安卓內容提供器Content Provider

1.功能

用來實現跨程序數據共享的功能,如電話,短信,媒體庫什麼的都要給其它的程序共享數據,內容提供器可以選擇一部分數據進行共享,保證我們的隱私數據

2.運行時權限

android6.0加入的,下面列舉需要申請的危險權限

1.CALENDER(日曆) : READ_CALENDAR WRITE_CALENDAR

2.CAMERA (相機) : CAMERA

3.CONTANTS (內容): READ_CONTANTS , WRITE_CONTANTS , GET_ACCOUNTS

4.LOCATION(位置): ACCESS_FINE_LOCATION , ACCESS_COARSE_LOCATION

5.MICROPHONE(麥克風): RECORD_AUDIO

6.PHONE(電話):READ_PHONE_STATE , CALL_PHONE , READ_CALL_LOG , WRITE_CALL_LOG , ADD_VOICEMAIL , USE_SIP , PROCESS_OUTGOING_CALLS

7.SENSORS(傳感器) : BODY_SENSORS

8.SMS(短信) : SEND_SMS , RECEIVE_SMS , READ_SMS , RECEIVE_WAP_PUSH , RECEIVE_MMS

9.STORAGE(存儲) : READ_EXTERNAL_STORAGE , WRITE_EXTERNAL_STORAGE

以下是我自己改進的申請權限的模板

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

在開頭新建一個List用來存儲沒有申請到的權限

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

要申請什麼權限就在String[] 裏面寫好

call.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String[] permissions = new String[]{Manifest.permission.CALL_PHONE};
                initPermission(permissions);
                call();
            }
        });

      private void initPermission(String[] permissions) {

        notpermissed.clear();
        for (int i=0;i<permissions.length;i++){
            if (ContextCompat.checkSelfPermission(this,permissions[i]) != PackageManager.PERMISSION_GRANTED){
                notpermissed.add(permissions[i]);
            }
        }

        if (notpermissed.size()>0){
            ActivityCompat.requestPermissions(this,permissions,1);
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        boolean permissed = false;
        if (requestCode == 1){
            for (int i=0;i<permissions.length;i++){
                if (grantResults[i] == -1){
                    permissed = true;
                }
            }

            if (permissed){
                Toast.makeText(this, "權限未通過", Toast.LENGTH_SHORT).show();
            }else {
                Toast.makeText(this, "權限通過", Toast.LENGTH_SHORT).show();
            }

        }
    }

3.訪問其他程序中的數據

增刪改查都是使用一個Uri參數代替,被稱爲內容URI,通常寫法爲content://com.example.app.provider/table1

然後 Uri uri = Uri.parse(“content://com.example.app.provider/table1”);

Cursor cursor = getContentResolver().query(

  uri,

projection,

selection,

selectionArgs,

sortOrder);

將數據從Cursor對象中提取出來

if(cursor !=null){
while(cursor.moveToNext()){
String column1 = cursor.getString(cursor.getColumnIndex("column1"));
int column2 = cursor.getInt(cursor.getColumnIndex("column2"));
}
cursor.close();
}

向table1表中添加數據

ContentValues values = new ContentValues();
values.put("column1","text");
values.put("column2",1);
getContentResolver().insert(uri,values);

更新

ContentValues values = new ContentValues();
values.put("column1","text");
getContentResolver().update(uri,values,"column1=? and column2 = ?",new String[]{"text","1"});

刪除

getContentResolver().delete(uri,"column2=?",new String[]{"1"});

舉例:讀取電話簿裏的聯繫人:

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

List<String> list = new ArrayList<>();
    ArrayAdapter<String> adapter;

ListView listView = findViewById(R.id.list);
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
        listView.setAdapter(adapter);

call.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String[] permissions = new String[]{Manifest.permission.READ_CONTACTS};
                initPermission(permissions);
                readcontent();
            }
        });

裏面傳入的Uri是做好封裝之後的

private void readcontent() {
        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));
                    list.add(displayname + "\n" + number);
                }
            }
            adapter.notifyDataSetChanged();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (cursor!=null)
            cursor.close();
        }
    }

創建內容提供器

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;
import android.widget.Switch;

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

public class MyProvider extends ContentProvider {
    public static final int TABLE1_DIR = 0;
    public static final int TABLE1_ITEM = 1;
    public static final int TABLE2_DIR = 2;
    public static final int TABLE2_ITEM = 3;
    private static UriMatcher uriMatcher;

    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI("com.example.app.provider","table1",TABLE1_DIR);
        uriMatcher.addURI("com.example.app.provider","table1/#",TABLE1_ITEM);
        uriMatcher.addURI("com.example.app.provider","table2",TABLE2_DIR);
        uriMatcher.addURI("com.example.app.provider","table2/#",TABLE2_ITEM);
    }


    //初始化內容提供器的時候調用
    @Override
    public boolean onCreate() {
        return false;
    }

    //從內容提供器中查詢數據
    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {
        switch (uriMatcher.match(uri)){
            case TABLE1_DIR:
                //查詢table1的數據
                break;
            case TABLE1_ITEM:
                //查詢table1單條數據
                break;
            case TABLE2_DIR:
                break;
            case TABLE2_ITEM:
                break;
        }
        return null;
    }


    @Nullable
    @Override
    public String getType(@NonNull Uri uri) {
        switch (uriMatcher.match(uri)){
            case TABLE1_DIR:
                return "vnd.android.cursor.dir/vnd.com.example.app.provider.table1";
            case TABLE1_ITEM:
                return "vnd.android.cursor.item/vnd.com.example.app.provider.table1";
            case TABLE2_DIR:
                return "vnd.android.cursor.dir/vnd.com.example.app.provider.table2";
            case TABLE2_ITEM:
                return "vnd.android.cursor.item/vnd.com.example.app.provider.table2";
            default:
                break;
        }
        return null;
    }


    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        return null;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {
        return 0;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {
        return 0;
    }
}