这个例子实现了一个完整的数据库操作示例。首先运行项目,初始化数据库(创建数据库、创建表);然后点击左方向键向表中插入一条数据,按右方向键删除一条数据,按数字键1修改表中指定的一条数据,数字键2可以删除一个表,数字键1 删除数据库。代码如下:
 
package eoe.android.Demo;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Color;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;

public class Activity01 extends Activity
{
private static int miCount = 0;

/* 数据库对象 */
private SQLiteDatabase mSQLiteDatabase = null;

/* 数据库名 */
private final static String DATABASE_NAME = "demo.db";
/* 表名 */
private final static String TABLE_NAME = "table1";

/* 表中的字段 */
private final static String TABLE_ID = "_id";
private final static String TABLE_NUM = "num";
private final static String TABLE_DATA = "data";

/* 创建表的sql语句 */
private final static String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + TABLE_ID + " INTEGER PRIMARY KEY," + TABLE_NUM + " INTERGER,"+ TABLE_DATA + " TEXT)";

/* 线性布局 */
LinearLayout m_LinearLayout = null;
/* 列表视图-显示数据库中的数据 */
ListView m_ListView = null;


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

/* 创建LinearLayout布局对象 */
m_LinearLayout = new LinearLayout(this);
/* 设置布局LinearLayout的属性 */
m_LinearLayout.setOrientation(LinearLayout.VERTICAL);
m_LinearLayout.setBackgroundColor(android.graphics.Color.BLACK);

/* 创建ListView对象 */
m_ListView = new ListView(this);
LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
m_ListView.setBackgroundColor(Color.BLACK);

/* 添加m_ListView到m_LinearLayout布局 */
m_LinearLayout.addView(m_ListView, param);

/* 设置显示m_LinearLayout布局 */
setContentView(m_LinearLayout);

// 打开已经存在的数据库
mSQLiteDatabase = this.openOrCreateDatabase(DATABASE_NAME, MODE_PRIVATE, null);

// 获取数据库Phones的Cursor
try
{
/* 在数据库mSQLiteDatabase中创建一个表 */
mSQLiteDatabase.execSQL(CREATE_TABLE);
}
catch (Exception e)
{
UpdataAdapter();
}
}


public boolean onKeyUp(int keyCode, KeyEvent event)
{
switch (keyCode)
{
case KeyEvent.KEYCODE_DPAD_LEFT:
AddData();
break;
case KeyEvent.KEYCODE_DPAD_RIGHT:
DeleteData();
break;
case KeyEvent.KEYCODE_1:
UpData();
break;
case KeyEvent.KEYCODE_2:
DeleteTable();
break;
case KeyEvent.KEYCODE_3:
DeleteDataBase();
break;
}
return true;
}


/* 删除数据库 */
public void DeleteDataBase()
{
this.deleteDatabase(DATABASE_NAME);
this.finish();
}


/* 删除一个表 */
public void DeleteTable()
{
mSQLiteDatabase.execSQL("DROP TABLE " + TABLE_NAME);
this.finish();
}


/* 更新一条数据 */
public void UpData()
{
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miCount);
cv.put(TABLE_DATA, "修改后的数据" + miCount);

/* 更新数据 */
mSQLiteDatabase.update(TABLE_NAME, cv, TABLE_NUM + "=" + Integer.toString(miCount - 1), null);

UpdataAdapter();
}


/* 向表中添加一条数据 */
public void AddData()
{
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miCount);
cv.put(TABLE_DATA, "测试数据库数据" + miCount);
/* 插入数据 */
mSQLiteDatabase.insert(TABLE_NAME, null, cv);
miCount++;
UpdataAdapter();
}


/* 从表中删除指定的一条数据 */
public void DeleteData()
{

/* 删除数据 */
mSQLiteDatabase.execSQL("DELETE FROM " + TABLE_NAME + " WHERE _id=" + Integer.toString(miCount));

miCount--;
if (miCount < 0)
{
miCount = 0;
}
UpdataAdapter();
}


/* 更行试图显示 */
public void UpdataAdapter()
{
// 获取数据库Phones的Cursor
Cursor cur = mSQLiteDatabase.query(TABLE_NAME, new String[] { TABLE_ID, TABLE_NUM, TABLE_DATA }, null, null, null, null, null);

miCount = cur.getCount();
if (cur != null && cur.getCount() >= 0)
{
// ListAdapter是ListView和后台数据的桥梁
ListAdapter adapter = new SimpleCursorAdapter(this,
// 定义List中每一行的显示模板
// 表示每一行包含两个数据项
android.R.layout.simple_list_item_2,
// 数据库的Cursor对象
cur,
// 从数据库的TABLE_NUM和TABLE_DATA两列中取数据
new String[] { TABLE_NUM, TABLE_DATA },
// 与NAME和NUMBER对应的Views
new int[] { android.R.id.text1, android.R.id.text2 });

/* 将adapter添加到m_ListView中 */
m_ListView.setAdapter(adapter);
}
}


/* 按键事件处理 */
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == KeyEvent.KEYCODE_BACK)
{
/* 退出时,不要忘记关闭 */
mSQLiteDatabase.close();
this.finish();
return true;
}
return super.onKeyDown(keyCode, event);
}
}