ContentProvider使用示例

1赴蝇、MyContentProvider

public class MyContentProviderextends ContentProvider {

private static final StringTAG ="MyContentProvider";

? ? private Contextcontext;

? ? private SQLiteDatabasesqLiteDatabase;

? ? public static final StringAUTHORITY ="com.examp.mycontentprovider.MyContentProvider";

? ? public static final int PROVIDER_CODE =0;

? ? private static final UriMatcheruriMatcher =new UriMatcher(UriMatcher.NO_MATCH);

? ? static {

????????????uriMatcher.addURI(AUTHORITY, MyDBHelper.TABLE_NAME, PROVIDER_CODE);

? ? }

????public MyContentProvider() {

????}

????/**

????* 通過uri匹配表名

????*

? ? * @param uri

? ? * @return

? ? */

? ? private StringgetTableName(Uri uri) {

????????String tableName =null;

? ? ? ? switch (uriMatcher.match(uri)) {

????????????????case PROVIDER_CODE:

????????????????tableName = MyDBHelper.TABLE_NAME;

????????????????break;

? ? ? ? }

????????return tableName;

? ? }

@Override

? ? public boolean onCreate() {

????????????init();

????return false;

? ? }

????private void init() {

????????context = getContext();

? ? ? ? sqLiteDatabase =new MyDBHelper(context).getWritableDatabase();

? ? }

@Nullable

@Override

? ? public Cursorquery(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {

????????String tableName = getTableName(uri);

? ? ? ? if (tableName ==null) {

????????????Log.e(TAG, "query: 未匹配到uri");

? ? ? ? ? ? throw new IllegalArgumentException("Unsupported URI:" + uri);

? ? ? ? }

????????return sqLiteDatabase.query(tableName, projection, selection, selectionArgs, null, null, ????????????sortOrder, null);

? ? }

@Nullable

@Override

? ? public StringgetType(@NonNull Uri uri) {

????????return null;

? ? }

????@Nullable

????@Override

? ? public Uriinsert(@NonNull Uri uri, @Nullable ContentValues values) {

????????????String tableName = getTableName(uri);

? ? ? ????? if (tableName ==null) {

????????????Log.e(TAG, "insert: 未匹配到uri");

? ? ? ? ? ? throw new IllegalArgumentException("Unsupported URI:" + uri);

? ? ? ? ????}

????????????sqLiteDatabase.insert(tableName, null, values);

? ? ? ????? context.getContentResolver().notifyChange(uri, null);

? ? ? ????? Log.d(TAG, "insert: 添加成功");

? ? ? ? ????return uri;

? ? }

????@Override

? ? public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {

????????????String tableName = getTableName(uri);

? ? ? ????? if (tableName ==null) {

????????????Log.e(TAG, "delete: 未匹配到uri");

? ? ? ? ? ? throw new IllegalArgumentException("Unsupported URI:" + uri);

? ? ? ? ????}

????????????int count =sqLiteDatabase.delete(tableName, selection, selectionArgs);

? ? ? ????? if (count >0) {

????????????context.getContentResolver().notifyChange(uri, null);

? ? ? ? }

????????????Log.d(TAG, "delete: 刪除成功");

? ? ? ? ????Log.d(TAG, "delete: count=" + count);

? ? ? ? return count;

? ? }

????@Override

? ? public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {

????????????String tableName = getTableName(uri);

? ? ? ????? if (tableName ==null) {

????????????????throw new IllegalArgumentException("Unsupported URI:" + uri);

? ? ? ? ????}

????????????int row =sqLiteDatabase.update(tableName, values, selection, selectionArgs);

? ? ? ????? if (row >0) {

????????????????context.getContentResolver().notifyChange(uri, null);

? ? ? ? }

????????return row;

? ? }

}

2、MyDBHelper

public class MyDBHelperextends SQLiteOpenHelper {

/**

* 庫名

? ? private static final StringDBNAME ="provider.db";

? ? /**

* 表明測試用

? ? public static final StringTABLE_NAME ="provider_data";

? ? /**

* 版本號

? ? private static final int VERSION =1;

? ? /**

????* 建表的sql語句

????*/

? ? private static final StringSQL ="create table " +TABLE_NAME +"(id integer primary key Autoincrement,name text)";

? ? private Contextcontext;

? ? public MyDBHelper(Context context) {

????????super(context, DBNAME, null, VERSION);

? ? ? ? this.context = context;

? ? }

@Override

? ? public void onCreate(SQLiteDatabase db) {

????????db.execSQL(SQL);

? ? ? ? Toast.makeText(context, "建表成功", Toast.LENGTH_SHORT).show();

? ? ? ? Log.d("MyContentProvider", "onCreate: 建表成功");

? ? }

????@Override

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

????}

}

3膘掰、在MainActivity中使用

public class MainActivityextends AppCompatActivityimplements View.OnClickListener {

private static final StringTAG ="MyContentProvider";

? ? @Override

? ? protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

? ? ? ? setContentView(R.layout.activity_main);

? ? ? ? initView();

? ? }

private void initView() {

????????Button bt_init = findViewById(R.id.bt_init);

? ? ? ? bt_init.setOnClickListener(this);

? ? ? ? Button bt_add = findViewById(R.id.bt_add);

? ? ? ? bt_add.setOnClickListener(this);

? ? ? ? Button bt_delete = findViewById(R.id.bt_delete);

? ? ? ? bt_delete.setOnClickListener(this);

? ? ? ? Button bt_update = findViewById(R.id.bt_update);

? ? ? ? bt_update.setOnClickListener(this);

? ? ? ? Button bt_query = findViewById(R.id.bt_query);

? ? ? ? bt_query.setOnClickListener(this);

? ? }

@Override

? ? public void onClick(View v) {

????????switch (v.getId()) {

????????????case R.id.bt_init:

????????????????????init();

????????????????break;

? ? ? ? ? ? case R.id.bt_add:

????????????????????toAdd();

????????????????break;

? ? ? ? ? ? case R.id.bt_delete:

????????????????toDelete();

????????????????break;

? ? ? ? ? ? case R.id.bt_update:

????????????????toUpdate();

????????????break;

? ? ? ? ? ? case R.id.bt_query:

????????????????toQuery();

????????????break;

? ? ? ? }

}

????private void init() {

????????getContentResolver().delete(nameUri, null, null);

? ? }

????private UrinameUri = Uri.parse("content://com.examp.mycontentprovider.MyContentProvider/provider_data");

? ? private void toAdd() {

????????ContentValues contentValues =new ContentValues();

? ? ? ? contentValues.put("name", "水貨");

? ? ? ? getContentResolver().insert(nameUri, contentValues);

? ? }

????private void toDelete() {

????????????getContentResolver().delete(nameUri, "name=?", new String[]{"水貨"});

? ? }

????private void toUpdate() {

????????ContentValues contentValues =new ContentValues();

? ? ? ? contentValues.put("name", "太陽");

? ? ? ? getContentResolver().update(nameUri, contentValues, "id=?", new String[]{"21"});

? ? }

private void toQuery() {

????????????Cursor nameCursor = getContentResolver().query(nameUri, new String[]{"id", "name"}, null, null, null);

? ? ? ? ????if (nameCursor !=null) {

????????????????while (nameCursor.moveToNext()) {

????????????????Log.e(TAG, "id:" + nameCursor.getInt(nameCursor.getColumnIndex("id"))

????????????????+" name:" + nameCursor.getString(nameCursor.getColumnIndex("name")));

? ? ? ? ? ? }

????????????????Log.d(TAG, "toQuery: 查詢成功");

? ? ? ? ? ????? nameCursor.close();

? ? ? ? }

????}

}

4识埋、activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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:gravity="center_horizontal"

? ? android:orientation="vertical"

? ? tools:context=".MainActivity">

? ? ? ? android:id="@+id/bt_init"