本文讲如何使用Android中内置的SQLite轻量数据库，Android SDK中已经对其进行了封装，使用起来相当简单。创建类继承SQLiteOpenHelper就可以将数据库的创建和应用版本更新后数据库的重建纳入自动管理中。本文实现一个简单的Sqlite数据库，存储人名和电话号码。
主Activity 类SqliteSample.java 代码：
public class SqliteSample extends Activity {
private DBHelper mDBHelper = null;
private Button btCreateDb = null;
private Button btInsertData = null;
private Button btViewData = null;
private Button btDelOne = null;
private Button btClearAll = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btCreateDb = (Button)findViewById(R.id.Button01);
btCreateDb.setOnClickListener(new ClickViewHandler());
btInsertData = (Button)findViewById(R.id.Button02);
btInsertData.setOnClickListener(new ClickViewHandler());
btInsertData.setEnabled(false);
btViewData = (Button)findViewById(R.id.Button03);
btViewData.setOnClickListener(new ClickViewHandler());
btViewData.setEnabled(false);
btDelOne = (Button)findViewById(R.id.Button04);
btDelOne.setOnClickListener(new ClickViewHandler());
btDelOne.setEnabled(false);
btClearAll = (Button)findViewById(R.id.Button05);
btClearAll.setOnClickListener(new ClickViewHandler());
btClearAll.setEnabled(false);
}
public class ClickViewHandler implements OnClickListener {
@Override
public void onClick(View v) {
if (v == btCreateDb) {
createDB();
} else if (v == btInsertData) {
insertSomeRecords();
} else if (v == btViewData) {
ViewRecords();
} else if (v == btDelOne) {
DelOne();
} else if (v == btClearAll) {
mDBHelper.delAllPeople();
}
}
}
private void createDB() {
String DB_NAME = ＂sqlitedb1＂;
mDBHelper = new DBHelper(
SqliteSample.this, DB_NAME, null, 1);
assert(mDBHelper != null);
btCreateDb.setEnabled(false);
btInsertData.setEnabled(true);
btViewData.setEnabled(true);
btDelOne.setEnabled(true);
btClearAll.setEnabled(true);
}
private void insertSomeRecords() {
mDBHelper.addPeople(＂张三＂, ＂18600000000＂);
mDBHelper.addPeople(＂李四＂, ＂13200000000＂);
mDBHelper.addPeople(＂王五＂, ＂13200000000＂);
}
private void ViewRecords() {
// Make the query
Cursor c = mDBHelper.getWritableDatabase().query(
DBHelper.TB_NAME,null,null,null,null,null,
DBHelper.NAME + ＂ ASC＂);
StringBuilder sbRecords = new StringBuilder(＂＂);
if (c.moveToFirst()) {
int idxID = c.getColumnIndex(DBHelper.ID);
int idxName = c.getColumnIndex(DBHelper.NAME);
int idxNumber = c.getColumnIndex(DBHelper.NUMBER1);
// Iterator the records
do {
sbRecords.append(c.getInt(idxID));
sbRecords.append(＂.＂);
sbRecords.append(c.getString(idxName));
sbRecords.append(＂,＂);
sbRecords.append(c.getString(idxNumber));
sbRecords.append(＂/n＂);
} while (c.moveToNext());
}
c.close();
// Refresh the content of TextView
((TextView)(findViewById(
R.id.TextView01))).setText(sbRecords);
}
private void DelOne() {
int id;
Cursor c = mDBHelper.getWritableDatabase().query(
DBHelper.TB_NAME,null,null,null,null,null,
DBHelper.NAME + ＂ ASC＂);
if (c.moveToFirst()) {
int idxID = c.getColumnIndex(DBHelper.ID);
id = c.getInt(idxID);
mDBHelper.delPeople(id);
}
}
}
ui界面 main.xml 代码，主要是几个button的放置：
<?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＂ />
<TableRow android:id=＂@+id/TableRow01＂ android:layout_width=＂wrap_content＂ android:layout_height=＂wrap_content＂>
<Button android:text=＂创建数据库＂ android:id=＂@+id/Button01＂
android:height=＂30px＂ android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ />
<Button android:text=＂插入几条记录＂ android:id=＂@+id/Button02＂
android:height=＂30px＂ android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ />
</TableRow>
<TableRow android:id=＂@+id/TableRow01＂ android:layout_width=＂wrap_content＂ android:layout_height=＂wrap_content＂>
<Button android:text=＂删除一条＂ android:id=＂@+id/Button04＂
android:height=＂30px＂ android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ />
<Button android:text=＂清除所有＂ android:id=＂@+id/Button05＂
android:height=＂30px＂ android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ />
</TableRow>
<Button android:text=＂查看记录＂ android:id=＂@+id/Button03＂
android:height=＂30px＂ android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ android:layout_gravity=＂center＂/>
<TextView android:text=＂...＂ android:id=＂@+id/TextView01＂
android:layout_width=＂wrap_content＂
android:layout_height=＂wrap_content＂ />
</LinearLayout>
数据库操作类 DBHelper.java 代码：
package jtapp.sqlitesamples;
public class DBHelper extends SQLiteOpenHelper {
public static final String TB_NAME = ＂people＂;
public static final String ID = ＂_id＂;
public static final String NAME = ＂name＂;
public static final String NUMBER1 = ＂number1＂;
public DBHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
this.getWritableDatabase();
}
/**
* should be invoke when you never use DBhelper
* To release the database and etc.
*/
public void Close() {
this.getWritableDatabase().close();
}
public void onCreate(SQLiteDatabase db) {
db.execSQL(＂CREATE TABLE IF NOT EXISTS ＂
+ TB_NAME + ＂ (＂
+ ID + ＂ INTEGER PRIMARY KEY,＂
+ NAME + ＂ VARCHAR,＂
+ NUMBER1 + ＂ VARCHAR)＂);
}
public void onUpgrade(SQLiteDatabase db,
int oldVersion, int newVersion) {
db.execSQL(＂DROP TABLE IF EXISTS ＂+TB_NAME);
onCreate(db);
}
public void addPeople(String name, String number) {
ContentValues values = new ContentValues();
values.put(DBHelper.NAME, name);
values.put(DBHelper.NUMBER1, number);
this.getWritableDatabase().insert(
DBHelper.TB_NAME, DBHelper.ID, values);
}
public void delPeople(int id) {
this.getWritableDatabase().delete(
DBHelper.TB_NAME, this.ID + ＂ = ＂ + id, null);
}
public void delAllPeople() {
this.getWritableDatabase().delete(
DBHelper.TB_NAME, null, null);
}
}
本文主要以例子的方式展示了安卓开发中SQLite的增啥改查的使用,本文提供一个SQLite增删改查的DBHelper类,主要用来操作SQLite数据库,读者可以自己复制该类的代码使用,感谢阅读本文