主要将实现一下两个功能：
1、使用commons-fileupload实现文件的上传（包括图片）；
2、使用jquery-form.js实现表单提交成功的回调函数。
页面设计fileupload.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=UTF-8">
<title>文件上传</title>
<script src="static/js/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript" src="static/js/jquery-form.js"></script>
<script type="text/javascript">
function subimtBtn() {
var form = $("form[name=fileForm]");
var options = {
url:'${pageContext.servletContext.contextPath}/servlet/imageUploadServlet',
type:'post',
success:function(data)
{
var jsondata = eval("("+data+")");
if(jsondata.error == "0"){
var url = jsondata.url;
alert(url)
$("#img").attr("src",url);
}else{
var message = jsondata.message;
alert(message);
}
}
};
form.ajaxSubmit(options);
//$("#fileForm").submit();
}
</script>
</head>
<body>
<div class="modal-body">
<form action='${pageContext.servletContext.contextPath}/servlet/imageUploadServlet' enctype="multipart/form-data" method="post" id="fileForm" name="fileForm">
<input type="file" name="filename">
</form>
</div>
<div class="modal-footer">
<button class="btn btn-primary" onclick="subimtBtn();">提交</button>
</div>
<div>
<img alt="img" src="" id="img">
</div>
</body>
</html>
servlet实现：imageUploadServlet.java
package com.system.comtrol;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONObject;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
/**
* Servlet implementation class ImageUploadServlet
*/
@WebServlet("/servlet/imageUploadServlet")
public class ImageUploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#service(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
PrintWriter out = response.getWriter();
// 文件保存目录路径
String savePath = request.getServletContext().getRealPath("/")+ "attached";
// 文件保存目录URL
String saveUrl = request.getContextPath() + "/attached";
// 定义允许上传的文件扩展名
HashMap<String, String> extMap = new HashMap<String, String>();
extMap.put("image", "gif,jpg,jpeg,png,bmp");
// 最大文件大小
long maxSize = 1000000;
response.setContentType("text/html; charset=UTF-8");
if (!ServletFileUpload.isMultipartContent(request)) {
out.println(getError("请选择文件。"));
return;
}
// 检查目录
File uploadDir = new File(savePath);
if (!uploadDir.isDirectory()) {
out.println(getError("上传目录不存在。"));
return;
}
// 检查目录写权限
if (!uploadDir.canWrite()) {
out.println(getError("上传目录没有写权限。"));
return;
}
String dirName = request.getParameter("dir");
if (dirName == null) {
dirName = "image";
}
if (!extMap.containsKey(dirName)) {
out.println(getError("目录名不正确。"));
return;
}
// 创建文件夹
savePath += dirName + "/";
saveUrl += dirName + "/";
File saveDirFile = new File(savePath);
if (!saveDirFile.exists()) {
saveDirFile.mkdirs();
}
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
String ymd = sdf.format(new Date());
savePath += ymd + "/";
saveUrl += ymd + "/";
File dirFile = new File(savePath);
if (!dirFile.exists()) {
dirFile.mkdirs();
}
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setHeaderEncoding("UTF-8");
List items = upload.parseRequest(request);
Iterator itr = items.iterator();
while (itr.hasNext()) {
FileItem item = (FileItem) itr.next();
String fileName = item.getName();
if (!item.isFormField()) {
// 检查文件大小
if (item.getSize() > maxSize) {
out.println(getError("上传文件大小超过限制。"));
return;
}
// 检查扩展名
String fileExt = fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase();
if (!Arrays.<String> asList(extMap.get(dirName).split(",")).contains(fileExt)) {
out.println(getError("上传文件扩展名是不允许的扩展名。\n只允许" + extMap.get(dirName) + "格式。"));
return;
}
SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");
String newFileName = df.format(new Date()) + "_" + new Random().nextInt(1000) + "." + fileExt;
try {
File uploadedFile = new File(savePath, newFileName);
item.write(uploadedFile);
} catch (Exception e) {
out.println(getError("上传文件失败。"));
return;
}
JSONObject obj = new JSONObject();
obj.put("error", 0);
obj.put("url", saveUrl + newFileName);
out.println(obj.toString());
}
}
} catch (FileUploadException e1) {
e1.printStackTrace();
}
}
private String getError(String message) {
JSONObject obj = new JSONObject();
obj.put("error", 1);
obj.put("message", message);
return obj.toString();
}
}
项目中依赖的主要jar：commons-fileupload-1.2.jar，commons-io-1.4.jar
主要的两个js文件：jquery.min.js，jquery-form.js
这些可以去网上下载，也可以在附件中下载。