A左右ndroid正在使用Uri监视数据库中的更改

    在监控数据库在线原创文章是非常小的变化，基本上没有找到一个实际的问题。所以，如果你看到一个有点蓝牙源代码，写一个Demo。在这里，供大家参考，查看源代码：

    src有三个文件MyDataProvider、MainActivity和MyBean。看以下：

    MyDataProvider.java:

public class MyDataProvider extends ContentProvider
{
// public static final String SCHEME = "test";
public static final String SCHEME = "content"; // 源代码里面规定这样写，所以这个地方改变不了
public static final String HOST = "com.zyj";
public static final String PORT = "497393102";
public static final String PATH = "simple";
public static final int ALARMS = 1;
public static final String SHARE_LIST_TYPE = "com.zyj.test.dir/";
public static final int ALARMS_ID = 2;
public static final String SHARE_TYPE = "com.zyj.test.item/";
private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH);
private SQLiteOpenHelper mDB = null;
// ===content://com.zyj:497393102/simple
public static final Uri CONTENT_URI = Uri.parse(SCHEME + "://" + HOST + ":" + PORT + "/" + PATH);
// 加入Uri的匹配方式，返回的就是上面自己定义的整数类型。1代表操作的是一个批量，2操作的是单独的一个对象
static
{
sURIMatcher.addURI(HOST + ":" + PORT, PATH, ALARMS);
sURIMatcher.addURI(HOST + ":" + PORT, PATH + "/#", ALARMS_ID);
}
@Override
public boolean onCreate()
{
mDB = new MyDB(getContext()); // 获取数据库的引用
return mDB != null;
}
@Override
public String getType(Uri uri)
{
// 得到我们自己定义的Uri的类型。看上面你自己的定义
int match = sURIMatcher.match(uri);
switch (match)
{
case ALARMS:
{
return SHARE_LIST_TYPE;
}
case ALARMS_ID:
{
return SHARE_TYPE;
}
default:
{
throw new IllegalArgumentException("Unknown URI: " + uri);
}
}
}
@Override
public Uri insert(Uri uri, ContentValues values)
{
// 首先是看Uri和我们自己定义的是否匹配。，匹配则将数据属性插入到数据库中并同志更新
SQLiteDatabase db = mDB.getWritableDatabase();
if (sURIMatcher.match(uri) != ALARMS)
{
throw new IllegalArgumentException("Unknown/Invalid URI " + uri);
}
ContentValues filteredValues = new ContentValues();
filteredValues.put(MyDB.BEAN_ID, values.getAsInteger(MyDB.BEAN_ID));
filteredValues.put(MyDB.MESSAGE, values.getAsString(MyDB.MESSAGE));
filteredValues.put(MyDB.TASK_PROGRESS, values.getAsFloat(MyDB.TASK_PROGRESS));
long rowID = db.insert(MyDB.TABLET, null, filteredValues);
if (rowID != -1)
{
getContext().getContentResolver().notifyChange(uri, null);
}
return CONTENT_URI;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs)
{
// 首先是看Uri和我们自己定义的是否匹配，，匹配则进行删除
SQLiteDatabase db = mDB.getWritableDatabase();
int count = 0;
int match = sURIMatcher.match(uri);
switch (match)
{
case ALARMS:
case ALARMS_ID:
String where = null;
// 这里对selection进行匹配操作，看你传递的是一个批量还是一个单独的文件
if (selection != null)
{
if (match == ALARMS)
{
where = "( " + selection + " )";
}
else
{
where = "( " + selection + " ) AND ";
}
}
else
{
where = "";
}
if (match == ALARMS_ID)
{
// 假设你传递的是一个单独的文件，也就是Uri后面加入了/item的，那么在这里把该值与数据库中的属性段进行比較，返回sql语句中的where
String segment = uri.getPathSegments().get(1);
long rowId = Long.parseLong(segment);
where += " ( " + MyDB.BEAN_ID + " = " + rowId + " ) ";
}
count = db.delete(MyDB.TABLET, where, selectionArgs);
break;
default:
throw new UnsupportedOperationException("Cannot delete URI: " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
{
// 基本同上了
SQLiteDatabase db = mDB.getWritableDatabase();
int count;
long rowId = 0;
int match = sURIMatcher.match(uri);
switch (match)
{
case ALARMS:
case ALARMS_ID:
{
String myWhere;
if (selection != null)
{
if (match == ALARMS)
{
myWhere = "( " + selection + " )";
}
else
{
myWhere = "( " + selection + " ) AND ";
}
}
else
{
myWhere = "";
}
if (match == ALARMS_ID)
{
String segment = uri.getPathSegments().get(1);
rowId = Long.parseLong(segment);
myWhere += " ( " + MyDB.BEAN_ID + " = " + rowId + " ) ";
}
if (values.size() > 0)
{
count = db.update(MyDB.TABLET, values, myWhere, selectionArgs);
}
else
{
count = 0;
}
break;
}
default:
{
throw new UnsupportedOperationException("Cannot update URI: " + uri);
}
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
{
SQLiteDatabase db = mDB.getReadableDatabase();
SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); //SQLiteQueryBuilder是一个构造SQL查询语句的辅助类
int match = sURIMatcher.match(uri);
switch (match)
{
case ALARMS:
{
qb.setTables(MyDB.TABLET);
break;
}
case ALARMS_ID:
{
qb.setTables(MyDB.TABLET);
qb.appendWhere(MyDB.BEAN_ID + "=");
qb.appendWhere(uri.getPathSegments().get(1));
break;
}
default:
throw new IllegalArgumentException("Unknown URI: " + uri);
}
Cursor ret = qb.query(db, projection, selection, selectionArgs, null, null, sortOrder);
if (ret != null)
{
ret.setNotificationUri(getContext().getContentResolver(), uri);
Log.d("zyj", "created cursor " + ret + " on behalf of ");
}
else
{
Log.d("zyj", "query failed in downloads database");
}
return ret;
}
private static class MyDB extends SQLiteOpenHelper
{
// 这里就是数据库了，数据库字段、名称、表名等...
private static final String DATABASE = "test_database";
public static final String TABLET = "test_table";
public static String ID = "_id";
public static String BEAN_ID = "_bean_id";
public static String MESSAGE = "_message";
public static String TASK_PROGRESS = "_progress";
private SQLiteDatabase mDB = null;
private final String msql = "CREATE TABLE IF NOT EXISTS " + TABLET + "( " + ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, " + BEAN_ID + " TEXT, " + MESSAGE + " TEXT, " + TASK_PROGRESS
+ " TEXT )";
private MyDB(Context context)
{
super(context, DATABASE, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db)
{
mDB = db;
mDB.execSQL(msql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
// 升级。自己能够去实现
}
}
}

    MyBean.java一个实例对象

public class MyBean
{
public int id = 0;
public String message = null;
public float progress = 0.0f;
public MyBean(int id)
{
this.id = id;
}
}

     MainActivity.java主界面了

public class MainActivity extends Activity
{
TextView mMessage = null;
private ContentObserver mDatabaseListener = null;
private Handler mHand = null;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mMessage = (TextView) findViewById(R.id.message);
init();
// 注冊数据库的监听。相应的是特定的Uri
getContentResolver().registerContentObserver(MyDataProvider.CONTENT_URI, true, mDatabaseListener);
}
@Override
protected void onDestroy()
{
super.onDestroy();
// 注销掉监听
 getContentResolver().unregisterContentObserver(mDatabaseListener);
}
private void init()
{
mHand = new Handler();
// 数据库变动时的回调
 mDatabaseListener = new ContentObserver(mHand)
{
@Override
public boolean deliverSelfNotifications()
{
System.out.println("deliverSelfNotifications ---------------- ");
return super.deliverSelfNotifications();
}
@Override
public void onChange(boolean selfChange, Uri uri)
{
System.out.println("onChange ---------------- " + uri.toString());
super.onChange(selfChange, uri);
}
@Override
public void onChange(boolean selfChange)
{
System.out.println("onChange ---------------- ...");
super.onChange(selfChange);
}
};
}
private int count = 0;
public void onViewClick(View view)
{
switch (view.getId())
{
case R.id.add:
// 插入数据
 ContentValues calues = new ContentValues();
calues.put("_bean_id", count++);
calues.put("_message", "AAAAAAAAAAAAAAAAAAAAA");
calues.put("_progress", 0.0f);
getContentResolver().insert(MyDataProvider.CONTENT_URI, calues);
break;
case R.id.del:
// 假设找不到指定的_bean_id=1、2、3的，则数据库不进行增减。但还是会调用回调方法
getContentResolver().delete(Uri.parse(MyDataProvider.CONTENT_URI.toString() + "/1"), null, null);
getContentResolver().delete(Uri.parse(MyDataProvider.CONTENT_URI.toString() + "/2"), null, null);
getContentResolver().delete(Uri.parse(MyDataProvider.CONTENT_URI.toString() + "/3"), null, null);
break;
case R.id.modify:
ContentValues values = new ContentValues();
values.put("_message", "ZZZZZZZZZZZZZZZZZZZZZ");
// 这两中方法一样，这样就能够更加明确Uri中在后面加入的/item了数字的意思了
getContentResolver()
.update(Uri.parse(MyDataProvider.CONTENT_URI.toString() + "/5"), values, null, null);
getContentResolver().update(MyDataProvider.CONTENT_URI, values, "_bean_id=?
", new String[] { "6" });                break;            case R.id.query:                showMessage(getContentResolver().query(MyDataProvider.CONTENT_URI, null, null, null, null));                break;        }    }    private void showMessage(Cursor c)    {        if (c == null)        {            return;        }        final StringBuffer sb = new StringBuffer();        if (c.getCount() > 0)        {            while (c.moveToNext())            {                MyBean bean = new MyBean(c.getInt(c.getColumnIndex("_bean_id")));                bean.message = c.getString(c.getColumnIndex("_message"));                bean.progress = c.getFloat(c.getColumnIndex("_progress"));                sb.append(bean.id + "\t\t\t:" + bean.message + "\t\t\t,progress = " + bean.progress + "\n");            }        }        c.close();        mHand.post(new Runnable()        {            public void run()            {                mMessage.setText(sb.toString());            }        });    }}

    activity_main.xml    上面就是四个button，以下就是一个TextView显示控件

<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:orientation="vertical"
android:padding="10.0dip" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:orientation="vertical" >
<Button
android:id="@+id/add"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="onViewClick"
android:text="Add" />
<Button
android:id="@+id/del"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="onViewClick"
android:text="Delete" />
<Button
android:id="@+id/modify"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="onViewClick"
android:text="Modify" />
<Button
android:id="@+id/query"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="onViewClick"
android:text="Query" />
</LinearLayout>
<ScrollView
android:layout_width="fill_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:maxHeight="20dip" >
<TextView
android:id="@+id/message"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="20sp" />
</ScrollView>
</LinearLayout>

    最后就是AndroidManifest.xml了。和平时一样的，仅仅只是在里面将你自定义的ContentProvider写上，类似我的这样：

    <provider
            android:name=”com.example.databasetest.MyDataProvider”
            android:authorities=”com.zyj:497393102″ />
    上面的authorities属性是一定要写的。它就是上面MyDataProvider.java里面的CONTENT_URI的HOST + “:” + PORT，能够看以下画的。就比較清楚了。

    content://com.example.project:200/folder/subfolder/etc
    \———/  \—————————/ \—/ \————————–/
    scheme                 host               port        path
                    \——————————–/
                              authority   

    然后就没有了，能够自己执行，感受一下Uri和数据库的监听。

    有错误我希望你能来部出，谢谢！！

！