ContentProvider使用示例

1、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() {

}

/**

* 通过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: 删除成功");

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 {

/**

* 库名

private static final StringDBNAME ="provider.db";

/**

* 表明测试用

public static final StringTABLE_NAME ="provider_data";

/**

* 版本号

private static final int VERSION =1;

/**

* 建表的sql语句

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、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", "水货");

getContentResolver().insert(nameUri, contentValues);

}

private void toDelete() {

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

}

private void toUpdate() {

ContentValues contentValues =new ContentValues();

contentValues.put("name", "太阳");

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: 查询成功");

nameCursor.close();

}

4、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"