Android 中如何调用 getContentResolver()

在Android开发中，我们经常需要与手机的数据库进行交互。而在Android系统中，我们可以通过getContentResolver()方法来获取ContentResolver对象，从而实现与数据库的交互。getContentResolver()方法是一个Context类中的方法，因此我们可以在任何继承自Context类的地方调用它。

java
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 调用getContentResolver()方法获取ContentResolver对象
        ContentResolver resolver = getContentResolver();
        // 进行后续的数据库操作
        // ...
    }
}

java
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 调用getContentResolver()方法获取ContentResolver对象
        ContentResolver resolver = getContentResolver();
        // 查询联系人数据
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                new String[]{ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME,
                        ContactsContract.CommonDataKinds.Phone.NUMBER},
                null,
                null,
                null);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                String name = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                String number = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
                Log.d("Contact", "Name: " + name + ", Number: " + number);
            }
            cursor.close();
        }
    }
}