转载自:http://blog.csdn.net/woshixuye/article/details/8281385
一、提出需求
有A,B,C三个应用,B中的数据需要被共享,所以B中定义了内容提供者ContentProvider;A应用修改了B应用的数据,插入了一条数据。有这样一个需求,此时C应用需要得到数据被修改的通知并处理相应操作。
二、示例代码
A应用 /** * 对内容提供者进行操作 * * @author XY * */ public class MainActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } public void insert(View v) { Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person"); ContentResolver resolver = this.getContentResolver(); ContentValues values = new ContentValues(); values.put("name", "xy_new_new"); values.put("phone", "xy_new_111"); resolver.insert(uri, values); } } B应用 package cn.xy.cotentProvider.app.providers; 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.util.Log; import cn.xy.cotentProvider.service.DBOpeningHelper; /** * @author XY * */ public class PersonProvider extends ContentProvider { private DBOpeningHelper dbHelper; // 若不匹配采用UriMatcher.NO_MATCH(-1)返回 private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH); // 匹配码 private static final int CODE_NOPARAM = 1; private static final int CODE_PARAM = 2; static { // 对等待匹配的URI进行匹配操作,必须符合cn.xyCompany.providers.personProvider/person格式 // 匹配返回CODE_NOPARAM,不匹配返回-1 MATCHER.addURI("cn.xyCompany.providers.personProvider", "person", CODE_NOPARAM); // #表示数字 cn.xyCompany.providers.personProvider/person/10 // 匹配返回CODE_PARAM,不匹配返回-1 MATCHER.addURI("cn.xyCompany.providers.personProvider", "person/#", CODE_PARAM); } @Override public boolean onCreate() { dbHelper = new DBOpeningHelper(this.getContext()); return true; } /** * 外部应用向本应用插入数据 */ @Override public Uri insert(Uri uri, ContentValues values) { SQLiteDatabase db = dbHelper.getWritableDatabase(); switch (MATCHER.match(uri)) { case CODE_NOPARAM: // 若主键值是自增长的id值则返回值为主键值,否则为行号,但行号并不是RecNo列 long id = db.insert("person", "name", values); Uri insertUri = ContentUris.withAppendedId(uri, id); // 发出变化通知(非必须)设监听者为null。 // 若设置某个监听者则不管有多少个监听者,该监听者一定可以获得该通知 getContext().getContentResolver().notifyChange(uri, null); return insertUri; default: throw new IllegalArgumentException("this is unkown uri:" + uri); } } ...... } C应用 package cn.xt.contentProvider.lisenter; import android.app.Activity; import android.content.ContentResolver; import android.database.ContentObserver; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.util.Log; public class MainActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person"); ContentResolver resolver = this.getContentResolver(); resolver.registerContentObserver(uri, true, new PersonContentObserver(new Handler())); } private class PersonContentObserver extends ContentObserver { public PersonContentObserver(Handler handler) { super(handler); } // 得到数据的变化通知,该方法只能粗略知道数据的改变,并不能判断是哪个业务操作进行的改变 @Override public void onChange(boolean selfChange) { // select * from person order by id desc limit 1 // 取得最近插入的值(序号大——>小并取第一个) Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person"); ContentResolver resolver = MainActivity.this.getContentResolver(); Cursor cursor = resolver.query(uri, null, null, null, "id desc limit 1"); if(cursor.moveToFirst()) { String name = cursor.getString(cursor.getColumnIndex("name")); Log.i("lisenter", name); } } } }
分类: Android Pro
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