ajax servlet上传文件

Java代码

package com.wang;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

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 org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.diskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class UploadServlet
 */
@WebServlet("/UploadServlet")
public class UploadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	// 上传文件存储目录
	private static final String UPLOAD_DIRECTORY = "upload";

	// 上传配置
	private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3; // 3MB
	private static final int MAX_FILE_SIZE = 1024 * 1024 * 40; // 40MB
	private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB

	/**
	 * 上传数据及保存文件
	 */
	protected void doPost(HttpServletRequest request,HttpServletResponse response) throws servletexception,IOException {
		// 检测是否为多媒体上传
		if (!ServletFileUpload.isMultipartContent(request)) {
			// 如果不是则停止
			PrintWriter writer = response.getWriter();
			writer.println("Error: 表单必须包含 enctype=multipart/form-data");
			writer.flush();
			return;
		}
		// 配置上传参数
		diskFileItemFactory factory = new diskFileItemFactory();
		// 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
		factory.setSizeThreshold(MEMORY_THRESHOLD);
		// 设置临时存储目录
		factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
		ServletFileUpload upload = new ServletFileUpload(factory);
		// 设置最大文件上传值
		upload.setFileSizeMax(MAX_FILE_SIZE);
		// 设置最大请求值 (包含文件和表单数据)
		upload.setSizeMax(MAX_REQUEST_SIZE);
		// 构造临时路径来存储上传的文件
		// 这个路径相对当前应用的目录
		String uploadpath = getServletContext().getRealPath("./")
				+ File.separator + UPLOAD_DIRECTORY;
		// 如果目录不存在则创建
		File uploadDir = new File(uploadpath);
		if (!uploadDir.exists()) {
			uploadDir.mkdir();
		}
		try {
			// 解析请求的内容提取文件数据
			@SuppressWarnings("unchecked")
			List<FileItem> formItems = upload.parseRequest(request);
			if (formItems != null && formItems.size() > 0) {
				// 迭代表单数据
				for (FileItem item : formItems) {
					// 处理不在表单中的字段
					if (!item.isFormField()) {
						String fileName = new File(item.getName()).getName();
						String filePath = uploadpath + File.separator
								+ fileName;
						File storeFile = new File(filePath);
						// 在控制台输出文件的上传路径
						System.out.println(filePath);
						// 保存文件到硬盘
						item.write(storeFile);
						request.setAttribute("message","文件上传成功!");
					}
				}
			}
		} catch (Exception ex) {
			request.setAttribute("message","错误信息: " + ex.getMessage());
		}
		// 跳转到 message.jsp
		PrintWriter out = response.getWriter();
		out.print("success");
		out.flush();
		out.close();
	}
}

HTML代码

<!DOCTYPE html>
<html>
<head>
<title>upload.html</title>
<Meta name="keywords" content="keyword1,keyword2,keyword3">
<Meta name="description" content="this is my page">
<Meta name="content-type" content="text/html; charset=UTF-8">
<!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
</head>
<body>
	<form id="uploadForm" enctype="multipart/form-data">
		<input id="file" type="file" name="file" />
		<button id="upload" type="button">upload</button>
	</form>
</body>
<script type="text/javascript"
	src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
	$("#upload").click(function() {
		$.ajax({
			url:'http://127.0.0.1:8080/u/UploadServlet',type:'POST',cache:false,data:new FormData($('#uploadForm')[0]),processData : false,contentType : false
		}).done(function(res) {
			alert(res);
		}).fail(function(res) {
			alert(res);
		});
	});
</script>
</html>

一：commons-upload在解析request的inputstream会首先获取boundary，这里面记录着文件流的起始和结束位置。

ajax servlet上传文件

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