Android -- ContentProvider cross-Program Data Access

Two programs A and B, and program A have two classes. One inherits Activity, and the other inherits ContentProviderB. The other inherits Activity and creates A database in program, create two tables in the database to enable program B to access the data in program A to inherit the Activity class: Create A database and create A table in the database, insert data in the table [html] package cn. mrzhu. test24; import android. app. activity; import android. content. contentValues; import android. database. sqlite. SQLiteDatabase; import android. OS. bundle; public class Provider extends Activity {/** Called when the activity is first created. * // @ Override public void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. main); // create a database SQLiteDatabase db = openOrCreateDatabase ("test24.db", MODE_PRIVATE, null); // create a table db.exe cSQL ("create table test1 (_ id integer, name varchar (20), age integer) "); db.exe cSQL (" create table test2 (_ id integer, name varchar (20), age integer )"); // Add data ContentValues values = new ContentValues (); values to the test1 table. put ("name", "zhangsan"); values. put ("age", 30); db. insert ("test1", "name", values); values. clear (); values. put ("name", "lisi"); values. put ("age", 40); db. insert ("test1", "name", values); // Add data values to table test2. clear (); values. put ("name", "Peter"); values. put ("age", 20); db. insert ("test2", "name", values); values. clear (); values. put ("name", "Mike"); values. put ("age", 25); db. insert ("test2", "name", values) ;}} class that inherits ContentProvider in program A: AndroidManifest. register [html] <provider android: name = "MyContentProvider" android: authorities = "cn. mrzhu. test24 "> </provider> android: authorities =" cn. mrzhu. test24 "provides A uri for access to program B. Only program B can access data in program A [html] package cn. mrzhu. test24; import android. content. contentProvider; import android. content. contentValues; import android. content. context; import android. content. uriMatcher; import android. database. cursor; import android. database. sqlite. SQLiteDatabase; import android.net. uri; public class MyContentProvider extends ContentProvider {// Uri filter. This filter can be used to retrieve the UriMatcher um; static final String AUTHORITY = "cn. mrzhu. test24 "; @ Override public int delete (Uri uri, String selection, String [] selectionArgs) {return 0 ;}@ Override public String getType (Uri uri) {// TODO Auto-generated method stub return null;} @ Override public Uri insert (Uri uri, ContentValues values) {// TODO Auto-generated method stub return null ;} @ Override public boolean onCreate () {// initialize the filter um = new UriMatcher (UriMatcher. NO_MATCH); // Add the content to be filtered. The uri sent from other programs is filtered. If the field is test1, the code is 1 um. addURI (AUTHORITY, "test1", 1); um. addURI (AUTHORITY, "test2", 2); return false ;}@ Override public Cursor query (Uri uri, String [] projection, String selection, String [] selectionArgs, String sortOrder) {SQLiteDatabase db = getContext (). openOrCreateDatabase ("test24.db", Context. MODE_PRIVATE, null); Cursor cs = null; // filter the uri and obtain the returned value int code = um. match (uri); // execute different query statements switch (code) {case 1: cs = db based on different return values. rawQuery ("select * from test1", null); break; case 2: cs = db. rawQuery ("select * from test2", null); break;} // After the query statement is executed, return the return cs;} @ Override public int update (Uri uri, contentValues values, String selection, String [] selectionArgs) {// TODO Auto-generated method stub return 0 ;}} B Program: access the data [html] package cn of program A through the uri provided by the class inheriting ContentProvider in program. mrzhu. test24x; import android. app. activity; import android. content. contentResolver; import android. database. cursor; import android.net. uri; import android. OS. bundle; import android. util. log; public class Main extends Activity {/** Called when the activity is first created. * // @ Override public void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. main); // obtain the ContentResolver object ContentResolver cr = getContentResolver (); // specify the uri and specify the table Uri = uri for the operation. parse ("content: // cn. mrzhu. test24/test1 "); // run the query method to return a result set Cursor cs = cr. query (uri, null, null); // traverses the result set and retrieves the data while (cs. moveToNext () {Log. I ("System. out "," _ id "+ cs. getInt (0) + "name" + cs. getString (1) + "age" + cs. getInt (2 ));}}}