Android内容提供器-读取通讯录

要访问安卓手机里的通讯录、短信、媒体库等，要用内容提供器，要用到ContentResolver类，通过Context的getContentResolver()就可以获取到该实例，该实例可以增删查改。
测试小实例：

AndroidManifest.xml 配置用到的权限

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.contactstest">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
    application>
    <uses-permission android:name="android.permission.READ_CONTACTS"/>
manifest>

activity_main.xml ListView布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <ListView
        android:id="@+id/contacts_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    ListView>
LinearLayout>

入口 MainActivity.java

package com.example.contactstest;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    ArrayAdapter<String> adapter;

    List<String> contactsList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView contactsView = findViewById(R.id.contacts_view);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, contactsList);
        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()) {
                    String displayName = cursor.getString(cursor.getColumnIndex(
                            ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
                    String number = cursor.getString(cursor.getColumnIndex(
                            ContactsContract.CommonDataKinds.Phone.NUMBER));
                    contactsList.add(displayName + "\n" + number);
                }
                adapter.notifyDataSetChanged();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantsResults) {
        switch (requestCode) {
            case 1:
                if(grantsResults.length > 0 && grantsResults[0] == PackageManager.PERMISSION_GRANTED) {
                    readContacts();
                } else {
                    Toast.makeText(this, "您阻止了权限！", Toast.LENGTH_SHORT).show();
                }
                break;
                default:
        }
    }
}