SQLite实例——dummynote.java

先附上源代码。代码不断更新中，主要实现一个记事本的功能，涉及SQLite的CRUD操作。

dummynote.java

package com.example.dummynote;

import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.Menu;
import android.view.MenuItem;
import android.R.bool;
import android.app.ListActivity;
import android.database.Cursor;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;

public class DummyNote extends ListActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		getListView().setEmptyView(findViewById(R.id.empty));//设置列表为空时的显示内容为 empty文本框
		setAdapter();
	}

	private String[] note_array={
		/*"hangsome",
		"lushichuanshuo",
		"android",
		"library"*/
	};
	private NotesDbAdapter mDbHelper ;
	private Cursor mNoteCursor;

	private void setAdapter(){
		mDbHelper = new NotesDbAdapter(this);
		mDbHelper.open();
		fillData();
	}

	private void fillData(){
		mNoteCursor = mDbHelper.getall();
		startManagingCursor(mNoteCursor);

		String[] from = new String[]{NotesDbAdapter.NOTE};
		int[] to = new int[]{android.R.id.text1};//android.R.id.text1是Android 框架里面的TextView的一个标识符

		//Now create a simple cursor adapter
		SimpleCursorAdapter adapter =
				new SimpleCursorAdapter(this, android.R.layout.simple_list_item_1, mNoteCursor, from, to);
		setListAdapter(adapter);
		}

	//Add a entity
	private int mNoteNumber = 1;
	protected static final int MENU_INSERT = Menu.FIRST;

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		 super.onCreateOptionsMenu(menu);
		 menu.add(0,MENU_INSERT, 0, "新增记事");
		return super.onCreateOptionsMenu(menu);
	}
	public boolean onOptionsItemSelected(MenuItem item){
		switch(item.getItemId()){
		case MENU_INSERT:
			String noteName = "Note "+ mNoteNumber++;
			mDbHelper.create(noteName);
			fillData();
			return true;
		}
		return super.onOptionsItemSelected(item);
	}

}<p>
</p>

NotesDbAdapter.java<pre name="code" class="java">package com.example.dummynote;

import java.util.Date;

import android.content.ContentValues;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.*;
import android.util.Log;
public class NotesDbAdapter {
	private static final String TAG = "notes";

	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 =
			"create table notes("
			+"_id INTEGER PRIMARY KEY,"
			+"note TEXT NOT NULL,"
			+"created INTEGER"
			+");";

	private static class DatabaseHelper extends SQLiteOpenHelper{
		public DatabaseHelper(Context context) {
			super(context, DATABASE_NAME,null,DATABASE_VERSION);
			// TODO Auto-generated constructor stub
		}

		@Override//创建数据表
		public void onCreate(SQLiteDatabase db) {
			// TODO Auto-generated method stub
			try {
				db.execSQL(DATABASE_CREATE);
				Log.d(TAG, "onCreate !");
			} catch (Exception e) {
				Log.d(TAG, e.toString());
			}
		}

		@Override//更新数据表
		public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

			try {
				// TODO Auto-generated method stub
				db.execSQL("DROP TABLE IF EXISTS "+DATABASE_TABLE);
				onCreate(db);
				Log.d(TAG, "inUpgrade!");
			} catch (Exception e) {
				Log.d(TAG, "onUpgrade failure!");
			}
		}
}

	private Context mCtx = null;	 //抽象界面
	private DatabaseHelper dbHelper; //数据库工具类
	private SQLiteDatabase db;		 //数据库类
	/** COnstructor**/
	public NotesDbAdapter(Context ctx){
		this.mCtx=ctx;
	}

	public NotesDbAdapter open () throws SQLException{
		dbHelper = new DatabaseHelper(mCtx);
		db = dbHelper.getWritableDatabase();//数据库不存在就创造一个，若存在就根据版本库来决定是否更新数据库

		return this;
	}

	public void close(){
		dbHelper.close();
	}

	public static final String  ROWID = "_id";
	public static final String  NOTE = "note";
	public static final String  CREATED = "created";

	String[] strCols = new String[]{
			ROWID,
			NOTE,
			CREATED
	};
	//检索。返回的是指针。少内存
	public Cursor getall() {
		return db.query(DATABASE_TABLE,//Which table to select
					strCols,//Which columns to return
					null,   //Where clause
					null,   //Where arguments
					null,   //Group By clause
					null,   //Having clause
					null    //Order-by clause
					);
	}

	//增加
	public long create(String Note){
		Date now = new Date();
		ContentValues args = new ContentValues();
		args.put(NOTE, Note);
		args.put(CREATED, now.getDate());

		return db.insert(DATABASE_TABLE, null, args);
	}
}