Implementation of the Android content provider

Then the above "Android content provider profile" is further implemented by content providers.

Each content provider class uses a URI (Universal Resource Identifier, Universal Resource Identifier) as a separate identity, in the form of: content://com.example.app.provider/ Table1. Other applications access different content providers through different URIs and get/manipulate the data inside.

For example, in this project, it corresponds to the following URI:

Actions added by Content://com.wuyudong.db.personprovider/insert
Content://com.wuyudong.db.personprovider/delete deleted actions
Content://com.wuyudong.db.personprovider/update Updated operations
Content://com.wuyudong.db.personprovider/query the operation of the query

To add code in Persondbprovider.java:

 Packagecom.wuyudong.db;ImportAndroid.content.ContentProvider;Importandroid.content.ContentValues;ImportAndroid.content.UriMatcher;ImportAndroid.database.Cursor;Importandroid.database.sqlite.SQLiteDatabase;ImportAndroid.net.Uri; Public classPersondbproviderextendsContentProvider {//defines a URI that matches the URI to match if the path does not meet the conditional return-1    Private StaticUrimatcher Matcher =NewUrimatcher (Urimatcher.no_match); Private Static Final intINSERT = 1; Private Static Final intDELETE = 2; Private Static Final intUPDATE = 3; Private Static Final intQUERY = 4; PrivatePersonsqliteopenhelper Helper; Static {        //add a set of matching rules Com.wuyudong.db.personproviderMatcher.adduri ("Com.wuyudong.db.personprovider", "Insert", INSERT); Matcher.adduri ("Com.wuyudong.db.personprovider", "delete", DELETE); Matcher.adduri ("Com.wuyudong.db.personprovider", "Update", UPDATE); Matcher.adduri ("Com.wuyudong.db.personprovider", "Query", QUERY); } @Override Public BooleanonCreate () {helper=NewPersonsqliteopenhelper (GetContext ()); return false; } @Override PublicCursor query (Uri uri, string[] projection, string selection, string[] Selectionargs, string sortOrder) { if(Matcher.match (uri) = =QUERY) {            //returns the result set of the querySqlitedatabase db =helper.getreadabledatabase (); Cursor Cursor= Db.query ("person", projection, selection, Selectionargs,NULL,NULL, SortOrder); returncursor; } Else {            Throw NewIllegalArgumentException ("Path mismatch, cannot perform query operation"); }} @Override PublicString getType (Uri uri) {//TODO auto-generated Method Stub        return NULL; } @Override Publicuri insert (URI uri, contentvalues values) {//TODO auto-generated Method Stub        return NULL; } @Override Public intDelete (Uri Uri, String selection, string[] selectionargs) {//TODO auto-generated Method Stub        return0; } @Override Public intupdate (URI Uri, contentvalues values, String selection, string[] selectionargs) {//TODO auto-generated Method Stub        return0; }}

Create a new project named other with the following layout:

<Relativelayoutxmlns: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"Tools:context=". Mainactivity " >    <ButtonAndroid:onclick= "click"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "read data from DB" /></Relativelayout>

Click on the button to kill the com.wuyudong.db process

When you click the button, the com.wuyudong.db process runs again, and the data in the person table in the database is printed

Further refine other operations, modify layouts

<LinearLayoutxmlns: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 " >    <ButtonAndroid:onclick= "click"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "read data from DB" />     <ButtonAndroid:onclick= "Delete"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "Delete data from DB" />      <ButtonAndroid:onclick= "Update"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "Modify data for db" />       <ButtonAndroid:onclick= "Insert"Android:layout_width= "Wrap_content"Android:layout_height= "Wrap_content"Android:text= "Add DB data" /></LinearLayout>

Next implement the other methods in Persondbprovider

 Packagecom.wuyudong.db;ImportAndroid.content.ContentProvider;Importandroid.content.ContentValues;ImportAndroid.content.UriMatcher;ImportAndroid.database.Cursor;Importandroid.database.sqlite.SQLiteDatabase;ImportAndroid.net.Uri; Public classPersondbproviderextendsContentProvider {//defines a URI that matches the URI to match if the path does not meet the conditional return-1    Private StaticUrimatcher Matcher =NewUrimatcher (Urimatcher.no_match); Private Static Final intINSERT = 1; Private Static Final intDELETE = 2; Private Static Final intUPDATE = 3; Private Static Final intQUERY = 4; PrivatePersonsqliteopenhelper Helper; Static {        //add a set of matching rules Com.wuyudong.db.personproviderMatcher.adduri ("Com.wuyudong.db.personprovider", "Insert", INSERT); Matcher.adduri ("Com.wuyudong.db.personprovider", "delete", DELETE); Matcher.adduri ("Com.wuyudong.db.personprovider", "Update", UPDATE); Matcher.adduri ("Com.wuyudong.db.personprovider", "Query", QUERY); } @Override Public BooleanonCreate () {helper=NewPersonsqliteopenhelper (GetContext ()); return false; } @Override PublicCursor query (Uri uri, string[] projection, string selection, string[] Selectionargs, string sortOrder) { if(Matcher.match (uri) = =QUERY) {            //returns the result set of the querySqlitedatabase db =helper.getreadabledatabase (); Cursor Cursor= Db.query ("Person", projection, selection, Selectionargs,NULL,NULL, SortOrder); returncursor; } Else {            Throw NewIllegalArgumentException ("Path mismatch, cannot perform query operation"); }} @Override PublicString getType (Uri uri) {//TODO auto-generated Method Stub        return NULL; } @Override Publicuri insert (URI uri, contentvalues values) {if(Matcher.match (uri) = =INSERT) {            //returns the result set of the querySqlitedatabase db =helper.getwritabledatabase (); Db.insert ("Person",NULL, values); } Else {            Throw NewIllegalArgumentException ("Path mismatch, cannot perform insert operation"); }        return NULL; } @Override Public intDelete (Uri Uri, String selection, string[] selectionargs) {if(Matcher.match (uri) = =DELETE) {            //returns the result set of the querySqlitedatabase db =helper.getwritabledatabase (); Db.delete ("Person", Selection, Selectionargs); } Else {            Throw NewIllegalArgumentException ("Path mismatch, cannot perform delete operation"); }        return0; } @Override Public intupdate (URI Uri, contentvalues values, String selection, string[] selectionargs) {if(Matcher.match (uri) = =UPDATE) {            //returns the result set of the querySqlitedatabase db =helper.getwritabledatabase (); Db.update ("Person", values, selection, Selectionargs); } Else {            Throw NewIllegalArgumentException ("Path mismatch, cannot perform modify operation"); }        return0; }}

Implementation of the Android content provider