自己动手写一个java版简单云相册_java

动手写一个java版简单云相册,实现的功能是：
用户可以一次上传一个至多个文件。
用户可以下载其他人上传的图片。
用户可以查看其他所有人的图片。
用户只能删除通过自己IP上传的图片。

用到的技术：
文件上传下载、设计模式、Dom4j、xPath等。

先看下2个页面：

源代码：

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
  xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
  http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
 <display-name></display-name>
 <servlet>
  <servlet-name>UploadServlet</servlet-name>
  <servlet-class>cn.hncu.servlets.UploadServlet</servlet-class>
 </servlet>
 <servlet>
  <servlet-name>cloudPhotoServlet</servlet-name>
  <servlet-class>cn.hncu.servlets.cloudPhotoServlet</servlet-class>
 </servlet>
 <servlet>
  <servlet-name>DownServlet</servlet-name>
  <servlet-class>cn.hncu.servlets.DownServlet</servlet-class>
 </servlet>
 <servlet>
  <servlet-name>DelServlet</servlet-name>
  <servlet-class>cn.hncu.servlets.DelServlet</servlet-class>
 </servlet>

 <servlet-mapping>
  <servlet-name>UploadServlet</servlet-name>
  <url-pattern>/upload</url-pattern>
 </servlet-mapping>
 <servlet-mapping>
  <servlet-name>cloudPhotoServlet</servlet-name>
  <url-pattern>/cloudPhoto</url-pattern>
 </servlet-mapping>
 <servlet-mapping>
  <servlet-name>DownServlet</servlet-name>
  <url-pattern>/servlet/DownServlet</url-pattern>
 </servlet-mapping>
 <servlet-mapping>
  <servlet-name>DelServlet</servlet-name>
  <url-pattern>/servlet/DelServlet</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>

index.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
  <title>chx云相册</title>
  <script type="text/javascript">
    function delFile(input){
      table = input.parentElement.parentElement.parentElement;//table.nodeName TBODY

      table.removeChild(input.parentElement.parentElement);
    }
    var t=1;
    function addFile(input){
      tr = input.parentElement.parentElement;
      //alert(tr.nodeName);
      var str = "<td>选择文件：</td>"+
        "<td> <input type='file' name='file"+t+"'> </td> "+
        "<td>文件说明：</td>"+
        "<td> <input type='text' name='text"+t+"'> </td> "+
        "<td> <input type='button' value='删除文件' onclick='delFile(this)'> </td>";
      tr.insertAdjacentHTML("beforeBegin",str);
    }

    function move(){
      window.location.href="/myPhoto/cloudPhoto";
    }
  </script>

  <style type="text/css">
    #font{
      color:red;
    }

  </style>
 </head>

 <body>
  <h1><font id="font">相册上传：</font></h1>
  <form action="/myPhoto/upload" method="post" enctype="multipart/form-data">
    <table border="1px;double;#ff0000">
      <tr>
        <td>选择文件：</td>
        <td> <input type="file" name="file1"> </td>
        <td>文件说明：</td>
        <td> <input type="text" name="text1"> </td>
        <td> <input type="button" value="删 除 文 件" onclick="delFile(this)"> </td>
      </tr>
      <tr>
        <td colspan=2> <input type="submit" value="上 传 文 件"> </td>
        <td colspan=3> <input type="button" value="添 加 文 件" onclick="addFile(this)"> </td>
      </tr>
    </table>
  </form>
  <form action="/myPhoto/cloudPhoto" method="post" enctype="multipart/form-data">
    <table border="1px;double;#ff0000">
      <tr>
        <td colspan=5><input type="submit" value="进 入 云 相 册" onclick="move()"></td>
      </tr>
    </table>
  </form>
 </body>
</html>

photo.xml:

<?xml version="1.0" encoding="UTF-8"?>
<photos>

</photos>

MyUtils.java:

package cn.hncu.utils;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

public class MyUtils {

  /**
   * @return 获取UUID
   */
  public static String getUUID(){
    return UUID.randomUUID().toString().replace("-", "");
  }

  /**
   * @param uuid
   * @return 通过uuid，获得打散后的路径
   */
  public static String getDir(String uuid){
    String dir1 = Integer.toHexString( uuid.hashCode() & 0xf );
    String dir2 = Integer.toHexString( (uuid.hashCode() & 0xf0)>>4 );
    return "/"+dir1+"/"+dir2;
  }

  //日期时间格式
  private static SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
  /**
   * @return 返回的是上传的时候的日期时间
   */
  public static String getCurrentDateTime(){
    return sdf.format(new Date());
  }

}

Dom4jFactory.java:

package cn.hncu.utils;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class Dom4jFactory {
  private static Document dom=null;
  private static String path;
  //静态块！只会运行一次！特点是在类加载的时候就执行
  static{
    try {
      SAXReader sax = new SAXReader();
      //因为我们的资源已经从myelipse中发布到tomcat服务器中了，所以跟原来的纯Java项目不一样了。
      //利用当前类找到它的类加载器，然后通过该类加载器再去获得资源路径
      path = Dom4jFactory.class.getClassLoader().getResource("photo.xml").getPath();
      //getClassLoader()返回：加载此对象所表示的类或接口的类加载器
      //public URL getResource(String name)返回：读取资源的 URL 对象；如果找不到该资源，或者调用者没有足够的权限获取该资源，则返回 null。
      //此方法首先搜索资源的父类加载器；如果父类加载器为 null，则搜索的路径就是虚拟机的内置类加载器的路径。
      //public String getPath()获取此 URL 的路径部分。
      System.out.println(path);
      dom = sax.read(new FileInputStream(path));
    } catch (FileNotFoundException e) {
      throw new RuntimeException(e);
    } catch (DocumentException e) {
      throw new RuntimeException(e);
    }
  }

  /**
   * @return 获取相册的Document
   */
  public static Document getDocument(){
    return dom;
  }

  /**
   * 进行photo.xml的保存，保存到本地
   */
  public static boolean save(){
    try {
      XMLWriter w = new XMLWriter(new FileOutputStream(path));
      w.write(dom);
      w.close();
      return true;
    } catch (UnsupportedEncodingException e) {
      return false;
    } catch (FileNotFoundException e) {
      return false;
    } catch (IOException e) {
      return false;
    }
  }

  public static boolean del(String uuid){
    Node node = dom.selectSingleNode("[@uuid='"+uuid+"']");
    if(node==null){
      return false;
    }
    node.getParent().remove(node);
    return true;
  }

  /**
   * 测试用
   * @param args
   */
  public static void main(String[] args){
    System.out.println( getDocument() );
  }
}

PhotoModel.java-值对象

package cn.hncu.domain;
/**
 * 值对象封装
 * @author 陈浩翔
 * 2016-7-24
 */
public class PhotoModel {

  private String uuid;//uuid
  private String realName="";//图片真实文件名(上传时的文件名)
  private String ext;//后缀名
  private String dir;//打散后的路径
  private String dateTime;//上传文件的时间
  private String ip;//上传者的IP
  private String desc;//文件的说明
  public String getUuid() {
    return uuid;
  }
  public void setUuid(String uuid) {
    this.uuid = uuid;
  }
  public String getRealName() {
    return realName;
  }
  public void setRealName(String realName) {
    this.realName = realName;
  }
  public String getExt() {
    return ext;
  }
  public void setExt(String ext) {
    this.ext = ext;
  }
  public String getDir() {
    return dir;
  }
  public void setDir(String dir) {
    this.dir = dir;
  }
  public String getDateTime() {
    return dateTime;
  }
  public void setDateTime(String dateTime) {
    this.dateTime = dateTime;
  }
  public String getIp() {
    return ip;
  }
  public void setIp(String ip) {
    this.ip = ip;
  }
  public String getDesc() {
    return desc;
  }
  public void setDesc(String desc) {
    this.desc = desc;
  }
  @Override
  public String toString() {
    return "PhotoModel [uuid=" + uuid + ", realName=" + realName + ", ext="
        + ext + ", dir=" + dir + ", dateTime=" + dateTime + ", ip="
        + ip + ", desc=" + desc + "]";
  }

}

PhotoDao.java:

package cn.hncu.photoDao.Dao;

import java.util.List;

import cn.hncu.domain.PhotoModel;

public interface PhotoDao {
  /**
   * @param photo
   * @return 数据的保存
   */
  public boolean save(PhotoModel photo);

  /**
   * @return 返回所所有的图片信息
   */
  public List<PhotoModel> getAll();

  /**
   * @param uuid
   * @return 通过uuid 查找那个被封装的值对象
   */
  public PhotoModel getSingleByUuid(String uuid);

  /**
   * @param uuid
   * @return 通过uuid删除photos.xml中该图片的信息
   */
  public boolean deleteXml(String uuid);

  /**
   * @param dir
   * @return 通过路径删除服务器磁盘中该图片的信息
   */
  public boolean deleteFile(String pathFileName);
}

PhotoSerImpl.java:

package cn.hncu.photoDao.impl;

import java.io.File;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Node;

import cn.hncu.domain.PhotoModel;
import cn.hncu.photoDao.Dao.PhotoDao;
import cn.hncu.utils.Dom4jFactory;

public class PhotoSerImpl implements PhotoDao{

  @Override
  public boolean save(PhotoModel photo) {
    Document dom = Dom4jFactory.getDocument();

    Element root = dom.getRootElement();
    //添加属性
    Element p = root.addElement("photo");
    p.addAttribute("uuid", photo.getUuid());
    p.addAttribute("realName", photo.getRealName());
    p.addAttribute("dateTime", photo.getDateTime());
    p.addAttribute("ip", photo.getIp());
    p.addAttribute("ext", photo.getExt());
    p.addAttribute("dir", photo.getDir());
    p.addAttribute("desc", photo.getDesc());
    return Dom4jFactory.save();
  }

  @Override
  public List<PhotoModel> getAll() {
    List<PhotoModel> list = new ArrayList<PhotoModel>();
    Document dom = Dom4jFactory.getDocument();
    Element root = dom.getRootElement();
    Iterator<Element> it = root.elementIterator("photo");
    //通过DOM4J获得photo元素的迭代器,也可以通过xPath来找到所有的 photo
    //List<Node> lists = dom.selectNodes("//photo[@uuid]");
    //Iterator<Node> it = lists.iterator();
    while(it.hasNext()){
      Element e = it.next();
      PhotoModel photo = new PhotoModel();
      photo.setUuid(e.attributeValue("uuid"));
      photo.setRealName(e.attributeValue("realName"));
      photo.setDateTime(e.attributeValue("dateTime"));
      photo.setExt(e.attributeValue("ext"));
      photo.setIp(e.attributeValue("ip"));
      photo.setDir(e.attributeValue("dir"));
      photo.setDesc(e.attributeValue("desc"));
      list.add(photo);
    }
    return list;
  }

  @Override
  public PhotoModel getSingleByUuid(String uuid) {
    List<PhotoModel> photos=getAll();
    for(PhotoModel photo:photos){
      if(photo.getUuid().equals(uuid)){
        return photo;
      }
    }
    return null;
  }

  @Override
  public boolean deleteXml(String uuid) {
    Document dom = Dom4jFactory.getDocument();
    Element e = (Element) dom.selectSingleNode("//photo[@uuid='"+uuid.trim()+"']");
    return e.getParent().remove(e);
  }

  @Override
  public boolean deleteFile(String pathFileName) {
    try {
      File file = new File(pathFileName);
      if(file.exists()){
        file.delete();
      }
      return true;
    } catch (Exception e) {
      return false;
    }
  }
}

PhotoDaoFactory.java:

package cn.hncu.photoDao.factory;

import cn.hncu.photoDao.impl.PhotoSerImpl;

/**
 * 工厂方法
 * @author 陈浩翔
 * 2016-7-24
 */
public class PhotoDaoFactory {
  public static PhotoSerImpl getPhotoDao(){
    return new PhotoSerImpl();
  }
}

上传-UploadServlet.java:

package cn.hncu.servlets;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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 cn.hncu.domain.PhotoModel;
import cn.hncu.photoDao.Dao.PhotoDao;
import cn.hncu.photoDao.factory.PhotoDaoFactory;
import cn.hncu.utils.Dom4jFactory;
import cn.hncu.utils.MyUtils;

public class UploadServlet extends HttpServlet {
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html;charset=utf-8");
    response.getWriter().print("<h1>很抱歉，本页面不支持GET方式访问！！！</h1>");
    response.getWriter().print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
  }
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html;charset=utf-8");
    final PrintWriter out = response.getWriter();

    //防黑-非multipart表单提交
    //使用上传工具的方式
    boolean boo = ServletFileUpload.isMultipartContent(request);
    if(!boo){
      out.print("<h1>不支持普通表单的提交方式！</h1>");
      return;
    }

    File file = new File("d:/photoCache");
    if(!file.exists()){
      file.mkdir();
    }

    DiskFileItemFactory fiFactory = new DiskFileItemFactory(1024*10,file);

    ServletFileUpload upload = new ServletFileUpload(fiFactory);
    upload.setHeaderEncoding("utf-8");//设置文件名编码
    String path = getServletContext().getRealPath("/photos");

    FileItem fi = null;
    try {
      List<FileItem> list = upload.parseRequest(request);
      PhotoModel photo = new PhotoModel();//数据封装---需要7个属性
      photo.setRealName("");
      int cont=0;
      for(FileItem f:list){
        if(cont!=0 && cont%2==0 && !photo.getRealName().equals("")){
          photo = new PhotoModel();//重新数据封装
        }
        fi=f;
        if(fi.isFormField()){//普通表单组件
          //得到文件说明
          String desc = fi.getString("utf-8");
          photo.setDesc(desc);//#1
        }else{

          //防黑3-如果在file组件中不选择文件
          if(fi.getSize()==0){
            photo.setRealName("");
            cont++;
            continue;
          }
          String fileName = fi.getName();
          fileName = fileName.substring( fileName.lastIndexOf("\\")+1);//真实文件名
          photo.setRealName(fileName);//#2
          String ext = fileName.substring(fileName.lastIndexOf("."));//扩展名
          photo.setExt(ext);//#3
          photo.setDateTime(MyUtils.getCurrentDateTime());//#4
          photo.setIp( request.getRemoteAddr() );//#5
          String uuid = MyUtils.getUUID();
          photo.setUuid(uuid);//#6
          photo.setDir( MyUtils.getDir(uuid) );//#7

          //打散目录
          File dFile = new File(path+photo.getDir());
          if(!dFile.exists()){
            dFile.mkdirs();
          }

          fi.write(new File(path+photo.getDir()+"/"+photo.getUuid()+photo.getExt()));

        }

        cont++;

        if(cont%2==0 && !photo.getRealName().equals("")){
          PhotoDao dao = PhotoDaoFactory.getPhotoDao();
          boo = dao.save(photo);
          //存入磁盘-法二：FileUtils.copyInputStreamToFile(in, new File(fileName2));//※2※ 把图片文件存储到服务器硬盘
          photo = new PhotoModel();//重新数据封装
        }
      }
    } catch (FileUploadException e) {
      e.printStackTrace();
    } catch (Exception e) {
      e.printStackTrace();
    }finally{
      if(fi!=null){
        fi.delete();
      }
      if(Dom4jFactory.save()){
        out.print("<h1>上传成功！</h1>");
        out.print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
      }else{
        out.print("<h1>上传失败！</h1>");
        out.print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
      }
    }
  }
}

显示所有文件-cloudPhotoServlet.java

package cn.hncu.servlets;

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

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hncu.domain.PhotoModel;
import cn.hncu.photoDao.Dao.PhotoDao;
import cn.hncu.photoDao.factory.PhotoDaoFactory;

public class cloudPhotoServlet extends HttpServlet {
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    String pwd = (String) request.getParameter("pwd");
    if ("chx".equals(pwd)) {
      doPost(request, response);
    } else {
      response.setContentType("text/html;charset=utf-8");
      response.getWriter().print("<h1>很抱歉，你没有权限访问！！！</h1>");
    }
  }

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

    response.setContentType("text/html;charset=utf-8");
    PrintWriter out = response.getWriter();
    out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
    out.println("<HTML>");
    out.println(" <HEAD><TITLE>CHX云相册</TITLE></HEAD>");
    out.println(" <BODY>");

    out.println("<table border='1px;double;#ff0000'>");
    out.println("<tr>");
    out.println("<td>文件名</td>");
    out.println("<td>上传时间");
    out.println("<td>文件</td>");
    out.println("<td>文件说明</td>");
    out.println("<td>操作</td> ");
    out.println("</tr>");

    String tdWH = "style='width:200px; height:200px;'";

    // 显示所有图片
    PhotoDao dao = PhotoDaoFactory.getPhotoDao();
    List<PhotoModel> photos = dao.getAll();
    for (PhotoModel photo : photos) {
      String fileName = photo.getRealName();
      String time = photo.getDateTime();

      // 输出图片
      String path = request.getContextPath() + "/photos/"
          + photo.getDir() + "/" + photo.getUuid() + photo.getExt();
      // System.out.println(path);
      // /myPhoto/photos//7/c/a1237a48a6aa451cb22fa78b15bafcea.jpg
      String img = "<a href='" + path + "'><img src='" + path + "'/></a>";
      String desc = photo.getDesc();

      String delStr = "<a href='/myPhoto/servlet/DelServlet?uuid="
          + photo.getUuid() + "'>删除</a>";
      String downStr = "<a href='/myPhoto/servlet/DownServlet?uuid="
          + photo.getUuid() + "'>下载</a>";

      out.println("<tr>");
      out.println("<td " + tdWH + "> " + fileName + " </td>");
      out.println("<td " + tdWH + ">" + time + "</td>");
      out.println("<td " + tdWH + ">" + img + "</td>");
      out.println("<td " + tdWH + ">" + desc + "</td>");
      out.println("<td " + tdWH + ">" + delStr + " " + downStr
          + "</td>");
      out.println("</tr>");
    }

    out.println("<tr>");
    out.println("</tr>");

    out.println("</table>");

    out.println(" </BODY>");
    out.println("</HTML>");
    out.flush();
    out.close();
  }

}

删除文件-DelServlet.java

package cn.hncu.servlets;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hncu.domain.PhotoModel;
import cn.hncu.photoDao.Dao.PhotoDao;
import cn.hncu.photoDao.factory.PhotoDaoFactory;

public class DelServlet extends HttpServlet {

  //注入
  private PhotoDao dao = PhotoDaoFactory.getPhotoDao();
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    doPost(request, response);
  }

  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    String uuid = request.getParameter("uuid");
    String ip = request.getRemoteAddr();
    response.setContentType("text/html;charset=utf-8");

    PrintWriter out = response.getWriter();

    PhotoModel photo = dao.getSingleByUuid(uuid);

    if(photo!=null){
      if(!photo.getIp().equals(ip)){
        out.print("<h1>你没有权限删除这个文件！！！</h1>");
        out.print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
        return ;
      }

      //1.删除数据库中的信息
      boolean boo = dao.deleteXml(uuid);

      if(boo){
        String fileName = "photos/"+photo.getDir()+"/"+photo.getUuid()+photo.getExt();
        String pathFileName = getServletContext().getRealPath(fileName);
        if(dao.deleteFile(pathFileName)){
          //重定向到相册页面
          response.sendRedirect("/myPhoto/cloudPhoto?pwd=chx");
        }else{
          out.print("<h1>无法从服务器中删除，文件正在被占用！！！</h1>");
          out.print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
        }
      }else{
        out.print("<h1>该文件已经不存在！！！</h1>");
        out.print("<a href='javascript:history.go(-1)'>返回上一页</a> ");
      }
    }
  }
}

下载文件-DownServlet.java

package cn.hncu.servlets;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hncu.domain.PhotoModel;
import cn.hncu.photoDao.Dao.PhotoDao;
import cn.hncu.photoDao.factory.PhotoDaoFactory;

public class DownServlet extends HttpServlet {
  private PhotoDao dao = PhotoDaoFactory.getPhotoDao();

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

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

    String uuid = request.getParameter("uuid");
    System.out.println(uuid);
    PhotoModel photo = dao.getSingleByUuid(uuid);
    System.out.println(photo);
    if(photo!=null){
      //设置响应头--内容接收程序--浏览器看到这个响应头，就会把它认为的下载程序打开
      //(如果识别迅雷那么就会自动打开迅雷，如果没有则会打开一个“文件另存为”的对话框)
      response.setContentType("application/force-download");

      String realName = photo.getRealName();

      String agent = request.getHeader("User-Agent");
      System.out.println(agent);
      if(agent.indexOf("Mozilla")!=-1){//火狐浏览器
        response.setHeader("Content-Disposition", "attachment;filename="+ new String(realName.getBytes("GB2312"),"ISO-8859-1"));
      }else{
        //解决中文乱码问题（只要用下面一句对文件名进行编码就行了）
        realName = URLEncoder.encode(realName, "utf-8");//使用指定的编码机制将字符串转换为 application/x-www-form-urlencoded 格式。
        response.setHeader("Content-Disposition", "attachment;filename=\""+realName+"\"");
        //注意：“cttachment;”不能少，否则浏览器会直接在新窗口中打开
      }

      String fileName = "photos/" + photo.getDir()+"/"+photo.getUuid()+photo.getExt();
      String pathFileName = getServletContext().getRealPath(fileName);

      InputStream in = new FileInputStream(pathFileName);
      OutputStream out = response.getOutputStream();

      byte buf[] = new byte[2048];
      int len=0;
      while( (len=in.read(buf))!=-1 ){
        out.write(buf, 0, len);
      }
      out.close();
      in.close();
    }else{
      response.setContentType("text/html;charset=utf-8");
      response.getWriter().println("<h1>该文件已经被删除了</h1>");
    }
  }

}

演示结果

这个我就不演示啦，图片在前面也有，所有的源码我都给了。有兴趣的可以自己取改进一下咯。
其实这个还能上传其他任意类型文件哦，因为我们没有防护后缀名的，而且我们是用字符流传输，全都不会失真(可以当云盘来处理了~~)！！

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