SQLHelper

MyDataBaseAdapter

import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class MyDataBaseAdapter { // 用于打印log private static final String TAG = "MyDataBaseAdapter"; // 表中一条数据的名称 public static final String KEY_ID = "_id"; // 表中一条数据的内容 public static final String KEY_NUM = "num"; // 表中一条数据的id public static final String KEY_DATA = "data"; // 数据库名称为data private static final String DB_NAME = "Examples_06_06.db"; // 数据库表名 private static final String DB_TABLE = "table1"; // 数据库版本 private static final int DB_VERSION = 1; // 本地Context对象 private Context mContext = null; // 创建一个表 private static final String DB_CREATE = "CREATE TABLE " + DB_TABLE + " (" + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NUM + " INTERGER," + KEY_DATA + " TEXT)"; // 执行open（）打开数据库时，保存返回的数据库对象 private SQLiteDatabase mSQLiteDatabase = null; // 由SQLiteOpenHelper继承过来 private DatabaseHelper mDatabaseHelper = null; private static class DatabaseHelper extends SQLiteOpenHelper { /* 构造函数-创建一个数据库 */ DatabaseHelper(Context context) { // 当调用getWritableDatabase() // 或 getReadableDatabase()方法时 // 则创建一个数据库 super(context, DB_NAME, null, DB_VERSION); } /* 创建一个表 */ @Override public void onCreate(SQLiteDatabase db) { // 数据库没有表时创建一个 db.execSQL(DB_CREATE); } /* 升级数据库 */ @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS notes"); onCreate(db); } } /* 构造函数-取得Context */ public MyDataBaseAdapter(Context context) { mContext = context; } // 打开数据库，返回数据库对象 public void open() throws SQLException { mDatabaseHelper = new DatabaseHelper(mContext); mSQLiteDatabase = mDatabaseHelper.getWritableDatabase(); } // 关闭数据库 public void close() { mDatabaseHelper.close(); } /* 插入一条数据 */ public long insertData(int num, String data) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_NUM, num); initialValues.put(KEY_DATA, data); return mSQLiteDatabase.insert(DB_TABLE, KEY_ID, initialValues); } /* 删除一条数据 */ public boolean deleteData(long rowId) { return mSQLiteDatabase.delete(DB_TABLE, KEY_ID + "=" + rowId, null) > 0; } /* 通过Cursor查询所有数据 */ public Cursor fetchAllData() { return mSQLiteDatabase.query(DB_TABLE, new String[] { KEY_ID, KEY_NUM, KEY_DATA }, null, null, null, null, null); } /* 查询指定数据 */ public Cursor fetchData(long rowId) throws SQLException { Cursor mCursor = mSQLiteDatabase.query(true, DB_TABLE, new String[] { KEY_ID, KEY_NUM, KEY_DATA }, KEY_ID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } /* 更新一条数据 */ public boolean updateData(long rowId, int num, String data) { ContentValues args = new ContentValues(); args.put(KEY_NUM, num); args.put(KEY_DATA, data); return mSQLiteDatabase.update(DB_TABLE, args, KEY_ID + "=" + rowId, null) > 0; } }

Activity01

import android.app.Activity; import android.database.Cursor; 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; /* 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; MyDataBaseAdapter m_MyDataBaseAdapter; /** 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); /* 构造MyDataBaseAdapter对象 */ m_MyDataBaseAdapter = new MyDataBaseAdapter(this); /* 取得数据库对象 */ m_MyDataBaseAdapter.open(); 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; } return true; } /* 更新一条数据 */ public void UpData() { m_MyDataBaseAdapter.updateData(miCount - 1, miCount, "修改后的数据" + miCount); UpdataAdapter(); } /* 向表中添加一条数据 */ public void AddData() { m_MyDataBaseAdapter.insertData(miCount, "测试数据库数据" + miCount); miCount++; UpdataAdapter(); } /* 从表中删除指定的一条数据 */ public void DeleteData() { /* 删除数据 */ m_MyDataBaseAdapter.deleteData(miCount); miCount--; if (miCount < 0) { miCount = 0; } UpdataAdapter(); } /* 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 */ m_MyDataBaseAdapter.close(); this.finish(); return true; } return super.onKeyDown(keyCode, event); } /* 更行试图显示 */ public void UpdataAdapter() { // 获取数据库Phones的Cursor Cursor cur = m_MyDataBaseAdapter.fetchAllData(); 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[] {MyDataBaseAdapter.KEY_NUM, MyDataBaseAdapter.KEY_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); } } }