(Android Review) Basic use of ContentProvider

1. Some databases are not available on the outside.
2, ContentProvider let a program in the data can let the B program use
3, ContentProvider is mainly shared data. Contentobserver can be added to observe changes in the data
4. Authorities in <provider/> is mainly used to distinguish different provider
5, Content://cn.itcast.aqlite.provider ((/person)/id)
Analytical:
content://-----> Fixed notation, must have
Cn.itcast.aqlite.provider:------"Application name for this application
Person: Table Name


6, a application through the B application of the ContentProvider Access B application Database


7, the use of ContentProvider query several ways:
1) without table name
2) only representative name

3) with table name and ID

This is the case with the previous example.

1, Sqliteprovider

Package Com.example.provider;import Com.example.sqlitetest.dbopenhelper;import Android.content.ContentProvider; Import Android.content.contenturis;import Android.content.contentvalues;import Android.content.urimatcher;import Android.database.cursor;import Android.database.sqlite.sqlitedatabase;import Android.net.Uri;import Android.widget.switch;public class Sqliteprovider extends ContentProvider {private Urimatcher matcher;private Dbopenhelper helper;public static final int person = 1;public static final int person_id = 2;private Sqlitedatabase db; @Ov Erridepublic Boolean onCreate () {//is executed on first boot, will reside in the background for a long time, and will not be executed unless killed. Matcher = new Urimatcher (urimatcher.no_match); Matcher.adduri ("Com.example.provider", "person", person);//Set a URI, If matched to person, returns 1matcher.adduri ("Com.example.provider", "person/#", person_id); helper = new Dbopenhelper (GetContext ( )); return true;} @Overridepublic Cursor query (Uri uri, string[] projection, string selection,string[] Selectionargs, string sortOrder) {Sy Stem.out.println ("--------->query");d B = helper.getreadabledatabase (); switch (Matcher.match (URI)) {case Person_id:long ID = Contenturis.parseid (URI);//Gets the URI of the last id//selection = "id=" + ID; Add the ID to the query condition. This method only solves the condition of the query with ID only selection = Selection = = null? "Id=" + id:selection+ "and id=" + id;//This time can process the query conditions may not only have the case of the ID cases Person:return db.query ("person", projection, Selec tion, selectionargs,null, null, SortOrder);d efault:throw new RuntimeException ("Uri does not match");}} @Overridepublic String getType (Uri uri) {switch (Matcher.match (URI)) {case Person_id:return "with ID. Operation Specifies person"; Person:return "no ID. Operation All person";d efault:break;} return null;} @Overridepublic uri insert (URI uri, contentvalues values) {sqlitedatabase db = helper.getwritabledatabase (); switch ( Matcher.match (URI)) {case Person:long id = db.insert ("person", "id", values);//insert record, get Idreturn Contenturis.withappendedid (URI, id);d efault:throw new RuntimeException ("indicates illegal");}} @Overridepublic int Delete (URI Uri, String selection, string[] SelectioNargs) {Sqlitedatabase db = helper.getwritabledatabase (); switch (Matcher.match (URI)) {case Person_id:long ID = Contenturis.parseid (URI);//Gets the URI of the last id//selection = "id=" + ID; Add the ID to the query condition. This method only solves the condition of the query with ID only selection = Selection = = null? "Id=" + id:selection+ "and id=" + id;//This time can process the query conditions may not only have the case of the ID cases Person:return db.delete ("person", selection, Selec Tionargs);d efault:throw new RuntimeException ("Uri does not match");}} /** * Sometimes it may not change ... * don't know why * * @Overridepublic int update (URI uri, contentvalues values, String selection,string[] Selecti Onargs) {Sqlitedatabase db = helper.getwritabledatabase (); switch (Matcher.match (URI)) {case Person_id:long ID = Contenturis.parseid (URI);//Gets the URI of the last id//selection = "id=" + ID; Add the ID to the query condition. This method only solves the condition of the query with ID only selection = Selection = = null? "Id=" + id:selection+ "and id=" + id;//This time can process the query conditions may not only have the case of the ID cases Person://return db.delete ("person", selection, SEL Ectionargs); return db.update ("person", values, Selection, Selectionargs);d efault:throw new RuNtimeexception ("Uri cannot Match");}} @Override//public int update (URI uri, contentvalues values, String selection, string[] Selectionargs) {// Sqlitedatabase db = Helper.getwritabledatabase ()//switch (Matcher.match (URI)) {//matches incoming uri//case person_id://with a match Long id = Contenturis.parseid (URI);//Get URI Last id//selection = Selection = = null? "Id=" + id:selection + "and id=" + id;//Build Query conditions//case person://return db.update ("person", values, selection, Selectiona RGS);//default://throw new RuntimeException ("URI not recognized:" + URI);//}//}}

The other code in this example is actually the same as before. Thanks, ContentProvider, remember to add the appropriate registration code in the early androidmanifest.xml:

<provider android:name= "Com.example.provider.SQLiteProvider"            android:authorities= "Com.example.provider"            />

2, b application of the Providertest

Package Com.example.test;import Com.example.pojo.person;import Android.content.contentresolver;import Android.content.contentvalues;import Android.database.cursor;import Android.net.uri;import Android.test.androidtestcase;public class Providertest extends Androidtestcase {/** * The execution order of this program: *. class, Dex-&gt ;. apk, install, open process (open main thread), * Create a Providertest object (the way the member variable is here GetContext (), when there is no GetContext ()), SetContext () Test method, GetContext () */public void Test1 () {Contentresolver resolver = GetContext (). Getcontentresolver ();//Note that It is not possible to speak resolver as a global variable contentvalues values = new Contentvalues (); Uri parse = uri.parse ("Content://com.example.provider"); Resolver.insert (parse, values); Resolver.delete (parse, NULL, NULL); Resolver.update (parse, values, NULL, NULL); Resolver.query (parse, NULL, NULL, NULL, NULL);/** * content:// Com.example.provider: Decision to access the application's database */}public void Testquery () {Contentresolver resolver = GetContext (). Getcontentresolver ();/** * Content://com.example.proVider/person * content://Fixed notation * com.example.provider:authorities * Person: Table name *///uri Uri = Uri.parse ("Content://com.exa Mple.provider/person ");//query Uri URI = Uri.parse (" CONTENT://COM.EXAMPLE.PROVIDER/PERSON/10 ") without ID;//with ID for query// Cursor C = resolver.query (URI, NULL, "ID>?", New string[]{"" "}, NULL); Cursor C = resolver.query (URI, NULL, NULL, NULL, NULL), while (C.movetonext ()) {person p = new Person (c.getint (0), C.getstrin G (1), C.getint (2)); SYSTEM.OUT.PRINTLN (P);}} public void Testinsert () {Contentresolver resolver = GetContext (). Getcontentresolver (); Uri uri = uri.parse ("Content://com.example.provider/person"); Contentvalues values = new Contentvalues (), Values.put ("name", "Li Kaifu"), Values.put ("balance", 12345); Uri Uri1 = Resolver.insert (URI, values);//Insert data and get UriSystem.out.println (URI1) of the data;} public void Testupdate () {Contentresolver resolver = GetContext (). Getcontentresolver ();//uri Uri = Uri.parse ("content:/ /com.example.provider/person/102 ");//Specify ID, modify only one record URI uri = Uri.parse (" Content:Com.example.provider/person ");//Do not specify an ID, modify the entire table contentvalues values = new Contentvalues (); Values.put (" Name "," Kaifu Lili "); Values.put (" balance ", 9999); Resolver.update (URI, values, NULL, NULL);} public void Testdelete () {Contentresolver resolver = GetContext (). Getcontentresolver (); Uri uri = uri.parse ("content://com.example.provider/person/104"); Resolver.delete (URI, NULL, NULL);} public void Testgettype () {Contentresolver resolver = GetContext (). Getcontentresolver (); String type1 = Resolver.gettype (Uri.parse ("Content://com.example.provider/person"));    String type2 = Resolver.gettype (Uri.parse ("content://com.example.provider/person/102")); System.out.println (type1); System.out.println (type2);}}

SOURCE Download: