顾名思义ContentProvider就是将自己的数据提供给别人，ContentResolver则是接受别人的数据

 

自定义一个类继承ContentProvider类

public class MyContentProvider extends ContentProvider {

 private static final String AUTHORITY = "com.example.contentprovider.MyContentProvider";//记得在清单文件中注册provide并命名，name必须为该类的完整名称（加包名），添加authority（域名）【为了让别人访问】，一般以包名命名

 private static final int INSERT = 1; private static final int DELETE = 2; private static final int UPDATE = 3; private static final int QUERY = 4; MyHelp myhelp;//数据库的创建在这里就不说了 private static Context context; private ContentResolver mContent; static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH); 匹配URI类 static{//在类加载的时候添加这些URI  matcher.addURI(AUTHORITY, "insert", INSERT);  matcher.addURI(AUTHORITY, "delete", DELETE);  matcher.addURI(AUTHORITY, "update", UPDATE);  matcher.addURI(AUTHORITY, "query", QUERY);   } 

 @Override

 public int delete(Uri uri, String selection, String[] selectionArgs) {   // TODO Auto-generated method stub    if(matcher.match(uri)==DELETE)  {    SQLiteDatabase db=myhelp.getWritableDatabase();      db.delete("person", selection, selectionArgs);      mContent.notifyChange(uri, null);           }else  {    throw new IllegalArgumentException("uri not matched!");  }  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        if(matcher.match(uri)==INSERT)  {    SQLiteDatabase db=myhelp.getWritableDatabase();   db.insert("person", null, values);      mContent.notifyChange(uri, null);           }else  {    throw new IllegalArgumentException("uri not matched!");  }    return null; }

 @Override

 public boolean onCreate() {   // TODO Auto-generated method stub  context = this.getContext();  myhelp = new MyHelp(context);  mContent = context.getContentResolver();  return false; }

 @Override

 public Cursor query(Uri uri, String[] projection, String selection,   String[] selectionArgs, String sortOrder) {   // TODO Auto-generated method stub    if(matcher.match(uri)==QUERY)  {    SQLiteDatabase db=myhelp.getWritableDatabase();   db.query("person", projection, selection, selectionArgs, null, null, null);      mContent.notifyChange(uri, null);           }else  {    throw new IllegalArgumentException("uri not matched!");  }  return null; }

 @Override

 public int update(Uri uri, ContentValues values, String selection,   String[] selectionArgs) {   // TODO Auto-generated method stub  if(matcher.match(uri)==UPDATE)  {    SQLiteDatabase db=myhelp.getWritableDatabase();      db.update("person", values, selection, selectionArgs);      mContent.notifyChange(uri, null);           }else  {    throw new IllegalArgumentException("uri not matched!");  }  return 0; }

}

 

在另一个测试应用中，这两个不是一个应用，用于访问上面的应用，要用到ContentResolver

 

public class MainActivity extends Activity {

 private static final String AUTHORITY = "com.example.contentprovider.MyContentProvider"; ContentResolver mContent;     @Override    protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                mContent = getContentResolver();                mContent.registerContentObserver(Uri.parse("content://"+AUTHORITY), true,new MyObserver(new Handler()));//注册监视，观察数据是否发生改变（可以不加该方法）            }        class MyObserver extends ContentObserver    {

  public MyObserver(Handler handler) {

   super(handler);   // TODO Auto-generated constructor stub     }

  @Override

  public void onChange(boolean selfChange) {    // TODO Auto-generated method stub   super.onChange(selfChange);   Toast.makeText(MainActivity.this, "is changed...", 0).show();  }           }        public void insert(View v)//按钮的点击事件，在布局文件中已经定义    {      Uri uri = Uri.parse("content://" + AUTHORITY + "/insert");

  ContentValues cv = new ContentValues();

  cv.put("id", 4);

  cv.put("name", "tom");  mContent.insert(uri, cv);    }        public void delete(View v)    {      Uri uri = Uri.parse("content://" + AUTHORITY + "/delete");     mContent.delete(uri, "id=?", new String[]{String.valueOf(4)});    }        public void update(View v)    {      Uri uri = Uri.parse("content://" + AUTHORITY + "/update");     ContentValues cv = new ContentValues();

  cv.put("name", "lily");

  mContent.update(uri, cv, "id=?",

    new String[] { String.valueOf(2) });    }        public void query(View v)    {      Uri uri = Uri.parse("content://" + AUTHORITY + "/query");     mContent.query(uri, null, null, null, null);    }