Re: Java Singleton , Framework Design Patterns
You have been very helpful.
Your information is very much along the same lines I was headed.
Best Regards
Zahid
On Sat, 14 Dec 2019 at 12:19, Martin Gainty wrote:
> MG>maybe.. see below
>
>
> From: Zahid Rahman
> Sent: Friday, December 13, 2019 5:09 PM
> To: Struts Users Mailing List
> Subject: Re: Java Singleton , Framework Design Patterns
>
> Hi,
>
> >?am interested to know which topic prompts your question ?
> As you can see from the log file (below) the spring framework creates and
> destroys a singleton of a bean.
> So the singleton pattern is used by the container.
> I was also informed that the singleton is used to create a login screen.
> That also appears to be the case from the page
> http://www.blackwasp.co.uk/Singleton.aspx.
>
> The login screen I will be using is the login.java and login.jsp in the
> struts2 "blank app" in "struts-examples-master".
> The struts framework also helps me with duplicate form submission.
> So do I need to use the singleton pattern ?
>
> MG>here is ted husted struts-blank login.java (un-edited)
> /*
> * $Id: Login.java 471756 2006-11-06 15:01:43Z husted $
> *
> * Licensed to the Apache Software Foundation (ASF) under one
> * or more contributor license agreements. See the NOTICE file
> * distributed with this work for additional information
> * regarding copyright ownership. The ASF licenses this file
> * to you under the Apache License, Version 2.0 (the
> * "License"); you may not use this file except in compliance
> * with the License. You may obtain a copy of the License at
> *
> * http://www.apache.org/licenses/LICENSE-2.0
> *
> * Unless required by applicable law or agreed to in writing,
> * software distributed under the License is distributed on an
> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
> * KIND, either express or implied. See the License for the
> * specific language governing permissions and limitations
> * under the License.
> */
> package example;
> public class Login extends ExampleSupport {
> public String execute() throws Exception {
> if (isInvalid(getUsername())) return INPUT;
> if (isInvalid(getPassword())) return INPUT;
> return SUCCESS;
> }
> private boolean isInvalid(String value) {
> return (value == null || value.length() == 0);
> }
> private String username;
> public String getUsername() {
> return username;
> }
> public void setUsername(String username) {
> this.username = username;
> }
> private String password;
> public String getPassword() {
> return password;
> }
> public void setPassword(String password) {
> this.password = password;
> }
> }
>
> //no singleton yet as there is no public static ClassName getInstance()
> //with private constructor pointing to getInstance()
>
> //BUT singleton is used to instantate and set default ObjectFactory for
> XmlConfigurationProvider
> //as seen here in ConfigurationTestBase.java
> package com.opensymphony.xwork2.config.providers;
> public abstract class ConfigurationTestBase extends
> com.opensymphone.xwork2.XWorkTestCase {
> protected com.opensymphony.xwork2.config.ConfigurationProvider
> buildConfigurationProvider(final String filename) {
> configuration = new
> com.opensymphony.xwork2.config.providers.MockConfiguration();
>
> ((com.opensymphony.xwork2.config.providers.MockConfiguration)configuration).selfRegister();
> container = configuration.getContainer();
> XmlConfigurationProvider prov = new
> XmlConfigurationProvider(filename, true);
>
> prov.setObjectFactory(container.getInstance(com.opensymphony.xwork2.ObjectFactory.class));
>
> //but the provider does not use Spring Object Factory which we can remedy
> here
>
> prov.setObjectFactory(container.getInstance(com.opensymphony.xwork2.spring.SpringObjectFactory.class));
>
> //as you mention we must follow springs example of declaring singleton
> bean in ./WEB-INF/context.xml
>
> http://www.springframework.org/dtd/spring-beans.dtd";>
>
> class="com.opensymphony.xwork2.spring.SpringObjectFactory" singleton="true"
> />
>
> //where struts specifies default ObjectFactory thru
> ./classes/org/apache/struts2/default.properties
> ### if specified, the default object factory can be overridden here
> ### Note: short-hand notation is supported in some cases, such as "spring"
> ### Alternatively, you can provide a
> com.opensymphony.xwork2.ObjectFactory subclass name here
>
> struts.objectFactory=com.opensymphony.xwork2.spring.SpringObjectFactory.class
>
> //the line
> struts.objectFactory=com.opensymphony.xwork2.spring.SpringObjectFactory.class
> in default.properties should be sufficient
> //to route all instances of ObjectFactory to SpringObjectFactory
>
> does this help?
>
> 2019-12-13 21:01:06,882 [main] [DEBUG]
> o.s.b.f.s.DefaultListableBeanFactory - Pre-instantiating singletons in
>
> org.springframewor
Re: Java Singleton , Framework Design Patterns
MG>maybe.. see below
From: Zahid Rahman
Sent: Friday, December 13, 2019 5:09 PM
To: Struts Users Mailing List
Subject: Re: Java Singleton , Framework Design Patterns
Hi,
>?am interested to know which topic prompts your question ?
As you can see from the log file (below) the spring framework creates and
destroys a singleton of a bean.
So the singleton pattern is used by the container.
I was also informed that the singleton is used to create a login screen.
That also appears to be the case from the page
http://www.blackwasp.co.uk/Singleton.aspx.
The login screen I will be using is the login.java and login.jsp in the
struts2 "blank app" in "struts-examples-master".
The struts framework also helps me with duplicate form submission.
So do I need to use the singleton pattern ?
MG>here is ted husted struts-blank login.java (un-edited)
/*
* $Id: Login.java 471756 2006-11-06 15:01:43Z husted $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package example;
public class Login extends ExampleSupport {
public String execute() throws Exception {
if (isInvalid(getUsername())) return INPUT;
if (isInvalid(getPassword())) return INPUT;
return SUCCESS;
}
private boolean isInvalid(String value) {
return (value == null || value.length() == 0);
}
private String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
private String password;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
//no singleton yet as there is no public static ClassName getInstance()
//with private constructor pointing to getInstance()
//BUT singleton is used to instantate and set default ObjectFactory for
XmlConfigurationProvider
//as seen here in ConfigurationTestBase.java
package com.opensymphony.xwork2.config.providers;
public abstract class ConfigurationTestBase extends
com.opensymphone.xwork2.XWorkTestCase {
protected com.opensymphony.xwork2.config.ConfigurationProvider
buildConfigurationProvider(final String filename) {
configuration = new
com.opensymphony.xwork2.config.providers.MockConfiguration();
((com.opensymphony.xwork2.config.providers.MockConfiguration)configuration).selfRegister();
container = configuration.getContainer();
XmlConfigurationProvider prov = new XmlConfigurationProvider(filename,
true);
prov.setObjectFactory(container.getInstance(com.opensymphony.xwork2.ObjectFactory.class));
//but the provider does not use Spring Object Factory which we can remedy here
prov.setObjectFactory(container.getInstance(com.opensymphony.xwork2.spring.SpringObjectFactory.class));
//as you mention we must follow springs example of declaring singleton bean in
./WEB-INF/context.xml
http://www.springframework.org/dtd/spring-beans.dtd";>
//where struts specifies default ObjectFactory thru
./classes/org/apache/struts2/default.properties
### if specified, the default object factory can be overridden here
### Note: short-hand notation is supported in some cases, such as "spring"
### Alternatively, you can provide a
com.opensymphony.xwork2.ObjectFactory subclass name here
struts.objectFactory=com.opensymphony.xwork2.spring.SpringObjectFactory.class
//the line
struts.objectFactory=com.opensymphony.xwork2.spring.SpringObjectFactory.class
in default.properties should be sufficient
//to route all instances of ObjectFactory to SpringObjectFactory
does this help?
2019-12-13 21:01:06,882 [main] [DEBUG]
o.s.b.f.s.DefaultListableBeanFactory - Pre-instantiating singletons in
org.springframework.beans.factory.support.DefaultListableBeanFactory@6f1d30d:
defining beans [numberGenerator]; root of factory hierarchy
2019-12-13 21:01:06,882 [main] [DEBUG] o.s.b.f.s.DefaultListableBeanFactory
- Creating shared instance of singleton bean 'numberGenerator'
2019-12-13 21:01:06,882 [main] [DEBUG] o.s.b.f.s.DefaultListableBeanFactory
- Creating instance of bean 'numberGenerator'
2019-12-13 21:01:06,895 [main] [DEBUG] o.s.b.f.s.DefaultListableB
RE: have plan to upgrade version of spring in struts 2 Spring plugin?
Hi, Thank you so much! Yes we will upgrade Spring gradually during Struts 2.6.x releases - Struts 2.5 is under maintenance mode only for security releases. However, recent Struts 2.5.22 uses Spring 4.3.25.RELEASE [1]; doesn't it work for you? Regards. [1] https://mvnrepository.com/artifact/org.apache.struts/struts2-core/2.5.22 >-Original Message- >From: Sai Man Yau >Sent: Wednesday, December 11, 2019 7:58 AM >To: user@struts.apache.org >Subject: have plan to upgrade version of spring in struts 2 Spring plugin? > >Dear Struts 2 Team, > >Thanks for your hard work to maintain such great framework to sustain all other >developers. Thanks!! > >Since struts is using spring is some of the component, I would like to ask >will there >a plan to upgrade the spring dependencies for Struts 2 Spring plugin because of >the Spring has officially announced most of the versions will be EOL in coming >years. Thanks. > >Reference quote: >"The current version (2.5.10.1) of the Struts 2 Spring plugin has transitive >dependencies to the Spring 4.1.6.RELEASE version. " > >Regards, >Simon > >- >To unsubscribe, e-mail: user-unsubscr...@struts.apache.org >For additional commands, e-mail: user-h...@struts.apache.org - To unsubscribe, e-mail: user-unsubscr...@struts.apache.org For additional commands, e-mail: user-h...@struts.apache.org
