></input> <input
type="button" onclick="openUpload_();" value="上传" /></td>
</tr>
</div>
</body>
</html>
文件上传的JSP代码，需要注意的是在head标签内添加<base target="_self">以防止页面跳转时弹出新窗口，用户选择指定文件，点击上传时就提交表单访问指定后台代码
<%@ include file="/WEB-INF/jsp/header.jsp" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta http-equiv="pragma" content="no-cache" />
<base target="_self">
<title>文件上传</title>
</head>
<body>
<h5>文件上传</h5><hr/>
<form id="file_upload_id" name="file_upload_name" action="<%=root%>/CommonController.jhtml?method=doFileUpload" method="post" enctype="multipart/form-data">
<input type="hidden" name="functionId" value="${functionId}"/>
<input type="hidden" name="fileType" value="${fileType}"/>
<input type="hidden" name="maxSize" value="${maxSize}"/>
<div><input type="file" name="file_upload"/></div>
<c:if test="${maxSize!=null}">
<div style="font: 12">文件最大不能超过${maxSize}MB</div>
</c:if>
<c:if test="${fileType!=null}">
<div style="font: 12">文件格式必须是：${fileType}</div>
</c:if>
<div><input type="submit" value="上传"/></div>
</form>
</body>
</html>
CommonController目前有两个方法，一个是跳转到上传页面的方法，一个是执行上传操作的方法doFileUpload，上传方法运行的大概逻辑是：首先获取页面的请求参数，fileType用于限制上传文件格式，
maxSize用于限制上传文件最大值，随后创建上传目录上传即可。
public class CommonController extends BaseController {
Log log = LogFactory.getLog(CommonController.class);
Properties fileUploadPro = null;
public CommonController(){
fileUploadPro = PropertiesUtil.getPropertiesByClass("fileupload.properties");
}
@Override
public ModeAndView init(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
return null;
}
/**
* 跳转到文件上传页
* @param request
* @param response
* @return
* @throws ServletException
* @throws IOException
*/
public ModeAndView goFileUpload(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String functionId = request.getParameter("functionId");
String fileType = request.getParameter("fileType");
String maxSize = request.getParameter("maxSize");
ModeAndView mav = new ModeAndView("/WEB-INF/jsp/common/fileUpload.jsp");
if(functionId!=null && !"".equals(functionId.trim())){
mav.addObject("functionId", functionId);
}
if(fileType!=null && !"".equals(fileType.trim())){
mav.addObject("fileType", fileType);
}
if(maxSize!=null && !"".equals(maxSize.trim())){
mav.addObject("maxSize", maxSize);
}
return mav;
}
/**
* 上传文件
* @param request
* @param response
* @return
* @throws ServletException
* @throws IOException
*/
@SuppressWarnings("unchecked")
public ModeAndView doFileUpload(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//获取并解析文件类型和支持最大值
String functionId = request.getParameter("functionId");
String fileType = request.getParameter("fileType");
String maxSize = request.getParameter("maxSize");
//临时目录名
String tempPath = fileUploadPro.getProperty("tempPath");
//真实目录名
String filePath = fileUploadPro.getProperty("filePath");
FileUtil.createFolder(tempPath);
FileUtil.createFolder(filePath);
DiskFileItemFactory factory = new DiskFileItemFactory();
//最大缓存
factory.setSizeThreshold(5*1024);
//设置临时文件目录
factory.setRepository(new File(tempPath));
ServletFileUpload upload = new ServletFileUpload(factory);
if(maxSize!=null && !"".equals(maxSize.trim())){
//文件最大上限
upload.setSizeMax(Integer.valueOf(maxSize)*1024*1024);
}
try {
//获取所有文件列表
List<FileItem> items = upload.parseRequest(request);
for (FileItem item : items) {
if(!item.isFormField()){
//文件名
String fileName = item.getName();
//检查文件后缀格式
String fileEnd = fileName.substring(fileName.lastIndexOf(".")+1).toLowerCase();
if(fileType!=null && !"".equals(fileType.trim())){
boolean isRealType = false;
String[] arrType = fileType.split(",");
for (String str : arrType) {
if(fileEnd.equals(str.toLowerCase())){
isRealType = true;
break;
}
}
if(!isRealType){
//提示错误信息:文件格式不正确
super.printJsMsgBack(response, "文件格式不正确!");
return null;
}
}
//创建文件唯一名称
String uuid = UUID.randomUUID().toString();
//真实上传路径
StringBuffer sbRealPath = new StringBuffer();
sbRealPath.append(filePath).append(uuid).append(".").append(fileEnd);
//写入文件
File file = new File(sbRealPath.toString());
item.write(file);
//上传成功，向父窗体返回数据:真实文件名,虚拟文件名,文件大小
StringBuffer sb = new StringBuffer();
sb.append("window.returnValue='").append(fileName).append(",").append(uuid).append(".").append(fileEnd).append(",").append(file.length()).append("';");
sb.append("window.close();");
super.printJsMsg(response, sb.toString());
log.info("上传文件成功,JS信息："+sb.toString());
}//end of if
}//end of for
}catch (Exception e) {
//提示错误:比如文件大小
super.printJsMsgBack(response, "上传失败,文件大小不能超过"+maxSize+"M!");
log.error("上传文件异常!",e);
return null;
}
return null;
}
}
至此一个文件上传即已实现，而且能够基本满足不同模块的上传通用性，我还留着个functionId参数用于以后针对不同模块上传文件到不同目录。