The technical principles of Android supported the SQLite framework in the Java class library
The technical principles of Android support the implementation of the SQLite framework in the Java class library
Android is an open source operating system based on Linux, which is widely used for mobile devices.In Android application development, SQLite is a lightweight embedded database that is widely used in storage and retrieval application data.Android developers support the SQLite database through Android support the SQLite framework in the Java library.This article will introduce the technical principles of Android to support the SQLite framework and provide the corresponding Java code example.
Technical principle:
Android supports the implementation of the following key principles:
1. SQLite database engine: SQLite is a self -contained, zero -configuration, independent database engine.Android has built -in SQLite database engine, which is embedded in the Android operating system and can be used directly in the application without being installed and configured separately.
2. SQLite database file: Each Android application can have one or more SQLite database files.These database files are stored on the device's local storage in the form of files.Each database file contains multiple tables, and each table consists of rows and columns.
3. AndroidProvider: ContentProvider is a data access layer provided by Android.It allows to share data between programs and provide operations such as adding, deletion, modification, and other operations.ContentProvider can encapsulate the SQLite database and provide standard interfaces for other applications to access.
4. SQLiteOpenhelper: SQLiteOpenhelper is an auxiliary class that is used to manage the creation and version control of the database.Each SQLite database requires a SQLiteOpenhelper object to handle the creation and update operation of the database.Developers can inherit the SQLiteOpenhelper class and realize the custom operation of the database.
5. SQL statement: In Android support the SQLite framework, developers can use the SQL statement to add, delete and modify the operation.Common SQL statements include Create Table, Insert Into, UPDATE (Update Data), and Select (Query Data).
Java code example:
Below is a simple Java code example. It demonstrates how to use Android to support the SQLite framework to create a database and insert a data into the table:
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MyDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "my_database";
private static final int DATABASE_VERSION = 1;
private static final String TABLE_NAME = "my_table";
private static final String COLUMN_NAME = "data";
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTableQuery = "CREATE TABLE " + TABLE_NAME + " (" +
COLUMN_NAME + " TEXT)";
db.execSQL(createTableQuery);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Perform the corresponding operation when the database version is upgraded
}
public void insertData(String data) {
SQLiteDatabase db = getWritableDatabase();
String insertQuery = "INSERT INTO " + TABLE_NAME + " (" +
COLUMN_NAME + ") VALUES ('" + data + "')";
db.execSQL(insertQuery);
db.close();
}
}
In the above example, we customize a auxiliary MyDataBasehelper inherited from SQLiteopenhelper.In the OnCreate method, we used the SQL statement to create a table called My_table.In the INSERTDATA method, we inserted a data into the table using the SQL statement.
Summarize:
Android supports the SQLite framework in the form of a Java class library to provide the operation and management function of the SQLite database.Through SQLiteOpenhelper, SQLiteDataBase, and SQL statements, developers can easily create and manage databases, and conduct data addition, deletion, modification and investigation.For the data storage and management needs of Android applications, Android supports the SQLite framework is a feature -rich and easy to use option.
