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\WebFlowDemo\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
page13，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。
最后告诉大家一个好消息，《Grails权威指南》最晚将在下个月出版，喜欢Grails的朋友到时可以买一本系统地学习一下Grails这个强大的框架，为自己今后的开发注入新的活力。关于此书的一些说明可以看一下《Grails权威指南》译者序（草稿）
附：
朝花夕拾——Groovy & Grails
posted on 2007-09-08 00:39
山风小子 阅读(5986)
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Groovy & Grails