struts 2 + spring
DESCRIPTION
Use Struts 2 along with Spring, and use Hibernate as DAO and ORM.TRANSCRIPT
Struts 2 + Spring
Aug 19th, 2009Bryan Hsueh
Agenda
• Layer architecture: Presentation, Business Logic, DB• Spring framework• Model-View-Controller • Struts 2
– Case A: Simple POJO– Case B: Decouple web layer (Action) from Service– Case C: Use Service and DTO
• Integration between layers
Layer Architecture
• Client : – Presentation
• Application Server : – Business Logic
• Database : – Data Modeling
Spring Modules
Core
Strutsor
SpringMVC Context
Web
AOP JMS JCA
DAO
ORM(Hibernate)
JMX
……
DBbrowser
Model-View-Controller
Controller Model
DBBusinessServiceObject
FrontController
ServletController
ViewJSP
Browser
Server API
getXyz()
Model-View-Controller• Provide a loose coupling between View and Model, which can
make application significantly easier to create and maintain.• View:
– Presentation: JSP, Tablib, Tiles, Validation, etc.• Controller:
– application flow is mediated by a central/front controller– front controller delegates requests to a handler/controller/action– each handler acts as an adapter between the request and the Model– control is usually then forwarded to appropriate View
• Model:– represents, or encapsulates, an application's business logic or state– provide business APIs to be used by upper layers
Struts 2
DB
* One way of interpreting Struts 2 MVC. Why put Action in Model?
A Simple POJO (case A)
public String add() {
....
return “success”;
}
public String update() {
....
return “success”;
}
public String login() {
....
if (ok) return “success”;
else return “error”;
}
}
public class User {
private String name;
private String gender;
private Date birth;
public String getName() {
return name;
}
void setName(String s) {
name = s;
}
public Date getBirth() { ... }
void setBirth(Date d) { ... }
public String getGender() { ... }
void setGender(String s) { ... }
Could use simple POJO as Action in Struts 2
In struts.xml<action name=“user_add" class="xxx.User" method="add">
<result>/jsp/user.jsp</result><result name=“error”>/jsp/error.jsp</result>
</action> <action name=“user_delete" class="xxx.User" method=“update">
<result>/jsp/user.jsp</result> </action> <action name=“user_login" class="xxx.User" method=“login">
<result name=“success”>/jsp/user.jsp</result><result name=“error”>error.jsp</result>
</action>
<action name=“user_*" class="xxx.User" method=“{1}"> <result>/jsp/user.jsp</result><result name=“error”>/jsp/error.jsp</result>
</action>
The Action in Struts 2• The Action class actually plays more role as Controller.
– Handle the interaction between View and Model– Use the data and APIs from Model (business service)– Heavily coupled with the view page (navigation logic)
• (new in Struts 2) Can also add properties, to be used by View.– Combine ActionForm (in Struts 1) in the Action
• (new in Struts 2) Could use POJO (model) as Action– Works with simple object. But …– Heavy coupling of navigation logic in each function
• Forward to different view: also in action mapping (struts.xml)• Not easy to manage the coupling between layers
• Business layer should not tie to the web layer framework.– In most cases, Action will extend from ActionSupport class
ActionSupport class (case B)
public class UserAction extends ActionSupport
{
private User user;
private String name;
private String gender;
private Date birth;
public String getName() {
return name;
}
void setName(String s) {
name = s;
}
public Date getBirth() { ... }
void setBirth(Date d) { ... }
public String getGender() { ... }
void setGender(String s) { ... }
public class ActionSupport implements Action, Validateable, ValidationAware, TextProvider, LocaleProvider, Serializable
public String add() {
user.add();
....
return “success”;
}
public String update() {
user.update();
....
return “success”;
}
public String login() {
user.login();
....
if (ok) return “success”;
else return “error”;
}
}
Decouple business service from web layer
In struts.xml<action name=“user_add" class="xxx.UserAction" method="add">
<result>/jsp/user.jsp</result><result name=“error”>/jsp/error.jsp</result>
</action> <action name=“user_delete" class="xxx.UserAction" method=“update">
<result>/jsp/user.jsp</result> </action> <action name=“user_login" class="xxx.UserAction" method=“login">
<result name=“success”>/jsp/user.jsp</result><result name=“error”>error.jsp</result>
</action>
<action name=“user_*" class="xxx.UserAction" method=“{1}"> <result>/jsp/user.jsp</result><result name=“error”>/jsp/error.jsp</result>
</action>
Service and DTO (case C)
public class UserAction extends ActionSupport
{
private AccountService accountService;
private User user;
public AccountService getAccountServic() {
return user;
}
void setAccountServic(AccountService s) {
accountService = s;
}
public User getUser() {
return user;
}
void setUser(User u) {
user = u;
}
public String add() {
accountService.add(user);
....
return “success”;
}
public String update() {
accountService.update(user);
....
return “success”;
}
public String login() {
accountService.login(user);
....
if (ok) return “success”;
else return “error”;
}
}
Use Business Service and DTO (Data Transfer Object)
Service and DTOpublic class AccountService {
public String add(User u) {
....
}
public String update(User u) {
....
}
public String login(User u) {
....
}
}
public class User {
private String name;
private String gender;
private Date birth;
public String getName() {
return name;
}
void setName(String s) {
name = s;
}
public Date getBirth() { ... }
void setBirth(Date d) { ... }
public String getGender() { ... }
void setGender(String s) { ... }
}
DTO: simple Java bean, reduce overheadBusiness Service Object:
- implement business logic and provide service API to upper layers- managed by container- usually fewer service objects than DTOs- use Data Access Object (DAO) to get data (DTO) from DB
Web and Business Layers
DB
BusinessServiceObject
Web Service, XML-RPC, etc.
* Business layer should not tie to web layer framework.
Spring MVC
Struts
Integration between layers• Client: Presentation
– struts.xml– For simple case, can configure business service object as Action – Most likely will need to implement ActionSupport class and invoke
business service and server APIs
• Server: Business Logic– applicationContext.xml– Provide business service object and APIs for upper layers– Should not tie to any frontend framework– Use Data Access Object (DAO) to access data
• DB: Data Modeling– hibernate.xml– DAO, DTO