MyContentProvider

 package com.example.shad_fnst.mycontentprovider;

 import android.app.Activity;
 import android.content.ContentResolver;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.Toast;

 public class MainActivity extends Activity{

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
     }

     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         // Inflate the menu; this adds items to the action bar if it is present.
         getMenuInflater().inflate(R.menu.menu_main, menu);
         return true;
     }

     public void onClickAddName(View view){
         ContentValues values = new ContentValues();

         values.put(StudentsProvider.NAME,
                 ((EditText)findViewById(R.id.txtName)).getText().toString());
         values.put(StudentsProvider.GRADE,
                 ((EditText)findViewById(R.id.txtGrade)).getText().toString());
         Uri uri = getContentResolver().insert(StudentsProvider.CONTENT_URI, values);
         Toast.makeText(getBaseContext(),
                 uri.toString(), Toast.LENGTH_LONG).show();
     }

     public void onClickRetrieveStudents(View view){
         // Retrieve student records
         String URL = "content://com.example.provider.College/students";
         Uri students = Uri.parse(URL);
         //Cursor c = managedQuery(students, null, null, null, "name");
         ContentResolver contentResolver = getContentResolver();
         Cursor cursor = contentResolver.query(StudentsProvider.CONTENT_URI, null, null, null, "name");
         if(cursor.moveToFirst()){
             do{
                 String message = cursor.getString(cursor.getColumnIndex(StudentsProvider._ID)) + ", " +
                         cursor.getString(cursor.getColumnIndex(StudentsProvider.NAME)) + ", " +
                         cursor.getString(cursor.getColumnIndex(StudentsProvider.GRADE));
                 Toast.makeText(this,message, Toast.LENGTH_SHORT).show();
             }while(cursor.moveToNext());
         }
         cursor.close();
     }
 }

MainActivity.java

 package com.example.shad_fnst.mycontentprovider;

 import android.content.ContentProvider;
 import android.content.ContentUris;
 import android.content.ContentValues;
 import android.content.Context;
 import android.content.UriMatcher;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.database.sqlite.SQLiteQueryBuilder;
 import android.net.Uri;
 import android.text.TextUtils;

 import java.sql.SQLException;
 import java.util.HashMap;

 /**
  * Created by shad-fnst on 2015/07/27.
  */
 public class StudentsProvider extends ContentProvider{

     static final String PROVIDER_NAME = "com.example.provider.College";
     static final String URL = "content://" + PROVIDER_NAME + "/students";
     static final Uri CONTENT_URI = Uri.parse(URL);

     static final String _ID = "id";
     static final String NAME = "name";
     static final String GRADE = "grade";

     private static HashMap<String, String> STUDENTS_PROJECTION_MAP;

     static final int STUDENTS = 1;
     static final int STUDENT_ID = 2;

     static final UriMatcher uriMatcher;
     static {
         uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
         uriMatcher.addURI(PROVIDER_NAME, "students", STUDENTS);
         uriMatcher.addURI(PROVIDER_NAME, "students/#", STUDENT_ID);
     }

     /**
      * Database specific constant declarations
      */
     private SQLiteDatabase db;
     static final String DATABASE_NAME = "College";
     static final String STUDENTS_TABLE_NAME = "students";
     static final int DATABASE_VERSION = 1;
     static final String CREATE_DB_TABLE =
             " CREATE TABLE " + STUDENTS_TABLE_NAME +
                     " ( id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                     " name TEXT NOT NULL, " +
                     " grade TEXT NOT NULL);";

     /**
      * Helper class that actually creates and manages
      * the provider's underlying data repository.
      * @return
      */
     private static class DatabaseHelper extends SQLiteOpenHelper{
         DatabaseHelper(Context context){

             super(context, DATABASE_NAME, null, DATABASE_VERSION);
         }

         @Override
         public void onCreate(SQLiteDatabase db){
             db.execSQL(CREATE_DB_TABLE);
         }

         @Override
         public void onUpgrade(SQLiteDatabase db, int oldVersion,
                               int newVersion){
             db.execSQL("DROP TABLE IF EXISTS " + STUDENTS_TABLE_NAME);
             onCreate(db);
         }
     }

     @Override
     public boolean onCreate(){
         Context context = getContext();
         DatabaseHelper dbHelper =new DatabaseHelper(context);
         /**
          * Create a write able database which will trigger its
          * creation if it doesn't already exist.
          */
         db = dbHelper.getWritableDatabase();
         return (db == null) ? false:true;
     }

     @Override
     public Uri insert(Uri uri, ContentValues values){
         /**
          * Add a new student record
          */
         long rowID = db.insert(STUDENTS_TABLE_NAME, "", values);
         /**
          * If record is added successfully
          */
         if(rowID > 0){
             Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
             getContext().getContentResolver().notifyChange(_uri, null);     //通知其他ContentObserver数据改变
             return uri;
         }
         //throw new SQLException("Failed to add a record into " + uri);
         return uri;
     }

     @Override
     public Cursor query(Uri uri, String[] projection, String selection,
                         String[] selectionArgs, String sortOrder){
         SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
         qb.setTables(STUDENTS_TABLE_NAME);

         switch (uriMatcher.match(uri)){
             case STUDENTS:
                 qb.setProjectionMap(STUDENTS_PROJECTION_MAP);
                 break;
             case STUDENT_ID:
                 qb.appendWhere( _ID + "=" + uri.getPathSegments().get(1));
                 break;
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
         if(sortOrder == null || sortOrder == ""){
             sortOrder =NAME;
         }
         Cursor c = qb.query(db, projection, selection, selectionArgs,
                 null, null, sortOrder);
         c.setNotificationUri(getContext().getContentResolver(), uri);

         return c;
     }

 /*
     @Override
     public Cursor query(Uri uri, String[] projection, String selection,
                         String[] selectionArgs, String sortOrder){
         //SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
         //qb.setTables(STUDENTS_TABLE_NAME);

         Cursor cursor = null;
         switch (uriMatcher.match(uri)){
             case STUDENTS:
                 cursor = db.query(STUDENTS_TABLE_NAME, projection, selection, selectionArgs, null, null, null);
                 break;
             case STUDENT_ID:
                 //qb.appendWhere( _ID + "=" + uri.getPathSegments().get(1));
                 break;
         }

         return cursor;
     }
     */

     @Override
     public int delete(Uri uri, String selection, String[] selectionArgs){
         int count = 0;

         switch (uriMatcher.match(uri)){
             case STUDENTS:
                 count = db.delete(STUDENTS_TABLE_NAME, selection, selectionArgs);
                 break;
             case STUDENT_ID:
                 String id = uri.getPathSegments().get(1);
                 count = db.delete(STUDENTS_TABLE_NAME, _ID + " = " + id +
                         (!TextUtils.isEmpty(selection) ? " AND (" +
                         selection + ')' : ""), selectionArgs);
                 break;
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }

         getContext().getContentResolver().notifyChange(uri, null);
         return count;
     }

     @Override
     public int update(Uri uri, ContentValues values, String selection,
                       String[] selectionArgs){
         int count = 0;

         switch (uriMatcher.match(uri)){
             case STUDENTS:
                 count = db.update(STUDENTS_TABLE_NAME, values, selection, selectionArgs);
                 break;
             case STUDENT_ID:
                 count = db.update(STUDENTS_TABLE_NAME, values, _ID +
                         " = " +uri.getPathSegments().get(1) +
                         (!TextUtils.isEmpty(selection) ? " AND (" +
                         selection + ')' : ""), selectionArgs);
                 break;
             default:
                 throw new IllegalArgumentException("Unknown URI " + uri);
         }
         getContext().getContentResolver().notifyChange(uri, null);
         return  count;
     }

     @Override
     public String getType(Uri uri){
         switch (uriMatcher.match(uri)){
             /**
              * Get all students records
              */
             case STUDENTS:
                 return "vnd.android.cursor.dir/vnd.example.students";
             /**
              * Get a particular student
              */
             case STUDENT_ID:
                 return "vnd.android.cursor.item/vnd.example.students";
             default:
                 throw new IllegalArgumentException("Unsupported URI: " + uri);

         }
     }
 }

StudentsProvider.java

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.shad_fnst.mycontentprovider"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="17" >
     </uses-sdk>

     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name="com.example.shad_fnst.mycontentprovider.MainActivity"
             android:label="@string/app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>

         <provider
             android:authorities="com.example.provider.College"
             android:name=".StudentsProvider">
         </provider>

     </application>

 </manifest>

AndroidMainfest.xml

 <LinearLayout xmlns: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:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     android:paddingBottom="@dimen/activity_vertical_margin"
     android:orientation="vertical"
     tools:context=".MainActivity">

     <TextView
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="Name" />
     <EditText
         android:id="@+id/txtName"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" />

     <TextView
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="Grade" />
     <EditText
         android:id="@+id/txtGrade"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content" />

     <Button
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="Add Name"
         android:id="@+id/btnAdd"
         android:onClick="onClickAddName" />

     <Button
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:text="Retrieve Students"
         android:id="@+id/btnRetrieve"
         android:onClick="onClickRetrieveStudents" />

 </LinearLayout>

activity_main.xml