安卓 Content Provider + SQLite 实验

Colazxk.xyz

2024-04-12 帮助1人

实验十二 SQL content Provider实验

一、实验目的

熟悉Content Provider的使用；

二、实验内容

1、实现ContentProvider和ContentResolver通过URI的调用；
2、实现ContentProvider对数据库SQLite的功能：增、删、改、查；
3、数据库的表结构自行设计；

三、实验要求

1、配置SQLite 数据库的运行环境
2、熟悉ContentProvider对数据库SQLite增、删、改、查的具体操作和流程
3、充分理解SQLite数据库的使用原理和方式

参考：
https://blog.csdn.net/alovelypeach/article/details/112250226
对原博主表示感谢！
原博主（alovelypeach）并未提到应用程序清单文件AndroidManifest.xml，导致copy代码并不能正常运行，本文将对原博主的实验内容进行完善及说明
学新通

四、实验过程

使用软件：Android Studio

①创建项目

②编写布局文件

③编写MainActivity类

实验需要读取通讯录，如果没有给予读取通讯录权限，应用将不能正常运行
需要使用

ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED

判断是否有读取通讯录权限
如没有权限，则使用

ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);

弹出Android的请求权限对话框。
有权限才启动ContentActivity，进行下一步操作
代码如下：

public void toOne(View view) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
            Toast.makeText(this,"未允许读取通讯录权限！",Toast.LENGTH_SHORT).show();
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)== PackageManager.PERMISSION_GRANTED)
        {
            Intent intent = new Intent(MainActivity.this,ContentActivity.class);
            startActivity(intent);
        }
    }

效果如下：
学新通

④编写ContentActivity类

想要获取到通讯录中的号码，需要先获取LOOKUP_KEY，再根据LOOKUP_KEY到ContactsContract.CommonDataKinds.Phone中查询NUMBER

Cursor cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, new String[]{ContactsContract.CommonDataKinds.Phone.NUMBER},ContactsContract.Data.LOOKUP_KEY "=?", new String[]{lookUp_Key},null);

获取通讯录姓名、号码代码如下：

public String getAllPhoneNumbers(String lookUp_Key){
        StringBuilder allPhoneNo = new StringBuilder();
        String[] proj2 = {ContactsContract.CommonDataKinds.Phone.NUMBER};
        String selection = ContactsContract.Data.LOOKUP_KEY "=?";
        String[] selectionArgs = {lookUp_Key};
        ContentResolver resolver = getContentResolver();
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,proj2,selection,selectionArgs,null);
        while(cursor.moveToNext()){
            allPhoneNo.append(cursor.getString(0)).append(" ");
        }
        return allPhoneNo.toString();
    }

    private CharSequence getQueryData() {

        StringBuilder stringBuilder = new StringBuilder();
        ContentResolver resolver = getContentResolver();
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                null,null,null,null);

        String name = ContactsContract.Contacts.DISPLAY_NAME;
        String key = ContactsContract.Contacts.LOOKUP_KEY;
        int displayNameIndex = cursor.getColumnIndex(name);
        int KeyIndex = cursor.getColumnIndex(key);
        for (cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()) {
            String displayName = cursor.getString(displayNameIndex);
            String Key = cursor.getString(KeyIndex);
            String displayPhone = getAllPhoneNumbers(Key);
            stringBuilder.append(displayName).append(" ").append(displayPhone).append("\n");
        }
        cursor.close();
        return stringBuilder.toString();
    }

⑤编写SQLActivity、PersionProvider、PersonDBOpenHelper类

将通讯录插入到数据库的代码如下：

public void btnCreate(View view) {

        PersonDBOpenHelper helper = new PersonDBOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        resolver = getContentResolver();
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
            Toast.makeText(this,"未允许读取通讯录权限！",Toast.LENGTH_SHORT).show();
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)== PackageManager.PERMISSION_GRANTED)
        {
            Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                    null,null,null,null);
            String name = ContactsContract.Contacts.DISPLAY_NAME;
            String key = ContactsContract.Contacts.LOOKUP_KEY;
            int displayNameIndex = cursor.getColumnIndex(name);
            int KeyIndex = cursor.getColumnIndex(key);
            for (cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()) {
                String displayName = cursor.getString(displayNameIndex);
                String Key = cursor.getString(KeyIndex);
                String displayPhone = getAllPhoneNumbers(Key);
                values = new ContentValues();
                values.put("name",displayName);
                values.put("phone",displayPhone);
                db.insert("info",null,values);
            }
            cursor.close();
            db.close();
            btnQueryAll(view);
            Toast.makeText(this,"插入成功！",Toast.LENGTH_SHORT).show();

        }
    }

使用

db.execSQL("create table info(_id integer primary key autoincrement,name varchar(50),phone varchar(20),UNIQUE(phone))");

创建含有_id、name、phone字段的SQLite数据库，其中_id为主键，自增，phone不可重复。

⑥修改应用程序清单文件AndroidManifest.xml

需要加入

<uses-permission android:name="android.permission.READ_CONTACTS" />

声明需要读取通讯录权限
需要加入

<provider
    android:authorities="com.example.test05_contentprovider.PersonProvider"
    android:name="PersonProvider"
    android:exported="false" />

以包含内容提供者
android:authorities的书写方式为Provider的包名 Provider的类名

五、完整源码

温馨提示：直接copy代码会出现包名和你新建项目时设置的包名不一致等问题，如无法正常运行，可根据编译器输出的错误提示排查。

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@ id/toOne"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/toOne"
        android:onClick="toOne" />

    <Button
        android:id="@ id/toTwo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/toTwo"
        android:onClick="toTwo" />

</LinearLayout>

contentlayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ContentActivity">

    <TextView
        android:id="@ id/hint"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/hint"
        android:textSize="30sp" />

    <TextView
        android:id="@ id/callName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20sp" />

</LinearLayout>

sqllayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SQLActivity">

    <EditText
        android:id="@ id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:hint="@string/id" />

    <EditText
        android:id="@ id/editText2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:hint="@string/name" />

    <EditText
        android:id="@ id/editText3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:hint="@string/phone" />

    <Button
        android:id="@ id/add"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/add"
        android:onClick="btnAdd" />

    <Button
        android:id="@ id/delete"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/delete"
        android:onClick="btnDelete" />

    <Button
        android:id="@ id/update"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/update"
        android:onClick="btnUpdate" />

    <Button
        android:id="@ id/query"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/query"
        android:onClick="btnQuery" />

    <Button
        android:id="@ id/addContent"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/addContent"
        android:onClick="btnCreate" />

    <Button
        android:id="@ id/queryAll"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/queryAll"
        android:onClick="btnQueryAll" />

    <EditText
        android:id="@ id/eT"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="15dp"
        android:layout_weight="1"
        android:gravity="start|top"
        android:inputType="textMultiLine" />

</LinearLayout>

strings.xml

<resources>
    <string name="app_name">test05_contentprovider</string>
    <string name="id">id</string>
    <string name="name">姓名</string>
    <string name="phone">号码</string>
    <string name="add">增加</string>
    <string name="delete">删除</string>
    <string name="update">修改</string>
    <string name="query">查询</string>
    <string name="addContent">插入通讯录数据</string>
    <string name="queryAll">查看所有数据</string>
    <string name="toOne">访问通讯录</string>
    <string name="toTwo">数据库</string>
    <string name="hint">读取到的联系人姓名 号码：</string>
</resources>

MainActivity.java

package com.example.test05_contentprovider;

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

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void toOne(View view) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
            Toast.makeText(this,"未允许读取通讯录权限！",Toast.LENGTH_SHORT).show();
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)== PackageManager.PERMISSION_GRANTED)
        {
            Intent intent = new Intent(MainActivity.this,ContentActivity.class);
            startActivity(intent);
        }
    }

    public void toTwo(View view) {
        Intent intent = new Intent(MainActivity.this,SQLActivity.class);
        startActivity(intent);
    }
}

ContentActivity.java

package com.example.test05_contentprovider;

import android.Manifest;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.widget.TextView;

import androidx.annotation.Nullable;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

public class ContentActivity extends Activity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.contentlayout);
        TextView textView = (TextView) findViewById(R.id.callName);
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
            textView.setText("未允许读取通讯录权限！");
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)== PackageManager.PERMISSION_GRANTED)
        {
            textView.setText(getQueryData());
        }
    }

    public String getAllPhoneNumbers(String lookUp_Key){
        StringBuilder allPhoneNo = new StringBuilder();
        String[] proj2 = {ContactsContract.CommonDataKinds.Phone.NUMBER};
        String selection = ContactsContract.Data.LOOKUP_KEY "=?";
        String[] selectionArgs = {lookUp_Key};
        ContentResolver resolver = getContentResolver();
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,proj2,selection,selectionArgs,null);
        while(cursor.moveToNext()){
            allPhoneNo.append(cursor.getString(0)).append(" ");
        }
        return allPhoneNo.toString();
    }

    private CharSequence getQueryData() {

        StringBuilder stringBuilder = new StringBuilder();
        ContentResolver resolver = getContentResolver();
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                null,null,null,null);

        String name = ContactsContract.Contacts.DISPLAY_NAME;
        String key = ContactsContract.Contacts.LOOKUP_KEY;
        int displayNameIndex = cursor.getColumnIndex(name);
        int KeyIndex = cursor.getColumnIndex(key);
        for (cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()) {
            String displayName = cursor.getString(displayNameIndex);
            String Key = cursor.getString(KeyIndex);
            String displayPhone = getAllPhoneNumbers(Key);
            stringBuilder.append(displayName).append(" ").append(displayPhone).append("\n");
        }
        cursor.close();
        return stringBuilder.toString();
    }


}

SQLActivity.java

package com.example.test05_contentprovider;

import android.Manifest;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class SQLActivity extends Activity {
    private final Uri uri = Uri.parse("content://com.example.test05_contentprovider.PersonProvider/info");
    private ContentValues values;
    private ContentResolver resolver;
    private EditText et_id;
    private EditText et_name;
    private EditText et_phone;
    private EditText et_queryAll;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.sqllayout);

        et_id = (EditText) findViewById(R.id.editText1);
        et_name = (EditText) findViewById(R.id.editText2);
        et_phone = (EditText) findViewById(R.id.editText3);
        et_queryAll = (EditText) findViewById(R.id.eT);
    }

    public String getAllPhoneNumbers(String lookUp_Key){
        StringBuilder allPhoneNo = new StringBuilder();
        String[] proj2 = {ContactsContract.CommonDataKinds.Phone.NUMBER};
        String selection = ContactsContract.Data.LOOKUP_KEY "=?";
        String[] selectionArgs = {lookUp_Key};
        ContentResolver resolver = getContentResolver();
        Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,proj2,selection,selectionArgs,null);
        while(cursor.moveToNext()){
            allPhoneNo.append(cursor.getString(0)).append(" ");
        }
        return allPhoneNo.toString();
    }

    public void btnCreate(View view) {

        PersonDBOpenHelper helper = new PersonDBOpenHelper(this);
        SQLiteDatabase db = helper.getWritableDatabase();
        resolver = getContentResolver();
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
            Toast.makeText(this,"未允许读取通讯录权限！",Toast.LENGTH_SHORT).show();
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)== PackageManager.PERMISSION_GRANTED)
        {
            Cursor cursor = resolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
                    null,null,null,null);
            String name = ContactsContract.Contacts.DISPLAY_NAME;
            String key = ContactsContract.Contacts.LOOKUP_KEY;
            int displayNameIndex = cursor.getColumnIndex(name);
            int KeyIndex = cursor.getColumnIndex(key);
            for (cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()) {
                String displayName = cursor.getString(displayNameIndex);
                String Key = cursor.getString(KeyIndex);
                String displayPhone = getAllPhoneNumbers(Key);
                values = new ContentValues();
                values.put("name",displayName);
                values.put("phone",displayPhone);
                db.insert("info",null,values);
            }
            cursor.close();
            db.close();
            btnQueryAll(view);
            Toast.makeText(this,"插入成功！",Toast.LENGTH_SHORT).show();

        }
    }

    public void btnAdd(View view) {
        resolver = getContentResolver();
        values = new ContentValues();
        if (et_name.length() != 0 && et_phone.length() != 0){
            values.put("name",et_name.getText().toString());
            values.put("phone",et_phone.getText().toString());
            Uri newUri = resolver.insert(uri,values);
            Toast.makeText(this,"增加成功",Toast.LENGTH_SHORT).show();
            btnQueryAll(view);
        } else {
            et_name.setHint("请在此输入需增加的姓名");
            et_phone.setHint("请在此输入需增加的号码");
        }
    }

    public void btnQuery(View view) {
        resolver = getContentResolver();
        if (et_name.length() != 0){
            Cursor cursor = resolver.query(uri,new String[]{"_id","name","phone"},"name=?",new String[]{et_name.getText().toString()},null);
            if (cursor.getCount() != 0){
                cursor.moveToFirst();
                et_id.setText(cursor.getString(0));
                et_name.setText(cursor.getString(1));
                et_phone.setText(cursor.getString(2));
                cursor.close();
            }
            else {
                Toast.makeText(this,"未查询到结果！",Toast.LENGTH_SHORT).show();
            }
        }
        else {
            et_name.setHint("请在此输入需查询的姓名");
            et_phone.setHint("号码");
        }
    }

    public void btnQueryAll(View view) {
        resolver = getContentResolver();

        List<Map<String,String>> data = new ArrayList<Map<String,String>>();
        Cursor cursor = resolver.query(uri,new String[]{"_id","name","phone"},null,null,null);
        while (cursor.moveToNext()){
            Map<String,String> map = new HashMap<String,String>();
            map.put("_id",cursor.getString(0));
            map.put("name",cursor.getString(1));
            map.put("phone",cursor.getString(2));
            data.add(map);
        }
        cursor.close();
        et_queryAll.setText(new String(data.toString()));
    }

    public void btnUpdate(View view) {
        resolver = getContentResolver();
        values = new ContentValues();
        if (et_name.length() != 0 && et_phone.length() != 0){
            values.put("phone",et_phone.getText().toString());
            int updateCount = resolver.update(uri,values,"name=?",new String[]{et_name.getText().toString()});
            Toast.makeText(this,"成功更新了"   updateCount   "条记录",Toast.LENGTH_SHORT).show();
            btnQueryAll(view);
        } else {
                et_name.setHint("请在此输入需修改的姓名");
                et_phone.setHint("请在此输入修改后的号码");
        }
    }

    public void btnDelete(View view) {
        resolver = getContentResolver();
        if (et_name.length() != 0){
            int deleteCount = resolver.delete(uri,"name=?",new String[]{et_name.getText().toString()});
            Toast.makeText(this,"成功删除了"   deleteCount   "条记录",Toast.LENGTH_SHORT).show();
            btnQueryAll(view);
        } else {
            et_name.setHint("请在此输入需删除的姓名");
            et_phone.setHint("号码");
        }
    }
}

PersionProvider.java

package com.example.test05_contentprovider;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

public class PersonProvider extends ContentProvider {

    private static UriMatcher mUriMatcher = new UriMatcher(-1);

    private static final int SUCCESS = 1;

    private PersonDBOpenHelper helper;

    static {
        mUriMatcher.addURI("com.example.test05_contentprovider.PersonProvider","info",SUCCESS);
    }

    @Override
    public boolean onCreate() {
        helper = new PersonDBOpenHelper(getContext());
        return false;
    }

    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        int code = mUriMatcher.match(uri);
        if (code == SUCCESS) {
            SQLiteDatabase db = helper.getReadableDatabase();
            long rowId = db.insert("info",null,values);
            if (rowId>0) {
                Uri insertedUri = ContentUris.withAppendedId(uri,rowId);

                getContext().getContentResolver().notifyChange(insertedUri,null);
                return insertedUri;
            }
            db.close();
            return uri;
        }else {
            try {
                throw new IllegalAccessException("插入失败，路径不正确！");
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] strings, @Nullable String s, @Nullable String[] strings1, @Nullable String s1) {
        int code = mUriMatcher.match(uri);
        if (code == SUCCESS) {
            SQLiteDatabase db = helper.getReadableDatabase();
            return db.query("info",strings,s,strings1,null,null,s1);
        }else {
            try {
                throw new IllegalAccessException("查询失败，路径不正确！");
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Nullable
    @Override
    public String getType(@NonNull Uri uri) {
        return null;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues contentValues, @Nullable String s, @Nullable String[] strings) {

        int code = mUriMatcher.match(uri);
        if (code == SUCCESS) {
            SQLiteDatabase db = helper.getReadableDatabase();
            int count = db.update("info",contentValues,s,strings);
            if (count>0) {
                getContext().getContentResolver().notifyChange(uri,null);
            }
            db.close();
            return count;
        }else {
            try {
                throw new IllegalAccessException("更新失败，路径不正确！");
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return 0;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String s, @Nullable String[] strings) {
        int code = mUriMatcher.match(uri);
        if (code == SUCCESS) {
            SQLiteDatabase db = helper.getReadableDatabase();
            int count = db.delete("info",s,strings);
            if (count>0) {
                getContext().getContentResolver().notifyChange(uri,null);
            }
            db.close();
            return count;
        }else {
            try {
                throw new IllegalAccessException("删除失败，路径不正确！");
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return code;
    }
}

PersonDBOpenHelper.java

package com.example.test05_contentprovider;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class PersonDBOpenHelper extends SQLiteOpenHelper {

    public PersonDBOpenHelper(Context context) {
        super(context,"person.db",null,1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table info(_id integer primary key autoincrement,name varchar(50),phone varchar(20),UNIQUE(phone))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test05_contentprovider">

    <uses-permission android:name="android.permission.READ_CONTACTS" />
    <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/Theme.Test05_contentprovider">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".ContentActivity" />
        <activity android:name=".SQLActivity" />

        <provider
            android:authorities="com.example.test05_contentprovider.PersonProvider"
            android:name="PersonProvider"
            android:exported="false" />
    </application>

</manifest>

六、最终效果

需要手机或模拟器中的通讯录有内容
学新通
打开应用，点击“访问通讯录”，将会询问读取通讯录权限

允许后，再次点击，成功读取到通讯录姓名及电话号码。

点击“数据库”，点击“插入通讯录数据”，即可把通讯录数据插入到数据库中，同时将所有数据显示。
学新通
在姓名和号码框中输入数据，点击“增加”（id会自动递增，无需输入），添加成功，即可显示出添加后的记录

在姓名框中输入想删除的姓名，点击“删除”，删除成功，即可显示出删除后的结果

学新通
在姓名框中输入需修改的姓名，在号码框中输入修改后的号码，点击“修改”，修改成功，即可显示出修改后的结果

在姓名框中输入姓名，点击“查询”，即可显示id、号码

如果在姓名或号码输入框中没有输入内容，就点击了增加、删除、修改、查询，将会在输入框中显示相应提示信息
学新通

这篇好文章是转载于：学新通技术网