File upload demo

package cn.learn.utils;

import java.io.File;
import java.util.UUID;

public class FileUploadUtils {

	// 得到上传文件真实名称 c:\a.txt a.txt
	public static String getRealName(String filename) {

		int index = filename.lastIndexOf("\\") + 1;

		return filename.substring(index);

	}

	// 获取随机名称 a.txt
	public static String getUUIDFileName(String filename) {
		int index = filename.lastIndexOf(".");
		if (index != -1) {

			return UUID.randomUUID() + filename.substring(index);
		} else {
			return UUID.randomUUID().toString();
		}
	}

	// 目录分离算法
	public static String getRandomDirectory(String filename) {

		// int hashcode = filename.hashCode();
		//
		// // System.out.println(hashcode);
		//
		// // int类型数据在内存中占32位。转换成16进制数，就得到8个16进制数
		// String hex = Integer.toHexString(hashcode);
		//
		// // System.out.println(hex); // 056d9363
		//
		// return "/" + hex.charAt(0) + "/" + hex.charAt(1);

		int hashcode = filename.hashCode();

		System.out.println(Integer.toBinaryString(hashcode));

		int a = hashcode & 0xf;

		hashcode = hashcode >>> 4;

		int b = hashcode & 0xf;

		return "/" + a + "/" + b;

	}

}

package cn.learn.web.servlet;

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

import javax.servlet.ServletException;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.IOUtils;

import cn.learn.utils.FileUploadUtils;

public class Upload4Servlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");

		// 1.创建 DiskFileItemFactory
		File file = new File(this.getServletContext().getRealPath("/temp"));// 获取temp目录部署到tomcat后的绝对磁盘路径
		DiskFileItemFactory factory = new DiskFileItemFactory(1024 * 100, file); // 使用默认的.

		// 2.创建ServletFileUpload
		ServletFileUpload upload = new ServletFileUpload(factory);
		boolean flag = upload.isMultipartContent(request); // 用于判断是否是上传操作.
		if (flag) {
			// 解决上传文件名称中文乱码
			upload.setHeaderEncoding("utf-8");

			// 设置上传文件大小
			// upload.setSizeMax(1024 * 1024 * 10);// 总大小为10m

			try {
				List<FileItem> items = upload.parseRequest(request);// 解决request,得到所有的上传项FileItem

				// 3.得到所有上传项
				for (FileItem item : items) {
					if (!item.isFormField()) {
						// 上传组件

						String name = item.getName(); // 上传文件名称
						// 得到上传文件真实名称

						String filename = FileUploadUtils.getRealName(name);

						// 得到随机名称
						String uuidname = FileUploadUtils
								.getUUIDFileName(filename);

						// 得到随机目录
						String randomDirectory = FileUploadUtils
								.getRandomDirectory(filename);
						// 注意:随机目录可能不存在，需要创建.
						String parentPath = this.getServletContext()
								.getRealPath("/upload");
						File rd = new File(parentPath, randomDirectory);

						if (!rd.exists()) {
							rd.mkdirs();
						}

						IOUtils.copy(item.getInputStream(),
								new FileOutputStream(new File(rd, uuidname)));

						// 删除临时文件
						item.delete();
					}
				}

			} catch (FileUploadException e) {
				// e.printStackTrace();
				response.getWriter().write(e.getMessage());
				return;
			}
		} else {
			response.getWriter().write("不是上传操作");
			return;
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}