java追加文件下载

package com.zcr.until;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class GetFilePlace 
{
    /**
     * 读取文件，获取保存的根目录
     * @return  保存的根目录
     */
    public   String getFilePath(String fileProperties)
    {
        String dir = System.getProperty("user.dir");  //获得tomcat所在的工作路径  
        
        //获取到存储了文件存储位置的filedir.properties 文件路径
       // String realDir = dir + File.separator + "src" + File.separator +"META-INF" + File.separator + "config" + File.separator + "picture.properties";
       String realDir = dir.substring(0, dir.length()-4) + File.separator +"webapps" + File.separator + "appDataGenerate" +File.separator + "WEB-INF"
                + File.separator + "classes" + File.separator + "META-INF" + File.separator + "config" + File.separator + fileProperties;

       
       /* String realDir = dir.substring(0, dir.length()-4) + File.separator +"webapps" + File.separator + "appDataGenerate" 
                      + File.separator + "classes" + File.separator + "META-INF" + File.separator + "config" + File.separator + fileProperties;
    */
        System.out.println("realDir = " + realDir);
        return realDir;
    }
    
    
    /**
     * 获取filePath路径【properities文件】中key对应的值，
     * @param filePath properities文件路径【包含properities文件】
     * @param key 要查找的key值
     * @return key对应的value
     */
     public   String GetValueByKey(String filePath, String key) 
     {
         Properties pps = new Properties();
         try {
              InputStream in = new BufferedInputStream (new FileInputStream(filePath));  
              pps.load(in);
             String value = pps.getProperty(key);
             in.close();
             return value;
             
         }catch (IOException e) {
             e.printStackTrace();
             return null;
         }
     }
    
    /**
     * 查询properities文件中可以对应的存储地点
     * @param key 查询主键
     * @return    key对应的存储地址
     */
    public  String getFileDirFromProperties(String key,String fileProperties)
    {
        return GetValueByKey(getFilePath(fileProperties),key);
    }
    
    public static void main(String[] args)
    {
        System.out.println(new GetFilePlace().getFileDirFromProperties("brandLogo","picture.properties"));
    }
}

package com.zcr.until;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import javax.servlet.http.HttpServletRequest;

public class URLConnectionDownloader
{    
    //单纯测试下载
    public static void main(String[] args)
    {
        download("http://stocardapp.s3-external-3.amazonaws.com/ios/icons/[email protected]", "E:\\xiazai.jpg");
    }
    

    /**
     * 将urlString的文件下载到
     * @param filePathName        properties文件中的文件存储名
     * @param fileProperties    查找的properties文件    
     * @param urlString            待下载的文件url
     * @param fileName             生成的文件名称
     */
    public static void downloadToSelectedFolder(String filePathName,String fileProperties,String urlString,String fileName,HttpServletRequest request)
    {
        //获得picture.properties 文件中，key为android_banner_url的值
        String pathSavePath = new GetFilePlace().getFileDirFromProperties("android_banner_url","picture.properties");
        
        //获得服务器（tomcat）pathSavePath的相对位置
        String path = request.getSession().getServletContext().getRealPath(pathSavePath);
        
        //获得文件存储的绝对路径
        String generateFileName = path + File.separator + fileName;
        
        download(urlString,generateFileName);
    }
    
    
    
    /**
       * 下载文件到本地
       *
       * @param urlString
       *          被下载的文件地址
       * @param filename
       *          本地文件名
       */
    public static void download(String urlString, String filename)  
    {
        // 构造URL
        URL url;
        try
        {
            url = new URL(urlString);
             // 打开连接
            URLConnection con = url.openConnection();
            // 输入流
            InputStream is = con.getInputStream();
            // 1K的数据缓冲
            byte[] bs = new byte[1024];
            // 读取到的数据长度
            int len;
            // 输出的文件流s
            OutputStream os = new FileOutputStream(filename);
            // 开始读取
            while ((len = is.read(bs)) != -1) {
              os.write(bs, 0, len);
            }
            // 完毕，关闭所有链接
            os.close();
            is.close();
        }
        catch (MalformedURLException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }   
}

URLConnectionDownloader.downloadToSelectedFolder("android_banner_url","picture.properties","http://stocardapp.s3-external-3.amazonaws.com/ios/icons/[email protected]","2x.png",request);