Android——访问其他程序中的数据之读取系统联系人

我们先在电话薄中手动添加几个联系人，以便稍后进行读取

新建一个Contacts项目

public class MainActivity extends AppCompatActivity {
ArrayAdapter<String> adapter;
List<String> contactList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView contactsView = (ListView) findViewById(R.id.contacts_view);
        adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,contactList);
        contactsView.setAdapter(adapter);
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
        }else{
            readContacts();
        }

    }
    private void readContacts(){
        Cursor cursor= null;
        try{
            cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,null,null,null,null);
            if (cursor!=null){
                while (cursor.moveToNext()){
                    //获取联系人姓名
                    String displayName = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                    //获取联系人电话号码
                    String number = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                    contactList.add(displayName+"\n"+number);
                }
                adapter.notifyDataSetChanged();
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (cursor!=null){
                cursor.close();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode){
            case 1:
                if (grantResults.length>0&&grantResults[0]==PackageManager.PERMISSION_GRANTED){
                    readContacts();
                }else{
                    Toast.makeText(this,"你拒绝了这个权限",Toast.LENGTH_SHORT).show();
                }
                break;
                default:
        }
    }
}

这个代码也是类似于访问系统危险权限的一个模板式过程吧。。。