`
jinjiankang
  • 浏览: 113478 次
  • 性别: Icon_minigender_1
  • 来自: 北京
社区版块
存档分类
最新评论
文章列表
学习一下,JspRun 6.0.0 如何修改Tomcat 6.0.18的默认主页:   %Tomcat 6.0.18%/conf/server.xml: <Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> <Connector port="8009" protocol="AJP/1.3" redirectPort=&quo ...
POJO类的某个属性可以是一个Serializable 类的实例,该属性被保存在Datastore中的数据类型是com.google.appengine.api.datastore.Blob。 该属性需要使用 @Persistent(serialized=true) 批注。 import java.io.Serializable; public class DownloadableFile implements Serializable { private byte[] content; private String filename; private ...
这下可要多读几遍了。
Embedded classes allow you to model a field value using a class without creating a new datastore entity and forming a relationship. 你可以使用嵌套类作为POJO的属性,这样,嵌套类就不会作为单独实体被保存在datastore中,也不和POJO类形成关联关系。   The embedded class does not need a primary key field because it is not stored as a separate entity. ...
You can modify an object after the PersistenceManager has been closed by declaring the class as "detachable." To do this, add the detachable attribute to the @PersistenceCapable annotation: import javax.jdo.annotations.IdentityType; import javax.jdo.annotations.PersistenceCapable; ...
The following features of the JDO interface are not supported by the App Engine implementation: contains() syntax for query filters on Collection fields. You can test that a multi-valued property (a Collection field) has a value using an equality filter: collection == "value" 下面 ...
The datastore is designed with web applications in mind, with an emphasis on read and query performance. 要知道,datastore是为Web应用程序而设计的,其重点关注的是读取和查询的性能。   All queries are pre-indexed for fast results over very large data sets. 为了在大量数据集中快速查询到结果,在datastore中所做的所有查询都必须事先建立索引。与在关系型数据库系统中建立索引的方式不同,在Googl ...
文档中有:“java.lang.String:   A value longer than 500 bytes throws a JDOFatalUserException.”。经测试,对String类型属性,最多可将500个汉字,或者500个英文字母保存进Datastore。再多一根稻草,则抛出: java.lang.IllegalArgumentException: 属性名: String properties must be 500 characters or less. Instead, use com.google.appengine.api.datastore.Text, whi ...
Global site tag (gtag.js) - Google Analytics