Groovy轻松入门——Grails实战之遗留数据库处理篇（更新于2007.09.23）

由于在过去一段时间内，已有多位朋友向我询问如何用Grails处理遗留数据库，为了回答这个问题。我给出一个实例，并适当讲解，不足之处，敬请谅解。

在Grails0.6+中，配置稍有不同，详见 朝花夕拾——Groovy & Grails

我使用的数据库为MySQL5，其中存在一个名为legacy_dev的schema，legacy_dev中有一张表叫user：

1，创建Grails应用程序，我将它命名为legacy：grails create-app legacy
2，创建一个域类User：grails create-domain-class User
3，修改grails-app\domain\User.groovy的内容，如下所示：

class User {
    String userId
    String password

     static constraints = {
        userId(blank: false , maxSize: 16 )
        password(blank: false , maxSize: 45 )
    }
}

4，生成与域类User相关的所有Grails应用程序工件(artifact)：grails generate-all User
5，将grails-app\conf\DevelopmentDataSource.groovy的内容改为：

class DevelopmentDataSource {
    boolean pooling = true
    // 将这行注释掉
    // String dbCreate = 'update' // one of 'create', 'create-drop','update'
    // url和driver要正确
   String url = " jdbc:mysql://localhost:3306/legacy_dev "
   String driverClassName = " com.mysql.jdbc.Driver "
   String username = " root "
   String password = "" // 这里为您的密码 :)
}

6，自行配置Hibernate：
hibernate.cfg.xml

<? xml version='1.0' encoding='UTF-8' ?>
<! DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd" >

< hibernate-configuration >
     < session-factory >
         < property name ="connection.driver_class" > com.mysql.jdbc.Driver </ property >
         < property name ="connection.url" > jdbc:mysql://localhost:3306/legacy_dev </ property >
         < property name ="connection.username" > root </ property >
         < property name ="connection.password" ></ property >
         < property name ="connection.pool_size" > 1 </ property >
         < property name ="dialect" > org.hibernate.dialect.MySQLDialect </ property >
         < property name ="current_session_context_class" > thread </ property >
         < property name ="cache.provider_class" > org.hibernate.cache.NoCacheProvider </ property >
         < property name ="show_sql" > true </ property >
         < property name ="hbm2ddl.auto" > validate </ property >
         < mapping resource ="User.hbm.xml" />
     </ session-factory >
</ hibernate-configuration >

User.hbm.xml

<? xml version="1.0" ?>
<! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

< hibernate-mapping >
     < class name ="User" table ="user" >
         < id name ="userId" column ="user_id" type ="java.lang.String" length ="16" >
             < generator class ="assigned" />
         </ id >
         < property name ="password" column ="password" type ="java.lang.String" length ="45" />
     </ class >
</ hibernate-mapping >

最后，别忘了修改grails-app\controllers\UserController.groovy以及各GSP的代码
（试验代码时，请不要在Edit User页面中更新用户的userId，否则出发生异常，因为‘主键’不可更改。
在自己的应用程序中，可以disable掉Edit User页面中的User Id文本域）
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 ) ]
        [ user : User.findByUserId(params.id) ]
    }

    def delete = {
         // def user = User.get( params.id )
        def user = User.findByUserId(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 )
        def user = User.findByUserId(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 )
        def user = User.findByUserId(params.id)
         if (user) {
            user.properties = params
             if (user.save()) {
                 // redirect(action:show,id:user.id)
                redirect(action:show,id:user.userId)
            }
             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)
            redirect(action:show,id:user.userId)
        }
         else {
            render(view: ' create ' ,model:[user:user])
        }
    }

}

grails-app\views\user\list.gsp

< html >
     < head >
          < meta http-equiv ="Content-Type" content ="text/html; charset=UTF-8" />
          < meta name ="layout" content ="main" />
          < title > User List </ title >
     </ head >
     < body >
         < div class ="nav" >
             < span class ="menuButton" >< a href ="${createLinkTo(dir:'')}" > Home </ a ></ span >
             < span class ="menuButton" >< g:link action ="create" > New User </ g:link ></ span >
         </ div >
         < div class ="body" >
            < h1 > User List </ h1 >
             < g:if test ="${flash.message}" >
                  < div class ="message" >
                       ${flash.message}
                  </ div >
             </ g:if >
            < table >
              < thead >
                < tr >
                
                            < g:sortableColumn property ="userId" title ="User Id" />

                            < g:sortableColumn property ="password" title ="Password" />

                         < th ></ th >
                </ tr >
              </ thead >
              < tbody >
                < g:each in ="${userList}" >
                     < tr >
                        

                             < td > ${it.userId?.encodeAsHTML()} </ td >

                             < td > ${it.password?.encodeAsHTML()} </ td >

                        < td class ="actionButtons" >
                 
                 < span class ="actionButton" >< g:link action ="show" id ="${it.userId}" > Show </ g:link ></ span >
                        </ td >
                     </ tr >
                </ g:each >
              </ tbody >
            </ table >
                < div class ="paginateButtons" >
                    < g:paginate total ="${User.count()}" />
                </ div >
         </ div >
     </ body >
</ html >

grails-app\views\user\show.gsp

< html >
     < head >
          < meta http-equiv ="Content-Type" content ="text/html; charset=UTF-8" />
           < meta name ="layout" content ="main" />
          < title > Show User </ title >
     </ head >
     < body >
         < div class ="nav" >
             < span class ="menuButton" >< a href ="${createLinkTo(dir:'')}" > Home </ a ></ span >
             < span class ="menuButton" >< g:link action ="list" > User List </ g:link ></ span >
             < span class ="menuButton" >< g:link action ="create" > New User </ g:link ></ span >
         </ div >
         < div class ="body" >
            < h1 > Show User </ h1 >
            < g:if test ="${flash.message}" >
                  < div class ="message" > ${flash.message} </ div >
            </ g:if >
            < div class ="dialog" >
                  < table >

                    < tbody >
                    
                         < tr class ="prop" >
                               < td valign ="top" class ="name" > User Id: </ td >

                                     < td valign ="top" class ="value" > ${user.userId} </ td >

                         </ tr >

                         < tr class ="prop" >
                               < td valign ="top" class ="name" > Password: </ td >

                                     < td valign ="top" class ="value" > ${user.password} </ td >

                         </ tr >

                    </ tbody >
                  </ table >
            </ div >
            < div class ="buttons" >
                < g:form controller ="user" >
         
         < input type ="hidden" name ="id" value ="${user?.userId}" />
                  < span class ="button" >< g:actionSubmit value ="Edit" /></ span >
                  < span class ="button" >< g:actionSubmit value ="Delete" /></ span >
                </ g:form >
            </ div >
         </ div >
     </ body >
</ html >

grails-app\views\user\create.gsp

< html >
     < head >
          < meta http-equiv ="Content-Type" content ="text/html; charset=UTF-8" />
          < meta name ="layout" content ="main" />
          < title > Create User </ title >
     </ head >
     < body >
         < div class ="nav" >
             < span class ="menuButton" >< a href ="${createLinkTo(dir:'')}" > Home </ a ></ span >
             < span class ="menuButton" >< g:link action ="list" > User List </ g:link ></ span >
         </ div >
         < div class ="body" >
            < h1 > Create User </ h1 >
            < g:if test ="${flash.message}" >
                  < div class ="message" > ${flash.message} </ div >
            </ g:if >
            < g:hasErrors bean ="${user}" >
                 < div class ="errors" >
                     < g:renderErrors bean ="${user}" as ="list" />
                 </ div >
            </ g:hasErrors >
            < g:form action ="save" method ="post" >
                < div class ="dialog" >
                 < table >
                     < tbody >



                                   < tr class ='prop' >< td valign ='top' class ='name' >< label for ='userId' > User Id: </ label ></ td >< td valign ='top' class ='value ${hasErrors(bean:user,field:'userId','errors')}' >< input type ="text" name ='userId' value ="${user?.userId?.encodeAsHTML()}" /></ td ></ tr >

                                   < tr class ='prop' >< td valign ='top' class ='name' >< label for ='password' > Password: </ label ></ td >< td valign ='top' class ='value ${hasErrors(bean:user,field:'password','errors')}' >< input type ="text" name ='password' value ="${user?.password?.encodeAsHTML()}" /></ td ></ tr >

                     </ tbody >
                </ table >
                </ div >
                < div class ="buttons" >
                      < span class ="formButton" >
                         < input type ="submit" value ="Create" ></ input >
                      </ span >
                </ div >
             </ g:form >
         </ div >
     </ body >
</ html >

grails-app\views\user\edit.gsp

< html >
     < head >
          < meta http-equiv ="Content-Type" content ="text/html; charset=UTF-8" />
          < meta name ="layout" content ="main" />
          < title > Edit User </ title >
     </ head >
     < body >
         < div class ="nav" >
             < span class ="menuButton" >< a href ="${createLinkTo(dir:'')}" > Home </ a ></ span >
             < span class ="menuButton" >< g:link action ="list" > User List </ g:link ></ span >
             < span class ="menuButton" >< g:link action ="create" > New User </ g:link ></ span >
         </ div >
         < div class ="body" >
            < h1 > Edit User </ h1 >
            < g:if test ="${flash.message}" >
                  < div class ="message" > ${flash.message} </ div >
            </ g:if >
            < g:hasErrors bean ="${user}" >
                 < div class ="errors" >
                     < g:renderErrors bean ="${user}" as ="list" />
                 </ div >
            </ g:hasErrors >


            < g:form controller ="user" method ="post" >
         
         < input type ="hidden" name ="id" value ="${user?.userId}" />
                < div class ="dialog" >
                 < table >
                     < tbody >



                 < tr class ='prop' >< td valign ='top' class ='name' >< label for ='userId' > User Id: </ label ></ td >< td valign ='top' class ='value ${hasErrors(bean:user,field:'userId','errors')}' >< input type ="text" name ='userId' value ="${user?.userId?.encodeAsHTML()}" /></ td ></ tr >

                 < tr class ='prop' >< td valign ='top' class ='name' >< label for ='password' > Password: </ label ></ td >< td valign ='top' class ='value ${hasErrors(bean:user,field:'password','errors')}' >< input type ="text" name ='password' value ="${user?.password?.encodeAsHTML()}" /></ td ></ tr >

                     </ tbody >
                 </ table >
                </ div >

                < div class ="buttons" >
                      < span class ="button" >< g:actionSubmit value ="Update" /></ span >
                      < span class ="button" >< g:actionSubmit value ="Delete" /></ span >
                </ div >
             </ g:form >
         </ div >
     </ body >
</ html >

好了，整个处理过程已经呈现给大家了，希望对大家有用 :)

附：朝花夕拾——Groovy & Grails

Groovy轻松入门——Grails实战之遗留数据库处理篇（更新于2007.09.23）

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