系统应用的调用

权限

首先我们需要添加权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/><!--读SD卡权限-->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/><!--写SD卡权限-->
<uses-permission android:name="android.permission.CAMERA"/><!--照相机权限-->
<uses-permission android:name="android.permission.CALL_PHONE" /><!--打电话权限-->

A. 打电话

如果是用真机测试需要动态获取权限

String[] strings = new String[]{Manifest.permission.CALL_PHONE};
 if (Build.VERSION.SDK_INT>=23) {
            for (int i=0;i<strings.length;i++) {
                if (ActivityCompat.checkSelfPermission(this,strings[i]) != PackageManager.PERMISSION_GRANTED) {
                    requestPermissions(strings,100);
                }
            }
        }

  		Intent intent2 = new Intent();
    	intent2.setAction(Intent.ACTION_CALL);
        Uri uri1 = Uri.parse("tel:"+tel);
        intent2.setData(uri1);
        startActivity(intent2);

B. 打开浏览器

 		Intent intent1 = new Intent();
        intent1.setAction(Intent.ACTION_VIEW);
        Uri uri = Uri.parse("https://www.baidu.com");
        intent1.setData(uri);
        startActivity(intent1);

C. 摄像机

  		Intent intent3 = new Intent();
        intent3.setAction(MediaStore.ACTION_VIDEO_CAPTURE);
        startActivityForResult(intent3,VIDEO);

 @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == VIDEO && resultCode == Activity.RESULT_OK) {
            Uri uri = data.getData();
            videoView.setVideoURI(uri);
            videoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                @Override
                public void onPrepared(MediaPlayer mp) {
                    videoView.start();
                }
            });
        }
    }

D. 照相机

 SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss");
                Intent intent4 = new Intent();
                intent4.setAction(MediaStore.ACTION_IMAGE_CAPTURE);

                Date date = new Date();
                String format = sdf.format(date);
                String name = "IMG_"+format+".jpg";
                String path = "/mnt/sdcard/DCIM/Screenshots/"+name;
                ContentResolver contentResolver = getContentResolver();
                ContentValues values = new ContentValues();
                values.put(MediaStore.Images.Media.DATA,path);

                Uri u = contentResolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
                intent4.putExtra(MediaStore.EXTRA_OUTPUT,u);
                startActivityForResult(intent4,IMAGE);

 @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == IMAGE && resultCode == Activity.RESULT_OK) {
            Uri uri = data.getData();
            imageView.setImageURI(uri);
        }
    }