让javamail直接添加上传文件为附件的DataSource代码

一般的javamil发送附件的代码如下：
                bodypart = new mimebodypart();
                datasource datasource = new filedatasource("c:\测试附件.doc");
                bodypart.setdatahandler(new datahandler(datasource));
                bodypart.setfilename(mimeutility.encodeword("测试附件.doc","gb2312", null));
                multipart.addbodypart(bodypart);
由于javamail 的包里默认的对javax.activation.datasource只有两个实现:
分别是：filedatasource和urldatasource。
因此在webapp里为了不把上传的文件再保存为本地文件，然后再使用filedatasource,
我结合apache的commons fileupload组件，写了一个实现了datasource的uploadfiledatasource。

其实代码非常简单,具体代码如下：

package com.lizongbo.util;

import java.io.*;

import javax.activation.*;
import org.apache.commons.fileupload.fileitem;

/**
 * <p>title: uploadfile datasource for javamail</p>
 * <p>description: </p>
 * <p>copyright: copyright (c) 2005</p>
 * <p>company: zongboli</p>
 * @author lizongbo
 * @version 1.0
 */
public class uploadfiledatasource implements datasource {
    private fileitem uploadfileitem = null;
    public uploadfiledatasource() {
    }

    public uploadfiledatasource(fileitem uploadfile) {
        this.uploadfileitem = uploadfile;
    }
    public string getcontenttype() {
        return uploadfileitem.getcontenttype();
    }

    public inputstream getinputstream() throws ioexception {
        return uploadfileitem.getinputstream();
    }

    public string getname() {
        return uploadfileitem.getname();
    }

    public outputstream getoutputstream() throws ioexception {
        return null;
    }

    public static void main(string[] args) {
    }
}

附在struts里的使用例子：

if (diskfileupload.ismultipartcontent(servletrequest)) {
            diskfileupload fileupload = new diskfileupload();
            fileupload.setsizemax(1024 * 1024);
            try {
                list filelist = fileupload.parserequest(servletrequest);
                iterator itr = filelist.iterator();
                fileitem item;
                while (itr.hasnext()) {
                    item = (fileitem) itr.next();
                    if (item.isformfield()) {
                        logger.debug(item.getfieldname() + "=" +
                                     item.getstring() + "");
                    } else {
                     mimebodypart   bodypart = new mimebodypart();
                     datasource datasource = new com.webmail.util.uploadfiledatasource(item);
                     bodypart.setdatahandler(new datahandler(datasource));
                     multipart.addbodypart(bodypart);                    }
                }
            } catch (org.apache.commons.fileupload.fileuploadbase.
                     sizelimitexceededexception sle) {
                logger.debug("size is too large", sle);
            } catch (org.apache.commons.fileupload.fileuploadbase.
                     unknownsizeexception use) {
                logger.debug("unknown size ", use);
            } catch (org.apache.commons.fileupload.fileuploadexception fue) {
                logger.debug(fue.getmessage() + "  ");
            } catch (exception e) {
                logger.debug("chucuo", e);
            }

        } else {
            logger.debug("没有附件!!!");
        }

由于《用javamail免认证方式发送邮件给163.com的用户的完整代码实例。》 代码被人copy直接运行, 给我带来了很大的麻烦（发了很多垃圾邮件到我邮箱 :( ），
从现在开始发布的代码，一律转为小写之后再进行发布，以仅供阅读参考。

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