SQLite实例——dummynote(记事本)

DummyNote.java

package com.example.dummynote;

import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.util.Log;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.R.bool;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

public class DummyNote extends ListActivity {
	private static final String TAG = "notes";
	@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
		registerForContextMenu(getListView());				//调用 registerForContextMenu() 方法，为视图注册上下文菜单。
		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();
	}
	
	
	//fillData()刷新数据
	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 an entity
	private int mNoteNumber = 1;
	protected static final int MENU_INSERT = Menu.FIRST;
	protected static final int MENU_DELETE = Menu.FIRST+1;
	
	@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,"新增记事");
		 menu.add(0,MENU_DELETE,"删除记事");
		 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;
		case MENU_DELETE:
			mDbHelper.delete(getListView().getSelectedItemId());
			fillData();
			return true;
		}
		return super.onOptionsItemSelected(item);
	}

	
	
	//NoteEdit Activity的跳转设置
	private static final int ACTIVITY_EDIT = 0x1001;

	@Override
	protected void onListItemClick(ListView l,View v,int position,long id) {
		super.onListItemClick(l,v,position,id);
		Intent intent = new Intent(this,NoteEdit.class);
		intent.putExtra(NotesDbAdapter.ROWID,id);//id代表绑定到这个“ListView”项目的“row ID”
	    startActivityForResult(intent,ACTIVITY_EDIT);
	}
	//startActivityForResult()和onActivityResult()方法是配套使用。
	//前者负责调用其他Activity
	//猴子负责处理从其他Activity返回的消息
	@Override
	protected void onActivityResult(int requestCode,int resultCode,Intent intent) {
		// TODO Auto-generated method stub
		super.onActivityResult(requestCode,resultCode,intent);
		fillData();
	}



	
	
	//长按删除
	@Override
	public void onCreateContextMenu(ContextMenu menu,ContextMenuInfo menuInfo) {
		menu.add(0,"删除记事");
		menu.setHeaderTitle("要如何处理这笔记录?");
		super.onCreateContextMenu(menu,menuInfo);
	}
	
	@Override
	public boolean onContextItemSelected(MenuItem item) {
		AdapterView.AdapterContextMenuInfo info =
				(AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
		
		switch(item.getItemId()){
		case MENU_DELETE:
			mDbHelper.delete(info.id);
			fillData();
			break;
		}
		return super.onContextItemSelected(item);
	}
	
}

NoteDbAdapter.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";
	
	
	//query single entry
		public Cursor get(long rowId)throws sqlException {
			Cursor mCursor = db.query(DATABASE_TABLE,//Which table to select
						new String[]{ROWID,NOTE,CREATED},//Which columns to return
						ROWID+"="+rowId,//Where clause
						null,//Where arguments
						null,//Group By clause
						null,//Having clause
						null    //Order-by clause
						);
			if(mCursor!=null){
				mCursor.moveToFirst();//指针移到一开始
			}
			return mCursor;
		}
		
		
	//query single entry
	public Cursor getall() {
		return db.query(DATABASE_TABLE,//Which table to select
					new String[]{ROWID,//Which columns to return
					null,//Where clause
					null,//Where arguments
					null,//Group By clause
					null,//Having clause
					null    //Order-by clause
					);
	}
	
	//add an entity
	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,args);
	}
	
	
	//remove an entity
	public boolean delete(long rowId){
		return db.delete(DATABASE_TABLE,ROWID+"="+rowId,null)>0;//delete失败返回0
	}
	
	
	//update an entity
	public boolean update(long rowId,String note){
		ContentValues args = new ContentValues();
		args.put(NOTE,note);
		
		return db.update(DATABASE_TABLE,args,null)>0;
	}
}

NoteEdit.java

package com.example.dummynote;

import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class NoteEdit extends Activity{

	private NotesDbAdapter mDbHelper;

	@Override
	protected void onCreate(Bundle SavedInstanceState){
		super.onCreate(SavedInstanceState);
		mDbHelper = new NotesDbAdapter(this);
		mDbHelper.open();
		setContentView(R.layout.note_edit);
		findViews();
		showViews(SavedInstanceState);
	}

	private EditText field_note;
	private Button   button_confirm;
	private void findViews() {
		// TODO Auto-generated method stub
		field_note = (EditText) findViewById(R.id.note);
		button_confirm = (Button) findViewById(R.id.confirm);
	}
	
	private Long mRowId;
	private void showViews(Bundle savedInstanceState) {
		mRowId = savedInstanceState != null?
				savedInstanceState.getLong(NotesDbAdapter.ROWID) : null;
		/*saveInstanceState 这个“bundle”数据容器中，取出Activity上一次处于“stop”状态是，键值为“_id”(NotesDbAdapter.ROWID)的内容值。如果这个ACtivity是
		全新打开的或是之前的行程已经被回收了，那么“mRouId”的值被设为“null”*/
				
		if (mRowId == null) {
			Bundle extras = getIntent().getExtras();
			mRowId = extras != null ? extras.getLong(NotesDbAdapter.ROWID) : null;
		}
		
		populateFields();//根据RowId查询记录，并显示在EditText中
		
		button_confirm.setOnClickListener(new View.OnClickListener(){
			
			@Override
			public void onClick(View v) {
				mDbHelper.update(mRowId,field_note.getText().toString());
				setResult(RESULT_OK);
				finish();
			}
		});
	}
	
	private void populateFields() {
		if (mRowId != null){
			Cursor note = mDbHelper.get(mRowId);
			startManagingCursor(note);
			
			field_note.setText(note.getString(note.getColumnIndexOrThrow(NotesDbAdapter.NOTE)));
		}
		
	}

}

原文链接：https://www.f2er.com/sqlite/199665.html

SQLite实例——dummynote(记事本)

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