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Groovy轻松入门——Grails实战之Web Flow篇

分类：Groovy作者：编程之家AI导航网

摘要：Spring Web Flow是Spring家族中的一位成员，他能简化Web应用的开发。在Grails0.6中就集成了Spring Web Flow这一Web应用开发利器。下面通过一个实例向大家展示一下在Grails中如何方便的使用Spring Web Flow。

Spring Web Flow是Spring家族中的一位成员，他能简化Web应用的开发。在Grails0.6中就集成了Spring Web Flow这一Web应用开发利器。下面通过一个实例向大家展示一下在Grails中如何方便的使用Spring Web Flow。

1，“grails create-app WebFlowDemo”，输出如下：

D:/_DEV/grails_apps>grails create-app WebFlowDemo
Welcome to Grails 0.6 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:/D/MY_DEV/grails0.6
Base Directory: D:/_DEV/grails_apps
Environment set to development
Note: No plugin scripts found
Running script D:/D/MY_DEV/grails0.6/scripts/CreateApp.groovy
Overriding prevIoUs deFinition of reference to groovyJarSet
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/src
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFl
owDemo/src/java
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/src/groovy
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/controllers
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/services
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/domain
[mkdir] Created dir:
D:/_DEV/grails_apps/WebFlowDemo/grails-app/taglib
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/utils
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/views
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/views/layouts
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/i18n
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/conf
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/test
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/test/unit
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/test/integration
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/scripts
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app
[mkdir] Created dir:
D:/_DEV/grails_apps/WebFlowDemo/web-app/js
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app/css
[mkdir] Created dir:
D:/_DEV/grails_apps/WebFlowDemo/web-app/images
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/classes
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app/meta-inf
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/lib
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/conf/spring
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/conf/hibernate
[propertyfile] Creating new property file: 
D:/_DEV/grails_apps/WebFlowDemo/application.properties
[copy] copying 2 files to
D:/_DEV/grails_apps/WebFlowDemo
[copy] copying 2 files to 
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF
[copy] copying 5 files to
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/tld
[copy] copying 131 files to
D:/_DEV/grails_apps/WebFlowDemo/web-app
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/conf
[copy] copying 13 files to 
D:/_DEV/grails_apps/WebFlowDemo/grails-app
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/conf/spring
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo
[propertyfile] Updating property file: 
D:/_DEV/grails_apps/WebFlowDemo/application.properties
Created Grails Application at D:/_DEV/grails_apps/WebFlowDemo
D:/_DEV/grails_apps>
2，“cd WebFlowDemo”，进入工程目录

3，“grails create-domain-class User”，创建一个域类User，输出如下

D:/_DEV/grails_apps/WebFlowDemo>grails create-domain-class User
Welcome to Grails 0.6 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:/D/MY_DEV/grails0.6
Base Directory: D:/_DEV/grails_apps/WebFlowDemo
Environment set to development
Note: No plugin scripts found
Running script 
D:/D/MY_DEV/grails0.6/scripts/CreateDomainClass.groovy
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo/grails-app/domain
Created  for User
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo/test/integration
Created Tests for User
D:/_DEV/grails_apps/WebFlowDemo>

4，将grails-app/domain/User.groovy修改为如下内容： 
class  User  implements  Serializable { 
String username
String password
}

5，“grails generate-all User”，生成所有与域类User相关的目录和文件，输出如下

D:/_DEV/grails_apps/WebFlowDemo>grails generate-all User
Welcome to Grails 0.6 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:/D/MY_DEV/grails0.6
Base Directory: D:/_DEV/grails_apps/WebFlowDemo
Environment set to development
Note: No plugin scripts found
Running script 
D:/D/MY_DEV/grails0.6/scripts/Generateall.groovy
[mkdir] Created dir: 
C:/Documents and Settings/Daniel/.grails/0.6/projects/WebFlowDemo/classes
Compiling 5 source files to 
C:/Documents and Settings/Daniel/.grails/0.6/projects/WebFlowDemo/classes
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/grails-app/i18n
[copy] copying 8 files to
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/grails-app/i18n
[copy] copying 1 file to 
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/spring
[copy] copying 1 file to 
C:/Documents and Settings/Daniel/.grails/0.6/projects/WebFlowDemo/classes
[copy] copying 1 file to 
C:/Documents and Settings/Daniel/.grails/0.6/projects/WebFlowDemo/classes
Generating views for domain class User 
Generating controller for domain class User 
Finished generation for domain class User
D:/_DEV/grails_apps/WebFlowDemo>

6，将grails-app/controllers/UserController.groovy修改为如下内容 

class  UserController {
def index  =  { redirect(action:list,params:params) }
//  the delete,save and update actions only accept POST requests
def allowedMethods  =  
[delete: ' POST ',save: ' POST ',update: ' POST ' ]
def list  =  {
if ( ! params.max)params.max  =   10
[ userList: User.list( params ) ]
}
def show  =  {
[ user : User.get( params.id ) ]
}
def delete  =  {
def user  =  User.get( params.id )
if (user) {
user.delete()
flash.message  =   " User ${params.id} deleted. "
redirect(action:list)
}
else  {
flash.message  =   
" User not found with id ${params.id} "
redirect(action:list)
}
}
def edit  =  {
def user  =  User.get( params.id )
if ( ! user) {
flash.message  =   
" User not found with id ${params.id} "
redirect(action:list)
}
else  {
return  [ user : user ]
}
}
def update  =  {
def user  =  User.get( params.id )
if (user) {
user.properties  =  params
if (user.save()) {
flash.message  =   
" User ${params.id} updated. "
redirect(action:show,id:user.id)
}
else  {
render(view: ' edit ',model:[user:user])
}
}
else  {
flash.message  =   
" User not found with id ${params.id} "
redirect(action:edit,id:params.id)
}
}
def create  =  {
def user  =   new  User()
user.properties  =  params
return  [ ' user ' :user]
}
def save  =  {
def user  =   new  User()
user.properties  =  params
if (user.save()) {
flash.message  =   
" User ${user.id} created. "
redirect(action:show,id:user.id)
}
else  {
render(view: ' create ',model:[user:user])
}
}
def loginSystemFlow  =  {
login {
on( " login " ) {
if  ( " daniel "   
!=  params.username  ||   " 123 "   
!=  params.password) {
flash.message  =   
" username or password is invalid "
def user = new User()
user.properties = params
flash.user = user
return error ()
} else {
// 仅仅用来演示如何使用flow scope
flow.message = 
"Welcome,${params.username}"
}
}.to "ok"
on("register").to "showRegisterView"
}

ok()

showRegisterView()
}
}


on("login"){...}.to "ok"表示点击login按钮后所要去的页面为ok，如果验证失败（"daniel" != params.username || "123" != params.password），则利用内置的error()，使用户返回login页面；而on("register").to "showRegisterView"是类似的，不再累述。


7，在grails-app/views/user/目录下新建一个名为“loginSystem”的子目录，该名称为UserController.groovy中的loginSystemFlow的“loginSystem”相对应。

8，在grails-app/views/user/loginSystem/目录下新建login.gsp，ok.gsp，showRegisterView.gsp三个GSP文件（这三个文件的文件名与

def loginSystemFlow = {
login {
...
}

ok()

showRegisterView()
}

中粗体突显的state名相对应，其中login为start state，而ok和showRegisterView为end state） ，并将其内容修改为：
login.gsp 

< html >
< head >
< Meta  http-equiv ="Content-Type"  
content ="text/html; charset=UTF-8"   />
< Meta  name ="layout"  content ="main"   />
< title > Login Page </ title >
</ head >
< body >
< div  class ="nav" >
< span  class ="menuButton" >< a  class ="home"
href ="${createLinkTo(dir:'')}" > Home </ a >
</ span >
</ div >
< div  class ="body" >
< h1 >
Login Page
</ h1 >
< g:if  test ="${message }" >
< div  class ="message" >
${message }
</ div >
</ g:if >
< g:form  action ="loginSystem"  method ="post" >
< div  class ="dialog" >
< table >
< tbody >
< tr  class ='prop' >
< td  valign ='top'  class ='name' >
< label  for ='username' >
Username:
</ label >
</ td >
< td  valign ='top'  class ='value  
${hasErrors(bean:user,field:'username','errors')}' >
< input  type ="text"  
id ='username'  name ='username'
value ="${user?
.username?.encodeAsHTML()}"   />
</ td >
</ tr >
< tr  class ='prop' >
< td  valign ='top'  class ='name' >
< label  for ='password' >
Password:
</ label >
</ td >
< td  valign ='top'  class =
'value  ${hasErrors(bean:user,field:'password','errors')}' >
< input  type ="text"  
id ='password'  name ='password'
value ="${user?
.password?.encodeAsHTML()}"   />
</ td >
</ tr >
</ tbody >
</ table >
</ div >
< div  class ="buttons" >
< span  class ="button" >< g:submitButton  class ="save"
name ="login"  value ="Login" ></ g:submitButton >
</ span >
</ div >
< g:link  action ="loginSystem"  event ="register" > 
Register </ g:link >
</ g:form >
</ div >
</ body >
</ html >
ok.gsp
${message } < br  />
< g:link  action ="loginSystem" > back to login page </ g:link >
showRegisterView.gsp
This is a register page  < br  />
< g:link  action ="loginSystem" > back to login page </ g:link >


9，“grails run-app”，启动Grails应用，输出如下

D:/_DEV/grails_apps/WebFlowDemo>grails run-app
Welcome to Grails 0.6 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:/D/MY_DEV/grails0.6
Base Directory: D:/_DEV/grails_apps/WebFlowDemo
Environment set to development
Note: No plugin scripts found
Running script D:/D/MY_DEV/grails0.6/scripts/RunApp.groovy
[mkdir] Created dir: 
D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/lib
Compiling 1 source files to 
C:/Documents and Settings/Daniel/.grails/0.6/projects/WebFlowDemo/classes
Running Grails application..
2007-09-08 00:12:24.443::INFO:  Logging to STDERR via org.mortbay.log.StdErrLog
2007-09-08 00:12:24.521::INFO:  jetty-6.1.4
2007-09-08 00:12:26.425:/WebFlowDemo:
INFO:  Set web app root system property: '@grails.project.key@' 
= [D:/_DEV/grails_apps/WebFlowDemo/web-app/]
2007-09-08 00:12:26.425:/WebFlowDemo:
INFO:  Initializing Log4J from 
[D:/_DEV/grails_apps/WebFlowDemo/web-app/WEB-INF/classes/log4j.properties]
2007-09-08 00:12:26.472:/WebFlowDemo:
INFO:  Loading Spring root WebApplicationContext
[9282] hibernate.ConfigurableLocalSessionfactorybean
Building new Hibernate SessionFactory
[9922] mvc.GrailsUrlHandlerMapping Neither 'urlMap' 
nor 'mappings' set on SimpleUrlHandlerMapping
[12750] commons.GrailsConfigUtils [GrailsContextLoader] Grails application loaded.
[12797] mvc.GrailsWebRequestFilter Initializing filter 'grailsWebRequest'
[12797] mvc.GrailsWebRequestFilter Filter 'grailsWebRequest' configured successfully
[12797] filter.UrlMappingsFilter Initializing filter 'urlMapping'
[12797] filter.UrlMappingsFilter Initializing filter 'urlMapping'
[12797] filter.UrlMappingsFilter Filter 'urlMapping' configured successfully
[12797] filter.UrlMappingsFilter Filter 'urlMapping' configured successfully
[12797] filter.GrailsReloadServletFilter Initializing filter 'reloadFilter'
[12797] filter.GrailsReloadServletFilter Filter 'reloadFilter' configured successfully
[12891] servlet.GrailsdispatcherServlet Initializing servlet 'grails'
[12954] servlet.GrailsdispatcherServlet 
FrameworkServlet 'grails': initialization started
2007-09-08 00:12:36.562:/WebFlowDemo:
INFO:  Loading WebApplicationContext for Spring FrameworkServlet 'grails'
[13485] servlet.GrailsdispatcherServlet 
Using context class [org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext] 
for servlet 'grails'
[13485] servlet.GrailsdispatcherServlet 
Using MultipartResolver [org.springframework.web.multipart
.commons.CommonsMultipartResolver@dd7404]
[13485] servlet.GrailsdispatcherServlet 
Using LocaleResolver [org.springframework.web.servlet.i18n.SessionLocaleResolver@ebbf5c]
[13500] servlet.GrailsdispatcherServlet 
Unable to locate ThemeResolver with name 'themeResolver': 
using default [org.springframework.web.servlet.
theme.FixedThemeResolver@192c766]
[13516] servlet.GrailsdispatcherServlet 
No HandlerAdapters found in servlet 'grails': using default
[13532] servlet.GrailsdispatcherServlet 
Unable to locate RequestToViewNameTranslator with name 'viewNameTranslator': 
using default [org.springfra
mework.web.servlet.view.DefaultRequestToViewNameTranslator@a40575]
[13532] servlet.GrailsdispatcherServlet 
Using MultipartResolver 
[org.springframework.web.multipart.commons.CommonsMultipartResolver@dd7404]
[13532] servlet.GrailsdispatcherServlet 
FrameworkServlet 'grails': initialization completed in 578 ms
[13532] servlet.GrailsdispatcherServlet Servlet 'grails' configured successfully
2007-09-08 00:12:37.374::INFO:  Started SelectChannelConnector@0.0.0.0:8080
Server running. browse to http://localhost:8080/WebFlowDemo

10，访问 http://localhost:8080/WebFlowDemo/user/loginSystem


11，输入任意登录信息，并按一下Login按钮，我直接按Login按钮 :)


12，输入daniel和123，并按一下Login按钮
Welcome,daniel
back to login page

13，点击"back to login page"链接，在点击login页面上的Register链接
This is a register page
back to login page

一个最简单的Spring Web Flow应用完成。

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