下面是一个用来上传下达的小程序,希望大家给予指教.

import java.io.*;
import java.util.*;
import java.text.*;
import javax.mail.*;
import javax.servlet.*;
import javax.activation.*;
import javax.servlet.http.*;
import javax.mail.internet.*;
import javax.mail.internet.mimemultipart;

/**
*  @author  
*
*<p>
*<p> 【使用例】
*<p>　　try {
*<p>　　　　upload load=new upload();
*<p>　　　　load.setdir("i://ztytest//");　　　　 *<p>　　　　load.doupload(req,res);　      　　　 *<p>                                                 //httpservletrequest req
*<p>                                                 //httpservletresponse res
*<p>　　}
*<p>　　catch( exception e ) {
*<p>　　　　return;
*<p>　　}
*/

public class upload extends httpservlet {
    public string strdir;

    public upload()
    {
    }

    public void doupload(httpservletrequest req, httpservletresponse res)
        throws ioexception,messagingexception
    {
      string boundary=req.getheader("content-type");
      int pos=boundary.indexof('=');
      boundary=boundary.substring(pos+1);
      boundary="--"+ boundary;
      servletinputstream in=req.getinputstream() ;
      byte[] bytes=new byte[512];
      int state=0;
      bytearrayoutputstream buffer=new bytearrayoutputstream();
      string name=null;
      string value=null;
      string filename=null;
      string contenttype=null;

      int i=in.readline(bytes,0,512);

      while (-1!=i)
      {
        string st=new string(bytes,0,i);
        if (st.startswith(boundary))
        {
            state=0;
            system.out.println(filename);
            if (null!=name)
            {
                if(buffer.size()>2)
                {
                    fileoutputstream outstream = new fileoutputstream(strdir+filename);
                    outstream.write(buffer.tobytearray(), 0, buffer.tobytearray().length);
                    outstream.close();
                }
                name=null;
                value=null;
                filename=null;
                contenttype=null;
                buffer=new bytearrayoutputstream();
            }
        }//end of st.startswith(boundary)
        else if (st.startswith("content-disposition: form-data") && state==0)
        {
            stringtokenizer tokenizer=new stringtokenizer(st,";=/"");
            while(tokenizer.hasmoretokens())
            {
                string token=tokenizer.nexttoken();
                if(token.trim().startswith("name"))
                {
                    name=tokenizer.nexttoken();
                    state=2;
                }
                else if(token.trim().startswith("filename"))
                {
                    filename=tokenizer.nexttoken();
                    stringtokenizer ftokenizer=new stringtokenizer(filename,"//");
                    filename=ftokenizer.nexttoken();
                    while(ftokenizer.hasmoretokens())
                        filename=ftokenizer.nexttoken();
                    state=1;
                    break;
                }
            }
        }//end state=0
        else if (st.startswith("content-type") && state==1)
        {
            pos=st.indexof(":");
            contenttype=st.substring(pos+2,st.length()-2);

        }//end state=1
        else if (state==1)
            state=3;
        else if (st.equals("/r/n")&&state==2)
            state=4;
        else if (state==3)
            buffer.write(bytes,0,i);
        else if (state==4)
            value=value==null?st:value+st;

        i=in.readline(bytes,0,512);
      }//end while

    }

    public void setdir(string strsavepath)
    {
        strdir =strsavepath;
    }

    class bytedatasource implements datasource
    {
        byte[] bytes;
        string contenttype;
        string name;

        bytedatasource(byte[] bytes,string contenttype,string name)
        {
            this.bytes=bytes;
            this.contenttype=contenttype;
            this.name=name;
        }

        public string getcontenttype()
        {
            return contenttype;
        }

        public inputstream getinputstream()
        {
            return new bytearrayinputstream(bytes,0,bytes.length-2);
        }

        public string getname()
        {
            return name;
        }

        public outputstream getoutputstream() throws ioexception
        {
            throw new filenotfoundexception();
        }
    }//end of class
}