学习笔记，转自：http://ask.csdn.net/questions/2710

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try {
    URL u=new URL("http://wx.yseasy.com/erweima_1.asp?val=yyy");
    InputStream in = u.openStream();
    FileOutputStream fs=new FileOutputStream("/xxx/yy.png");
    byte[] buf=new byte[1024];
    int r;
    while((r=in.read(buf))>0)
        fs.write(buf,0,r);
    in.close();
    fs.close();
} catch (Exception e) {
    e.printStackTrace();
}

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