【Java 转 Android】33，高级 Android 开发面试解答之线程篇

public Uri insert(Uri uri, ContentValues values) {

// 添加数据

SQLiteDatabase db = dbHelpe

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r.getWritableDatabase();

Uri uriReturn = null;

switch (uriMatcher.match(uri)) {

case BOOK_DIR:

case BOOK_ITEM:

long newBookId = db.insert("Book", null, values);

uriReturn = Uri.parse("content://" + AUTHORITY + "/book/" + newBookId);

break;

case CATEGORY_DIR:

case CATEGORY_ITEM:

long newCategoryId = db.insert("Category", null, values);

uriReturn = Uri.parse("content://" + AUTHORITY + "/category/" + newCategoryId);

break;

default:

break;

}

return uriReturn;

}

@Override

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

// 更新数据

SQLiteDatabase db = dbHelper.getWritableDatabase();

int updatedRows = 0;

switch (uriMatcher.match(uri)) {

case BOOK_DIR:

updatedRows = db.update("Book", values, selection, selectionArgs);

break;

case BOOK_ITEM:

String bookId = uri.getPathSegments().get(1);

updatedRows = db.update("Book", values, "id = ?", new String[] { bookId });

break;

case CATEGORY_DIR:

updatedRows = db.update("Category", values, selection, selectionArgs);

break;

case CATEGORY_ITEM:

String categoryId = uri.getPathSegments().get(1);

updatedRows = db.update("Category", values, "id = ?", new String[] { categoryId });

break;

default:

break;

}

return updatedRows;

}

@Override

public int delete(Uri uri, String selection, String[] selectionArgs) {

// 删除数据

SQLiteDatabase db = dbHelper.getWritableDatabase();

int deletedRows = 0;

switch (uriMatcher.match(uri)) {

case BOOK_DIR:

deletedRows = db.delete("Book", selection, selectionArgs);

break;

case BOOK_ITEM:

String bookId = uri.getPathSegments().get(1);

deletedRows = db.delete("Book", "id = ?", new String[] { bookId });

break;

case CATEGORY_DIR:

deletedRows = db.delete("Category", selection, selectionArgs);

break;

case CATEGORY_ITEM:

String categoryId = uri.getPathSegments().get(1);

deletedRows = db.delete("Category", "id = ?", new String[] { categoryId });

break;

default:

break;

}

return deletedRows;

}

@Override

public String getType(Uri uri) {

switch (uriMatcher.match(uri)) {

case BOOK_DIR:

return "vnd.android.cursor.dir/vnd.com.example.databasetest. provider.book";

case BOOK_ITEM:

return "vnd.android.cursor.item/vnd.com.example.databasetest. provider.book";

case CATEGORY_DIR:

return "vnd.android.cursor.dir/vnd.com.example.databasetest. provider.category";

case CATEGORY_ITEM:

return "vnd.android.cursor.item/vnd.com.example.databasetest. provider.category";

}

return null;

}

}

public class MyDatabaseHelper extends SQLiteOpenHelper {

public static final String CREATE_BOOK = "create table Book ("

• "id integer primary key autoincrement, "

• "author text, "

• "price real, "

• "pages integer, "

• "name text)";

public static final String CREATE_CATEGORY = "create table Category ("

• "id integer primary key autoincrement, "

• "category_name text, "

• "category_code integer)";

private Context mContext;

public MyDatabaseHelper(Context context, String name,

SQLiteDatabase.CursorFactory factory, int version) {

super(context, name, factory, version);

mContext = context;

}

@Override

public void onCreate(SQLiteDatabase db) {

db.execSQL(CREATE_BOOK);

db.execSQL(CREATE_CATEGORY);

// Toast.makeText(mContext, "Create succeeded", Toast.LENGTH_SHORT).show();

}

@Override

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

db.execSQL("drop table if exists Book");

db.execSQL("drop table if exists Category");

onCreate(db);

}

}

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

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.databasetest">

<application

android:allowBackup="true"

android:icon="@mipmap/ic_launcher"

android:label="@string/app_name"

android:supportsRtl="true"

android:theme="@style/AppTheme">

<activity android:name=".MainActivity">

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<provider

android:name=".DatabaseProvider"

android:authorities="com.example.databasetest.provider"

android:enabled="true"

android:exported="true" />

</application>

</manifest>

Provider 项目，访问 Database 项目的数据

public class MainActivity extends AppCompatActivity {

private String newId;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

Button addData = (Button) findViewById(R.id.add_data);

addData.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

// 添加数据

Uri uri = Uri.parse("content://com.example.databasetest.provider/book");