android ContentProvider

   内容提供者对外提供共享数据，需要在清单文件中进行配置，必须在应用的包或者子包下。

ContentProvider类

public class PersonProvider extends ContentProvider //必须继承ContentProvider类
{
    private DBOpenHelper dbOpenHelper;
     private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
    private static final int PERSONS = 1;
    private static final int PERSON = 2;
    static{
        MATCHER.addURI("cn.itcast.providers.personprovider", "person", PERSONS);
        MATCHER.addURI("cn.itcast.providers.personprovider", "person/#", PERSON);
    }
    @Override
    public boolean onCreate() {
        dbOpenHelper = new DBOpenHelper(this.getContext());
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        switch (MATCHER.match(uri)) {
        case PERSONS:
            return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);

        case PERSON:
            long rowid = ContentUris.parseId(uri);
            String where = "personid="+ rowid;
            if(selection!=null && !"".equals(selection.trim())){
                where += " and "+ selection;
            }
            return db.query("person", projection, where, selectionArgs, null, null, sortOrder);
        default:
            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);
        }
    }

    @Override
    public String getType(Uri uri) {
        switch (MATCHER.match(uri)) {
        case PERSONS:
            return "vnd.android.cursor.dir/person";
        case PERSON:
            return "vnd.android.cursor.item/person";
        default:
            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);
        }
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        switch (MATCHER.match(uri)) {
        case PERSONS:
            long rowid = db.insert("person", "name", values);//主键值
            //  content://cn.itcast.provides.personprovider/person/10
            Uri insertUri = ContentUris.withAppendedId(uri, rowid);
            this.getContext().getContentResolver().notifyChange(uri, null);//发出数据变化通知
            return insertUri;

        default:
            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);
        }
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        int num = 0;
        switch (MATCHER.match(uri)) {
        case PERSONS:
            num = db.delete("person", selection, selectionArgs);
            break;
        case PERSON:
            long rowid = ContentUris.parseId(uri);
            String where = "personid="+ rowid;
            if(selection!=null && !"".equals(selection.trim())){
                where += " and "+ selection;
            }
            num = db.delete("person", where, selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);
        }
        return num;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        int num = 0;
        switch (MATCHER.match(uri)) {
        case PERSONS:
            num = db.update("person", values, selection, selectionArgs);
            break;
        case PERSON:
            long rowid = ContentUris.parseId(uri);
            String where = "personid="+ rowid;
            if(selection!=null && !"".equals(selection.trim())){
                where += " and "+ selection;
            }
            num = db.update("person", values, where, selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);
        }
        return num;
    }

}

清单文件配置：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="cn.itcast.db"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".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>
<uses-library android:name="android.test.runner" />

        <provider android:name=".PersonProvider" android:authorities="cn.itcast.providers.personprovider"/>
    </application>
    <uses-sdk android:minSdkVersion="8" />

<instrumentation android:name="android.test.InstrumentationTestRunner"
  android:targetPackage="cn.itcast.db" android:label="Tests for My App" />
  
</manifest> 

对内容提供者的使用：

public class AccessContentProviderTest extends AndroidTestCase {
    private static final String TAG = "AccessContentProviderTest";
    
    public void testInsert() throws Exception{                                       
        Uri uri = Uri.parse("content://cn.itcast.providers.personprovider/person");
        ContentResolver resolver = this.getContext().getContentResolver();
        ContentValues values = new ContentValues();
        values.put("name", "laoli");
        values.put("phone", "1860103838383");
        values.put("amount", "50000000000");
        resolver.insert(uri, values);
    }
    
    public void testDelete() throws Exception{
        Uri uri = Uri.parse("content://cn.itcast.providers.personprovider/person/20");
        ContentResolver resolver = this.getContext().getContentResolver();
        resolver.delete(uri, null, null);
    }
    
    public void testUpdate() throws Exception{
        Uri uri = Uri.parse("content://cn.itcast.providers.personprovider/person/1");
        ContentResolver resolver = this.getContext().getContentResolver();
        ContentValues values = new ContentValues();
        values.put("name", "zhangxiaoxiao");
        resolver.update(uri, values, null, null);
    }
    
    public void testQuery() throws Exception{
        Uri uri = Uri.parse("content://cn.itcast.providers.personprovider/person");
        ContentResolver resolver = this.getContext().getContentResolver();
        Cursor cursor = resolver.query(uri, null, null, null, "personid asc");
        while(cursor.moveToNext()){
            String name = cursor.getString(cursor.getColumnIndex("name"));
            Log.i(TAG, name);
        }
        cursor.close();
    }
}

 监听内容提供者的数据的变化：

1、打开数据变化的通知：

2、注册数据变化监听

 内容提供者中多个操作在同一个事物中执行：