Android 动态获取权限

代码是最好的老师！！！

import android.Manifest;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

import butterknife.ButterKnife;
import butterknife.OnClick;

public class MainActivity extends AppCompatActivity {

    public static final String CAMERA_PERMISSION = Manifest.permission.CAMERA;
    public static final int CAMEAR_REQUEST_CODE = 100;
    public static final int CAMERA_SETTING_CODE = 10;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.inject(this);
    }

    @OnClick(R.id.bt)
    public void onClick(View v) {
        if (ContextCompat.checkSelfPermission(this, CAMERA_PERMISSION) == PackageManager.PERMISSION_GRANTED) {
            openCamera();
        } else {
            ActivityCompat.requestPermissions(this, new String[]{CAMERA_PERMISSION}, CAMEAR_REQUEST_CODE);
        }
    }

    private void openCamera() {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        startActivity(intent);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case CAMEAR_REQUEST_CODE:
                for (int i = 0; i < permissions.length; i++) {
                    if (permissions[i].equalsIgnoreCase(CAMERA_PERMISSION)) {
                        if (grantResults[i] == PackageManager.PERMISSION_GRANTED) {
                            openCamera();
                        } else {
                            if (ActivityCompat.shouldShowRequestPermissionRationale(this, CAMERA_PERMISSION)) {
                                showSetPermissionPathTip();
                            } else {
                                //用户勾选
                                showRationalePermissionTip();
                            }
                        }
                    }
                }
                break;

        }
    }

    private void showSetPermissionPathTip() {
        new AlertDialog.Builder(this)
                .setTitle("提示")
                .setMessage("是否前往设置打开权限")
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        gotoSettings();
                        dialog.dismiss();
                    }
                })
                .setNegativeButton("取消", null)
                .show();
    }

    private void showRationalePermissionTip() {
        new AlertDialog.Builder(this)
                .setTitle("说明")
                .setMessage("因拍照需要权限，是否要打开权限")
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        showSetPermissionPathTip();
                        dialog.dismiss();
                    }
                })
                .setNegativeButton("取消", null)
                .show();
    }

    private void gotoSettings() {
        Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
        Uri packageURI = Uri.parse("package:" + this.getPackageName());
        intent.setData(packageURI);
        startActivityForResult(intent, CAMERA_SETTING_CODE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case CAMERA_SETTING_CODE:
                if (ContextCompat.checkSelfPermission(this, CAMERA_PERMISSION) == PackageManager.PERMISSION_GRANTED) {
                    openCamera();
                }
                break;

        }
    }
}