• 此类权限也必须在Manifest中申明，否则申请时不提示用户，直接回调开发者权限被拒绝。
  
• 同一个权限组的任何一个权限被授权了，这个权限组的其他权限也自动被授权。例如一旦WRITE_CONTACTS被授权了，App也有READ_CONTACTS和GET_ACCOUNTS了。
  
• 申请某一个权限的时候系统弹出的Dialog是对整个权限组的说明，而不是单个权限。例如我申请READ_EXTERNAL_STORAGE，系统会提示"允许xxx访问设备上的照片、媒体内容和文件吗？"。
  

public class MainActivity extends ListActivity {
	
	private static final int REQUESTCODE = 20094;
	
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		String[] array = {"在没有申请权限的情况下在SD卡创建文件会失败",
				"完整的授权过程演示",
				"演示PermissionsDispatcher",};
		setListAdapter(new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, new ArrayList<>(Arrays.asList(array))));
	}
	
	@Override
	protected void onListItemClick(ListView l, View v, int position, long id) {
		switch (position) {
			case 0:
				createFileWithoutRequestPermission(this);
				break;
			case 1:
				requestPermissionBeforeCreateFile();
				break;
			case 2:
				startActivity(new Intent(this, Activity1.class));
				break;
		}
	}
	
	/**
	 * 如果将targetSdkVersion改为22或以下，可以成功创建文件
	 * 相反，如果改为23或以上，则失败
	 */
	public static void createFileWithoutRequestPermission(Context context) {
		String fileName = new SimpleDateFormat("yyyy.MM.dd_HH.mm.ss", Locale.getDefault()).format(new Date());
		File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath(), fileName + ".txt");
		boolean createFile = false;
		try {
			createFile = file.createNewFile();//没有申请权限时就在SD卡创建文件会失败（当然，如果文件已经存在，返回值也是false）
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			Toast.makeText(context, "创建文件结果：" + createFile, Toast.LENGTH_SHORT).show();
		}
	}
	
	private void requestPermissionBeforeCreateFile() {
		//检查权限。结果：PERMISSION_GRANTED=0，有权限；PERMISSION_DENIED=-1，没有权限
		int state = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
		Toast.makeText(this, "写SD卡权限状态：" + state, Toast.LENGTH_SHORT).show();
		
		if (state != PackageManager.PERMISSION_GRANTED) {// 没有权限，申请权限
			//是否应该显示请求权限的说明。
			//加这个提醒的好处在于：第一次申请权限时不需要麻烦用户，但如果用户拒绝过一次权限后我们再次申请时
			//可以提醒用户授予该权限的必要性，免得再次申请时用户勾选"不再提醒"并拒绝，导致下次申请权限直接失败
			//返回值的特点：第一次请求权限之前调用返回false（不应该提醒）；如果用户拒绝了，则下次调用返回true（应该提醒）
			//如果之后再次请求权限时，用户拒绝了并选择了"不再提醒"，则下次调用返回false（不应该提醒，且不弹授权对话框）
			boolean state2 = ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
			if (state2) {
				// 一般是通过弹一个自定义的对话框告诉用户，我们为什么需要这个权限
				new AlertDialog.Builder(this)
						.setTitle("请求读写SD卡权限").setMessage("请求SD卡权限，作用是给你保存妹子图片")
						.setPositiveButton("知道了", (dialog, which) -> ActivityCompat.requestPermissions(MainActivity.this,
								new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUESTCODE))
						.create().show();
			} else {
				//请求用户授权几个权限，调用后系统会显示一个请求用户授权的提示对话框，开发者不能修改这个对话框
				ActivityCompat.requestPermissions(MainActivity.this,//api 23以后可以调用Activity的requestPermissions方法
						new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},//需要申请的权限数组
						REQUESTCODE);//请求码，会在回调onRequestPermissionsResult()时返回
			}
		} else {// 有权限了，去放肆吧。
			createFileWithoutRequestPermission(this);
		}
	}
	
	@Override
	//当用户处理完授权操作时，会回调Activity或Fragment的此方法，参数为：权限数组、授权结果数组
	public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
		super.onRequestPermissionsResult(requestCode, permissions, grantResults);
		if (grantResults.length > 0) {
			switch (requestCode) {
				case REQUESTCODE: {
					if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
						createFileWithoutRequestPermission(this);
					} else {
						Toast.makeText(this, "你拒绝了权限，我们已经没法愉快的玩耍了，我将在3秒后关闭！", Toast.LENGTH_SHORT).show();
						new Handler().postDelayed(this::finish, 3 * 1000);
					}
				}
			}
		}
	}
}

compile ‘com.github.hotchemi:permissionsdispatcher:2.4.0‘
annotationProcessor ‘com.github.hotchemi:permissionsdispatcher-processor:2.4.0‘

allprojects {
    repositories {
        jcenter()
        mavenCentral()//或 maven { url ‘http://oss.jfrog.org/artifactory/oss-snapshot-local/‘ }
    }
}

targetSdkVersion 25

Activity1PermissionsDispatcher.onRequestPermissionsResult(this, requestCode, grantResults);

@RuntimePermissions
public class Activity1 extends Activity {
	
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		TextView tv = new TextView(this);
		setContentView(tv);
		tv.setBackgroundColor(Color.YELLOW);
		tv.setOnClickListener(v -> Activity1PermissionsDispatcher.createFileWithCheck(Activity1.this));
	}
	@NeedsPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)
	void createFile() {
		Toast.makeText(this, "【NeedsPermission，用户允许了该权限】", Toast.LENGTH_SHORT).show();
		MainActivity.createFileWithoutRequestPermission(Activity1.this);
	}
	@OnPermissionDenied(Manifest.permission.WRITE_EXTERNAL_STORAGE)
	void doOnPermissionDenied() {
		Toast.makeText(this, "【OnPermissionDenied，用户拒绝了该权限】", Toast.LENGTH_SHORT).show();
	}
	@OnShowRationale(Manifest.permission.WRITE_EXTERNAL_STORAGE)
	void doOnShowRationale(final PermissionRequest request) {
		Toast.makeText(this, "【OnShowRationale，此时应该显示请求权限的说明】", Toast.LENGTH_SHORT).show();
		// 一般是通过弹一个自定义的对话框告诉用户，我们为什么需要这个权限
		new AlertDialog.Builder(this)
				.setTitle("请求读写SD卡权限").setMessage("请求SD卡权限，这样我才能给你保存妹子图片哦")
				.setPositiveButton("我知道了", (dialog, which) -> request.proceed())
				.setNegativeButton("我不需要", (dialog, which) -> request.cancel())
				.create().show();
	}
	@OnNeverAskAgain(Manifest.permission.WRITE_EXTERNAL_STORAGE)
	void doOnNeverAskAgain() {
		Toast.makeText(this, "你拒绝了读写SD卡权限并选择了\"不再提醒\"，" +
				"\n已经没法愉快的玩耍了，我将在3秒后关闭！", Toast.LENGTH_SHORT).show();
		new Handler().postDelayed(this::finish, 3 * 1000);
	}
	@Override
	public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
		super.onRequestPermissionsResult(requestCode, permissions, grantResults);
		Activity1PermissionsDispatcher.onRequestPermissionsResult(this, requestCode, grantResults);
	}
}

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package permission.bqt.com.permissiontest;
import android.support.v4.app.ActivityCompat;
import java.lang.ref.WeakReference;
import permission.bqt.com.permissiontest.Activity1;
import permissions.dispatcher.PermissionRequest;
import permissions.dispatcher.PermissionUtils;
final class Activity1PermissionsDispatcher {
    private static final int REQUEST_CREATEFILE = 0;
    private static final String[] PERMISSION_CREATEFILE = new String[]{"android.permission.WRITE_EXTERNAL_STORAGE"};
    private Activity1PermissionsDispatcher() {
    }
    static void createFileWithCheck(Activity1 target) {
        if(PermissionUtils.hasSelfPermissions(target, PERMISSION_CREATEFILE)) {
            target.createFile();
        } else if(PermissionUtils.shouldShowRequestPermissionRationale(target, PERMISSION_CREATEFILE)) {
            target.doOnShowRationale(new Activity1PermissionsDispatcher.CreateFilePermissionRequest(target));
        } else {
            ActivityCompat.requestPermissions(target, PERMISSION_CREATEFILE, 0);
        }
    }
    static void onRequestPermissionsResult(Activity1 target, int requestCode, int[] grantResults) {
        switch(requestCode) {
        case 0:
            if(PermissionUtils.verifyPermissions(grantResults)) {
                target.createFile();
            } else if(!PermissionUtils.shouldShowRequestPermissionRationale(target, PERMISSION_CREATEFILE)) {
                target.doOnNeverAskAgain();
            } else {
                target.doOnPermissionDenied();
            }
        default:
        }
    }
    private static final class CreateFilePermissionRequest implements PermissionRequest {
        private final WeakReference<Activity1> weakTarget;
        private CreateFilePermissionRequest(Activity1 target) {
            this.weakTarget = new WeakReference(target);
        }
        public void proceed() {
            Activity1 target = (Activity1)this.weakTarget.get();
            if(target != null) {
                ActivityCompat.requestPermissions(target, Activity1PermissionsDispatcher.PERMISSION_CREATEFILE, 0);
            }
        }
        public void cancel() {
            Activity1 target = (Activity1)this.weakTarget.get();
            if(target != null) {
                target.doOnPermissionDenied();
            }
        }
    }
}