安卓：读取系统联系人

1、编辑布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.kh18_1.MainActivity">

    <ListView
        android:id="@+id/contacts_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</RelativeLayout>

2、编辑MainActivity.java文件

import android.Manifest;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.provider.ContactsContract;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
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 {
    ListView contactsview;
    //存放数据
    List<String> contactsList = new ArrayList<>();
    ArrayAdapter<String> adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化view
        initview();
    }

    private void initview() {
        //获取listview
        contactsview = (ListView) findViewById(R.id.contacts_view);
        //适配器是为了将构造函数中把要适配的数据传入 当前提供的数据是字符串 所以泛型为String 第二个参数是子项的布局
        adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, contactsList);
        contactsview.setAdapter(adapter);
        //判断用户是否已经授权给我们了 如果没有，调用下面方法向用户申请授权，之后系统就会弹出一个权限申请的对话框
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)
                != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(
                    MainActivity.this, new String[]{Manifest.permission.READ_CONTACTS}, 1);
        } else {
            readContacts();
        }
    }
    //调用并获取联系人信息
    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);
                }
                //刷新
                adapter.notifyDataSetChanged();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }


    }

    //回调方法，无论哪种结果，最终都会回调该方法，之后在判断用户是否授权，
    // 用户同意则调用readContacts（）方法，失败则会弹窗提示失败
    @Override
    public void onRequestPermissionsResult(int requestCode,String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    readContacts();
                } else {
                    Toast.makeText(this, "获取联系人权限失败", Toast.LENGTH_SHORT).show();
                }
                break;
            default:
        }
    }
}

3、运行