org.b3log.latke.repository.gae

Class GAERepository

java.lang.Object

org.b3log.latke.repository.gae.GAERepository

All Implemented Interfaces:

Repository

public final class GAERepository
extends Object
implements Repository

Google App Engine repository implementation, wraps The Datastore Java API(Low-level API) of GAE.

Transaction

The invocation of add, update and remove MUST in a transaction. Invocation of method get (by id) in a transaction will try to get object from transaction snapshot; if the invocation made is not in a transaction, retrieve object from datastore directly. See GAE 事务隔离 for more details.

Version:

1.1.7.2, Mar 28, 2014

Author:

Liang Ding

See Also:

Query, GAETransaction

Field Summary

Fields

Modifier and Type	Field and Description
private com.google.appengine.api.datastore.DatastoreService	datastoreService GAE datastore service.
private static com.google.appengine.api.datastore.Key	DEFAULT_PARENT_KEY Default parent key.
private static Set<Class<?>>	GAE_SUPPORTED_TYPES GAE datastore supported types.
private static Logger	LOGGER Logger.
private String	name Repository name.
private static int	QUERY_CHUNK_SIZE Query chunk size.
static ThreadLocal<GAETransaction>	TX The current transaction.
private boolean	writable Writable?

Constructor Summary

Constructors

Constructor and Description
GAERepository(String name) Constructs a GAE repository with the specified name.

Method Summary

Methods

Modifier and Type	Method and Description
String	add(JSONObject jsonObject) Adds the specified json object with the default parent key.
private String	add(JSONObject jsonObject, String parentKeyKind, String parentKeyName) Adds.
GAETransaction	beginTransaction()
long	count()
long	count(Query query)
static JSONObject	entity2JSONObject(com.google.appengine.api.datastore.Entity entity) Converts the specified entity to a json object.
static String	genTimeMillisId() Gets current date time string.
private JSONObject	get(int currentPageNum, int pageSize, int pageCount, Set<Projection> projections, Map<String,SortDirection> sorts, Filter filter) Gets the result object by the specified current page number, page size, page count, sorts, filter.
Map<String,JSONObject>	get(Iterable<String> ids)
private JSONObject	get(com.google.appengine.api.datastore.Key parentKey, String id) Gets a json object with the specified parent key and id.
JSONObject	get(Query query)
private JSONObject	get(com.google.appengine.api.datastore.Query query, int currentPageNum, int pageSize, int pageCount) Gets result json object by the specified query, current page number, page size, page count.
JSONObject	get(String id) Gets a json object by the specified id with the default parent key.
String	getName()
List<JSONObject>	getRandomly(int fetchSize)
private com.google.appengine.api.datastore.Cursor	getStartCursor(int currentPageNum, int pageSize, com.google.appengine.api.datastore.PreparedQuery preparedQuery) Gets the end cursor of the specified current page number, page size and the prepared query.
boolean	has(String id)
boolean	hasTransactionBegun()
boolean	isWritable()
private com.google.appengine.api.datastore.Query.CompositeFilter	processCompositeFilter(CompositeFilter compositeFilter) Converts the specified composite filter to a GAE composite filter.
private com.google.appengine.api.datastore.Query.FilterPredicate	processPropertyFiler(PropertyFilter propertyFilter) Converts the specified property filter to a GAE filter predicate.
void	remove(String id) Removes a json object by the specified id with the default parent key.
private void	remove(String id, String parentKeyKind, String parentKeyName) Removes.
static void	setProperties(com.google.appengine.api.datastore.Entity entity, JSONObject jsonObject) Sets the properties of the specified entity by the specified json object.
void	setWritable(boolean writable)
void	update(String id, JSONObject jsonObject) Updates a certain json object by the specified id and the specified new json object.
private void	update(String id, JSONObject jsonObject, String parentKeyKind, String parentKeyName) Updates.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOGGER

private static final Logger LOGGER

Logger.

datastoreService

private final com.google.appengine.api.datastore.DatastoreService datastoreService

GAE datastore service.

GAE_SUPPORTED_TYPES

private static final Set<Class<?>> GAE_SUPPORTED_TYPES

GAE datastore supported types.

DEFAULT_PARENT_KEY

private static final com.google.appengine.api.datastore.Key DEFAULT_PARENT_KEY

Default parent key. Kind is "parentKind", name is "parentKeyName".

writable

private boolean writable

Writable?

QUERY_CHUNK_SIZE

private static final int QUERY_CHUNK_SIZE

Query chunk size.

See Also:

Constant Field Values

TX

public static final ThreadLocal<GAETransaction> TX

The current transaction.

name

private String name

Repository name.

Constructor Detail

GAERepository

public GAERepository(String name)

Constructs a GAE repository with the specified name.

Parameters:

name - the specified name

Method Detail

add

public String add(JSONObject jsonObject)
           throws RepositoryException

Adds the specified json object with the default parent key.

Specified by:

add in interface Repository

Parameters:

jsonObject - the specified json object

Returns:

the generated object id

Throws:

RepositoryException - repository exception

add

private String add(JSONObject jsonObject,
         String parentKeyKind,
         String parentKeyName)
            throws RepositoryException

Adds.

Parameters:

jsonObject - the specified json object

parentKeyKind - the specified parent key kind

parentKeyName - the specified parent key name

Returns:

id

Throws:

RepositoryException - repository exception

update

public void update(String id,
          JSONObject jsonObject)
            throws RepositoryException

Updates a certain json object by the specified id and the specified new json object.

The parent key of the entity to update is the default parent key.

Invokes this method for an non-existent entity will create a new entity in database, as the same effect of method add(org.json.JSONObject).

Update algorithm steps:

1. Sets the specified id into the specified new json object
2. Creates a new entity with the specified id
3. Puts the entity into database

Note: the specified id is NOT the key of a database record, but the value of "oId" stored in database value entry of a record.

Specified by:

update in interface Repository

Parameters:

id - the specified id

jsonObject - the specified new json object

Throws:

RepositoryException - repository exception

See Also:

Keys.OBJECT_ID

update

private void update(String id,
          JSONObject jsonObject,
          String parentKeyKind,
          String parentKeyName)
             throws RepositoryException

Updates.

Parameters:

id - the specified id

jsonObject - the specified json object

parentKeyKind - the specified parent key kind

parentKeyName - the specified parent key name

Throws:

RepositoryException - repository exception

remove

public void remove(String id)
            throws RepositoryException

Removes a json object by the specified id with the default parent key.

Specified by:

remove in interface Repository

Parameters:

id - the specified id

Throws:

RepositoryException - repository exception

remove

private void remove(String id,
          String parentKeyKind,
          String parentKeyName)
             throws RepositoryException

Removes.

Parameters:

id - the specified id

parentKeyKind - the specified parent key kind

parentKeyName - the specified parent key name

Throws:

RepositoryException - repository exception

get

public JSONObject get(String id)
               throws RepositoryException

Gets a json object by the specified id with the default parent key.

Specified by:

get in interface Repository

Parameters:

id - the specified id

Returns:

a json object, returns null if not found

Throws:

RepositoryException - repository exception

get

public Map<String,JSONObject> get(Iterable<String> ids)
                           throws RepositoryException

Specified by:

get in interface Repository

Throws:

RepositoryException

get

private JSONObject get(com.google.appengine.api.datastore.Key parentKey,
             String id)
                throws RepositoryException

Gets a json object with the specified parent key and id.

Parameters:

parentKey - the specified parent key

id - the specified id

Returns:

a json object, returns null if not found

Throws:

RepositoryException - repository exception

has

public boolean has(String id)
            throws RepositoryException

Specified by:

has in interface Repository

Throws:

RepositoryException

get

public JSONObject get(Query query)
               throws RepositoryException

Specified by:

get in interface Repository

Throws:

RepositoryException

get

private JSONObject get(int currentPageNum,
             int pageSize,
             int pageCount,
             Set<Projection> projections,
             Map<String,SortDirection> sorts,
             Filter filter)
                throws RepositoryException

Gets the result object by the specified current page number, page size, page count, sorts, filter.

Parameters:

currentPageNum - the specified current page number

pageSize - the specified page size

pageCount - if the pageCount specified with -1, the returned (pageCnt, recordCnt) value will be calculated, otherwise, the returned pageCnt will be this pageCount, and recordCnt will be 0, means these values will not be calculated

projections - the specified projections

sorts - the specified sorts

filter - the specified filter

Returns:

the result object, see return of get(org.b3log.latke.repository.Query) for details

Throws:

RepositoryException - repository exception

processCompositeFilter

private com.google.appengine.api.datastore.Query.CompositeFilter processCompositeFilter(CompositeFilter compositeFilter)
                                                                                 throws RepositoryException

Converts the specified composite filter to a GAE composite filter.

Parameters:

compositeFilter - the specified composite filter

Returns:

GAE composite filter

Throws:

RepositoryException - repository exception

processPropertyFiler

private com.google.appengine.api.datastore.Query.FilterPredicate processPropertyFiler(PropertyFilter propertyFilter)
                                                                               throws RepositoryException

Converts the specified property filter to a GAE filter predicate.

Parameters:

propertyFilter - the specified property filter

Returns:

GAE filter predicate

Throws:

RepositoryException - repository exception

getRandomly

public List<JSONObject> getRandomly(int fetchSize)
                             throws RepositoryException

Specified by:

getRandomly in interface Repository

Throws:

RepositoryException

count

public long count()

Specified by:

count in interface Repository

count

public long count(Query query)
           throws RepositoryException

Specified by:

count in interface Repository

Throws:

RepositoryException

entity2JSONObject

public static JSONObject entity2JSONObject(com.google.appengine.api.datastore.Entity entity)

Converts the specified entity to a json object.

Parameters:

entity - the specified entity

Returns:

converted json object

setProperties

public static void setProperties(com.google.appengine.api.datastore.Entity entity,
                 JSONObject jsonObject)
                          throws JSONException

Sets the properties of the specified entity by the specified json object.

Parameters:

entity - the specified entity

jsonObject - the specified json object

Throws:

JSONException - json exception

get

private JSONObject get(com.google.appengine.api.datastore.Query query,
             int currentPageNum,
             int pageSize,
             int pageCount)
                throws RepositoryException

Gets result json object by the specified query, current page number, page size, page count.

If the specified page count equals to -1, this method will calculate the page count.

Parameters:

query - the specified query

currentPageNum - the specified current page number

pageSize - the specified page size

pageCount - if the pageCount specified with -1, the returned (pageCnt, recordCnt) value will be calculated, otherwise, the returned pageCnt will be this pageCount, and recordCnt will be 0, means these values will not be calculated

Returns:

for example,

 {
     "pagination": {
       "paginationPageCount": 10, // May be specified by the specified query.pageCount
       "paginationRecordCount": "100" // If query.pageCount has been specified with not -1 or null, this value will
                                         be 0 also
     },
     "rslts": [{
         "oId": "...."
     }, ....]
 }
 

Throws:

RepositoryException - repository exception

genTimeMillisId

public static String genTimeMillisId()

Gets current date time string.

Returns:

a time millisecond string

beginTransaction

public GAETransaction beginTransaction()

Specified by:

beginTransaction in interface Repository

hasTransactionBegun

public boolean hasTransactionBegun()

Specified by:

hasTransactionBegun in interface Repository

isWritable

public boolean isWritable()

Specified by:

isWritable in interface Repository

setWritable

public void setWritable(boolean writable)

Specified by:

setWritable in interface Repository

getName

public String getName()

Specified by:

getName in interface Repository

getStartCursor

private com.google.appengine.api.datastore.Cursor getStartCursor(int currentPageNum,
                                                       int pageSize,
                                                       com.google.appengine.api.datastore.PreparedQuery preparedQuery)

Gets the end cursor of the specified current page number, page size and the prepared query.

Parameters:

currentPageNum - the specified current page number, MUST larger then 1

pageSize - the specified page size

preparedQuery - the specified prepared query

Returns:

the start cursor