上传文件

 

一.本程序所解决的问题
1. 能读取所有类型的文件,且不限制大小
2. 获取文件名时防止乱码(只需保证编码是gbk即可包括html)
3. 可以同时上传n个文件
4. 在n个浏览控件中,允许浏览控件的内容为空(即要判断文件内容是否存在(第五行),可通过是否存在文件名(第二行))如下,可以正常上传:

5. 上传相同文件名时,能自动修改文件名
6. 上传失败时，能自动删除上传失败的文件

二.本程序包括
1.一个核心代码
2.一个Servlet类
3.html文件

 

UpLoad   类的方法

import java.io.*; import javax.servlet.http.HttpServletRequest; import javax.servlet.ServletInputStream; public class UpLoad { private String saveDir = null;//用于设置保存在哪个目录下 private String savePath=null;//用于设置所要保持文件的完整路径,即saveDir+文件名 private String filename[] = new String[50];//文件名数组 private int count=0;//文件个数 private boolean existTheFile=true;//用于判断是否有存在文件(比如有三个上传控件,第二个为空,其他都文件对象) private String filetype[] = new String[50];//扩展名 private String sperator = null;//头尾信息跟上传文件的分隔符 private byte[] block = new byte[4096];//每次读取一行(使用Ｓervlet流),block保存每行的数据 private int L = -1;//用于获取ServletInputStream.readLine方法的返回值 boolean over=false;//此次传输是否结束 /** * 构造函数,参数表示文件所保持的路径位置 */ public UpLoad (String savepath) { saveDir = savepath; } /** * 上传文件的函数,参数为request */ public boolean start (HttpServletRequest request) throws Exception { if (saveDir == null) { return false; } count=0; String s =null; ServletInputStream in = request.getInputStream (); L = in.readLine (block, 0, block.length);//读取第一行即"-----------------------------7d8261a105a4"和换行 sperator = new String (block, 0, L);//转换成字符串 sperator=sperator.substring(0, sperator.length()-2);//取"-----------------------------7d8261a105a4" do{ try{ L = in.readLine (block, 0, block.length);//读取第二行即"Content-Disposition: form-data; name="file1"; filename="F:/zsy.txt""包括换行 String second = new String (block, 0, L);//转换成字符串 int index1 = second.indexOf ("filename=/""); int index2=0; if (index1 != -1) { second = second.substring (index1 + 10);//filename="之后的字符串 index1 = second.lastIndexOf ('//'); index2=second.lastIndexOf ('.'); filename[count]=second.substring(index1+1,index2); index1 = second.indexOf ("/""); filetype[count]=second.substring(index2,index1); L = -1; } existTheFile=true; }catch(Exception e){ existTheFile=false;//当上传控件,没有文件时就抛出异常.即不存在文件 } if(!existTheFile){ in.readLine (block, 0, block.length);//读取第三行 in.readLine (block, 0, block.length); //读取第四行 in.readLine (block, 0, block.length);//读取第5行 L=in.readLine (block, 0, block.length);//读取第6行 s = new String (block, 0, L); s=s.substring(0,sperator.length()+2); if(s.equals(sperator.concat("--"))){//判断是不是"-----------------------------7d8261a105a4--" //不能使用sperator+"--" over=true; break;//如果已经到结束标志,退出循环 } else continue;//如果未到结束标志,退出本次循环,继续下一次 } this.savePath=this.getPath(saveDir, filename[count], filetype[count], 0); FileOutputStream out = new FileOutputStream (this.savePath); in.readLine (block, 0, block.length);//读取第三行 in.readLine (block, 0, block.length); //读取第四行 try { L = in.readLine (block, 0, block.length);////读取第五行,第五行就是是所传文件内容 while (L != -1) { s = new String (block, 0, L); if (s.length () >=sperator.length()) { if ((s.substring(0, sperator.length())).equals (sperator)) {//判断文件内容是否结束 if((s.substring(0, sperator.length()+2)).equals(sperator.concat("--")))//判断是否到最末尾 over=true;//所有文件传输结束 break; } } out.write (block, 0, L);//写 L = in.readLine (block, 0, block.length);//读 } out.close (); } catch (Exception e) { out.close (); over=false; File tmp = new File (saveDir,savePath); if (!tmp.delete()) { System.out.println("操作失败:未完成文件未删除"); } } count++; if(over) break; }while(true); return over; } /** * 获取文件名(包括扩展名) */ public String[] getFileName () { String temp[]=new String[count]; for(int i=0;i<count;i++) temp[i]=filename[i]+filetype[i]; return temp; } /** * 此方法防止因文件名遇到相同而覆盖,自动修改文件名,修改方式跟windows原理一样 */ public String getPath(String SaveDir,String FileName,String FileType ,int deep){ File f=null; String path=null; f=new File(SaveDir + "//" + FileName+"("+deep+")"+FileType); if(f.exists()){ return getPath(SaveDir,FileName,FileType,++deep); } else{ // if(deep==0) return (SaveDir + "//" + FileName+FileType); path=SaveDir + "//" + FileName+"("+deep+")"+FileType; return path; } } } 

Servlet类(UpLoadServlet.java)

 

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; public class UpLoadServlet extends HttpServlet { public UpLoadServlet() { 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 { this.doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { String saveDir="..//webapps//";//用于设置保存在哪个目录下 UpLoad upLoad=new UpLoad(saveDir); try{ if(upLoad.start(request)); this.printMessage(response,upLoad.getFileName(),true,null); }catch(Exception e){ e.printStackTrace(); this.printMessage(response, upLoad.getFileName(),false,e.getMessage()); } } /** * 上传操作结果信息 */ public void printMessage(HttpServletResponse response,String[] filename,boolean sucess,String message){ PrintWriter out=null; response.setContentType("text/html; charset=GBK"); try{ out = response.getWriter(); }catch(Exception e){ out.println(e.getMessage()); } out.println("<!DOCTYPE HTML PUBLIC /"-//W3C//DTD HTML 4.01 Transitional//EN/">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); if(sucess){ if(filename.length!=0) out.print("成功上传文件:<br>"); else out.print("您没有选择文件!<br>"); for(int i=0;i<filename.length;i++){ out.print(filename[i]+"<br>"); } }else out.println(message); out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } public void init() throws ServletException { // Put your code here } } 

html文件(index.html)

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>index.html</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=gbk"> <!--<link rel="stylesheet" type="text/css" href="./styles.css" mce_href="styles.css">--> </head> <body> <form action="UpLoadServlet" method="POST" enctype="multipart/form-data"> <input name="upload" type="file" size="35" /> <br/> <input name="upload" type="file" size="35" /> <br/> <input name="upload" type="file" size="35" /> <br/> <input type="submit" value="上传" /> </form> </body> </html> 

 

 

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