利用Android中的SQLite进行CRUD

一、SQLite？

SQLite是一种轻量级的数据库，Android中自带有。

android可以借助SQLiteOpenHelper来对SQLite进行操作

二、效果图

三、代码编写与解析

1.编写操作系统的工具类DBHelper继承SQLiteOpenHelper

SQLiteOpenHelper是用来管理数据库的创建和版本的管理

package linys.util;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
/**
 * 
 * @Project: Android_SQLite
 * @Desciption: 
 * SQLiteOpenHelper
 * A helper class to manage database creation and version management
 * SQLiteOpenHelper 管理数据库的创建和版本的管理
 * @Author: LinYiSong
 * @Date: 2011-3-25~2011-3-25
 */
public class DBHelp extends SQLiteOpenHelper {
	/**
	 * 
	 * @param context
	 * @param name数据库文件名
	 * @param factory
	 * @param version
	 */
	public DBHelp(Context context, String name, CursorFactory factory,
			int version) {
		super(context, name, factory, version);
	}

	/**
	 * Called when the database is created for the first time.
	 * This is where the creation of tables and the initial population of the tables should happen
	 */
	@Override
	public void onCreate(SQLiteDatabase db) {
		System.out.println("SQLiteDatabase's OnCreate");
		
		db.execSQL("create table user(id int,name varchar(20))");
	}

	/**
	 * upgrade：升级，数据库版本从1-->2会调用这个函数
	 */
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		System.out.println("upgrade");
	}

}

2.编写Activity，对SQLite数据库进行操作

package linys.db;

import linys.util.DBHelp;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

/**
 * 
 * @Project: Android_SQLite
 * @Desciption: SQLite是一种轻量级的数据库
 * android可以借助SQLiteOpenHelper来对SQLite进行操作：
 * 
 * 操作类，继承SQLiteOpenHelper如DBHelp
 * 
 * 
 * adb:android debug bridge
 * android自带的调试工具，可以进入内核，进行操作
 * adb shell 进入内核
 * 编写的程序放在data/data对于的包（即我们在new出Program时指定的package
 * 
 * 如果程序有用到数据库，则数据库在database下
 * 对数据进行操作前，先切换的sqlite3模式下：sqlite3 数据库名
 *.schema可以查看数据库中创建的表格语句，
 * 
 * @Author: LinYiSong
 * @Date: 2011-3-10~2011-3-10
 */
public class SQLiteDemo extends Activity {
    /** Called when the activity is first created. */
	private Button createDataBaseBtn;
	private Button updateDataBaseBtn;
	private Button insertBtn;
	private Button updateBtn;
	private Button queryBtn;
	private Button deleteBtn;
	DBHelp dbHelp;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        createDataBaseBtn=(Button)this.findViewById(R.id.createDatabase);
        updateDataBaseBtn=(Button)this.findViewById(R.id.updateDatabase);
        insertBtn=(Button)this.findViewById(R.id.insert);
        updateBtn=(Button)this.findViewById(R.id.update);
        queryBtn=(Button)this.findViewById(R.id.query);
        deleteBtn=(Button)this.findViewById(R.id.delete);
        
        //注册监听器
        createDataBaseBtn.setOnClickListener(new CreateDBListener());
        updateDataBaseBtn.setOnClickListener(new UpdateDBListener());
        insertBtn.setOnClickListener(new InsertListener());
        updateBtn.setOnClickListener(new UpdateListener());
        queryBtn.setOnClickListener(new QueryListener());
        deleteBtn.setOnClickListener(new DeleteListener());
    }
    class CreateDBListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,1);
			dbHelp.getWritableDatabase();
		}}
    
    class UpdateDBListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,2);
			dbHelp.getWritableDatabase();
		}}
    
    
    class InsertListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			//准备数据
			ContentValues content=new ContentValues();
			content.put("id", "12");
			content.put("name", "linys");
			//操作数据库
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,2);
			SQLiteDatabase db=dbHelp.getWritableDatabase();
			db.insert("user", null, content);
		}}
    
    class DeleteListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			//操作数据库
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,2);
			SQLiteDatabase db=dbHelp.getWritableDatabase();
			db.delete("user","id=?",new String[]{"12"});
		}}
    
    class UpdateListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			//准备数据
			ContentValues content=new ContentValues();
			content.put("id", "12");
			content.put("name", "linyisong");
			//操作数据库
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,2);
			SQLiteDatabase db=dbHelp.getWritableDatabase();
			db.update("user", content, "id=?" ,new String[]{"12"});
		}}
    
    class QueryListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			dbHelp=new DBHelp(SQLiteDemo.this,"linys",null,2);
			SQLiteDatabase db=dbHelp.getReadableDatabase();
			//Cursor游标相当于java中的Iterator
			Cursor cursor=db.query("user", new String[]{"id","name"}, "id=?",new String[]{"12"}, null,null, null);
			while(cursor.moveToNext()){
				String id=cursor.getString(cursor.getColumnIndex("id"));
				String name=cursor.getString(cursor.getColumnIndex("name"));
				System.out.println("id: "+id+" name:"+name);
			}
		}}
}

四、补充：调试adb

1.adb:android debug bridge
2.android自带的调试工具，可以进入内核，进行操作:adb shell 进入内核
3.编写的程序放在data/data对于的包（即我们在new出Program时指定的package)
4.如果程序有用到数据库，则数据库在database下
5.对数据进行操作前，先切换的sqlite3模式下：sqlite3 数据库名
6.标准的sql语句也用，另外.schema可以查看数据库中创建的表格语句

利用Android中的SQLite进行CRUD

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