我是 Grails 技术的真正初学者。我为 Windows 64 位安装了 IDE Groovy/Grails Tool Suite™(GGTS,Grails 2.4.4)。

有关 JDK 和 Grails 的环境路径已正确更新。

我创建了一个名为“test”的新项目,添加了一个名为“test.User”的新域类,如下所示:

package test 
 
class User { 
 
    Integer id 
    String firstName 
    String lastName 
 
    static constraints = { 
        id(blank:false, unique:true) 
        firstName(blank:false) 
        lastName(blank:false) 
    } 
} 

应用静态脚手架来生成相应的 UserController 和与 CRUD 操作关联的 View 。

为了检查我的数据模型是否与 H2 数据库一起使用,我对 DataSource.groovy 文件进行了一些更新并且它可以工作:我添加了一个新用户抛出应用程序,当我在我的表 USER 上运行命令 SELECT* 时(使用 grails dbconsole) 并且我显示了我的新用户条目。所以,直到这里一切都好!

但现在我想使用不同的 JDBC 连接器将我的应用程序与另一个 SQL 数据库连接起来。我选择(为了兼容性)在我的 BuildConfig.groovy 文件中提出的那个并取消注释它:
runtime mysql:mysql-connector-java:5.1.29 

当我运行应用程序“run-app”时(默认情况下,我认为我们处于开发环境中)我注意到依赖项 mysql-connector-java-5.1.29.jar 已添加到我的 .m2 目录中(C:\Users\my_user_name.m2\repository\mysql\mysql-connector-java\5.1.29)。所以我认为依赖项在 Grails 中的一种 MAVEN 文件中正确注册。但是,该文件不会出现在 ivy-cache 目录中。正常吗?

我的 BuildConfig.groovy 文件内容:
grails.servlet.version = "3.0" // Change depending on target container compliance (2.5 or 3.0) 
grails.project.class.dir = "target/classes" 
grails.project.test.class.dir = "target/test-classes" 
grails.project.test.reports.dir = "target/test-reports" 
grails.project.work.dir = "target/work" 
grails.project.target.level = 1.6 
grails.project.source.level = 1.6 
//grails.project.war.file = "target/${appName}-${appVersion}.war" 
 
grails.project.fork = [ 
    // configure settings for compilation JVM, note that if you alter the Groovy version forked compilation is required 
    //  compile: [maxMemory: 256, minMemory: 64, debug: false, maxPerm: 256, daemon:true], 
 
    // configure settings for the test-app JVM, uses the daemon by default 
    test: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, daemon:true], 
    // configure settings for the run-app JVM 
    run: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false], 
    // configure settings for the run-war JVM 
    war: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false], 
    // configure settings for the Console UI JVM 
    console: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256] 
] 
 
grails.project.dependency.resolver = "maven" // or ivy 
grails.project.dependency.resolution = { 
    // inherit Grails' default dependencies 
    inherits("global") { 
        // specify dependency exclusions here; for example, uncomment this to disable ehcache: 
        // excludes 'ehcache' 
    } 
    log "error" // log level of Ivy resolver, either 'error', 'warn', 'info', 'debug' or 'verbose' 
    checksums true // Whether to verify checksums on resolve 
    legacyResolve false // whether to do a secondary resolve on plugin installation, not advised and here for backwards compatibility 
 
    repositories { 
        inherits true // Whether to inherit repository definitions from plugins 
 
        grailsPlugins() 
        grailsHome() 
        mavenLocal() 
        grailsCentral() 
        mavenCentral() 
        // uncomment these (or add new ones) to enable remote dependency resolution from public Maven repositories 
        //mavenRepo "http://repository.codehaus.org" 
        //mavenRepo "http://download.java.net/maven/2/" 
        //mavenRepo "http://repository.jboss.com/maven2/" 
    } 
 
    dependencies { 
        // specify dependencies here under either 'build', 'compile', 'runtime', 'test' or 'provided' scopes e.g. 
        runtime 'mysql:mysql-connector-java:5.1.29' 
        // runtime 'org.postgresql:postgresql:9.3-1101-jdbc41' 
        //test "org.grails:grails-datastore-test-support:1.0.2-grails-2.4" 
    } 
 
    plugins { 
        // plugins for the build system only 
        build ":tomcat:7.0.55" 
 
        // plugins for the compile step 
        compile ":scaffolding:2.1.2" 
        compile ':cache:1.1.8' 
        compile ":asset-pipeline:1.9.9" 
 
        // plugins needed at runtime but not for compilation 
        runtime ":hibernate4:4.3.6.1" // or ":hibernate:3.6.10.18" 
        runtime ":database-migration:1.4.0" 
        runtime ":jquery:1.11.1" 
 
        // Uncomment these to enable additional asset-pipeline capabilities 
        //compile ":sass-asset-pipeline:1.9.0" 
        //compile ":less-asset-pipeline:1.10.0" 
        //compile ":coffee-asset-pipeline:1.8.0" 
        //compile ":handlebars-asset-pipeline:1.3.0.3" 
    } 
} 

关于 DataSource.groovy 文件,我替换了有关驱动程序名称的行:
driverClassName = "org.h2.Driver" 

经过
driverClassName = "com.mysql.jdbc.Driver" 

对于每个环境(我知道我只使用开发环境,但这只是为了避免一些错误)我替换了以下几行:
url = "jdbc:h2:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 

经过
url = "jdbc:mysql://localhost/test" 

我还在默认用户名和密码(作为 root 用户)+ 驱动程序类名称下方添加了如下(再次针对每个环境):
driverClassName = "com.mysql.jdbc.Driver" 
username = "root" 
password = "" 

这是我的 DataSource.groovy 文件内容:
dataSource { 
    pooled = true 
    jmxExport = true 
    //driverClassName = "org.h2.Driver" 
    driverClassName = "com.mysql.jdbc.Driver" 
    username = "sa" 
    password = "" 
} 
hibernate { 
    cache.use_second_level_cache = true 
    cache.use_query_cache = false 
//    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 { 
            dbCreate = "update" // one of 'create', 'create-drop', 'update', 'validate', '' 
            //url = "jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
            url = "jdbc:mysql://localhost/test" 
            driverClassName = "com.mysql.jdbc.Driver" 
            username = "root" 
            password = "" 
        } 
    } 
    test { 
        dataSource { 
            dbCreate = "update" 
            //url = "jdbc:h2:mem:testDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
            url = "jdbc:mysql://localhost/test" 
            driverClassName = "com.mysql.jdbc.Driver" 
            username = "root" 
            password = "" 
        } 
    } 
    production { 
        dataSource { 
            dbCreate = "update" 
            //url = "jdbc:h2:prodDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
            url = "jdbc:mysql://localhost/test" 
            driverClassName = "com.mysql.jdbc.Driver" 
            username = "root" 
            password = "" 
            properties { 
               // See http://grails.org/doc/latest/guide/conf.html#dataSource for documentation 
               jmxEnabled = true 
               initialSize = 5 
               maxActive = 50 
               minIdle = 5 
               maxIdle = 25 
               maxWait = 10000 
               maxAge = 10 * 60000 
               timeBetweenEvictionRunsMillis = 5000 
               minEvictableIdleTimeMillis = 60000 
               validationQuery = "SELECT 1" 
               validationQueryTimeout = 3 
               validationInterval = 15000 
               testOnBorrow = true 
               testWhileIdle = true 
               testOnReturn = false 
               jdbcInterceptors = "ConnectionState" 
               defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED 
            } 
        } 
    } 
} 

现在,当我运行应用程序时,出现以下错误:
ERROR pool.ConnectionPool  - Unable to create initial connections of pool. 

这是整个错误堆栈:
2016-08-23 16:18:58,040 [localhost-startStop-1] ERROR pool.ConnectionPool  - Unable to create initial connections of pool. 
Message: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
    Line | Method 
->>  411 | handleNewInstance             in com.mysql.jdbc.Util 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1129 | createCommunicationsException in com.mysql.jdbc.SQLError 
|    358 | <init> . . . . . . . . . . .  in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect                   in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly . . . . . . in     '' 
|   2320 | createNewIO                   in     '' 
|    834 | <init> . . . . . . . . . . .  in     '' 
|     46 | <init>                        in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance . . . . . . in com.mysql.jdbc.Util 
|    416 | getInstance                   in com.mysql.jdbc.ConnectionImpl 
|    347 | connect . . . . . . . . . . . in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run                           in java.util.concurrent.FutureTask 
|   1142 | runWorker . . . . . . . . . . in java.util.concurrent.ThreadPoolExecutor 
|    617 | run                           in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run . . . . . . . . . . . . . in java.lang.Thread 
Caused by ConnectException: Connection refused: connect 
->>   79 | socketConnect                 in java.net.DualStackPlainSocketImpl 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|    345 | doConnect                     in java.net.AbstractPlainSocketImpl 
|    206 | connectToAddress . . . . . .  in     '' 
|    188 | connect                       in     '' 
|    172 | connect . . . . . . . . . . . in java.net.PlainSocketImpl 
|    392 | connect                       in java.net.SocksSocketImpl 
|    589 | connect . . . . . . . . . . . in java.net.Socket 
|    538 | connect                       in     '' 
|    434 | <init> . . . . . . . . . . .  in     '' 
|    244 | <init>                        in     '' 
|    256 | connect . . . . . . . . . . . in com.mysql.jdbc.StandardSocketFactory 
|    308 | <init>                        in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect . . . . . . . . . in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly             in     '' 
|   2320 | createNewIO . . . . . . . . . in     '' 
|    834 | <init>                        in     '' 
|     46 | <init> . . . . . . . . . . .  in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance             in com.mysql.jdbc.Util 
|    416 | getInstance . . . . . . . . . in com.mysql.jdbc.ConnectionImpl 
|    347 | connect                       in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run . . . . . . . . . . . . . in java.util.concurrent.FutureTask 
|   1142 | runWorker                     in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . . . . . . . . . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run                           in java.lang.Thread 
Error | 
2016-08-23 16:19:00,132 [localhost-startStop-1] ERROR pool.ConnectionPool  - Unable to create initial connections of pool. 
Message: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
    Line | Method 
->>  411 | handleNewInstance             in com.mysql.jdbc.Util 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1129 | createCommunicationsException in com.mysql.jdbc.SQLError 
|    358 | <init> . . . . . . . . . . .  in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect                   in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly . . . . . . in     '' 
|   2320 | createNewIO                   in     '' 
|    834 | <init> . . . . . . . . . . .  in     '' 
|     46 | <init>                        in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance . . . . . . in com.mysql.jdbc.Util 
|    416 | getInstance                   in com.mysql.jdbc.ConnectionImpl 
|    347 | connect . . . . . . . . . . . in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run                           in java.util.concurrent.FutureTask 
|   1142 | runWorker . . . . . . . . . . in java.util.concurrent.ThreadPoolExecutor 
|    617 | run                           in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run . . . . . . . . . . . . . in java.lang.Thread 
Caused by ConnectException: Connection refused: connect 
->>   79 | socketConnect                 in java.net.DualStackPlainSocketImpl 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|    345 | doConnect                     in java.net.AbstractPlainSocketImpl 
|    206 | connectToAddress . . . . . .  in     '' 
|    188 | connect                       in     '' 
|    172 | connect . . . . . . . . . . . in java.net.PlainSocketImpl 
|    392 | connect                       in java.net.SocksSocketImpl 
|    589 | connect . . . . . . . . . . . in java.net.Socket 
|    538 | connect                       in     '' 
|    434 | <init> . . . . . . . . . . .  in     '' 
|    244 | <init>                        in     '' 
|    256 | connect . . . . . . . . . . . in com.mysql.jdbc.StandardSocketFactory 
|    308 | <init>                        in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect . . . . . . . . . in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly             in     '' 
|   2320 | createNewIO . . . . . . . . . in     '' 
|    834 | <init>                        in     '' 
|     46 | <init> . . . . . . . . . . .  in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance             in com.mysql.jdbc.Util 
|    416 | getInstance . . . . . . . . . in com.mysql.jdbc.ConnectionImpl 
|    347 | connect                       in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run . . . . . . . . . . . . . in java.util.concurrent.FutureTask 
|   1142 | runWorker                     in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . . . . . . . . . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run                           in java.lang.Thread 
Error | 
2016-08-23 16:19:02,194 [localhost-startStop-1] ERROR pool.ConnectionPool  - Unable to create initial connections of pool. 
Message: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
    Line | Method 
->>  411 | handleNewInstance             in com.mysql.jdbc.Util 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1129 | createCommunicationsException in com.mysql.jdbc.SQLError 
|    358 | <init> . . . . . . . . . . .  in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect                   in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly . . . . . . in     '' 
|   2320 | createNewIO                   in     '' 
|    834 | <init> . . . . . . . . . . .  in     '' 
|     46 | <init>                        in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance . . . . . . in com.mysql.jdbc.Util 
|    416 | getInstance                   in com.mysql.jdbc.ConnectionImpl 
|    347 | connect . . . . . . . . . . . in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run                           in java.util.concurrent.FutureTask 
|   1142 | runWorker . . . . . . . . . . in java.util.concurrent.ThreadPoolExecutor 
|    617 | run                           in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run . . . . . . . . . . . . . in java.lang.Thread 
Caused by ConnectException: Connection refused: connect 
->>   79 | socketConnect                 in java.net.DualStackPlainSocketImpl 
Error | 
2016-08-23 16:19:02,205 [localhost-startStop-1] ERROR context.GrailsContextLoaderListener  - Error initializing the application: Error creating bean with name 'transactionManagerPostProcessor': Initialization of bean failed; nested exception is org.springframework.beans.factory.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': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
Message: Error creating bean with name 'transactionManagerPostProcessor': Initialization of bean failed; nested exception is org.springframework.beans.factory.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': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
    Line | Method 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | 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': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Caused by BeanCreationException: Error creating bean with name 'sessionFactory': Cannot resolve reference to bean 'hibernateProperties' while setting bean property 'hibernateProperties'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Caused by BeanCreationException: Error creating bean with name 'hibernateProperties': Cannot resolve reference to bean 'dialectDetector' while setting bean property 'properties' with key [hibernate.dialect]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Caused by BeanCreationException: Error creating bean with name 'dialectDetector': Invocation of init method failed; nested exception is org.springframework.jdbc.support.MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Caused by MetaDataAccessException: Error while extracting DatabaseMetaData; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  266 | run       in java.util.concurrent.FutureTask 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Caused by CommunicationsException: Communications link failure 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. 
->>  411 | handleNewInstance in com.mysql.jdbc.Util 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|   1129 | createCommunicationsException in com.mysql.jdbc.SQLError 
|    358 | <init> .  in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly in     '' 
|   2320 | createNewIO in     '' 
|    834 | <init> .  in     '' 
|     46 | <init>    in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance in com.mysql.jdbc.Util 
|    416 | getInstance in com.mysql.jdbc.ConnectionImpl 
|    347 | connect . in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run       in java.util.concurrent.FutureTask 
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run       in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run . . . in java.lang.Thread 
Caused by ConnectException: Connection refused: connect 
->>   79 | socketConnect in java.net.DualStackPlainSocketImpl 
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
|    345 | doConnect in java.net.AbstractPlainSocketImpl 
|    206 | connectToAddress in     '' 
|    188 | connect   in     '' 
|    172 | connect . in java.net.PlainSocketImpl 
|    392 | connect   in java.net.SocksSocketImpl 
|    589 | connect . in java.net.Socket 
|    538 | connect   in     '' 
|    434 | <init> .  in     '' 
|    244 | <init>    in     '' 
|    256 | connect . in com.mysql.jdbc.StandardSocketFactory 
|    308 | <init>    in com.mysql.jdbc.MysqlIO 
|   2498 | coreConnect in com.mysql.jdbc.ConnectionImpl 
|   2535 | connectOneTryOnly in     '' 
|   2320 | createNewIO in     '' 
|    834 | <init>    in     '' 
|     46 | <init> .  in com.mysql.jdbc.JDBC4Connection 
|    411 | handleNewInstance in com.mysql.jdbc.Util 
|    416 | getInstance in com.mysql.jdbc.ConnectionImpl 
|    347 | connect   in com.mysql.jdbc.NonRegisteringDriver 
|    266 | run . . . in java.util.concurrent.FutureTask 
|   1142 | runWorker in java.util.concurrent.ThreadPoolExecutor 
|    617 | run . . . in java.util.concurrent.ThreadPoolExecutor$Worker 
^    745 | run       in java.lang.Thread 
Error | 
Forked Grails VM exited with errorJava HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0 

似乎 Grails 找不到驱动程序或类似的东西。但是,我们已经看到 JAR 文件已在 .m2 目录中注册。我想知道一件事:这个 JAR 文件是否需要出现在 Grails 依赖项列表中:



整个列表不在图片上,但文件没有出现在列表中。正常吗?该文件是否必须只出现在 .m2 目录中(在 Ivy 缓存中这是相同的,该文件不存在)?当我运行应用程序时,您认为依赖项可用吗? Grails 是否识别驱动程序抛出类路径?

我真的迷路了。

非常感谢您的帮助。

请您参考如下方法:

但我会说按照以下步骤一一进行:

  • 检查您的机器上是否安装了 mysql 服务器。情况可能是您只安装了 Mysql-client。
  • 在您的 DataSource.groovy 中,我看到很多东西要么丢失要么配置不正确。我注意到的很少是:
    a) 缺少方言配置
    b) 缺少端口号。连接服务器

  • 下面是更正的 DataSource.groovy
    dataSource { 
        pooled = true 
        jmxExport = true 
        //driverClassName = "org.h2.Driver" 
        driverClassName = "com.mysql.jdbc.Driver" 
        dialect = "org.hibernate.dialect.MySQL5InnoDBDialect" 
        username = "sa" 
        password = "" 
    } 
    hibernate { 
        cache.use_second_level_cache = true 
        cache.use_query_cache = false 
    //    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 { 
                dbCreate = "update" // one of 'create', 'create-drop', 'update', 'validate', '' 
                //url = "jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
                url = "jdbc:mysql://localhost:3306/test"//you had a missing port here 
                driverClassName = "com.mysql.jdbc.Driver" 
                username = "root" 
                password = "" 
            } 
        } 
        test { 
            dataSource { 
                dbCreate = "update" 
                //url = "jdbc:h2:mem:testDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
                url = "jdbc:mysql://localhost/test" 
                driverClassName = "com.mysql.jdbc.Driver" 
                username = "root" 
                password = "" 
            } 
        } 
        production { 
            dataSource { 
                dbCreate = "update" 
                //url = "jdbc:h2:prodDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" 
                url = "jdbc:mysql://localhost/test" 
                driverClassName = "com.mysql.jdbc.Driver" 
                username = "root" 
                password = "" 
                properties { 
                   // See http://grails.org/doc/latest/guide/conf.html#dataSource for documentation 
                   jmxEnabled = true 
                   initialSize = 5 
                   maxActive = 50 
                   minIdle = 5 
                   maxIdle = 25 
                   maxWait = 10000 
                   maxAge = 10 * 60000 
                   timeBetweenEvictionRunsMillis = 5000 
                   minEvictableIdleTimeMillis = 60000 
                   validationQuery = "SELECT 1" 
                   validationQueryTimeout = 3 
                   validationInterval = 15000 
                   testOnBorrow = true 
                   testWhileIdle = true 
                   testOnReturn = false 
                   jdbcInterceptors = "ConnectionState" 
                   defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED 
                } 
            } 
        } 
    } 
    

    希望有帮助!!如果您在新的 DataSource.groovy 之后遇到任何问题,请告诉我。


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