/**
* 判断SDCard是否存在 [当没有外挂SD卡时，内置ROM也被识别为存在sd卡]
*
* @return
*/
public static boolean isSdCardExist() {
return Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
}

/**
* 获取SD卡根目录路径
*
* @return
*/
public static String getSdCardPath() {
boolean exist = isSdCardExist();
String sdpath = "";
if (exist) {
sdpath = Environment.getExternalStorageDirectory()
.getAbsolutePath();
} else {
sdpath = "不适用";
}
return sdpath;

}

//将资源图片存到本地

public void writeFile(){
    try {
        File file = new File(getCacheDir().getAbsolutePath()+
                "/renlian.jpg");
        Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.mipmap.a);
        savePic(bitmap,file);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

/**
 * 保存图片到本地
 *
 * @param b
 * @param filePath
 */
private void savePic(Bitmap b, File filePath) {
    FileOutputStream fos = null;
    try {
        fos = new FileOutputStream(filePath);
        if (null != fos) {
            b.compress(Bitmap.CompressFormat.PNG, 100, fos);
            fos.flush();
            fos.close();
            main();
        }
    } catch (FileNotFoundException e) {
        // e.printStackTrace();
    } catch (IOException e) {
        // e.printStackTrace();
    }
}

SD卡存储