sqlite实例
来源:互联网 发布:乌鲁木齐网络问政平台 编辑:程序博客网 时间:2024/06/05 03:56
SQLite是Android平台软件开发中会经常用到的数据库产品,作为一款轻型数据库,SQLite的设计目标就是是嵌入式的,而且目前已经在很多嵌入式产品中使用了它,它占用资源非常的低,在嵌入式设备中,可能只需要几百K的内存就够。
废话不多说,让我们来写一个sqlite的demo。
首先建立一个项目 目录如下:
在这里 为了便于测试,我用了junit测试,要想用junit测试,首先要在在AndroidManifest.xml中加入下面粗体部分的代码:
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="cn.com.karl.db"
- android:versionCode="1"
- android:versionName="1.0" >
- <uses-sdk android:minSdkVersion="8" />
- <application
- android:icon="@drawable/ic_launcher"
- android:label="@string/app_name" >
- <span style="font-weight: bold;"> <uses-library android:name="android.test.runner" /></span>
- <activity
- android:label="@string/app_name"
- android:name=".DbDemoActivity" >
- <intent-filter >
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- </application>
- <span style="font-weight: bold;"> <instrumentation android:name="android.test.InstrumentationTestRunner"
- android:targetPackage="cn.com.karl.db" android:label="Tests for My App" /></span>
- </manifest>
接下来在service包下建立DBOpenHandler类继承SQLiteOpenHelper
- public class DBOpenHandler extends SQLiteOpenHelper {
- public DBOpenHandler(Context context) {
- super(context, "person.db", null, 1);
- }
- @Override
- public void onCreate(SQLiteDatabase db) {
- db.execSQL("create table person(id integer primary key autoincrement,name varchar(20))");
- }
- @Override
- public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
- // TODO Auto-generated method stub
- }
- }
然后编写我们的增删改查的核心类
- public class PersonService {
- private DBOpenHandler dbOpenHandler;
- public PersonService(Context context){
- this.dbOpenHandler=new DBOpenHandler(context);
- }
- public void save(Person person){
- SQLiteDatabase db=dbOpenHandler.getWritableDatabase();
- db.execSQL("insert into person (name) values(?)", new Object[]{person.getName()});
- }
- public void delete(Integer id){
- SQLiteDatabase db=dbOpenHandler.getWritableDatabase();
- db.execSQL("delete from person where id=", new Object[]{id.toString()});
- }
- public void update(Person person){
- SQLiteDatabase db=dbOpenHandler.getWritableDatabase();
- db.execSQL("update person set name=? where" +
- " id=?", new Object[]{person.getName(),person.getId()});
- }
- public Person find(Integer id){
- Person person=null;
- SQLiteDatabase db=dbOpenHandler.getReadableDatabase();
- Cursor cursor=db.rawQuery("select * from person where id=?", new String[]{id.toString()});
- if(cursor.moveToFirst()) {
- person=new Person();
- person.setId(cursor.getInt(cursor.getColumnIndex("id")));
- person.setName(cursor.getString(cursor.getColumnIndex("name")));
- }
- return person;
- }
- public List<Person> findAll(Integer offset,Integer maxLength){
- List<Person> lists=new ArrayList<Person>();
- Person person=null;
- SQLiteDatabase db=dbOpenHandler.getReadableDatabase();
- Cursor cursor=db.rawQuery("select * from person limit ?,?", new String[]{offset.toString(),maxLength.toString()});
- while(cursor.moveToNext()){
- person=new Person();
- person.setId(cursor.getInt(cursor.getColumnIndex("id")));
- person.setName(cursor.getString(cursor.getColumnIndex("name")));
- lists.add(person);
- }
- return lists;
- }
- public long getCount(){
- SQLiteDatabase db=dbOpenHandler.getReadableDatabase();
- Cursor cursor=db.rawQuery("select count(*) from person ", null );
- cursor.moveToFirst();
- return cursor.getLong(0);
- }
- }
- public class Person {
- private int id;
- private String name;
- public int getId() {
- return id;
- }
- public void setId(int id) {
- this.id = id;
- }
- public String getName() {
- return name;
- }
- public void setName(String name) {
- this.name = name;
- }
- }
- public class DBOpenHandlerTest extends AndroidTestCase {
- private static final String TAG = "DBOpenHandlerTest";
- public void testCreate(){
- DBOpenHandler dbHandler=new DBOpenHandler(this.getContext());
- dbHandler.getWritableDatabase();
- }
- public void testSave() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- Person person = new Person();
- person.setName("xiaoming");
- personService.save(person);
- person = new Person();
- person.setName("xiaoli");
- personService.save(person);
- person = new Person();
- person.setName("xiaowang");
- personService.save(person);
- person = new Person();
- person.setName("xiaozhang");
- personService.save(person);
- }
- public void testUpate() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- Person person = personService.find(1);
- person.setName("lili");
- personService.update(person);
- }
- public void testDelete() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- personService.delete(1);
- }
- public void testFind() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- Person person = personService.find(1);
- Log.i(TAG, person.getName());
- }
- public void testFindAll() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- List<Person> persons = personService.findAll(0, 3);
- for(Person person : persons){
- Log.i(TAG, person.getName());
- }
- }
- public void testGetCount() throws Throwable{
- PersonService personService = new PersonService(this.getContext());
- Log.i(TAG, personService.getCount()+"");
- }
- }
会在上面的包下创建一个数据库person
然后测试 testSave方法 ,会在这张表中插入三条数据。
最后测试 testFindAll方法 ,接着看一下logcat控制台打印的信息:
OK! 已经打印出来了,其他测试不再复述。
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