根据 url地址 下载图片

/**下载图片   * 根据 url地址 下载图片到  imageDir中 调用   downImage（urlPath，imageDir） * Created by tangzheng on 2016/8/2. */public class Down {    //下载图片  通过url 下载到 imageDir    public void downImage(final String urlPath,  String imageDir) {        final String imageName = urlPath.substring(urlPath.lastIndexOf(File.separator) + 1);        final String filePath = imageDir + File.separator + imageName;        new Thread(new Runnable() {            @Override            public void run() {                HttpURLConnection connection = null;                try {                    URL url = new URL(urlPath);                    connection = (HttpURLConnection) url.openConnection();                    connection.setRequestMethod("GET");                    connection.setConnectTimeout(5000);                    connection.setReadTimeout(5000);                    if (connection.getResponseCode() == 200) {                        File file = new File(filePath);                        if (!file.exists()){                            file.createNewFile();                            Log.d("tag",filePath);                            InputStream inputStream = connection.getInputStream();                            OutputStream outputStream = new FileOutputStream(file);                            int len;                            byte[] buffer = new byte[1024];                            while ((len = inputStream.read(buffer)) != -1) {                                outputStream.write(buffer, 0, len);                            }                            outputStream.close();                            inputStream.close();                        }                    }                    connection.disconnect();                } catch (Exception e) {                    if (connection != null) {                        connection.disconnect();                    }                    e.printStackTrace();                }            }        }).start();    }}