利用Android中的SQLite进行CRUD

shisgmei

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