Android11

内容提供者的概念

应用程序创建的数据库默认是私有的,别的应用程序不可以访问里面的数据.
如果有需求把自己应用程序私有的数据库暴露给别的用户增删改查,就需要使用内容提供者.

内容提供者的工作方式

内容提供者BankDBBackdoor

//写一个类继承ContentProvider,重写n个方法public class BankDBBackdoor extends ContentProvider //清单文件中配置 <!-- 注册内容提供者数据 --><provider    android:name="com.itheima.db.BankDBBackdoor"    android:authorities="com.xxx.db" ></provider>//添加数据@Overridepublic Uri insert(Uri uri, ContentValues values) {    System.out.println("insert 添加数据");}

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内容解析者
MainActivity

// 得到内容提供者的解析器public void insert(View view) {         ContentResolver resolver = getContentResolver();    Uri uri = Uri.parse("content://com.xxx.db/account");    ContentValues values = new ContentValues();    values.put("name", "zhangsan");    values.put("money", 10000);    // 通过内容解析器让内容提供者添加一条数据    resolver.insert(uri, values);}

点击MainActivity中的增加insert,可以调用BankDBBackdoor中的insert

内容提供者的匹配规则

内容提供者

public static final int SUCCESS = 1;/** * 创建一个保安,检查uri的规则,如果uri匹配失败 返回-1 */static UriMatcher mUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);static {    mUriMatcher.addURI("com.itheima.db", "account", SUCCESS);}@Overridepublic Uri insert(Uri uri, ContentValues values) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {}else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }    return null;}

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内容解析者

public void insert(View view) {    Uri uri = Uri.parse("content://com.xxx.db/account");}

内容提供者的业务实现

内容提供者

@Overridepublic Uri insert(Uri uri, ContentValues values) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {        System.out.println("insert 添加数据");        MyDBOpenHelper helper = new MyDBOpenHelper(getContext());        SQLiteDatabase db = helper.getWritableDatabase();        db.insert("account", null, values);        //利用内容提供者的解析器,通知内容观察者数据发生了变化        getContext().getContentResolver().notifyChange(uri, null);    }else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }    return null;}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {        System.out.println("delete 删除数据");        MyDBOpenHelper helper = new MyDBOpenHelper(getContext());        SQLiteDatabase db = helper.getWritableDatabase();        db.delete("account",selection , selectionArgs);        //利用内容提供者的解析器,通知内容观察者数据发生了变化        getContext().getContentResolver().notifyChange(uri, null);    }else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }    return 0;}@Overridepublic int update(Uri uri, ContentValues values, String selection,        String[] selectionArgs) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {        System.out.println("update 更新数据");        MyDBOpenHelper helper = new MyDBOpenHelper(getContext());        SQLiteDatabase db = helper.getWritableDatabase();        db.update("account", values, selection, selectionArgs);        //利用内容提供者的解析器,通知内容观察者数据发生了变化        getContext().getContentResolver().notifyChange(uri, null);    }else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }    return 0;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection,        String[] selectionArgs, String sortOrder) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {        System.out.println("query 查询数据");        MyDBOpenHelper helper = new MyDBOpenHelper(getContext());        SQLiteDatabase db = helper.getReadableDatabase();        return db.query("account", projection, selection, selectionArgs, null, null, sortOrder);    }else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }}

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内容解析者

public void insert(View view) {    // 得到内容提供者的解析器    ContentResolver resolver = getContentResolver();    Uri uri = Uri.parse("content://com.itheima.db/account");    ContentValues values = new ContentValues();    values.put("name", "zhangsan");    values.put("money", 10000);    // 通过内容解析器让内容提供者添加一条数据    resolver.insert(uri, values);}public void delete(View view) {    ContentResolver resolver = getContentResolver();    Uri uri = Uri.parse("content://com.itheima.db/account");    resolver.delete(uri, "name=?", new String[]{"zhangsan"});}public void update(View view) {    ContentResolver resolver = getContentResolver();    Uri uri = Uri.parse("content://com.itheima.db/account");    ContentValues values = new ContentValues();    values.put("money", 20000);    resolver.update(uri, values, "name=?", new String[]{"zhangsan"});}public void query(View view) {    ContentResolver resolver = getContentResolver();    Uri uri = Uri.parse("content://com.itheima.db/account");    Cursor cursor = resolver.query(uri, new String[]{"name","money"}, null, null, null);    while(cursor.moveToNext()){        String name = cursor.getString(0);        float money = cursor.getFloat(1);        System.out.println("name:"+name+"----"+"money:"+money);    }    cursor.close();}

学习内容提供者的目的

• 主要学习系统的短信,联系人内容提供者

利用内容提供者添加删除用户的短信数据

//需要找到系统短信providers提供者的清单文件//TelephonyProvider<provider android:name="SmsProvider"    android:authorities="sms"    android:multiprocess="true"    android:readPermission="android.permission.READ_SMS"    android:writePermission="android.permission.WRITE_SMS" />//要主机名sms//对数据的操作自己的com.android.providers.telephony下的//database中的mmssms.db数据库的字段//利用内容提供者添加短信public void add(View view){    Uri uri = Uri.parse("content://sms");//全部的短信     ContentResolver resolver = getContentResolver();    ContentValues values = new ContentValues();    values.put("address", "110");    values.put("date", System.currentTimeMillis());    values.put("type", 1);    values.put("body", "恭喜您被评为见义勇为好市民,敢于扶老太太");    resolver.insert(uri, values);}//利用内容提供者删除短信public void delete(View view){    Uri uri = Uri.parse("content://sms");//全部的短信     ContentResolver resolver = getContentResolver();    resolver.delete(uri, "address=?", new String[]{"110"});}

• 需要权限短信的读写

  android:readPermission=”android.permission.READ_SMS”
  android:writePermission=”android.permission.WRITE_SMS”

小知识点-通知栏的提醒

高版本安卓4.0以上

//当点击按钮的时候 界面上显示一个通知public void click(View view){    NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);//系统服务    Notification notification = new Notification.Builder(this)    .setContentTitle("我是标题")    .setContentText("我是文本")    .setSmallIcon(R.drawable.ic_launcher)    .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher))    .build();    //显示一个通知    nm.notify(0, notification); }

低版本安卓4.0以下

//当点击按钮的时候 界面上显示一个通知public void click(View view){    NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);    Notification notification = new Notification(R.drawable.ic_launcher, "有新的消息到来了", System.currentTimeMillis());//过时的方法    Intent intent = new Intent();    intent.setAction(Intent.ACTION_CALL);    intent.setData(Uri.parse("tel://110"));    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent, 0);//延时通信    //设置通知的点击事件    notification.setLatestEventInfo(this, "我是标题", "我是文本", contentIntent);    nm.notify(0, notification);  }

需要权限打电话

<!-- 拨打电话 --><uses-permission android:name="android.permission.CALL_PHONE" />

装B神器

public void click(View view) {    new Thread() {        public void run() {            SystemClock.sleep(10000);            Uri uri = Uri.parse("content://sms");// 全部的短信            ContentResolver resolver = getContentResolver();            ContentValues values = new ContentValues();            values.put("address", "95533");            values.put("date", System.currentTimeMillis());            values.put("type", 1);            values.put("body",                    "尊敬的张先生:您的账户收到转账汇款30,000,002.34, 活期余额 60,333,002.57");            resolver.insert(uri, values);            NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);            Notification notification = new Notification(                    R.drawable.ic_launcher,                    "尊敬的张先生:您的账户收到转账汇款30,000,002.34, 活期余额 60,333,002.57",                    System.currentTimeMillis());            Intent intent = new Intent();            intent.setAction("android.intent.action.MAIN");            intent.addCategory("android.intent.category.DEFAULT");            intent.setType("vnd.android.cursor.dir/mms");            PendingIntent contentIntent = PendingIntent.getActivity(MainActivity.this,                    0, intent, 0);            // 设置通知的点击事件            notification.setLatestEventInfo(MainActivity.this, "95533", "尊敬的张先生:您的账户收到转账汇款30,000,002.34, 活期余额 60,333,002.57",                    contentIntent);            notification.defaults = Notification.DEFAULT_SOUND;            nm.notify(0, notification);        };    }.start();  }

联系人数据库的表结构

• raw_contact表:联系人的id表.

  contact_id列保存联系人的id

• data表:联系人的数据表.

  raw_contact_id表示属于哪个联系人

  data1 具体的数据

  mimetype_id 数据的类型

• mimetype表:联系人数据类型表

• 步骤

  1. 查询raw_contact表 获取联系人的contact_id
  2. 根据contact_id查询data表,获取联系人的数据
  3. 根据mimetype确定数据的类型

利用内容提供者读取联系人

• 代码

  public void readContacts(View view){    ContentResolver resolver = getContentResolver();    //查询raw_contact表    Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");    Uri datauri = Uri.parse("content://com.android.contacts/data");    Cursor cursor = resolver.query(uri, new String[]{"contact_id"}, null, null, null);    while(cursor.moveToNext()){        String id = cursor.getString(0);        System.out.println("Id:"+id);        //查询data表        Cursor datacursor = resolver.query(datauri, new String[]{"data1","mimetype"},            "raw_contact_id=?", new String[]{id}, null);        while(datacursor.moveToNext()){            String data1 = datacursor.getString(0);            System.out.println("data1:"+data1);            String mimetype = datacursor.getString(1);            System.out.println("mimetype:"+mimetype);        }        datacursor.close();        System.out.println("------------");    }    cursor.close();     }}

*权限注意

<!-- 读取联系人的权限 --><uses-permission android:name="android.permission.READ_CONTACTS"/>

联系人内容提供者的工具类

public class ContactInfoUtils {    public static List<ContactInfo> getAllContactInfos(Context context) {        List<ContactInfo> infos = new ArrayList<ContactInfo>();        ContentResolver resolver = context.getContentResolver();        // 查询raw_contact表        Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");        Uri datauri = Uri.parse("content://com.android.contacts/data");        Cursor cursor = resolver.query(uri, new String[] { "contact_id" },                null, null, null);        while (cursor.moveToNext()) {            String id = cursor.getString(0);            System.out.println("Id:" + id);            if (id != null) {                ContactInfo info = new ContactInfo();                // 查询data表                Cursor datacursor = resolver.query(datauri, new String[] {                        "data1", "mimetype" }, "raw_contact_id=?",                        new String[] { id }, null);                while (datacursor.moveToNext()) {                    String data1 = datacursor.getString(0);                    String mimetype = datacursor.getString(1);                    if ("vnd.android.cursor.item/name".equals(mimetype)) {                        info.setName(data1);                    } else if ("vnd.android.cursor.item/im".equals(mimetype)) {                        info.setQq(data1);                    } else if ("vnd.android.cursor.item/email_v2"                            .equals(mimetype)) {                        info.setEmail(data1);                    } else if ("vnd.android.cursor.item/phone_v2"                            .equals(mimetype)) {                        info.setPhone(data1);                    }                }                datacursor.close();                infos.add(info);            }        }        cursor.close();        return infos;    }}

删除联系人的细节

删除数据,不是将数据直接删除,而是将数据的id设置为空.

对id的非空判断,数据同步服务器时,只用判断id是null.

String id = cursor.getString(0);//避免空指针异常if (id != null) {}

添加数据到联系人数据库

public void save(View view) {    String name = et_name.getText().toString().trim();    String phone = et_phone.getText().toString().trim();    String email = et_email.getText().toString().trim();    Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");    Uri datauri = Uri.parse("content://com.android.contacts/data");    Cursor cursor = getContentResolver().query(uri, new String[] { "_id" },            null, null, "_id desc");    cursor.moveToFirst();    int _id = cursor.getInt(0);    int newId = _id + 1;    ContentValues values = new ContentValues();    values.put("contact_id", newId);    getContentResolver().insert(uri, values);    // 在data表里面添加数据.    // 1.添加name    ContentValues nameValue = new ContentValues();    nameValue.put("raw_contact_id", newId);    nameValue.put("data1", name);    nameValue.put("mimetype", "vnd.android.cursor.item/name");    getContentResolver().insert(datauri, nameValue);    // 2.添加email    ContentValues emailValue = new ContentValues();    emailValue.put("raw_contact_id", newId);    emailValue.put("data1", email);    emailValue.put("mimetype", "vnd.android.cursor.item/email_v2");    getContentResolver().insert(datauri, emailValue);    // 3.添加phone    ContentValues phoneValue = new ContentValues();    phoneValue.put("raw_contact_id", newId);    phoneValue.put("data1", phone);    phoneValue.put("mimetype", "vnd.android.cursor.item/phone_v2");    getContentResolver().insert(datauri, phoneValue);    Toast.makeText(this, "添加数据成功", 0).show();}

权限

<!-- 读取联系人 写入联系人 --><uses-permission android:name="android.permission.READ_CONTACTS"/><uses-permission android:name="android.permission.WRITE_CONTACTS"/>

内容观察者

意思是在,银行中安排个双重间谍,即是行长的内容提供者,也是检证会的内容提供者,检证会知道行长操作了银行数据的增删改,查询不需要.

利用内容观察者观察短信数据库的变化

在内容提供者的增删改中添加public int delete(Uri uri, String selection, String[] selectionArgs) {    int code = mUriMatcher.match(uri);    if (code == SUCCESS) {        //利用内容提供者的解析器,通知内容观察者数据发生了变化        getContext().getContentResolver().notifyChange(uri, null);    }else{        throw new IllegalArgumentException("口令 不正确,滚犊子");    }    return 0;}----------------------------------------------------------@Overrideprotected void onCreate(Bundle savedInstanceState) {    //注册内容观察者     Uri uri = Uri.parse("content://com.itheima.db/account");    getContentResolver().registerContentObserver(uri, true, new ContentObserver(new Handler()) {        @Override        public void onChange(boolean selfChange) {            System.out.println("我是观察者,我发现银行的数据库变化了.");            super.onChange(selfChange);        }       });}

练习_利用内容提供者开发短信的备份和还原

public class MainActivity extends Activity {    private MyObserver observer;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Uri uri = Uri.parse("content://sms");        observer = new MyObserver(new Handler());        getContentResolver().registerContentObserver(uri, true, observer);    }    private class MyObserver extends ContentObserver{        public MyObserver(Handler handler) {            super(handler);        }        @Override        public void onChange(boolean selfChange) {            super.onChange(selfChange);            System.out.println("onchange");        }    }}