Android 权限处理

package pers.hbolin.permissionsdemo

import android.Manifest
import android.app.Activity
import android.content.pm.PackageManager
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v4.app.ActivityCompat
import android.support.v4.content.ContextCompat
import android.support.v7.app.AlertDialog
import android.util.Log
import kotlinx.android.synthetic.main.activity_main.*
import android.provider.MediaStore
import android.content.Intent
import android.graphics.Bitmap


class MainActivity : AppCompatActivity() {
    val TAG = "MainActivity"

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        callReadContacts()

        button.setOnClickListener {
            // 使用Intent，可以不用在AndroidManifest.xml中配置权限
            // 也不需要动态配置权限，即可调用
            // 这里缺少判断，是否有东西响应这个Intent，不然会抛出异常的。
            val takeIntent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
            MainActivity@ this.startActivityForResult(takeIntent, 1)
        }
    }

    // 请求权限
    private fun callReadContacts() {
        // Here, thisActivity is the current activity
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {

            Log.d(TAG, "未获取到权限")

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.READ_CONTACTS)) {

                // Show an expanation to the user *asynchronously* -- don‘t block
                // this thread waiting for the user‘s response! After the user
                // sees the explanation, try again to request the permission.

                Log.d(TAG, "解释为什么需要权限")

                val builder = AlertDialog.Builder(this)
                builder.setTitle("解释为什么需要权限")
                        .setMessage("因为是在测试")
                        .setPositiveButton("确定") { _, _ ->
                            // 申请权限
                            ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.READ_CONTACTS), 1)
                        }
                        .setNegativeButton("取消") { _, _ -> }
                        .create().show()
            } else {

                // No explanation needed, we can request the permission.

                ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.READ_CONTACTS), 1)

                // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
                // app-defined int constant. The callback method gets the
                // result of the request.
            }
        } else {
            Log.d(TAG, "已获取到权限")
        }
    }

    // 请求回调
    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {

        if (requestCode == 1) {
            if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Log.d(TAG, "权限同意")
            } else {
                Log.d(TAG, "权限禁止")
            }
        }

    }

    // startActivityForResult 回调
    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        Log.d(TAG, "请求 $requestCode and 结果 $resultCode and data is null :${data == null}")
        if (requestCode == 1 && resultCode == Activity.RESULT_OK) {
            if (data?.hasExtra("data") == true) {
                Log.i(TAG, "data is not null")
                val bitmap = data.getParcelableExtra<Bitmap>("data")
                Log.d(TAG, "bitmap.width is ${bitmap.width}")
                imageView.setImageBitmap(bitmap) //imageView即为当前页面需要展示照片的控件，可替换
            }
        }
    }
}