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Groovy轻松入门——Grails实战之Ajax篇

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Ajax虽是“旧酒装新瓶”，但其威力着实不小。近两年来可谓红透半边天，它之所以能为大众接受，其中一个很大的原因就是提高了用户浏览体验，能更逼真的模拟出GUI界面。

作者：山风小子来源：蛟龍居 2007年11月18日

Ajax虽是“旧酒装新瓶”，但其威力着实不小。近两年来可谓红透半边天，它之所以能为大众接受，其中一个很大的原因就是提高了用户浏览体验，能更逼真的模拟出GUI界面。好了，Ajax的益处就说到这里，下面让我们看下Grails是如何帮助我们方便地应用Ajax的:

如果您对下面说设计的内容有点不解，那么您可以先看一下 Groovy轻松入门——Grails实战基础篇，然后开始我们的Ajax之旅。

1, 在命令行中输入：“grails create-app AjaxDemo”（注意：不带引号“”）创建一个Grails project，我将它命名为AjaxDemo：
D:\Temp\grails_apps>grails create-app AjaxDemo

Welcome to Grails 0.5 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-0.5
Base Directory: D:\Temp\grails_apps
Environment set to production
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-0.5\scripts\CreateApp.groovy
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\src
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\src\java
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\src\groovy
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\src\test
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\controllers
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\jobs
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\services
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\domain
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\taglib
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\utils
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\views
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\views\layouts
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\i18n
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-app\conf
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\grails-tests
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\scripts
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\js
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\css
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\images
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\classes
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\META-INF
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\lib
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\spring
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\hibernate
[propertyfile] Creating new property file: D:\Temp\grails_apps\AjaxDemo\application.properties
[copy] Copying 2 files to D:\Temp\grails_apps\AjaxDemo
[copy] Copying 2 files to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF
[copy] Copying 5 files to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\tld
[copy] Copying 119 files to D:\Temp\grails_apps\AjaxDemo\web-app
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-app\conf
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-app\conf
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-app\conf
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-app\conf
[copy] Copying 13 files to D:\Temp\grails_apps\AjaxDemo\grails-app
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\plugins\core\grails-app\taglib
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\plugins\core\grails-app\utils
[copy] Copying 7 files to D:\Temp\grails_apps\AjaxDemo\plugins\core\grails-app\taglib
[copy] Copying 4 files to D:\Temp\grails_apps\AjaxDemo\plugins\core\grails-app\utils
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\spring
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo
[propertyfile] Updating property file: D:\Temp\grails_apps\AjaxDemo\application.properties
Created Grails Application at D:\Temp\grails_apps/AjaxDemo
D:\Temp\grails_apps>

2，“cd AjaxDemo”，进入AjaxDemo目录，输入“grails create-domain-class User”，创建一个域类User：

D:\Temp\grails_apps\AjaxDemo>grails create-domain-class UserWelcome to Grails 0.5 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-0.5
Base Directory: D:\Temp\grails_apps\AjaxDemo
Environment set to production
Running script D:\D\MY_DEV\grails-0.5\scripts\CreateDomainClass.groovy
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-app\domain
Created  for User
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\grails-tests
Created Tests for User
D:\Temp\grails_apps\AjaxDemo>

3，“grails generate-all User”，生成scaffolding code（如：list.gsp等）：

D:\Temp\grails_apps\AjaxDemo>grails generate-all User
Welcome to Grails 0.5 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-0.5
Base Directory: D:\Temp\grails_apps\AjaxDemo
Environment set to production
Running script D:\D\MY_DEV\grails-0.5\scripts\GenerateAll.groovy
Compiling sources 
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\lib
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\spring
[copy] Copying 34 files to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\lib
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\grails-app\i18n
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\grails-app\views
[copy] Copying 2 files to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\grails-app\views
[mkdir] Created dir: D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\templates\scaffolding
[copy] Copying 5 files to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\templates\scaffolding
[native2ascii] Converting 7 files from D:\Temp\grails_apps\AjaxDemo\grails-app\i18n to 
D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\grails-app\i1
8n
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\spring
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\classes
[copy] Copying 1 file to D:\Temp\grails_apps\AjaxDemo\web-app\WEB-INF\classes
Generating views for domain class [User]
Generating list view for domain class [User]
list view generated at D:\Temp\grails_apps\AjaxDemo\.\grails-app\views\user\list.gsp
Generating show view for domain class [User]
Show view generated at D:\Temp\grails_apps\AjaxDemo\.\grails-app\views\user\show.gsp
Generating edit view for domain class [User]
Edit view generated at D:\Temp\grails_apps\AjaxDemo\.\grails-app\views\user\edit.gsp
Generating create view for domain class [User]
Create view generated at D:\Temp\grails_apps\AjaxDemo\.\grails-app\views\user\create.gsp
Generating controller for domain class [User]
Controller generated at .\grails-app\controllers\UserController.groovy
D:\Temp\grails_apps\AjaxDemo>

4，修改AjaxDemo\grails-app\controllers\UserController.groovy的内容为：

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()) {
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()) {
redirect(action:show,id:user.id)
}
else  {
render(view: ' create ' ,model:[user:user])
}
}
//  自己添加的Closure ajax定义
def ajax  =  {}

//  自己添加的Closure sayHello定义
def sayHello  =  {
render  " [${new Date()}] Hello, ${params.name} "
}
}

添加sayHello闭包的目的很明显，因为客户端需要调用。那为什么还要添加ajax这个闭包呢？其实添加 ajax 这个闭包的目的是使http://localhost:8080/AjaxDemo/user/ ajax 这个请求合法化，否则会发生404错误，找不到页面：
HTTP ERROR: 404

Not Found

RequestURI=/AjaxDemo/user/ajax

所以被客户端请求的每个 gsp页面，都需要在相应的Controller中添加以gsp文件名为变量名的Closure，如上面的ajax.gsp和ajax = {}所示，其中Closure中可以添加相关代码，我们这里仅仅是做Ajax的演示，所以就不需要代码

5，在AjaxDemo\grails-app\views\user目录下，新建ajax.gsp，用来演示remoteLink的用法，内容为：

< g:javascript  library ="prototype"   />
< div  id ="hello" > Content will be displayed here </ div >
< g:remoteLink  action ="sayHello"  params ="[name:'BlueSUN']"  
update ="hello" >Say Hello </ g:remoteLink >

params表示要传递的参数，而update表示返回结果显示的地方，注意update="hello"中的hello对应于div的id，表示结果将显示于div所在处。

点击链接后的界面：
[Fri May 11 17:46:47 CST 2007] Hello, BlueSUN
Say Hello

6，修改AjaxDemo\grails-app\views\user\ ajax.gsp，演示formRemote的用法，内容为：

<g:javascript library="prototype" />

<div id="hello">Content will be displayed here</div>
<div id="error"></div><g:remoteLink action="sayHello" params="[name:'BlueSUN']" 
update="hello">Say Hello</g:remoteLink>
<hr />
<g:formRemote name="test" url="[controller:'user',action:'sayHello']" 
update="[success:'hello',failure:'error']">
<input type="text" name="name" value="BlueSUN" />
<input type="submit" value="Say Hello" />
</g:formRemote >

原本用params传递的参数，现在可以以form的形式传递了，将想传递的内容输入name的textfield中即可。

默认值我设为BlueSUN，现在我将值改为terry，点击Say Hello按钮，结果如下：
[Fri May 11 18:16:17 CST 2007] Hello, terry
Say Hello

7，修改AjaxDemo\grails-app\views\user\ ajax.gsp和AjaxDemo\grails-app\controllers\UserController.groovy，演示remoteField的用法：
ajax.gsp:

<g:javascript library="prototype" />
<div id="hello">Content will be displayed here</div>
<div id="error"></div>
<g:remoteLink action="sayHello" params="[name:'BlueSUN']" 
update="hello">Say Hello</g:remoteLink>
<hr />
<g:formRemote name="test" url="[controller:'user',action:'sayHello']" 
update="[success:'hello',failure:'error']">
<input type="text" name="name" value="BlueSUN" />
<input type="submit" value="Say Hello" />
</g:formRemote >
<hr />
<g:remoteField action="sayHello2" update="hello"  name="name" value="" />
UserController.groovy:

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()) {
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()) {
redirect(action:show,id:user.id)
}
else {
render(view:'create',model:[user:user])
}
}
// 自己添加的Closure ajax定义
def ajax = {}

// 自己添加的Closure sayHello定义
def sayHello = {
render "[${new Date()}] Hello, ${params.name}"
}

// 自己添加的Closure sayHello2定义
def sayHello2 = {
render "[${new Date()}] Hello, ${params.value}"
}
}

由于用remoteField传递过来的参数名为value，又为了保留以前的演示，所以再定义一个sayHello2闭包，注意是params.value而非params.name

输入“BlueSUN” ，请注意输入时页面的相应更新效果，结果界面：
输入到一半，即输入“Blue”
[Fri May 11 18:34:03 CST 2007] Hello, Blue
Say Hello

紧接着输入“SUN”
[Fri May 11 18:32:42 CST 2007] Hello, BlueSUN
Say Hello

8，修改AjaxDemo\grails-app\views\user\ ajax.gsp，演示remoteFunction的用法，内容为：

<g:javascript library="prototype" />
<div id="hello">Content will be displayed here</div>
<div id="error"></div>
<g:remoteLink action="sayHello" params="[name:'BlueSUN']" 
update="hello">Say Hello</g:remoteLink>
<hr />
<g:formRemote name="test" url="[controller:'user',action:'sayHello']" 
update="[success:'hello',failure:'error']">
<input type="text" name="name" value="BlueSUN" />
<input type="submit" value="Say Hello" />
</g:formRemote >
<hr />
<g:remoteField action="sayHello2" update="hello"  name="name" value="" />
<hr />
<button onClick="${remoteFunction(action:'sayHello',
update:[success:'hello', failure:'error'], params:'\'name=\' + \'BlueSUN\'')}">
Say Hello</button>

点击Say Hello按钮后，结果页面：

[Fri May 11 18:48:37 CST 2007] Hello, BlueSUN
Say Hello

Say Hello

9，Grails也可以利用Ajax异步显示Server端返回的页面，新建页面AjaxDemo\grails-app\views\user\result.gsp:

< html >
< head >
< meta  http-equiv ="Content-Type"

 content ="text/html; charset=UTF-8" />
< meta  name ="layout"  content ="main"   />
< title > Result Page </ title >
</ head >
< body >
< div  class ="nav" >
< span  class ="menuButton" >

< a  href ="${createLinkTo(dir:'')}" > Home </ a ></ span >
</ div >
< div  class ="body" >
< h1 > ${name} </ h1 >
</ div >
</ body >
</ html >

修改AjaxDemo\grails-app\controllers\UserController.groovy:

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()) {
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()) {
redirect(action:show,id:user.id)
}
else  {
render(view: ' create ' ,model:[user:user])
}
}
//  自己添加的Closure ajax定义
def ajax  =  {}

//  自己添加的Closure sayHello定义
def sayHello  =  {
render  " [${new Date()}] Hello, ${params.name} "
}

//  自己添加的Closure sayHello2定义
def sayHello2  =  {
render  " [${new Date()}] Hello, ${params.value} "
}
//  自己添加的Closure displayResultPage定义
def displayResultPage  =  {
render(view: ' result ' , model:[name:params.name])
}
}

修改AjaxDemo\grails-app\views\user\ajax.gsp:

< g:javascript  library ="prototype"   />
< div  id ="hello" > Content will be displayed here </ div >
< div  id ="error" ></ div >
< g:remoteLink  action ="sayHello"  params ="[name:'BlueSUN']"  
update ="hello" > Say Hello </ g:remoteLink >
< hr  />
< g:formRemote  name ="test"  url ="[controller:'user',action:'sayHello']"  
update ="[success:'hello',failure:'error']" >
< input  type ="text"  name ="name"  value ="BlueSUN"   />
< input  type ="submit"  value ="Say Hello"   />
</ g:formRemote  >
< hr  />
< g:remoteField  action ="sayHello2"  
update ="hello"   name ="name"  value =""   />
< hr  />
< button  onClick ="${remoteFunction(action:'sayHello',
update:[success:'hello', failure:'error'], params:'\'name=\' + \'BlueSUN\'')}" 
> Say Hello </ button >
< hr  />
< g:formRemote  name ="test"  url ="[controller:'user',action:'displayResultPage']"  
update ="[success:'hello',failure:'error']" >
< input  type ="text"  name ="name"  value ="BlueSUN"   />
< input  type ="submit"  value ="Say Hello"   />
</ g:formRemote  >

输入“terry”，点击Say Hello按钮，结果页面（样式的丢失是因为在ajax.gsp中没有声明css，目的是抓重点，抛开一切琐碎的内容）：

最后要提醒大家一点，如果要使用中文，请将中文写在AjaxDemo\grails-app\i18n\messages_zh_CN.properties中，然后用<g:message code="key" />来显示。

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