Android学习笔记-SQLite的使用

界面文件activity_main.xml

< Button

android:id = "@+id/createButton"

android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:layout_below = "@id/hello_world"

android:text = "create database" />

< Button

android:id = "@+id/updateButton"

android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:layout_below = "@id/createButton"

android:text = "update database" />

< Button

android:id = "@+id/insertButton"

android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:layout_below = "@id/updateButton"

android:text = "insert database" />

< Button

android:id = "@+id/updateRecordButton"

android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:layout_below = "@id/insertButton"

android:text = "update record" />

< Button

android:id = "@+id/queryRecordButton"

android:layout_width = "fill_parent"

android:layout_height = "wrap_content"

android:layout_below = "@id/updateRecordButton"

android:text = "Query record" />

DatabaseHelper.java

package com.example.sqlite_01;

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 static final int VERSION = 1 ;

public DatabaseHelper(Context context, String name, CursorFactory factory,

int version) {

super (context, name, factory, version);

}

public DatabaseHelper(Context context, String name, int version) {

this (context, name, null , version);

}

public DatabaseHelper(Context context, String name) {

this (context, name, VERSION);

}

//第一次创建数据库的时候执行，实际上是在第一次得到SQLiteDatabase对象的时候调用

@Override

public void onCreate(SQLiteDatabase db) {

System.out.println( "Create a database" );

db.execSQL( "create table user(id int, name varchar(20))" );

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

System.out.println( "Update a database" );

}

/*

* abd shell进入当前App的目录下的databases目录下就可以看到创建的数据库

* 打开数据库sqlite3 test_db

* 查看当前数据库里的表以及创建表的语句 .schema

*/

}

MainActivity.java

package com.example.sqlite_01;

import android.support.v7.app.ActionBarActivity;

import android.content.ContentValues;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

public class MainActivity extends ActionBarActivity {

private Button createButton = null ;

private Button updateButton = null ;

private Button insertButton = null ;

private Button updateRecordButton = null ;

private Button queryRecordButton = null ;

@Override

protected void onCreate(Bundle savedInstanceState) {

super .onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

createButton = (Button) findViewById(R.id.createButton);

updateButton = (Button) findViewById(R.id.updateButton);

insertButton = (Button) findViewById(R.id.insertButton);

updateRecordButton = (Button) findViewById(R.id.updateRecordButton);

queryRecordButton = (Button) findViewById(R.id.queryRecordButton);

createButton.setOnClickListener( new CreateListener());

updateButton.setOnClickListener( new UpdateListener());

insertButton.setOnClickListener( new InsertListener());

updateRecordButton.setOnClickListener( new UpdateRecordListener());

queryRecordButton.setOnClickListener( new QueryListener());

}

class CreateListener implements OnClickListener{

@Override

public void onClick(View v) {

DatabaseHelper dbHelper = new DatabaseHelper(MainActivity. this , "test_db" );

SQLiteDatabase db = dbHelper.getReadableDatabase(); //执行了这一句才会创建数据库

}

class UpdateListener implements OnClickListener{

@Override

public void onClick(View v) {

DatabaseHelper dbHelper = new DatabaseHelper(MainActivity. this , "test_db" , 2 );

SQLiteDatabase db = dbHelper.getReadableDatabase(); //执行了这一句才会创建数据库

}

class InsertListener implements OnClickListener{

@Override

public void onClick(View v) {

ContentValues contentValues = new ContentValues();

contentValues.put( "id" , 1 );

contentValues.put( "name" , "umgsai" );

DatabaseHelper dbHelper = new DatabaseHelper(MainActivity. this , "test_db" , 2 );

SQLiteDatabase db = dbHelper.getWritableDatabase();

db.insert( "user" , null , contentValues);

}

class UpdateRecordListener implements OnClickListener{

@Override

public void onClick(View v) {

DatabaseHelper dbHelper = new DatabaseHelper(MainActivity. this , "test_db" , 2 );

SQLiteDatabase db = dbHelper.getWritableDatabase();

ContentValues values = new ContentValues();

values.put( "name" , "admin" );

db.update( "user" , values, "id = ?" , new String[]{ "1" });

}

class QueryListener implements OnClickListener{

@Override

public void onClick(View v) {

DatabaseHelper dbHelper = new DatabaseHelper(MainActivity. this , "test_db" , 2 );

SQLiteDatabase db = dbHelper.getReadableDatabase();

//db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy)

Cursor cursor = db.query( "user" , new String[]{ "id" , "name" }, "id = ?" , new String[]{ "1" }, null , null , "id" );

while (cursor.moveToNext()) {

String name = cursor.getString(cursor.getColumnIndex( "name" ));

System.out.println( "name>>>" + name);

}

可以通过adb shell命令来查看数据库

>abd shell

>ls -l (查看当前目录下的文件及文件夹)

>cd data (进入data目录)

>ls -l (查看当前目录下的文件及文件夹)

>cd data (进入data目录)

>ls -l (查看当前目录下的文件及文件夹)

>cd com.example.sqlite_01 (进入当前项目目录)

>ls -l (查看当前目录下的文件及文件夹)

>cd databases (进入databases目录)

>ls -l (此时就可以看到数据库文件test_db)

>sqlite3 test_db (使用sqlite打开test_db数据库)

>.schema (查看当前数据库中的表以及建表的语句)

>select * from user; (从user表中查询数据)

欢迎大家访问我的个人网站萌萌的IT人

Android学习笔记-SQLite的使用

Android学习笔记-SQLite的使用

你可能感兴趣的:(Android学习笔记-SQLite的使用)