Groovy轻松入门——Grails实战基础篇

在学习任何东西之前，最重要的是培养兴趣，Groovy世界最耀眼的技术之一－－Grails相信大家早已耳闻，我将通过Grails实战系列文章向您展现Grails的迷人风采，使您感受到Grails的魅力，以至疯狂地爱上Grails，并坠入Groovy的爱河。学Groovy，Grails与学Java一样，在实战之前需要搭建开发环境，您可以在 Groovy轻松入门－－搭建Groovy开发环境 学习到如何搭建Groovy环境，之后我会讲一下如何搭建Grails环境，然后手把手地写个Demo程序告终，我还会抽空写篇“Groovy轻松入门－－Grails实战之进阶篇”

一，搭建Grails环境
0，下载Grails( http://dist.codehaus.org/grails/grails-bin-1.0.zip)并解压到自己指定位置（我的位置是D:\D\MY_DEV\grails）
1，设置环境变量GRAILS_HOME（注意大写），过程与“设置环境变量GROOVY_HOME”相似
2，将%GRAILS_HOME%\bin添加到环境变量path中，过程与“将GROOVY_HOME目录下的bin追加到环境变量path中”相似
（如果只想进行Grails开发，可以不设GROOVY_HOME）

二，创建Grails Demo程序
3，打开“命令行”，选择当前目录（我的为D:\Temp\grails_apps），在黑底白字的窗口中输入“grails create-app demo”，不包括双引号“”，在您的屏幕中可以看到类似下面的输出结果：
D:\_DEV\grails_apps>grails create-app demo

Welcome to Grails 1.0 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-1.0

Base Directory: D:\_DEV\grails_apps
Environment set to development
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-1.0\scripts\CreateApp.groovy
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\src
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\src\java
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\src\groovy
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\controllers
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\services
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\domain
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\taglib
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\utils
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\views
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\views\layouts
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\i18n
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\conf
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\test
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\test\unit
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\test\integration
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\scripts
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\js
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\css
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\images
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\WEB-INF\classes
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\META-INF
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\lib
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\conf\spring
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\grails-app\conf\hibernate
[propertyfile] Creating new property file: D:\_DEV\grails_apps\demo\application.properties
     [copy] Copying 2 files to D:\_DEV\grails_apps\demo
     [copy] Copying 2 files to D:\_DEV\grails_apps\demo\web-app\WEB-INF
     [copy] Copying 5 files to D:\_DEV\grails_apps\demo\web-app\WEB-INF\tld
     [copy] Copying 87 files to D:\_DEV\grails_apps\demo\web-app
     [copy] Copying 17 files to D:\_DEV\grails_apps\demo\grails-app
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo
[propertyfile] Updating property file: D:\_DEV\grails_apps\demo\application.properties
Created Grails Application at D:\_DEV\grails_apps/demo
D:\_DEV\grails_apps>


通过“grails create-app”这个命令，Grails自动帮我们创建了开发所需的工程环境。其实您现在就已经拥有了一个可运行的Web应用程序，
然后进入demo目录(“cd demo”)，输入“grails run-app”，回车，启动这个‘五脏俱全’的程序雏形，打开浏览器，输入 http://localhost:8080/demo ，回车，看到了吧 让我们继续吧，请停止这个程序(Ctrl + C)

4，在“命令行”中输入“cd demo”，回车，以进入demo目录，然后再输入“grails create-domain-class User”创建domain class即类似于pojo的pogo，它对应MVC中的Model，不过由Grails自动创建的pogo是空的，需要自己添加属性，约束（constraints）等。输出结果如下所示：

D:\_DEV\grails_apps\demo>grails create-domain-class User

Welcome to Grails 1.0 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-1.0

Base Directory: D:\_DEV\grails_apps\demo
Environment set to development
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-1.0\scripts\CreateDomainClass.groovy
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo\grails-app\domain
Created  for User
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo\test\integration
Created Tests for User
D:\_DEV\grails_apps\demo>



5，进入D:\Temp\grails_apps\demo\grails-app\domain（这个目录中存放着所有的domain class），打开User.groovy，修改为如下内容：
class  User {
    String name
    String password
   
    String toString() {
         " $name : $password "    
    }
   
     static  constraints  =  {
        name(blank:  false )   
        password(blank:  false , size:  6 .. 16 )
    }
}   


contraints这个类变量是定义一些约束的，比如name不能为空白，password不能为空白而且长度在6到16之间（包括6和16）

6，在“命令行”中输入“grails generate-all User”，为User产生所有CRUD操作需要的代码（如控制器UserController.groovy）和页面（如list.gsp），输出结果如下所示：
D:\_DEV\grails_apps\demo>grails generate-all User

Welcome to Grails 1.0 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-1.0

Base Directory: D:\_DEV\grails_apps\demo
Environment set to development
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-1.0\scripts\GenerateAll.groovy
    [mkdir] Created dir: D:\_DEV\grails_apps\demo\web-app\WEB-INF\lib
    [mkdir] Created dir: C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\classes
  [groovyc] Compiling 7 source files to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\classes
    [mkdir] Created dir: C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\resources\grails-app\i18n
[native2ascii] Converting 10 files from D:\_DEV\grails_apps\demo\grails-app\i18n to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\re
sources\grails-app\i18n
     [copy] Copying 1 file to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\classes
     [copy] Copying 1 file to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\resources
     [copy] Copying 1 file to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo
[0] spring.GrailsWebApplicationContext Refreshing org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext@2b2057: display name [org
.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext@2b2057]; startup date [Tue Feb 05 23:26:45 CST 2008]; root of context hierarch
y
[16] spring.GrailsWebApplicationContext Bean factory for application context [org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationConte
xt@2b2057]: org.springframework.beans.factory.support.DefaultListableBeanFactory@eebf17
Generating views for domain class User ...
Generating controller for domain class User ...
Finished generation for domain class User
D:\_DEV\grails_apps\demo>


7，修改demo\grails-app\controllers\UserController.groovy的内容为： class UserController {

    def loginService // 新增的代码
   
    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 = {
        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 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.hasErrors() && 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(params)
        if(!user.hasErrors() && user.save()) {
            flash.message = "User ${user.id} created"
            redirect(action:show,id:user.id)
        }
        else {
            render(view:'create',model:[user:user])
        }
    }

    // 新增的代码
    def login = {
        if (request.method == 'POST') {
            User u = new User()
            u.properties = params
   
            if (!u.validate()) {
                render(view:'login', model:[user:u])
            }
   
            if (params.name && params.password) {
   
                def user = loginService.check(u)
               
                if (user) {
                    flash.message = "Welcome ${user.name}"
                    render(view: "ok", model: [user: user])
                } else {
                    flash.error = "Invalid ${u.name} with ${u.password}"
                    render(view: "login", model: [user: u])
                }   
            } else {
                render(view: "login", model: [user: u])
            }
        }
    }
}

大家或许也看到了LoginService这个类，我将在后面演示创建它，这个LoginService类封装了所有登陆相关的业务逻辑，Grails会自动将其注入到UserController中

8，在“命令行”中，输入“grails create-service Login”，创建LoginService.groovy，输出：
D:\_DEV\grails_apps\demo>grails create-service Login

Welcome to Grails 1.0 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-1.0

Base Directory: D:\_DEV\grails_apps\demo
Environment set to development
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-1.0\scripts\CreateService.groovy
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo\grails-app\services
Created Service for Login
     [copy] Copying 1 file to D:\_DEV\grails_apps\demo\test\integration
Created ServiceTests for Login
D:\_DEV\grails_apps\demo>



9，修改demo\grails-app\services\LoginService.groovy的内容为：

class LoginService {

    boolean transactional = true

    def check(User u) {
        def user = User.findWhere(name: u.name, password: u.password)
        return user
    }

}



10，在demo\grails-app\views\user目录下创建login.gsp和ok.gsp，它们对应MVC中的View，内容分别为：
login.gsp （复制demo\grails-app\views\user\create.gsp的内容到login.gsp中，并修改）:

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
        <meta name="layout" content="main" />
        <!-- 将Create User修改为Login -->
        <title>Login</title>        
    </head>
    <body>
        <div class="nav">
            <span class="menuButton"><a class="home" href="${createLinkTo(dir:'')}">Home</a></span>
            <span class="menuButton"><g:link class="list" action="list">User List</g:link></span>
        </div>
        <div class="body">
            <!-- 将Create User修改为Login -->
            <h1>Login</h1>
            <!-- 将flash.message修改为flash.error -->
            <g:if test="${flash.error}">
            <!-- 将class="message"修改为class="errors", 将flash.message修改为flash.error -->
            <div class="errors">${flash.error}</div>
            </g:if>
            <g:hasErrors bean="${user}">
            <div class="errors">
                <g:renderErrors bean="${user}" as="list" />
            </div>
            </g:hasErrors>
           
            <!-- 将action="save"修改为action="login" -->
            <g:form action="login" method="post" >
                <div class="dialog">
                    <table>
                        <tbody>
                       
                            <tr class="prop">
                                <td valign="top" class="name">
                                    <label for="name">Name:</label>
                                </td>
                                <td valign="top" class="value ${hasErrors(bean:user,field:'name','errors')}">
                                    <input type="text" id="name" name="name" value="${fieldValue(bean:user,field:'name')}"/>
                                </td>
                            </tr>
                       
                            <tr class="prop">
                                <td valign="top" class="name">
                                    <label for="password">Password:</label>
                                </td>
                                <td valign="top" class="value ${hasErrors(bean:user,field:'password','errors')}">
                                    <input type="text" maxlength="16" id="password" name="password" value="${fieldValue(bean:user,field:'password')}"/>
                                </td>
                            </tr>
                       
                        </tbody>
                    </table>
                </div>
                <div class="buttons">
                    <!-- 将value="Create"修改为value="Login" -->
                    <span class="button"><input class="save" type="submit" value="Login" /></span>
                </div>
            </g:form>
        </div>
    </body>
</html>



ok.gsp:

<g:if test="${flash.message}">
    <div class="message">${flash.message}</div>
</g:if>

Name: ${user?.name}   <br>
Password: ${user?.password}



11，修改demo\grails-app\conf\BootStrap.groovy，初始化数据库：将一个User实例保存到数据库(grails自带hsqldb和jetty)中，内容如下：
class BootStrap {

     def init = { servletContext ->
         new User(name: "demo", password: "123456").save()
     }

     def destroy = {
     }
}


12，在“命令行”中，输入“grails run-app”，运行我们的Web应用，输出如下：

D:\_DEV\grails_apps\demo>grails run-app

Welcome to Grails 1.0 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: D:\D\MY_DEV\grails-1.0

Base Directory: D:\_DEV\grails_apps\demo
Environment set to development
Note: No plugin scripts found
Running script D:\D\MY_DEV\grails-1.0\scripts\RunApp.groovy
  [groovyc] Compiling 4 source files to C:\Documents and Settings\Daniel\.grails\1.0\projects\demo\classes
Running Grails application..
2008-02-05 23:46:08.912::INFO:  Logging to STDERR via org.mortbay.log.StdErrLog
2008-02-05 23:46:08.066::INFO:  jetty-6.1.4
2008-02-05 23:46:08.347::INFO:  No Transaction manager found - if your webapp requires one, please configure one.
2008-02-05 23:46:09.081:/demo:INFO:  Set web app root system property: 'demo' = [D:\_DEV\grails_apps\demo\web-app\]
2008-02-05 23:46:09.081:/demo:INFO:  Initializing Log4J from [file:C:\Documents and Settings\Daniel/.grails/1.0/projects/demo/resources/log4j.pro
perties]
2008-02-05 23:46:09.113:/demo:INFO:  Initializing Spring root WebApplicationContext
[0] spring.GrailsWebApplicationContext Refreshing org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext@5facbd: display name [org
.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContext@5facbd]; startup date [Tue Feb 05 23:46:14 CST 2008]; parent: org.springframew
ork.web.context.support.XmlWebApplicationContext@1fef80a
[0] spring.GrailsWebApplicationContext Bean factory for application context [org.codehaus.groovy.grails.commons.spring.GrailsWebApplicationContex
t@5facbd]: org.springframework.beans.factory.support.DefaultListableBeanFactory@aa4c7c
2008-02-05 23:46:21.590:/demo:INFO:  Initializing Spring FrameworkServlet 'grails'
2008-02-05 23:46:21.871::INFO:  Started SelectChannelConnector@0.0.0.0:8080
Server running. Browse to http://localhost:8080/demo




13，打开浏览器，输入：http://localhost:8080/demo/user/login ，在Name处输入demo，Password处输入123456，点击‘Login’，跳转到成功页面：

Welcome demo
Name: demo
Password: 123456




如果您对Grails的工程目录不太熟悉，我这里为大家提供了一张表，详细地描述了各目录的用途：

《Grails权威指南》表3-1.Grails工程目录

目录名称 相关描述
grails-app 此目录包含了Grails应用程序的核心工件(core artifact)
+ conf 此目录包含了诸如DevelopmentDataSource.groovy的配置文件
+ controllers 此目录包含了处理请求(request)的控制器(controller)，Grails控制器将在第7章中进行讲解
+ domain 此目录包含了领域模型(domain model)，领域模型将在第4章进行讲解
+ i18n 此目录包含了用于国际化的消息束(message bundle)（译者注：指的是properties文件，如messages.properties）
+ services 此目录包含了封装业务逻辑的service文件，service将在第10章中进行讲解
+ taglib 此目录包含了辅助页面生成的动态标签库，动态标签将在第8章中进行讲解
+ views 此目录包含了Groovy服务器页面(GSP)以及JSP页面
+ layouts 此目录包含了GSP或JSP的布局(layout)，这些布局由SiteMesh提供支持，这将在第8章中进行讲解
grails-test 此目录包含了应用程序的单元测试
hibernate 此目录包含了可选的Hibernate配置文件，这将在第11章中进行讲解
lib 此目录包含了jar文件
spring 此目录包含了可选的Spring配置文件，这将在第11章中进行讲解
src 此目录包含了其他Groovy和Java资源
+ java 此目录包含了待编译的Java源文件
+ groovy 此目录包含了待编译的Groovy源文件
web-app 此目录包含了Web应用程序的资源（CSS，JavaScript等）


注：Grails1.0已将hibernate和spring两个目录移到grails-app\conf目录下了，
而grails-test目录也更名为test，test目录下有integration目录和unit目录，分别存放集成测试代码和单元测试代码

想象一下用您平时做项目时所用的框架组合（比如SSH）来创建同样的Web应用程序，您立刻会感受，Grails让我们专注于业务逻辑，而不用浪费时间在那些scaffolding code(如配置文件)上。从今天开始，您不用再羡慕那些Ruby程序员所用的RoR了，您大可以使用Grails来高效开发Web应用。

您也可以访问Grails官方网站（http://www.grails.org）进一步学习。

评论

1 楼 山风小子 2008-11-16  

转载请注明出处，谢谢！