Android開發—數據庫應用—訪問數據表（SQLite OpenHelper） —添加查詢

/* (程序頭部注釋開始)
* 程序的版權和版本聲明部分
* Copyright (c) 2011, 煙台大學計算機學院學生
* All rights reserved.
* 文件名稱：數據庫應用—添加查詢
* 作 者： 雷恆鑫
* 完成日期： 2012 年 08 月 14 日
* 版 本 號： V1.0
* 對任務及求解方法的描述部分
* 輸入描述：
* 問題描述：
* 程序輸出：
* 程序頭部的注釋結束
*/
 
方法：在“NotesDbAdapter”類中新增一個“getall”方法來查詢“notes”數據表中的所有數據，修改後的“DummyNote.java”文件如下：
[java] 
package com.demo.android.dummynote; 
 
import android.app.ListActivity; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.widget.ArrayAdapter; 
import android.widget.ListAdapter; 
import android.widget.SimpleCursorAdapter; 
import android.content.Intent; 
import android.widget.ListView; 
 
 
public class DummyNote extends ListActivity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
        //Tell the list view which view to display when the list is empty 
        getListView().setEmptyView(findViewById(R.id.empty)); 
        setAdapter(); 
    } 
    private String[] note_array = { 
            "gasolin", 
            "crota", 
            "louk", 
            "magicion" 
    };  
    private NotesDbAdapter mDbHelper; 
    private Cursor mNotesCursor; 
    private void setAdapter(){ 
        mDbHelper = new NotesDbAdapter(this); 
        mDbHelper.open(); 
        fillData(); 
    } 
    private void fillData(){ 
        mNotesCursor = mDbHelper.getall(); 
        startManagingCursor(mNotesCursor); 
         
        //Create an array to specify the field we want to display in the list 
        String[] from = new String[]{NotesDbAdapter.KEY_NOTE}; 
         
        //an array of the fields we want to bind those fields to 
        int[] to = new int[]{android.R.id.text1}; 
         
        //Now create a simple cursor adapter 
        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, 
                android.R.layout.simple_list_item_1,mNotesCursor,from,to); 
        setListAdapter(adapter); 
    } 
} 

修改後的“DummyDbAdapter.java”文件如下：
 
[java] 
package com.demo.android.dummynote; 
 
import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.database.sqlite.SQLiteDatabase.CursorFactory; 
 
public class NotesDbAdapter { 
    private static final String DATABASE_NAME = "notes.db"; 
    private static final int DATABASE_VERSION = 1; 
    private static final String DATABASE_TABLE = "notes"; 
    private static final String DATABASE_CREATE = "creat table notes(" 
            + "_id INTEGER PRIMARY KEY," + "note TEXT," + "created INTEGER," 
            + "modified INTEGER" + ");"; 
 
    private static class DatabaseHelper extends SQLiteOpenHelper { 
        public DatabaseHelper(Context context) { 
            super(context, DATABASE_NAME, null, DATABASE_VERSION); 
            // TODO Auto-generated constructor stub 
        } 
 
        @Override 
        public void onCreate(SQLiteDatabase db) { 
            // TODO Auto-generated method stub 
            db.execSQL(DATABASE_CREATE); 
 
        } 
 
        @Override 
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
            // TODO Auto-generated method stub 
            db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE); 
            onCreate(db); 
        } 
    } 
 
    private Context mCtx = null; 
    private DatabaseHelper dbHelper; 
    private SQLiteDatabase db; 
 
    public NotesDbAdapter(Context ctx) { 
        this.mCtx = ctx; 
    } 
 
    public NotesDbAdapter open() throws SQLException { 
        dbHelper = new DatabaseHelper(mCtx); 
        db = dbHelper.getWritableDatabase(); 
        return this; 
    } 
 
    public void close() { 
        dbHelper.close(); 
    } 
 
    private static final String KEY_ROWID = "_id"; 
    static final String KEY_NOTE = "note"; 
    private static final String KEY_CREATED = "created"; 
 
    // get all entries 
    public Cursor getall() { 
        return db.rawQuery("SELECT * FROM notes", null); 
 
    } 
} 

 
經驗積累：
1.我學會了如何使用“mDbHelper.getall()”語句。
2.“ListActivity”提供的“setListAdapter”方法，是將接口綁定到“ListView”界面組件上。
作者：leihengxin