fileupload实现图片上传

package fileupload;

import javax.servlet.http.HttpServlet;

import java.io.File;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Iterator;

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.FileUploadBase.SizeLimitExceededException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUploadServlet extends HttpServlet {

public FileUploadServlet() {

super();

}

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

// Put your code here

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doPost(request, response);

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

System.out.println("FileUploadServlet 39");

try{

final long MAX_SIZE = 3 * 1024 * 1024;// 设置上传文件最大为 3M

// 允许上传的文件格式的列表

final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",

"doc", "docx", "mp3", "wma", "m4a" };

response.setContentType("text/html");

// 设置字符编码为UTF-8, 这样支持汉字显示

response.setCharacterEncoding("UTF-8");

// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload

DiskFileItemFactory dfif = new DiskFileItemFactory();

dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘

dfif.setRepository(new File(request.getRealPath("/")

+ "imgs"));// 设置存放临时文件的目录,web根目录下的imgs目录

// 用以上工厂实例化上传组件

ServletFileUpload sfu = new ServletFileUpload(dfif);

// 设置最大上传尺寸

sfu.setSizeMax(MAX_SIZE);

PrintWriter out = response.getWriter();

// 从request得到 所有 上传域的列表

List fileList = null;

try {

fileList = sfu.parseRequest(request);

} catch (FileUploadException e) {// 处理文件尺寸过大异常

if (e instanceof SizeLimitExceededException) {

out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");

out.println("<a href="/" mce_href="/""upload.html/" target=/"_top/">返回</a>");

return;

}

e.printStackTrace();

}

// 没有文件上传

if (fileList == null || fileList.size() == 0) {

out.println("请选择上传文件<p />");

out.println("<a href="/" mce_href="/""upload.html/" target=/"_top/">返回</a>");

return;

}

// 得到所有上传的文件

Iterator fileItr = fileList.iterator();

// 循环处理所有文件

while (fileItr.hasNext()) {

FileItem fileItem = null;

String path = null;

long size = 0;

// 得到当前文件

fileItem = (FileItem) fileItr.next();

// 忽略简单form字段而不是上传域的文件域(<input type="text" />等)

if (fileItem == null || fileItem.isFormField()) {

continue;

}

// 得到文件的完整路径

path = fileItem.getName();

// 得到文件的大小

size = fileItem.getSize();

if ("".equals(path) || size == 0) {

out.println("请选择上传文件<p />");

out.println("<a href="/" mce_href="/""upload.html/" target=/"_top/">返回</a>");

return;

}

// 得到去除路径的文件名

String t_name = path.substring(path.lastIndexOf("//") + 1);

// 得到文件的扩展名(无扩展名时将得到全名)

String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);

// 拒绝接受规定文件格式之外的文件类型

int allowFlag = 0;

int allowedExtCount = allowedExt.length;

for (; allowFlag < allowedExtCount; allowFlag++) {

if (allowedExt[allowFlag].equals(t_ext))

break;

}

if (allowFlag == allowedExtCount) {

out.println("请上传以下类型的文件<p />");

for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)

out.println("*." + allowedExt[allowFlag]

+ "???");

out

.println("<p /><a href="/" mce_href="/""upload.html/" target=/"_top/">返回</a>");

return;

}

long now = System.currentTimeMillis();

// 根据系统时间生成上传后保存的文件名

String prefix = String.valueOf(now);

// 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下

String u_name = request.getRealPath("/") + "imgs/"

+ prefix + "." + t_ext;

try {

File file = new File(u_name);

// if(!file.exists()){

// System.out.print(file.mkdirs());

// System.out.print(file.mkdir());

// }

// 保存文件

fileItem.write(file);

out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext

+ " ??文件大小: " + size + "字节<p />");

out.println("<a href="/" mce_href="/""upload.html/" target=/"_top/">继续上传</a>");

} catch (Exception e) {

e.printStackTrace();

}

}

}catch(Exception e){

e.printStackTrace();

}

}

public void init() throws ServletException {

// Put your code here

}

}