Android中Sqlite数据库的应用

Android中Sqlite数据库的使用
依照习惯还是通过一个例子来熟悉,我只所以都把例子写在这里方便我以后查找使用,也可以共享给大家学习,如果大家有什么好的网址和Demo也可以告诉我,谢谢!共同进步！！！
DatabaseActivity.java启动类:

package com.example.Database;import android.app.Activity;import android.database.Cursor;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.Toast;public class DatabaseActivity extends Activity implementsButton.OnClickListener {DBAdapter db_ex;long id;/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);// 通过此类来进行数据库的相关操作db_ex = new DBAdapter(this, Constants.DB_NAME, Constants.DB_VERSION);Button add_btn = (Button) findViewById(R.id.Button01);Button cancel_btn = (Button) findViewById(R.id.Button02);Button update_btn = (Button) findViewById(R.id.Button03);Button check_btn = (Button) findViewById(R.id.Button04);add_btn.setOnClickListener(this);cancel_btn.setOnClickListener(this);update_btn.setOnClickListener(this);check_btn.setOnClickListener(this);}public void onClick(View v) {switch (v.getId()) {case R.id.Button01:// ---add 2 titles---// 每次操作数据库都要调用此函数open()db_ex.open();id = db_ex.insertTitle("1111111", "Android book", "Jim");id = db_ex.insertTitle("2222222", "Iphone book", "Edison");// ---获取所有标题---Cursor c = db_ex.getAllTitles();if (c.moveToFirst()) {do {DisplayTitle(c);} while (c.moveToNext());}db_ex.close();break;case R.id.Button02:// 删除一行数据db_ex.open();if (db_ex.deleteTitle(1)) {Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG).show();} else {Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show();}db_ex.close();break;case R.id.Button03:// 更新一条数据db_ex.open();if (db_ex.updateTitle(1, "1234567", "Programmer's Reference","Wrox Press")) {Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG).show();}else {Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show();}// 将更新后的数据显示出来Cursor c1 = db_ex.getTitle(1);if (c1.moveToFirst()) {DisplayTitle(c1);} else {Toast.makeText(this, "No title found", Toast.LENGTH_LONG).show();}db_ex.close();break;case R.id.Button04:// 检索一条特定的数据db_ex.open();Cursor c2 = db_ex.getTitle(2);if (c2.moveToFirst()) {DisplayTitle(c2);} else {Toast.makeText(this, "No title found", Toast.LENGTH_LONG).show();}db_ex.close();break;default:break;}}// 显示数据库中的所有数据public void DisplayTitle(Cursor c) {Toast.makeText(this,"id: " + c.getString(0) + "\n" + "ISBN: " + c.getString(1)+ "\n" + "TITLE: " + c.getString(2) + "\n"+ "PUBLISHER: " + c.getString(3), Toast.LENGTH_LONG).show();}}

2. DatabaseHelper.java这个类管理数据库的创建和版本管理

package com.example.Database;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.util.Log;//A helper class to manage database creation and version managementpublic class DatabaseHelper extends SQLiteOpenHelper {private static final String TAG = "DBAdapter";public DatabaseHelper(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);}@Override// 只有在第一次创建数据库的时候调用// Called when the database is created for the first timepublic void onCreate(SQLiteDatabase db) {// Execute a single SQL statement that is not a querydb.execSQL(Constants.DATABASE_CREATE);Log.i("", "execSQL");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {Log.w(TAG, "Upgrading database from version " + oldVersion + " to "+ newVersion + ", which will destroy all old data");db.execSQL("DROP TABLE IF EXISTS titles");onCreate(db);}}

3. DBAdapter.java是对数据库的增,删,改,查的操作都在这个类里面

package com.example.Database;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.SQLException;import android.database.sqlite.SQLiteDatabase;import android.util.Log;public class DBAdapter {DatabaseHelper DBHelper;SQLiteDatabase db;public DBAdapter(Context ctx, String base_name, int version) {DBHelper = new DatabaseHelper(ctx, base_name, null, version);}// 创建或打开一个读写数据库，每次写数据库都要调用此方法// 不在使用时，需调用close()public DBAdapter open() throws SQLException {// ---打开数据库--- 　 　db = DBHelper.getWritableDatabase();Log.i("", "getWritableDatabase");return this;}public void close() {// ---关闭数据库---DBHelper.close();}// ---向数据库中插入一个标题--- 　　public long insertTitle(String isbn, String title, String publisher) {ContentValues initialValues = new ContentValues();initialValues.put(Constants.KEY_ISBN, isbn);initialValues.put(Constants.KEY_TITLE, title);initialValues.put(Constants.KEY_PUBLISHER, publisher);return db.insert(Constants.TABLE_NAME, Constants.KEY_ROWID,initialValues);}// ---删除一个指定标题--- 　　public boolean deleteTitle(long rowId) {return db.delete(Constants.TABLE_NAME, Constants.KEY_ROWID + "="+ rowId, null) > 0;}// ---检索所有标题---public Cursor getAllTitles() {return db.query(Constants.TABLE_NAME, new String[] {Constants.KEY_ROWID, Constants.KEY_ISBN, Constants.KEY_TITLE,Constants.KEY_PUBLISHER }, null, null, null, null, null);}// ---检索一个指定标题--- 　public Cursor getTitle(long rowId) throws SQLException {Cursor mCursor = db.query(true, Constants.TABLE_NAME, new String[] {Constants.KEY_ROWID, Constants.KEY_ISBN, Constants.KEY_TITLE,Constants.KEY_PUBLISHER }, Constants.KEY_ROWID + "=" + rowId,null, null, null, null, null);if (mCursor != null) {mCursor.moveToFirst();}return mCursor;}// ---更新一个标题--- 　　public boolean updateTitle(long rowId, String isbn, String title,String publisher) {ContentValues args = new ContentValues();args.put(Constants.KEY_ISBN, isbn);args.put(Constants.KEY_TITLE, title);args.put(Constants.KEY_PUBLISHER, publisher);return db.update(Constants.TABLE_NAME, args, Constants.KEY_ROWID + "="+ rowId, null) > 0;}}

4.Constants.java文件主要是一些常量的保存:

package com.example.Database;public class Constants {public final static String DB_NAME = "dne_db";public final static int DB_VERSION = 1;public static final String TABLE_NAME = "titles";public static final String KEY_ROWID = "_id";public static final String KEY_ISBN = "isbn";public static final String KEY_TITLE = "title";public static final String KEY_PUBLISHER = "publisher";public static final String DATABASE_CREATE = "create table IF NOT EXISTS "+ TABLE_NAME + " (_id integer primary key autoincrement, "+ "isbn text, title text not null, " + "publisher text not null);";}

5.最后是main.xml文件:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical" android:layout_width="fill_parent"android:layout_height="fill_parent"><TextView android:layout_width="fill_parent"android:layout_height="wrap_content" android:text="@string/hello" /><Button android:text="add one row" android:id="@+id/Button01"android:layout_width="150dp" android:layout_height="wrap_content"></Button><Button android:text="delete one row" android:id="@+id/Button02"android:layout_width="150dp" android:layout_height="wrap_content"></Button><Button android:text="update one row" android:id="@+id/Button03"android:layout_width="150dp" android:layout_height="wrap_content"></Button><Button android:text="select one row" android:id="@+id/Button04"android:layout_width="150dp" android:layout_height="wrap_content"></Button></LinearLayout>

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