ContentProvider实现数据共享
主要类有两个：ContentProvider及ContentResolver
ContentProvider实现步骤：
1.定义ContentProvider类，继承ContentProProvider基类
2.在AndroidManifest.xml文件中注册，在<application.../>下添加
<provider
android:name=".providers.PersonContentProvider"
android:authorities="com.itheima28.sqlitedemo.providers.PersonContentProvider"
android:exported="true"是否允许其他应用程序调用
android:readPermission="aa.bb.cc.read"
android:writePermission="aa.bb.cc.write" >
</provider>
继承ContentProvider需要实现以下方法
@Override
public int delete(Uri arg0, String arg1, String[] arg2) {
// TODO Auto-generated method stub
return 0;
}
@Override
public String getType(Uri arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public Uri insert(Uri arg0, ContentValues arg1) {
// 根据Uri插入values对应数据
return null;
}
@Override
public boolean onCreate() {
// 其他应用程序第一次访问ContentProvider时，被创建，并立即调用onCreate方法
mOpenHelper = new PersonSQLiteOpenHelper(getContext());
return true;
}
@Override
public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,
String arg4) {
// TODO Auto-generated method stub
return null;
}
@Override
public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
// TODO Auto-generated method stub
return 0;
}
public class PersonContentProvider extends ContentProvider {
private static final String AUTHORITY = "com.itheima28.sqlitedemo.providers.PersonContentProvider";
private static final int PRESON_INSERT_CODE = 0; // 操作person表添加的操作的uri匹配码
private static final int PERSON_DELETE_CODE = 1;
private static final int PERSON_UPDATE_CODE = 2;
private static final int PERSON_QUERY_ALL_CODE = 3;
private static final int PERSON_QUERY_ITEM_CODE = 4;
private static UriMatcher uriMatcher;
private PersonSQLiteOpenHelper mOpenHelper; // person表的数据库帮助对象
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 添加一些uri(分机号)
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/insert
uriMatcher.addURI(AUTHORITY, "person/insert", PRESON_INSERT_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/delete
uriMatcher.addURI(AUTHORITY, "person/delete", PERSON_DELETE_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/update
uriMatcher.addURI(AUTHORITY, "person/update", PERSON_UPDATE_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/queryAll
uriMatcher.addURI(AUTHORITY, "person/queryAll", PERSON_QUERY_ALL_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/query/#
uriMatcher.addURI(AUTHORITY, "person/query/#", PERSON_QUERY_ITEM_CODE);
}
@Override
public boolean onCreate() {
mOpenHelper = new PersonSQLiteOpenHelper(getContext());
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
switch (uriMatcher.match(uri)) {
case PERSON_QUERY_ALL_CODE: // 查询所有人的uri
if(db.isOpen()) {
Cursor cursor = db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
return cursor;
// db.close(); 返回cursor结果集时, 不可以关闭数据库
}
break;
case PERSON_QUERY_ITEM_CODE: // 查询的是单条数据, uri末尾出有一个id
if(db.isOpen()) {
long id = ContentUris.parseId(uri);
Cursor cursor = db.query("person", projection, "_id = ?", new String[]{id + ""}, null, null, sortOrder);
return cursor;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return null;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case PERSON_QUERY_ALL_CODE: // 返回多条的MIME-type
return "vnd.android.cursor.dir/person";
case PERSON_QUERY_ITEM_CODE: // 返回单条的MIME-TYPE
return "vnd.android.cursor.item/person";
default:
break;
}
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
switch (uriMatcher.match(uri)) {
case PRESON_INSERT_CODE: // 添加人到person表中
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
long id = db.insert("person", null, values);
db.close();
return ContentUris.withAppendedId(uri, id);
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
switch (uriMatcher.match(uri)) {
case PERSON_DELETE_CODE: // 在person表中删除数据的操作
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
int count = db.delete("person", selection, selectionArgs);
db.close();
return count;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return 0;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
switch (uriMatcher.match(uri)) {
case PERSON_UPDATE_CODE: // 更新person表的操作
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
int count = db.update("person", values, selection, selectionArgs);
db.close();
return count;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return 0;
}
}
ContentPesolver
public class TextCase extends AndroidTestCase { private static final String TAG = "TextCase"; public void testInsert() { Uri uri = Uri.parse("content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/insert"); // 内容提供者访问对象 ContentResolver resolver = getContext().getContentResolver(); ContentValues values = new ContentValues(); values.put("name", "fengjie"); values.put("age", 90); uri = resolver.insert(uri, values); Log.i(TAG, "uri: " + uri); long id = ContentUris.parseId(uri); Log.i(TAG, "添加到: " + id); } public void testDelete() { Uri uri = Uri.parse("content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/delete"); // 内容提供者访问对象 ContentResolver resolver = getContext().getContentResolver(); String where = "_id = ?"; String[] selectionArgs = {"21"}; int count = resolver.delete(uri, where, selectionArgs); Log.i(TAG, "删除行: " + count); } public void testUpdate() { Uri uri = Uri.parse("content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/update"); // 内容提供者访问对象 ContentResolver resolver = getContext().getContentResolver(); ContentValues values = new ContentValues(); values.put("name", "lisi"); int count = resolver.update(uri, values, "_id = ?", new String[]{"20"}); Log.i(TAG, "更新行: " + count); } public void testQueryAll() { Uri uri = Uri.parse("content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/queryAll"); // 内容提供者访问对象 ContentResolver resolver = getContext().getContentResolver(); Cursor cursor = resolver.query(uri, new String[]{"_id", "name", "age"}, null, null, "_id desc"); if(cursor != null && cursor.getCount() > 0) { int id; String name; int age; while(cursor.moveToNext()) { id = cursor.getInt(0); name = cursor.getString(1); age = cursor.getInt(2); Log.i(TAG, "id: " + id + ", name: " + name + ", age: " + age); } cursor.close(); } } public void testQuerySingleItem() { Uri uri = Uri.parse("content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/query/#"); // 在uri的末尾添加一个id content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/query/20 uri = ContentUris.withAppendedId(uri, 20); // 内容提供者访问对象 ContentResolver resolver = getContext().getContentResolver(); Cursor cursor = resolver.query(uri, new String[]{"_id", "name", "age"}, null, null, null); if(cursor != null && cursor.moveToFirst()) { int id = cursor.getInt(0); String name = cursor.getString(1); int age = cursor.getInt(2); cursor.close(); Log.i(TAG, "id: " + id + ", name: " + name + ", age: " + age); } } }
监听ContentProvider数据改变
ContentProvider的方法导致了数据库数据发生改变，就会调用getContext().getContentResolver().notifyChange(uri,null)被调用。
1.注册监听器
getContentResolver().registerContentObserver(uri,true/false,new xxxContentObserver(new Handler()));
uri:待监听ContentProvider的Uri
true/false:true:监听uri目录及子目录；false:监听uri目
new xxxContentObserver(new Handler())：监听器实例
2.监听ContentProvider数据改变，需要继承ContentObserver基类，重写OnChange(boolean selfChange)方法，当数据发生改变此方法将被回调。
