Android之SQLite——11

 Android中，运行SQLite数据库的时候需要一个SQLiteOpenHelper对象

（SQLiteOpenHelper是一个抽象类（只能够继承之后被使用））

SQLiteOpenHelper继承

package DatabaseHelper;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;public class DatabaseHelper extends SQLiteOpenHelper {private final static int VERSION=1;//创建sqlite必须使用SQLiteOpenHelper中的getWritableDatabase()，或getReadableDatabase()public DatabaseHelper(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);// TODO Auto-generated constructor stub}public DatabaseHelper(Context context, String name,int version) {super(context, name, null, version);// TODO Auto-generated constructor stub}public DatabaseHelper(Context context, String name) {super(context, name, null, VERSION);// TODO Auto-generated constructor stub}@Overridepublic void onCreate(SQLiteDatabase db) {// TODO Auto-generated method stubSystem.out.println("sqlite is created");//定义键值对类型，与insert的键值对对应db.execSQL("create table user(id int,name varchar(20))");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stubSystem.out.println("sqlite is updated");}}

配置文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".MainActivity" >    <Button        android:id="@+id/button1"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="sqlitecreate"        android:text="@string/createsqlite" />    <Button        android:id="@+id/button2"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="sqliteupdate"        android:text="@string/updatesqlite" />    <Button        android:id="@+id/button3"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="sqliteinsert"        android:text="@string/insertsqlite" />    <Button        android:id="@+id/button4"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="dataupdate"        android:text="@string/dataupdate" />    <Button        android:id="@+id/button5"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="sqlitequery"        android:text="@string/querysqlite" />    <Button        android:id="@+id/button6"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="deletesqlite"        android:text="@string/deletesqlite" />    <Button        android:id="@+id/button7"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="closesqlite"        android:text="@string/closesqlite" />        <Button        android:id="@+id/button8"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="exitprogram"        android:text="@string/exitprogram"/></LinearLayout>

activitiy SQLite

package com.example.sqlite;import java.sql.SQLDataException;import DatabaseHelper.DatabaseHelper;import android.os.Bundle;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.view.Menu;import android.view.View;import android.widget.Button;public class MainActivity extends Activity {/*在button   android:onclick="函数名" 但中调用 可以部再次声明， 同时避免自己编写clicklistennerprivate Button createbutton;private Button updatebutton;private Button insertbutton;private Button dataupdatabutton;private Button querybutton;private Button deletebutton;private Button closebutton;private Button exitbutton;*/@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);/*createbutton = (Button) findViewById(R.id.button1);updatebutton= (Button) findViewById(R.id.button2);insertbutton = (Button) findViewById(R.id.button3);dataupdatabutton = (Button) findViewById(R.id.button4);querybutton = (Button) findViewById(R.id.button5);deletebutton = (Button) findViewById(R.id.button6);closebutton = (Button) findViewById(R.id.button7);exitbutton = (Button) findViewById(R.id.button8);*/}// 创建sqlitepublic void sqlitecreate(View view) {// 创建sqlite必须使用SQLiteOpenHelper中的getWritableDatabase()，或getReadableDatabase()// 但是SQLiteOpenHelper，是abstract类，所以必须继承后使用，在继承SQLiteOpenHelper时必须复写// 继承自父类的构造函数// Create/or open a database WritableDatabaseDatabaseHelper dbhelper = new DatabaseHelper(MainActivity.this,"sqlite_test3.db");SQLiteDatabase db = dbhelper.getWritableDatabase();System.out.println("sqlite is created");}// 更新sqlite版本public void sqliteupdate(View view) {DatabaseHelper dbhelper = new DatabaseHelper(MainActivity.this,"sqlite_test3.db", 2);SQLiteDatabase db = dbhelper.getWritableDatabase();System.out.println("sqlite is updated");}// 向sqlite插入内容public void sqliteinsert(View view) {ContentValues values = new ContentValues();// 键值对类型，与继承sqlteOpenHelper时sql与句定义的键值对格式一致// db.execSQL("create table user(id int,name varchar(20))");values.put("id", 1);values.put("name", "张三");//values.put("id", 2);//values.put("name", "李四");//values.put("id", 3);//values.put("name", "王五");DatabaseHelper dbhelper = new DatabaseHelper(MainActivity.this,"sqlite_test3.db", 2);SQLiteDatabase db = dbhelper.getWritableDatabase();db.insert("user", null, values);System.out.println("sqlite is inserted");}// 更新内容public void dataupdate(View view) {DatabaseHelper dbhelper = new DatabaseHelper(MainActivity.this,"sqlite_test3.db", 2);SQLiteDatabase db = dbhelper.getWritableDatabase();ContentValues values = new ContentValues();values.put("name", "王五");db.update("user", values, "id=?", new String[]{"1"});System.out.println("data is updated");}// 查询sqlitepublic void sqlitequery(View view) {DatabaseHelper dbhelper = new DatabaseHelper(MainActivity.this,"sqlite_test3.db", 2);SQLiteDatabase db = dbhelper.getWritableDatabase();Cursor cursor = db.query("user", new String[]{"id","name"}, "id=?", new String[]{"1"}, null, null, null);//cursor.moveToFirst();//刚创建 指向头部System.out.print(cursor.moveToNext());while (cursor.moveToNext()) {String name = cursor.getString(cursor.getColumnIndex("name"));System.out.println("query--->" + name);}System.out.println("sqlite is queryed");}// delete sqlitepublic void deletesqlite(View view) {this.deleteDatabase("sqlite_test3.db");System.out.println("sqlite is deleted");}// exit programpublic void exitprogram(View view) {System.exit(0);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}