servlet上传 前端实现

项目中很多地方都用到上传,这里做一个demo,还带进度条

package util.upload;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.UUID;

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

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

public class UploadServlet extends HttpServlet {

 private static final long serialVersionUID = -3100028422371321159L;
 private boolean isAllowed;
 private String upFileName;
    //定义合法后缀名的数组
 private String[] allowedExtName=new String[]
            {"zip","rar",//压缩文件
         "txt","doc","wps","docx","java",//文本
         "xls","xlsx",//表格
         "ppt","pptx",//幻灯片
         "pdf",//pdf
         "jpg","jpeg","bmp","gif","png"//图片
         };
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  doPost(request, response); 

 }

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  //设置编码格式为utf-8
  request.setCharacterEncoding("utf-8");
  response.setCharacterEncoding("utf-8"); 
  //获取session,保存进度和上传结果,上传开始为nok,当为Ok表示上传完成
  HttpSession session=request.getSession();
  session.setAttribute("result", "nok");
  session.setAttribute("error", "");
  String error="";
  upFileName="";
  isAllowed=false;
  //给上传的文件设一个最大值,这里是不得超过100MB
  int maxSize=100*1024*1024;
  //建立工厂对象和文件上传对象
  DiskFileItemFactory factory=new DiskFileItemFactory();
  ServletFileUpload upload=new ServletFileUpload(factory);
  //建立上传监听器和设置监听器
  UploadListener listener=new UploadListener();
  session.setAttribute("LISTENER", listener);
  upload.setProgressListener(listener);  
  //上传路径
  String path = request.getSession().getServletContext().getRealPath("/upload");
  String requestPath = request.getSession().getServletContext().getContextPath()+"/upload";
  File dirFile =new File(path);     //System.out.println(request.getSession().getServletContext().getContextPath());
  //若是文件夹不存在则建立    
  if  (!dirFile .exists()  && !dirFile .isDirectory())      
  {         
    dirFile .mkdir();    
  }    
  //根据日期建立文件夹,保存到对应日期的文件夹下
  Date date=new Date();
  SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMdd");
  String subDirName=sdf.format(date);
  File subDirFile=new File(path+"/"+subDirName);
  if  (!subDirFile .exists()  && !subDirFile .isDirectory())      
  {       
      subDirFile .mkdir();    
  }   
  try {  
   //解析上传请求
   List<FileItem> items=upload.parseRequest(request);   
   Iterator<FileItem> itr=items.iterator();   
   while(itr.hasNext()){      
    FileItem item=(FileItem)itr.next();
    //判断是否为文件域   
    if(!item.isFormField()){     if(item.getName()!=null&&!item.getName().equals("")){
      //获取上传文件大小和文件名称
      long upFileSize=item.getSize();   
      String fileName=item.getName();

      //获取文件后缀名
      String[] splitName=fileName.split("//.");
      String extName=splitName[splitName.length-1];
      //检查文件后缀名
      for(String allowed:allowedExtName)
      {
        if(allowed.equalsIgnoreCase(extName))
        {
            isAllowed=true;
        }       
      }
      if(!isAllowed){
          error="上传文件格式不合法!";
          break;
      }
      if(upFileSize>maxSize){
       error="您上传的文件太大了,请选择不超过100MB的文件!";
       break;
      }  
      //此时文件暂存在服务器的内存中,构造临时对象
      File tempFile=new File(makeFileName(fileName));

      //指定文件上传服务器的目录及文件名称
      File file=new File(path+"/"+subDirName+"/",tempFile.getName());

      item.write(file);//第一种写文件方法
      upFileName=requestPath+"/"+subDirName+"/"+tempFile.getName();
  if(upFileName.equals("")){
      error="没选择上传文件!";
  }
  System.out.println(upFileName);
      /*//构造输入流读文件 第二种写文件方法
      InputStream is=item.getInputStream();
      int length=0;
      byte[] by=new byte[1024];

      FileOutputStream fos=new FileOutputStream(file);

      while((length=is.read(by))!=-1){
       fos.write(by, 0, length);
       //Thread.sleep(10);
      }
      fos.close();
      //Thread.sleep(1000);*/
     }else{
      error="没选择上传文件!";
     }
    }
   }    
  } catch (Exception e) {
   e.printStackTrace();
   error="上传文件出现错误:"+e.getMessage();
  }
  if(!error.equals("")){ 
      System.out.println(error);
   session.setAttribute("error", error);
  }else{  

   session.setAttribute("result", "OK"); 
   session.setAttribute("filename",upFileName);
  }
 }
 /**
  * 为防止文件覆盖的现象发生,要为上传文件产生一个惟一的文件名
  * @param filename 原文件名
  * @return 生成的惟一文件名
  */
 private String makeFileName(String filename){ 

     return UUID.randomUUID().toString() + "_" + filename;
   } 
}

其中须要引入commons-fileupload-1.3.1.jar,commons-io-2.4.jar

上传过程当中,咱们须要实时获取上传进度等信息,引入的库里为咱们添加了一个ProgressListener接口,咱们再写一个类实现这个接口,上面类中添加该接口css

//建立工厂对象和文件上传对象
  DiskFileItemFactory factory=new DiskFileItemFactory();
  ServletFileUpload upload=new ServletFileUpload(factory);
  //建立上传监听器和设置监听器
  UploadListener listener=new UploadListener();
  session.setAttribute("LISTENER", listener);
  upload.setProgressListener(listener);

下面是这个监听类的具体实现代码html

package util.upload;

import org.apache.commons.fileupload.ProgressListener;

public class UploadListener implements ProgressListener{

    private volatile long 
    bytesRead = 0L,//上传的字节数
    contentLength = 0L,//总字节数
    item = 0L; 
     public UploadListener() 
        {
            super();
        }

     @Override
     public void update(long aBytesRead, long aContentLength, int anItem) {

        bytesRead = aBytesRead;
         contentLength = aContentLength;
         item = anItem;
     }
     public long getBytesRead() 
     {
         return bytesRead;
     }
     public long getContentLength() 
     {
         return contentLength;
     }

     public long getItem() 
     {
         return item;
     }
}

如今能获取上传进度等信息了,但还须要一个servlet返回给前端,下面实现前端

package util.upload;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;

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

import org.apache.commons.fileupload.ProgressListener;

import com.google.gson.Gson;
/**
 获取上传进度,上传路径,错误,上传结果等信息
 */

public class GetProgressServlet extends HttpServlet{

 private static final long serialVersionUID = -3596466520775012991L;

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

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      request.setCharacterEncoding("utf-8");
      response.setCharacterEncoding("utf-8");
      UploadListener listener= null;
      HttpSession session = request.getSession();
      String error=(String) session.getAttribute("error");
      String result= (String) session.getAttribute("result");
      String fileName=(String) session.getAttribute("filename");
      PrintWriter out = response.getWriter();
      long bytesRead = 0,contentLength = 0; 
      if (session != null)
        {
            listener = (UploadListener)session.getAttribute("LISTENER");

            if (listener == null)
            {
                return;
            }
            else
            {               
                bytesRead = listener.getBytesRead();//上传的字节数
                contentLength = listener.getContentLength();//总字节数

            }
            //本身定义的返回格式
            String rp=bytesRead+","
                    +contentLength+","
                    +error+","
                    +result+","
                    +fileName;

            //System.out.println(rp);
            out.print(rp);
            /*      //返回json格式数据
            Map<String,Object> map=new HashMap<String,Object>();
            map.put("bytesRead", bytesRead);
            map.put("contentLength", contentLength);
            map.put("error", error);
            map.put("result", result);
            map.put("fileName", fileName);
            Gson gson=new Gson();
            String json=gson.toJson(map);
            out.print(json);*/
            out.flush();
            out.close();    
        }
 }
}

后台上传的功能代码写完了,下面实现上传的前端,首先是htmlhtml5

<!DOCTYPE html>
    <html>
    <head>
        <meta charset="utf-8" />
        <script type="text/javascript" src="js/upfile.js" charset="utf-8"></script>
        <link rel="stylesheet" type="text/css" href="css/upfile.css">
    </head>
    <body >
        <a href="javascript:addOne()">添加</a>
        <div id="target">
            <input type="file" id="file" name="file" onchange="addfile(event)" multiple/>
        </div>
        <span id="test">0</span>
    </body> 
</html>

界面比较简单,就一个添加的a标签,负责上传的input隐藏起来

css文件主要渲染的上传进度的显示java

更多内容: https://www.shangmayuan.com

#file {
                display: none;
            }
            .pro{
                width:500px;
            }
            .pborder {

                position: relative;
                width: 500px; /* 宽度 */
                border: 1px solid #B1D632;
                padding: 1px;
            }

            .drawpro {
                width: 0px;
                display: block;
                position: relative;
                background: #B1D632;
                color: #333333;
                height: 20px; /* 高度 */
                line-height: 20px; /* 必须和高度一致,文本才能垂直居中 */
            }

            .pspan {
                position: absolute;
                width: 500px;
                text-align: center;
                font-weight: bold;
            }

接着是前端的重点,js文件web

//显示上传信息的html
var upfile_html = '<div class="pborder"><div class="drawpro">'
        + '<span class="pspan">0%</span></div></div><span name="path"></span><img src="common/upload/images/del.png"  width="20" height="20" name="del" onclick=abortUpload(this)>';

var targetDIV_id = "target";//显示上传文件的目标div的ID
var httpXML = null;//发送上传请求的XMLHttpRequest对象
var httpProgress = null;//发送请求进度信息的XMLHttpRequest对象
var oldFileList = new Array();//修改时保存已有附件信息的列表
var uplist = new Array();//保存上传文件的列表
var f_input;//上传文件的input对象
var flag = true;//是否能够上传下一个文件标志
var uurl = "Upload";//上传文件的请求url
var gurl = "getProgress";//获取上传进度信息的url
var cancelFlag = 0;//取消标志
var timer, waittimer;//定时器
var nowID = 0;//正在上传文件的id
var ID = 0;//队列中最后一个文件的id

/**
 * 文件对象
 */
function UploadFile(id, file) {
    this.id = id;
    this.file = file;
    this.state = 0;
    this.path = "";
}
/**
 * 初始化的方法
 */
window.onload = function init() {
    f_input = document.getElementById("file");
    var tdiv = document.getElementById(targetDIV_id);

    var oldspan = tdiv.getElementsByTagName("SPAN");

    for ( var i = 0; i < oldspan.length; i++) {
        oldFileList.push(oldspan[i].getAttribute("name"));
    }
}

/**
 * 选择一个文件上传
 */
function addOne() {
    f_input.value = null;
    f_input.click();
}

/**
 * 选中文件后将文件对象添加到队列,开始上传
 * 
 */
function addfile(evt) {
    var f = f_input.files[0];
    if (f != undefined) {
        var uf = new UploadFile(ID, f);
        uplist.push(uf);
        var div = document.createElement("DIV");
        div.setAttribute("id", "pro" + (ID));
        div.setAttribute("class", "pro");
        div.innerHTML = upfile_html;
        var targetDiv = document.getElementById(targetDIV_id);
        targetDiv.appendChild(div);
        div.getElementsByTagName("SPAN")[1].innerHTML = "文件名:"
                + uplist[ID].file.name;
        waittimer = setInterval("upload()", 1000);
        ID++;
    }
}
/**
 * 将队列中的文件上传
 */
function upload() {

    if (flag == true) {

        if (uplist.length > 0) {

            var uf;
            for ( var i = 0; i < uplist.length; i++) {
                if (uplist[i].state == 0) {
                    uf = uplist[i];
                    uplist[i].state = 1;
                    break;
                }
            }

            if (uf != undefined & uf != null) {
                flag = false;
                if (window.XMLHttpRequest) {
                    httpUP = new XMLHttpRequest();
                } else if (window.ActiveXObject) {
                    httpUP = new ActiveXObject("Microsoft.XMLHTTP");
                }
                var formData = new FormData();
                formData.append("file", uf.file);
                httpUP.open("POST", uurl, true);
              httpUP.upload.addEventListener('progress', uploadProgress, false);
                httpUP.send(formData);
                nowID = uf.id;
                timer = setInterval("getP()", 50);
            }
        }
    }
}

/**
 * 获取上传进度等信息
 */
function getP() {
    if (window.XMLHttpRequest) {
        httpProgress = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        httpProgress = new ActiveXObject("Microsoft.XMLHTTP");
    }
    httpProgress.onreadystatechange = onProgress;
    httpProgress.open("post", gurl, true);
    httpProgress.setRequestHeader("Content-type",
            "application/x-www-form-urlencoded");
    httpProgress.send("&timeStamp=" + (new Date()).getTime());
}

/**
 * 处理返回的上传信息,显示到界面
 */
function onProgress() {
    if (httpProgress.readyState == 4 && httpProgress.status == 200) {
        result = httpProgress.responseText;
        var result = result.replace(/(^/s*)|(/s*$)/g, "");
        var res = result.split(",");
        var now = parseInt(res[0]);
        var all = parseInt(res[1]);
        var err = res[2];
        var state = res[3];
        var path = res[4];
        var per = (now / all * 100).toFixed(2);
        var prodiv = document.getElementById("pro" + nowID);

        if (prodiv != null & prodiv != undefined) {
            if (err != "" & err != null & err.length > 0) {
                window.clearInterval(timer);
                if (cancelFlag == 1) {
                    err = "上传终止";
                    cancelFlag = 0;
                }
                prodiv.getElementsByTagName("DIV")[0].style.display = "none";
                prodiv.getElementsByTagName("SPAN")[1].innerHTML = err;
                httpUP.abort();
                flag = true;
                uplist[nowID].state = 3;
                return;
            }
            if (state == "OK") {
                prodiv.getElementsByTagName("DIV")[0].style.display = "none";
                var tmpf = uplist[nowID].file;
                prodiv.getElementsByTagName("SPAN")[1].innerHTML = "文件名:"
                        + tmpf.name;
                window.clearInterval(timer);
                flag = true;
                uplist[nowID].state = 2;
                uplist[nowID].path = path;
                return;
            }
            prodiv.getElementsByTagName("DIV")[1].style.width = per * 5 + "px";
            prodiv.getElementsByTagName("SPAN")[0].innerHTML = per + "%";

        }
    }
}

/**
 * 取消上传的方法
 */
function abortUpload(obj) {
    var idStr = obj.parentNode.id;
    var id = idStr.slice(3);
    if (uplist[id].state == 1) {
        httpUP.abort();
        flag = true;
        cancelFlag = 1;
    } else {
        uplist[id].state = 3;
    }
    document.getElementById(idStr).remove();

}
/**
 * 获取上传文件的路径
 * @returns 格式化后字符串
 */
function getFileListStr() {

    var str = "";
    if (oldFileList.length > 0) {
        for ( var i = 0; i < oldFileList.length; i++) {
            if (oldFileList[i] != null & oldFileList[i] != ""
                    & oldFileList[i] != undefined) {
                str = str + oldFileList[i] + ",";
            }

        }
    }
    for ( var i = 0; i < uplist.length; i++) {
        var f = uplist[i];
        if (f.state == 2) {
            str = str + f.path + ",";
        }
    }
    return str;
}
/**
 * 移除修改时已有的旧附件
 * 
 */
function removeOld(btn) {
    var num = btn.getAttribute("name");
    oldFileList[num - 1] = null;
    btn.parentNode.remove();
}
   function uploadProgress(e) {
                if (e.lengthComputable) {
                    var iBytesUploaded = e.loaded;
                    var iBytesTotal = e.total;
                    document.getElementById("test").innerHTML=iBytesUploaded+"/"+iBytesTotal;
                }
            }

使用ajax发送上传文件,获取上传进度,结果等信息。

使用的html5的file API,因此必须ie9以上的才能够兼容,火狐还有个问题,ajax请求不当即返回,直到全部ajax请求都发送完了,才都返回同一个结果,这就致使上传进度不显示。不过上传进度信息也可使用html5的file api获取,其中加了一点代码,页面下面test的div里的数值就是在前端获取到的进度。ajax

上传的都实现完了,接着是处理上传后的临时文件,由于使用的uuid命名文件,因此文件会生成不少,没用的须要定时处理。使用ServletContextListener:

在 Servlet API 中有一个 ServletContextListener 接口,它可以监听 ServletContext 对象的生命周期,实际上就是监听 Web 应用的生命周期。apache

当Servlet 容器启动或终止Web 应用时,会触发ServletContextEvent 事件,该事件由ServletContextListener 来处理。在 ServletContextListener 接口中定义了处理ServletContextEvent 事件的两个方法。

利用其特性,实现定时删除临时文件的功能,代码以下:json

package util.upload;

import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.Properties;
import java.util.Timer;
import java.util.TimerTask;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**  
 * 时间监听器  
 *   
 *  
 */  
public class TempFileListener implements ServletContextListener {  
    private Timer timer;  
    private SystemTaskTest systemTask;  
    private static String every_time_run;  
    static {  
        Properties prop = new Properties();  
        InputStream inStrem = TempFileManager.class.getClassLoader()  
                .getResourceAsStream("tempfile.properties");  
        try {  
            prop.load(inStrem);  
            System.out.println(inStrem);
            every_time_run = prop.getProperty("every_time_run");  

        } catch (IOException e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                inStrem.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
    }  

    // 监听器初始方法  
    public void contextInitialized(ServletContextEvent sce) {  

        timer = new Timer();  
        systemTask = new SystemTaskTest(sce.getServletContext()  
                .getRealPath("/"), sce.getServletContext());  
        try {  
            System.out.println("定时器已启动");
            // 监听器获取网站的根目录  
            String path = sce.getServletContext().getRealPath("/");  
            Long time = Long.parseLong(every_time_run) * 1000;// 循环执行的时间  
            System.out.println("time" + time);   
            // 第一个参数是要运行的代码,第二个参数是从何时开始运行,第三个参数是每隔多久在运行一次。重复执行  
            timer.schedule(systemTask, 10000, time);  
            System.out.println("已经添加任务调度表");
        } catch (Exception e) {  
            e.printStackTrace();
        }  
    }  

    public void contextDestroyed(ServletContextEvent sce) {  
        try {  
            timer.cancel();  
        } catch (Exception e) {  
        }  
    }  
}  

/**  
 * 时间任务器  
 * 
 */  
class SystemTaskTest extends TimerTask {  
    private ServletContext context;  
    private String path;  
    public SystemTaskTest(String path, ServletContext context) {  
        this.path = path;  
        this.context = context;  
    }  

    /**  
     * 把要定时执行的任务就在run中  
     */  
    public void run() {   
        TempFileManager etf;     
        try {  

            System.out.println("开始执行任务!");
            // 须要执行的代码  
            System.out.println(new Date().toLocaleString());  

            etf = new TempFileManager(path);  
            etf.run();        

            System.out.println("指定任务执行完成!");
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
}

上面只是监听器,负责定时调用删除临时文件的方法,具体实现是下面的类

package util.upload;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.Properties;


/**  
 * 删除服务器上的文件  
 * 
 */  

public class TempFileManager implements Runnable {  
    private String path;//路径  

    private static String RETENTION_TIME = "1440";// 文件保存的时间  一天单位分
    static {  
        Properties prop = new Properties();  
        InputStream inStrem = TempFileManager.class.getClassLoader()  
                .getResourceAsStream("execl.properties");  
        try {  
            prop.load(inStrem);  
            RETENTION_TIME = prop.getProperty("file_retention_time");  

        } catch (IOException e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                inStrem.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
    }  
    /**  
     * 构造函数。初始化参数  
     * @param path  
     */  
    public TempFileManager(String path) {  
        this.path = path;  

    }  
    /**  
     * 把线程要执行的代码放在run()中  
     */  
    public void run() {  
        System.out.println("文件管理开始=========");  
        path = path + "upload";  
        System.out.println("文件管理路径===" + path);  
        File file = new File(path);  
        deletefiles(file);  
    }  

    /**  
     * 批量删除文件  
     *   
     * @param folder  
     */  
    public void deletefiles(File folder) { 
    if(folder.isDirectory()){

        File[] files = folder.listFiles();
        if(files.length<=0){
            if(!folder.getAbsolutePath().equalsIgnoreCase(path)){
            if(canDeleteFile(folder)){
                if (folder.delete()) {  
                    System.out.println("文件夹" + folder.getName() + "删除成功!");  
                } else {  
                    System.out.println("文件夹" + folder.getName()  
                            + "删除失败!此文件夹内的文件可能正在被使用");  
                }  
            }
            }
        }
        for (int i = 0; i < files.length; i++) {  

            if(files[i].isDirectory())
            {
            deletefiles(files[i]);
            }else{
                deleteFile(files[i]); 
            }

        }  
    }
    }  

    /**  
     * 删除文件  
     *   
     * @param file  
     */  
    private void deleteFile(File file) {  
        try {  
            if (file.isFile()) {  
                // 删除符合条件的文件  
                if (canDeleteFile(file)) {  
                    if (file.delete()) {  
                        System.out.println("文件" + file.getName() + "删除成功!");  
                    } else {  
                        System.out.println("文件" + file.getName()  
                                + "删除失败!此文件可能正在被使用");  
                    }  
                } else {  

                }  
            } else {  
                System.out.println("没有能够删除的文件了");  
            }  

        } catch (Exception e) {  
            System.out.println("删除文件失败========");  
            e.printStackTrace();  
        }  
    }  

    /**  
     * 判断文件是否可以被删除  
     */  
    private boolean canDeleteFile(File file) {  
        Date fileDate = getfileDate(file);  
        Date date = new Date();  
        long time = (date.getTime() - fileDate.getTime()) / 1000 / 60  
                - Integer.parseInt(RETENTION_TIME);// 当前时间与文件间隔的分钟  
//        System.out.println("time=="+time);
        if (time > 0) {  
            return true;  
        } else {  
            return false;  
        }  

    }  

    /**  
     * 获取文件最后的修改时间  
     *   
     * @param file  
     * @return  
     */  
    private Date getfileDate(File file) {  
        long modifiedTime = file.lastModified();  
        Date d = new Date(modifiedTime);  
        return d;  
    }  

}

原文 

https://segmentfault.com/a/1190000023055077

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