android 之文件下载的实现思路

    从网上下载文件,写入sd卡.思路如下:
    1.创建一个http访问
        HttpURLConnection httpcon=(HttpURLConnection)url.openConnection()
    2.从HttpURLConnection中获取一个输入流
        InputStream httpInputStream=httcon.getInputStream()
    3.解析流
        一般用BufferedReader来获取.
        BufferedReader bfReader=new BufferedReader(new InputSreamReader(InputSream in))
        String line=bfReader.readLine();
    4.创建文件,生成对应的writer
        File fileWrite=new File(localPath);
        FileOutputStream fstream=new FileOutputStream(fileWrite);
        BufferedWriter bfWriter=new BufferedWriter(new OutputStreamWriter(fstream));
        bfWriter.writer(line,0,line.length())
    5.最后记得关闭流的reader和writer
   
    如果是非文本文件的话,最好还是按字节来读取和写入.

    最后,需要注意的是,要在android manifest.xml中定义用户权限
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>