初次使用反射时经常会抛异常，可能的原因有以下：
1.该类可能由于版本的原因不存在某个方法了所以获取不到，我们可以通过循环遍历类的所有方法来排查是不是此原因引起的，如果方法不存在就要使用其他的方法替代
2.传入的参数不正确导致没有正确反射到对应的方法，建议根据方法的参数和返回值正确书写代码，以下是一些反射获取方法的例子
public class Utils {private static final String TAG = Utils.class.getSimpleName();public static String getSystemProperty(String property, String defaultValue) {try {Class<?> clazz = Class.forName("android.os.SystemProperties");//获取类Method M[] = clazz.getMethods();//循环调试获取该类的所有方法for (Method m : M) {Log.i(TAG, "getSystemProperty: " + m.getName());}//如果存在该方法，再通过反射获取方法Method getter = clazz.getDeclaredMethod("get", String.class, String.class);//获取类的方法，参数依次为(方法名，参数类型，返回值类型)String value = (String) getter.invoke(null, property, defaultValue);//调用方法if (!TextUtils.isEmpty(value)) {return value;}} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read system properties");}return defaultValue;}public static Boolean getSystemPropertyBoolean(String property, Boolean defaultValue) {try {Class<?> clazz = Class.forName("android.os.SystemProperties");Method getter = clazz.getDeclaredMethod("getBoolean", String.class, Boolean.TYPE);//获取类的方法，参数依次为(方法名，参数类型，返回值类型)Boolean value = (Boolean) getter.invoke(null, new Object[] { property, defaultValue });if (!TextUtils.isEmpty(String.valueOf(value))) {return value;}} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read system properties boolean");}return defaultValue;}public static String getStorageVolumePath(StorageVolume storageVolume) {try {Class<?> storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");//通过反射调用系统hide的方法Method getPath = storageVolumeClazz.getMethod("getPath");//通过反射调用getPathLog.i(TAG, "getStorageVolumePath: " + getPath.invoke(storageVolume).toString());return getPath.invoke(storageVolume).toString(); //获取路径} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read Storage Volume Path");}return "";}public static Long getStorageVolumeMaxFileSize(StorageVolume storageVolume) {try {Class<?> storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");//通过反射调用系统hide的方法Method getMaxFileSize = storageVolumeClazz.getMethod("getMaxFileSize");//通过反射调用getPathLog.i(TAG, "getStorageVolumeMaxFileSize: " + getMaxFileSize.invoke(storageVolume));return (Long) getMaxFileSize.invoke(storageVolume); //获取路径} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read Storage Volume MaxFileSize");}return 0L;}public static String getStorageVolumeState(StorageManager storageManager, String path) {String result = "";try {Method getVolumeState = StorageManager.class.getDeclaredMethod("getVolumeState", String.class);getVolumeState.setAccessible(true);Log.i(TAG, "getStorageVolumeState: "+ getVolumeState.invoke(storageManager, path));result = (String) getVolumeState.invoke(storageManager, path);} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read method getVolumeState");}return result;}public static String getMediaFileMimeTypeForFile(String fileName) {try {Class<?> mediaFileClazz = Class.forName("android.media.MediaFile");//通过反射调用系统hide的方法Method getMimeTypeForFile = mediaFileClazz.getMethod("getMimeTypeForFile");//通过反射调用getPathreturn (String) getMimeTypeForFile.invoke(fileName); //获取路径} catch (Exception e) {Log.e(TAG, e.getMessage());Log.d(TAG, "Unable to read MediaFileMimeTypeForFile");}return fileName;}
