文件上传：commons-fileupload + Servlet 2.5

<form id="form1" method="post" action="Upload" enctype="multipart/form-data">
　　<table>
   　　　　<tr>
              <td width="25%" align="right">上传文件：</td>
              <td><input id="file1" type="file" NAME="file1" style="width: 300px;"></td>
          </tr>
          <tr align="center" valign="middle">
              <td height="60" colspan="2">
                 <input type="submit" id="BtnOK" value="确认上传">
                 <button onclick="javascript:window.opener == null;window.close();">取消上传</button>
              </td>
           </tr>
           <tr align="center" valign="middle">
               <td height="60" colspan="2"><input type="text" name="possess" value="非提交控件的值"></td>
           </tr>
　　</table>
</form>

import java.io.UnsupportedEncodingException;

import java.util.HashMap;  
import java.util.Iterator;  
import java.util.List;  
import java.util.Map;  
  
import javax.servlet.http.HttpServletRequest;  
  
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;  
  
/**
 * 编码问题（setHeaderEncoding），这个方法是从FileUploadBase类里继承的，
 * 根据其说明，当读取上传表单的各部分时会用到该encoding，如果没有指定
 * encoding * 则使用系统缺省的encoding。建议在这里设置成utf-8，并把jsp
 * 的charset也设置成utf-8，否则可能会出现乱码。
 *
 */
@SuppressWarnings("unchecked")
public class MutiFileUpload{  
  
　 public Map<String,String> parameters ;　　　　//保存普通form表单域  
   public Map<String,FileItem> files;　　　　　　//保存上传的文件  
  
　　//将文件保存在内存还是磁盘临时文件夹的默认临界值，值为10240，即10kb
    private int sizeThreshold = DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD;  
  
    private long sizeMax = 1024 * 1024 * 20  ;    　　//上传文件的大小限制; 
    private String encoding = "UTF-8";        　　　　//字符编码，当读取上传表单的各部分时会用到该encoding  
  
    public String getEncoding() {  
        return encoding; 
    }  
  
    public void setEncoding(String encoding) {  
        this.encoding = encoding;
    }  
  
    public long getSizeMax() {  
        return sizeMax;
    }  
  
    public void setSizeMax(long sizeMax) {  
        this.sizeMax = sizeMax;
    }  
  
    public int getSizeThreshold() {  
        return sizeThreshold;
    }  
  
    public void setSizeThreshold(int sizeThreshold) {  
        this.sizeThreshold = sizeThreshold;
    }  
  
    public void parse(HttpServletRequest request){  
  
        parameters = new HashMap<String,String>();
        files = new HashMap<String,FileItem>();
  
        
        DiskFileItemFactory factory = new DiskFileItemFactory();  
  
        //设置临界值约束
        factory.setSizeThreshold(sizeThreshold);  
  
        ServletFileUpload upload = new ServletFileUpload(factory);  
  
        upload.setSizeMax(sizeMax);  
        upload.setHeaderEncoding(encoding);  
  
        try {  
  
            List items = upload.parseRequest(request);  
            Iterator iterator = items.iterator();  
            while(iterator.hasNext()){  
  
                FileItem item = (FileItem)iterator.next();  
                if(item.isFormField()){                   
                    String fieldName = item.getFieldName();  
                    String value = new String(item.getString(encoding));  
                    parameters.put(fieldName, value);  
  
                }else{  
  
                    String fieldName = item.getFieldName();  
                    files.put(fieldName, item);  
                }  
            }  
  
        } catch (FileUploadException e) {  
            e.printStackTrace();  
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }  
    }  
  
    /** 得到上传文件的文件名 
     * @param item 
     * @return 
     */  
    public String getFileName(FileItem item){  
  
        String fileName = item.getName();  
        fileName = replace(fileName,"\\","/"); 
        fileName = fileName.substring(fileName.lastIndexOf("/")+1);  
        return fileName;  
  
    }  
  
    /**字符串替换 
     * @param source 
     * @param oldString 
     * @param newString 
     * @return 
     */  
    public static String replace(String source, String oldString, String newString) {  
  
        StringBuffer output = new StringBuffer();  
        int lengthOfSource = source.length();   
        int lengthOfOld = oldString.length();   
        int posStart = 0;   
        int pos;   
  
        while ((pos = source.indexOf(oldString, posStart)) >= 0) {  
  
            output.append(source.substring(posStart, pos));  
            output.append(newString);  
            posStart = pos + lengthOfOld;  
        }  
  
        if (posStart < lengthOfSource) {  
            output.append(source.substring(posStart));  
        }  
  
        return output.toString();  
    }  
}  

public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        MutiFileUpload fileUpload = new MutiFileUpload();
　　　　 //解析请求，分解form表单的元素
        fileUpload.parse(request);
        //测试非上传组件的数据是否可以获取
        System.out.println( fileUpload.parameters.get("possess") );  
        
        Iterator iterator = fileUpload.files.values().iterator();  
        while(iterator.hasNext()){  
            
            FileItem item = (FileItem) iterator.next();  
            String fileName = fileUpload.getFileName(item);  
　　　　　　　//获取上传文件路径
            String serverPath = request.getSession().getServletContext().getRealPath("");
　　　　　　　//创建上传的文件
            File file = new File( serverPath+"/upload/"+fileName);
            
            try {
                if( !file.isDirectory()){
　　　　　　　　　　　　//上传文件
                    item.write(file);
                }
            } catch (Exception e) {  
                e.printStackTrace();  
            }
        }  
    }