Android 學習之SQLite基本操作
Activity01.java
package com.lxt008;
import com.lxt008.R;
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.view.WindowManager;
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;
/* 數據庫對象 */
private SQLiteDatabase mSQLiteDatabase = null;
/* 數據庫名 */
private final static String DATABASE_NAME = "Examples_06_05.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";
/* 創建表的sql語句 */
private final static String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + TABLE_ID + " INTEGER PRIMARY KEY," + TABLE_NUM + " INTERGER,"+ TABLE_DATA + " TEXT)";
/* 線性佈局 */
LinearLayout m_LinearLayout = null;
/* 列表視圖-顯示數據庫中的數據 */
ListView m_ListView = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
/* 創建LinearLayout佈局對象 */
m_LinearLayout = new LinearLayout(this);
/* 設置佈局LinearLayout的屬性 */
m_LinearLayout.setOrientation(LinearLayout.VERTICAL);
m_LinearLayout.setBackgroundColor(android.graphics.Color.BLACK);
/* 創建ListView對象 */
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佈局 */
m_LinearLayout.addView(m_ListView, param);
/* 設置顯示m_LinearLayout佈局 */
setContentView(m_LinearLayout);
// 打開已經存在的數據庫
mSQLiteDatabase = this.openOrCreateDatabase(DATABASE_NAME, MODE_PRIVATE, null);
// 獲取數據庫Phones的Cursor
try
{
/* 在數據庫mSQLiteDatabase中創建一個表 */
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;
}
/* 刪除數據庫 */
public void DeleteDataBase()
{
this.deleteDatabase(DATABASE_NAME);
this.finish();
}
/* 刪除一個表 */
public void DeleteTable()
{
mSQLiteDatabase.execSQL("DROP TABLE " + TABLE_NAME);
this.finish();
}
/* 更新一條數據 */
public void UpData()
{
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miCount);
cv.put(TABLE_DATA, "修改後的數據" + miCount);
/* 更新數據 */
mSQLiteDatabase.update(TABLE_NAME, cv, TABLE_NUM + "=" + Integer.toString(miCount - 1), null);
UpdataAdapter();
}
/* 向表中添加一條數據 */
public void AddData()
{
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miCount);
cv.put(TABLE_DATA, "測試數據庫數據" + miCount);
/* 插入數據 */
mSQLiteDatabase.insert(TABLE_NAME, null, cv);
miCount++;
UpdataAdapter();
}
/* 從表中刪除指定的一條數據 */
public void DeleteData()
{
/* 刪除數據 */
mSQLiteDatabase.execSQL("DELETE FROM " + TABLE_NAME + " WHERE _id=" + Integer.toString(miCount));
miCount--;
if (miCount < 0)
{
miCount = 0;
}
UpdataAdapter();
}
/* 更行試圖顯示 */
public void UpdataAdapter()
{
// 獲取數據庫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和後臺數據的橋樑
ListAdapter adapter = new SimpleCursorAdapter(this,
// 定義List中每一行的顯示模板
// 表示每一行包含兩個數據項
android.R.layout.simple_list_item_2,
// 數據庫的Cursor對象
cur,
// 從數據庫的TABLE_NUM和TABLE_DATA兩列中取數據
new String[] { TABLE_NUM, TABLE_DATA },
// 與NAME和NUMBER對應的Views
new int[] { android.R.id.text1, android.R.id.text2 });
/* 將adapter添加到m_ListView中 */
m_ListView.setAdapter(adapter);
}
}
/* 按鍵事件處理 */
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == KeyEvent.KEYCODE_BACK)
{
/* 退出時,不要忘記關閉 */
mSQLiteDatabase.close();
this.finish();
return true;
}
if(keyCode==KeyEvent.KEYCODE_MENU)
{
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
return true;
}
return super.onKeyDown(keyCode, event);
}
}
這是一個數據庫基本操作Demo,調出鍵盤,輸入對應鍵值。
一、打開或創建數據庫
final static String DATABASE_NAME = "Examples_06_05.db";
SQLiteDatabase mSQLiteDatabase = this.openOrCreateDatabase(DATABASE_NAME, MODE_PRIVATE, null);
二、創建表
final static String TABLE_NAME = "table1";
mSQLiteDatabase.execSQL(CREATE_TABLE);
三、刪除表
mSQLiteDatabase.execSQL("DROP TABLE " + TABLE_NAME);
四、添加數據
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miCount);
cv.put(TABLE_DATA, "測試數據庫數據" + miCount);
/* 插入數據 */
mSQLiteDatabase.insert(TABLE_NAME, null, cv);
五、刪除數據
mSQLiteDatabase.execSQL("DELETE FROM " + TABLE_NAME + " WHERE _id=" + Integer.toString(miCount));
六、查詢
Cursor cur = mSQLiteDatabase.query(TABLE_NAME, new String[] { TABLE_ID, TABLE_NUM, TABLE_DATA }, null, null, null, null, null);
七、刪除數據庫
Context.deleteDatabase(String name)
八、關閉數據庫
/* 退出時,不要忘記關閉 */
mSQLiteDatabase.close();
九、調出軟鍵盤
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
十、常用方法
(返回值)方法名 | 方法描述 |
---|---|
(int) delete(String table,String whereClause,String[] whereArgs) | 刪除數據行的便捷方法 |
(long) insert(String table,String nullColumnHack,ContentValues values) | 添加數據行的便捷方法 |
(int) update(String table, ContentValues values, String whereClause, String[] whereArgs) | 更新數據行的便捷方法 |
(void) execSQL(String sql) | 執行一個SQL語句,可以是一個select或其他的sql語句 |
(void) close() | 關閉數據庫 |
(Cursor) query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) | 查詢指定的數據表返回一個帶遊標的數據集 |
(Cursor) rawQuery(String sql, String[] selectionArgs) | 運行一個預置的SQL語句,返回帶遊標的數據集(與上面的語句最大的區別就是防止SQL注入) |
通過query實現查詢的
public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)
各參數說明:
- table:表名稱
- colums:列名稱數組
- selection:條件子句,相當於where
- selectionArgs:條件語句的參數數組
- groupBy:分組
- having:分組條件
- orderBy:排序類
- limit:分頁查詢的限制
- Cursor:返回值,相當於結果集ResultSet