今天學習的時候學到了ContentProvider數據共享這個東東，所以自己寫了個小例子:
我們要開發ContentProvider的話，需要創建一個類去繼承ContentProvider,里面會讓你重寫四個方法，這四個方法就是數據共享用到的方法
包括SQLite的插入、查詢、刪除。。
所以，如何共享我們的數據，就看你如何重寫這幾個方法。
下面是操作步驟，我是用Android studio寫的
1、先看工程結構
2、我們建立一個繼承ContentProvider的類，創建步驟（右鍵→new→othet→Provider）
3、ContentProvider共享的數據是SQLite里面的數據，為了方便我把創建SQLite的數據庫和創建表的操作也寫在了ContentProvider的onCreate()方法里面了
? 代碼
package provider;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 toolclass.MySQLiteOpenHelper;public class MyContentProvider extends ContentProvider {private static final String AUTHORITY = "com.example.fanlei.mycontentprovider";//地址private static final String DB_FILE = "friends.db";//數據庫名稱private static final String DB_TABLE = "friends"; //表名private static final int URI_ROOT = -1;private static final int DB_TABLE_FRIENDS = 1;public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/" + DB_TABLE);//Uri所對應的資源private static final UriMatcher uriMatcher = new UriMatcher(URI_ROOT);//檢查傳過來的Uristatic {uriMatcher.addURI(AUTHORITY,DB_TABLE,DB_TABLE_FRIENDS);}private MySQLiteOpenHelper helper;private SQLiteDatabase db;public MyContentProvider() {}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {// Implement this to handle requests to delete one or more rows.throw new UnsupportedOperationException("Not yet implemented");}@Overridepublic String getType(Uri uri) {// TODO: Implement this to handle requests for the MIME type of the data// at the given URI.throw new UnsupportedOperationException("Not yet implemented");}@Overridepublic Uri insert(Uri uri, ContentValues values) {//檢查傳過來的Uri是否是正確的，若不正確，則拋出異常if (uriMatcher.match(uri) != DB_TABLE_FRIENDS){throw new IllegalArgumentException("Unknown URI:" + uri);}Long rawId = db.insert(DB_TABLE,null,values);Uri returnUri = ContentUris.withAppendedId(CONTENT_URI,rawId);getContext().getContentResolver().notifyChange(returnUri,null);return returnUri;}@Overridepublic boolean onCreate() {helper = new MySQLiteOpenHelper(getContext(),DB_FILE,null,1);db = helper.getWritableDatabase();String sql = "CREATE TABLE IF NOT EXISTS " + DB_TABLE +"(" +"_id primary key," +"name text," +"sexId text," +"address text);";db.execSQL(sql);return true;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection,String[] selectionArgs, String sortOrder) {//檢查傳過來的Uri是否是正確的，若不正確，則拋出異常if (uriMatcher.match(uri) != DB_TABLE_FRIENDS){throw new IllegalArgumentException("Unknown URI:" + uri);}Cursor cursor = db.query(true,DB_TABLE,projection,selection,selectionArgs,null,null,sortOrder,null);cursor.setNotificationUri(getContext().getContentResolver(),uri);return cursor;}@Overridepublic int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {// TODO: Implement this to handle requests to update one or more rows.throw new UnsupportedOperationException("Not yet implemented");} }
其實，ContentProvider里面重寫的方法也是封裝了SQLiteDataBase的方法的操作，只不過他需要一個具體的Uri去指向我們具體的資源。
ContentProvider開發完成后，我在主函數里面調用了我們寫的這個ContentProvider里面的方法，布局什么的都很簡單。
我只是插入了數據，查詢數據
下面是主函數:
package com.example.fanlei.mycontentproviderdemo;import android.annotation.TargetApi; import android.content.ContentResolver; import android.content.ContentValues; import android.database.Cursor; import android.net.Uri; import android.os.Build; import android.os.Bundle; import android.support.v7.app.ActionBarActivity; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import provider.MyContentProvider;public class MainActivity2 extends ActionBarActivity {private ContentResolver contentResolver;private Uri uri;private EditText et_1,et_2,et_3;private Button btn_1,btn_2;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main_activity2);contentResolver = getContentResolver();uri = MyContentProvider.CONTENT_URI;et_1 = (EditText) findViewById(R.id.et_1);et_2 = (EditText) findViewById(R.id.et_2);et_3 = (EditText) findViewById(R.id.et_3);btn_1 = (Button) findViewById(R.id.btn_1);btn_2 = (Button) findViewById(R.id.btn_2);//加入btn_1.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {ContentValues cv = new ContentValues();//鍵值 就是 列名cv.put("name",et_1.getText().toString());cv.put("sexId",et_2.getText().toString());cv.put("address",et_3.getText().toString());contentResolver.insert(uri,cv);Toast.makeText(MainActivity2.this,"加入成功",Toast.LENGTH_SHORT).show();}});//查詢btn_2.setOnClickListener(new View.OnClickListener() {@TargetApi(Build.VERSION_CODES.JELLY_BEAN)@Overridepublic void onClick(View v) {Cursor cursor = contentResolver.query(uri,null,"name like ?",new String[]{"%23%"},null,null);while (cursor.moveToNext()){String name = cursor.getString(cursor.getColumnIndex("name"));String sexId = cursor.getString(cursor.getColumnIndex("sexId"));String address = cursor.getString(cursor.getColumnIndex("address"));Log.d("asdasd",name+"^^"+sexId+"^^"+address);}}});} }
====================================以上是簡單的開發=======================================
下面是使用我們上面的工程創建的ContentProvider
先看工程結構：
我這里建立了一個工具類去存放上一個工程Uri。
布局什么的都很簡單，就一個TextView和Button，就不放了。
下面是主函數的代碼
package com.example.fanlei.textmycontentproviderdemo;import android.content.ContentResolver; import android.database.ContentObserver; import android.database.Cursor; import android.os.Bundle; import android.os.Handler; import android.support.v7.app.ActionBarActivity; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.TextView;import provider.PeopleInfoProvider;public class MainActivity extends ActionBarActivity {private TextView tv_show;private Button button;private ContentResolver contentResolver;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);contentResolver = getContentResolver();tv_show = (TextView) findViewById(R.id.tv_show);button = (Button) findViewById(R.id.btn);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Cursor cursor = contentResolver.query(PeopleInfoProvider.CONTENT_URI,null,null,null,null);StringBuilder sb = new StringBuilder();while (cursor.moveToNext()){String name = cursor.getString(cursor.getColumnIndex("name"));String sexId = cursor.getString(cursor.getColumnIndex("sexId"));String address = cursor.getString(cursor.getColumnIndex("address"));sb.append(name).append(sexId).append(address);}tv_show.setText(sb.toString());}});contentResolver.registerContentObserver(PeopleInfoProvider.CONTENT_URI,true,new MyObserver(new Handler()));}private class MyObserver extends ContentObserver{/*** Creates a content observer.* @param handler The handler to run {@link #onChange} on, or null if none.*/public MyObserver(Handler handler) {super(handler);}@Overridepublic void onChange(boolean selfChange) {super.onChange(selfChange);Cursor cursor = contentResolver.query(PeopleInfoProvider.CONTENT_URI,null,null,null,null);StringBuilder sb = new StringBuilder();while (cursor.moveToNext()){String name = cursor.getString(cursor.getColumnIndex("name"));String sexId = cursor.getString(cursor.getColumnIndex("sexId"));String address = cursor.getString(cursor.getColumnIndex("address"));sb.append(name).append(sexId).append(address);Log.d("-----update----",sb.toString());}tv_show.setText(sb.toString());}} }
對了，這里我寫了一個內部類去繼承了ContentObserver這個類，它的作用就是當共享的數據發生改變時，就會觸發這個方法。
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