grails - 初学者在Grails中面临困难

Question

我是Grails的新手。要连接数据库，只需更改用户名和密码，然后在dataSource.groovy文件中添加表名即可。代码如下:

dataSource {
    pooled = true
    jmxExport = true
    driverClassName = "com.mysql.jdbc.Driver"
    dialect = "org.hibernate.dialect.MySQLDialect"
    username = "root"
    password = ""
}
hibernate {
    cache.use_second_level_cache = true
    cache.use_query_cache = true
//    cache.region.factory_class = 'net.sf.ehcache.hibernate.EhCacheRegionFactory' // Hibernate 3
    cache.region.factory_class = 'org.hibernate.cache.ehcache.EhCacheRegionFactory' // Hibernate 4
    singleSession = true // configure OSIV singleSession mode
    flush.mode = 'manual' // OSIV session flush mode outside of transactional context
}

// environment specific settings
environments {
    development {
        dataSource {
           url = "jdbc:mysql://localhost/user"
           username = "root"
           password = ""
        }
    }
    test {
        dataSource {
            url = "jdbc:mysql://localhost/user_prod"
            username = "root"
            password = ""
        }
    }
    production {
        dataSource {
            dbCreate = "update"
            url = "jdbc:mysql://localhost/user_prod"
            username = "root"
            password = ""
        }
    }
}

单击运行方式按钮后，遇到以下错误:

    Line | Method
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread
Caused by BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.HibernateException: could not instantiate RegionFactory [org.hibernate.cache.ehcache.EhCacheRegionFactory]
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread
Caused by BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.HibernateException: could not instantiate RegionFactory [org.hibernate.cache.ehcache.EhCacheRegionFactory]
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread
Caused by HibernateException: could not instantiate RegionFactory [org.hibernate.cache.ehcache.EhCacheRegionFactory]
->>  334 | innerRun  in java.util.concurrent.FutureTask$Sync
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    166 | run       in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run       in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run . . . in java.lang.Thread
Caused by ClassNotFoundException: org.hibernate.cache.ehcache.EhCacheRegionFactory
->>  156 | findClass in org.codehaus.groovy.tools.RootLoader
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
|    423 | loadClass in java.lang.ClassLoader
|    128 | loadClass in org.codehaus.groovy.tools.RootLoader
|    356 | loadClass in java.lang.ClassLoader
|    186 | forName . in java.lang.Class
|    334 | innerRun  in java.util.concurrent.FutureTask$Sync
|    166 | run . . . in java.util.concurrent.FutureTask
|   1110 | runWorker in java.util.concurrent.ThreadPoolExecutor
|    603 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker
^    722 | run       in java.lang.Thread

Answer 1

问题在这一行:

Caused by ClassNotFoundException: org.hibernate.cache.ehcache.EhCacheRegionFactory

当Grails繁荣发展时，您往往会获得相当大的堆栈跟踪信息，这可能掩盖了真正的问题。如此大的堆栈可能仅占实际堆栈的10-20％，因为默认情况下会排除许多明显无用的堆栈帧。但总的来说，您经常会看到一连串的异常，但导致当前异常的异常显示如下。因此，最好从头开始阅读，因为这通常是核心问题。

我不确定为什么缺少ehcache依赖项-您是否在BuildConfig.groovy中将其排除在外？您可以添加一个依赖项:

dependencies {
   ...
   compile 'net.sf.ehcache:ehcache-core:2.4.8'
}

看看是否有帮助。

编辑

实际上不，这不是问题，因为它引用的是与Ehcache一起使用的Hibernate类，而不是Ehcache类。因此，这是一个Hibernate v3 / v4问题。 Grails现在默认为Hibernate 4.x，但包括使用Hibernate 3.x的配置设置。您显然在BuildConfig.groovy中切换到了Hibernate 3，但是没有更新 DataSource.groovy中的数据源配置-注释掉

cache.region.factory_class = 'org.hibernate.cache.ehcache.EhCacheRegionFactory' // Hibernate 4

并改用它:

cache.region.factory_class = 'net.sf.ehcache.hibernate.EhCacheRegionFactory' // Hibernate 3