Content providers and content watchers

Source: Internet
Author: User

1, create a content provider, inherit ContentProvider, as one of the four components, ContentProvider need to be configured in the configuration file

<provider             android:name="cn.itcast.mobilesafe.provider.AppLockedProvider"              android:authorities="cn.itcast.applockprovider">        </ Provider>


 PackageCn.itcast.mobilesafe.provider;ImportCn.itcast.mobilesafe.db.dao.AppLockedDao;ImportAndroid.content.ContentProvider;Importandroid.content.ContentValues;ImportAndroid.content.UriMatcher;ImportAndroid.database.Cursor;;ImportAndroid.util.Log;/*** This is the program lock content provider * When the data in the database changes, you need to update the data in a timely manner *@authorYGL **/ Public classApplockedproviderextendsContentProvider {Private Static Final intINSERT = 10; Private Static Final intDELETE = 11; Private Static FinalString TAG = "Applockedprovider"; //defines the match code for a URI (the return value when it does not match)    PrivateApplockeddao Appdao; Private StaticUrimatcher matcher=NewUrimatcher (Urimatcher.no_match); Private StaticUri urichange=uri.parse ("Content://cn.itcast.applockprovider"); Static{Matcher.adduri ("Cn.itcast.applockprovider", "Insert", INSERT); Matcher.adduri ("Cn.itcast.applockprovider", "delete", DELETE); }         Public BooleanonCreate () {Appdao=NewApplockeddao (GetContext ()); return false; }     PublicCursor query (Uri uri, string[] projection, string selection, string[] Selectionargs, string sortOrder) { //TODO auto-generated Method Stub        return NULL; }     PublicString getType (Uri uri) {//TODO auto-generated Method Stub        return NULL; } /** When data is inserted by the content provider, the data can be inserted into the database. * @see Android.content.contentprovider#insert (, Android.content.ContentValues)*/     Publicuri insert (URI uri, contentvalues values) {intresult=Matcher.match (URI); if(result==INSERT) {String Packname= (String) values.get ("Packname"); LOG.I (TAG,"The package to change is named" +packname); //Create a content watcher to tell the content provider that the data needs to be changedAppdao.add (packname); GetContext (). Getcontentresolver (). Notifychange (Urichange,NULL); }Else{            Throw NewIllegalArgumentException ("URI address is incorrect"); }        return NULL; }/** Delete data from the database when the content provider has a data delete operation * @see Android.content.contentprovider#delete (, java.lang.String, Java.lang.string[])*/     Public intDelete (Uri Uri, String selection, string[] selectionargs) {intresult=Matcher.match (URI); if(result==DELETE) {String Packname=selectionargs[0];            Appdao.delete (Packname); GetContext (). Getcontentresolver (). Notifychange (Urichange,NULL); }Else{            Throw NewIllegalArgumentException ("URI address is incorrect"); }        return0; }     Public intupdate (URI Uri, contentvalues values, String selection, string[] selectionargs) {//TODO auto-generated Method Stub        return0; }}

3. Operation of data via content provider (

 if(Appdao.find (PackageName)) {//Appdao.delete (PackageName); //working with content providers for data            getcontentresolver (). Delete (Uri.parse ("Content://cn.itcast.applockprovider/delete"), NULL, new string[]{packagename});         Iv_applock.setimagedrawable (Getresources (). getdrawable (r.drawable.unlocked)); }Else{         //Appdao.add (PackageName); //working with content providers for data           contentvalues cv= New Contentvalues ();          Cv.put ("Packname", PackageName); Getcontentresolver (). Insert (Uri.parse ("Content://cn.itcast.applockprovider/insert" ), CV);    Iv_applock.setimagedrawable (Getresources (). getdrawable (r.drawable.locked)); }

4, the Content observer observes the content provider, detects whether the data inside is changed (

true,new myobserve (new Handler ()));
/** Content Viewer*/    Private classMyobserveextendscontentobserver{ PublicMyobserve (Handler Handler) {Super(handler); }         Public voidOnChange (BooleanSelfchange) {            Super. OnChange (Selfchange); //re-update the contents of content providers when they are found to be changedpacknameslist=Appdao.getallpacknames (); }                }

Content providers and content watchers

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