commons-fileupload上传组件学习记录

      最近在用commons-fileupload做文件上传的时候遇到了一点小的麻烦，不过最终在学友的帮助下解决，在写之前先说明一下几个错误，在群里面问了上传页面中file选择框的name是否可以相同，很多人说name是不能相同的，不然就不知道是哪个上传的了，这种理解是错误的：

普通表单项name可以相同，在后台接收的时候就用String[]，而且在Struts2中我们也看到，在页面中相同名字的file框
name在Action中用File[] 接收，通过这两点分析，以及之后的实验发现，name完全可以相同，下面的FileItem分析
也可以说明这一点

 先贴一下FileUpload的工具类，这是做了一个封装：

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class FileUploadUtil {
	private Map fileField = new TreeMap(); 
	private Map formField = new TreeMap(); 
	private List<FileItem> list=new ArrayList<FileItem>();
	private int memoryBlock = 2048; 
	private File tempFolder = null; 
	private boolean multipart = false; 
	private HttpServletRequest request = null; 
	private final int maxSize = (int) Common.getByteSizeByBKMG(JavaCenterHome.jchConfig.get("upload_max_filesize")); 
	public FileUploadUtil(File tempFolder, int memeoryBlock) {
		this.tempFolder = tempFolder;
		this.memoryBlock = memeoryBlock;
	}
	public FileUploadUtil() {
	}
	public void parse(HttpServletRequest request, String charset) throws FileUploadException {
		this.request = request;
		multipart = FileUpload.isMultipartContent(request);
		if (multipart) {
			DiskFileItemFactory factory = new DiskFileItemFactory();
			factory.setSizeThreshold(memoryBlock);
			factory.setRepository(tempFolder);
			ServletFileUpload upload = new ServletFileUpload(factory);
			upload.setSizeMax(maxSize);
			List items;
			items = upload.parseRequest(request);
			Iterator iterator = items.iterator();
			while (iterator.hasNext()) {
				FileItem item = (FileItem) iterator.next();
				if (item.isFormField()) {
					processFormField(item, charset);
				} else {
					processUploadedFile(item);
				}
			}
		}
	}
	private void processFormField(FileItem item, String charset) {
		try {
			String name = item.getFieldName();
			String value = item.getString(charset);
			Object objv = formField.get(name);
			if (objv == null) {
				formField.put(name, value);
			} else {
				List values = null;
				if (objv instanceof List) {
					values = (List) objv;
					values.add(value);
				} else {
					String strv = (String) objv;
					values = new ArrayList();
					values.add(strv);
					values.add(value);
				}
				formField.put(name, values);
			}
		} catch (UnsupportedEncodingException e) {
			throw new IllegalArgumentException("the argument \"charset\" missing!");
		}
	}
	private void processUploadedFile(FileItem item) {
		String name = item.getFieldName();
		long size=item.getSize();
		if(size>0)
			list.add(item);
		fileField.put(name, list);
	}
	public static boolean write2file(FileItem item, File file) {
		boolean flag = false;
		try {
			item.write(file);
			flag = true;
		} catch (Exception e) {
		}
		return flag;
	}
	public List<FileItem> getFileItemList(String name) {
		if (multipart) {
			return (List<FileItem>) fileField.get(name);
		} else {
			return null;
		}
	}
	public String getParameter(String name) {
		String value = null;
		if (multipart) {
			Object obj = formField.get(name);
			if (obj != null && obj instanceof String) {
				value = (String) obj;
			}
		} else if (request != null) {
			value = request.getParameter(name);
		}
		return value;
	}
	public String[] getParameterValues(String name) {
		String[] values = null;
		if (multipart) {
			Object obj = formField.get(name);
			if (obj != null) {
				if (obj instanceof List) {
					values = (String[]) ((List) obj).toArray(new String[0]);
				} else {
					values = new String[] {(String) obj};
				}
			}
		} else if (request != null) {
			values = request.getParameterValues(name);
		}
		return values;
	}
	public File getRepository() {
		return this.tempFolder;
	}
	public int getSizeThreshold() {
		return this.memoryBlock;
	}
	public boolean isMultipart() {
		return this.multipart;
	}
	public int getMaxSize() {
		return maxSize;
	}
}

这个工具类有改动，之前没考虑到多文件上传，在Map只是这样存：

String name = item.getFieldName();
fileField.put(name, item);

这样有二点缺点：

1、如果name相同的话，前面上传的文件就会被后面上传的文件覆盖

2、如果上传文件的size为0，并且在最后面，那么最终fileFiled存放的是一个size为0的FilteItem这显然是无效的

上面最后改进后，对于多文件上传也可以起作用了。

下面来分析一下，这句话后,items中存的东西是怎样的：

List items;
items = upload.parseRequest(request);

 上面的意思是解析request，下面来看在我项目中一个表单提交后得到的装有FileItem的List

[name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000054.tmp, size=1bytes, isFormField=true, FieldName=productcategory_id,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000055.tmp, size=0bytes, isFormField=true, FieldName=self_type_id,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000056.tmp, size=0bytes, isFormField=true, FieldName=brand_id, 
 name=null,StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000057.tmp, size=18bytes, isFormField=true, FieldName=name, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000058.tmp, size=2bytes, isFormField=true, FieldName=productsn,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000059.tmp, size=1bytes, isFormField=true, FieldName=price,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000060.tmp, size=1bytes, isFormField=true, FieldName=marketprice, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000061.tmp, size=1bytes, isFormField=true, FieldName=weight,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000062.tmp, size=1bytes, isFormField=true, FieldName=weightunit,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000063.tmp, size=1bytes, isFormField=true, FieldName=base_sale_num, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000064.tmp, size=1bytes, isFormField=true, FieldName=product_unit,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000065.tmp, size=1bytes, isFormField=true, FieldName=store,
 name=http_imgloadCAEP58ES.jpg, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000066.tmp, size=141869bytes, isFormField=false, FieldName=productImages,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000067.tmp, size=16bytes, isFormField=true, FieldName=productImageParameterTypes, 
 name=http_imgloadCAFH1MHX.jpg, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000068.tmp, size=70138bytes, isFormField=false, FieldName=productImages, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000069.tmp, size=16bytes, isFormField=true, FieldName=productImageParameterTypes, 
 name=, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000070.tmp, size=0bytes, isFormField=false, FieldName=productImages, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000071.tmp, size=44bytes, isFormField=true, FieldName=description, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000072.tmp, size=0bytes, isFormField=true, FieldName=producttype_id,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000073.tmp, size=1bytes, isFormField=true, FieldName=valid_date,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000074.tmp, size=1bytes, isFormField=true, FieldName=ismarketable, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000075.tmp, size=1bytes, isFormField=true, FieldName=isbest, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000076.tmp, size=1bytes, isFormField=true, FieldName=isnew,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000077.tmp, size=1bytes, isFormField=true, FieldName=ishot,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000078.tmp, size=0bytes, isFormField=true, FieldName=metakeywords,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000079.tmp, size=0bytes, isFormField=true, FieldName=metadescription,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000080.tmp, size=8bytes, isFormField=true, FieldName=formhash, 
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000081.tmp, size=0bytes, isFormField=true, FieldName=id,
 name=null, StoreLocation=D:\Tomcat 6.0.20\webapps\JavaCenterHome\.\data\temp\upload_365228b4_12f048b1396__8000_00000082.tmp, size=1bytes, isFormField=true, FieldName=productsubmit]

 上面每一行就是一个FiteItem中的内容，也就是说使用commons-fileupload上传组件后，对于表单中的每一项它都会解析后构造成一个个的FileItem，我们只要操作这写FileItem就行了。