Question

我正在使用Spring创建一个GAE项目，该项目也将使用云SQL。在本地测试这个应用程序我指的是我的本地MySQL环境但是当我将它部署到GAE时，它将指向云SQL实例。所以我想根据环境在datasource bean中配置我的driverName。为此，我们通常在我们的java代码中使用以下

if (SystemProperty.environment.value() == SystemProperty.Environment.Value.Production) {
    // Load the class that provides the new "jdbc:google:mysql://" prefix.
    Class.forName("com.mysql.jdbc.GoogleDriver");
    url = "jdbc:google:mysql://<your-project-id>:<your-instance-name>/<your-database-name>?user=root";
} else {
    // Local MySQL instance to use during development.
    Class.forName("com.mysql.jdbc.Driver");
    url = "jdbc:mysql://127.0.0.1:3306/<your-database-name>?user=root";
}

现在我想在applicationcontext.xml中使用Spring Expression语言实现相同的功能。我之前没有这样做过，也无法实现。请指导我。这就是我试过的

<bean id="isDev" class="java.lang.Boolean">
    <constructor-arg value="#{ systemProperties[environment.value] == SystemProperty.Environment.Value.Development ? true : false }" />
</bean>

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="#{ isDev ? com.mysql.jdbc.Driver : com.mysql.jdbc.GoogleDriver }" />
.
.
.

但我得到例外，附上一部分例外

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.sandeepapplabs.custengage.services.FeedbackFormService com.sandeepapplabs.custengage.controllers.FeedbackFormController.feedbackFormService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.sandeepapplabs.custengage.daos.FeedbackFormDAO com.sandeepapplabs.custengage.services.impl.FeedbackFormServiceImpl.feedbackFormDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'feedbackFormDAO' defined in ServletContext resource [/WEB-INF/custengage-servlet.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in ServletContext resource [/WEB-INF/custengage-servlet.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is java.lang.NullPointerException

Answer 1

我相信你需要引用类名来使它们成为文字......

... 'com.mysql.jdbc.Driver' ...

然而，使用Spring Profiles（http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/beans.html#beans-definition-profiles-xml）更容易，并启用所需的配置文件。

Answer 2

您可以使用Spring配置文件来更改具体的bean类。我们假设您有两个配置文件：＆＃34; prod＆＃34;和＆＃34; dev＆＃34;。你的bean方法应该有@Profile注释，如下所示：

@Configuration
public class AppConfig {

...

  @Bean
  @Profile("prod")
  public Object prodDataSource() { 

    return new ...
  }

  @Bean
  @Profile("dev")
  public Object getDataSource() throws Exception {
    return new ...
  }

 }

如果您使用的是Maven，可以通过pom.xml选择配置文件：

<profiles>
    <profile>
        <id>dev</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <spring.profile>dev</spring.profile>
        </properties>
    </profile>

    <profile>
        <id>prod</id>
        <activation>
            <activeByDefault>false</activeByDefault>
            <property>
                <name>prod</name>
            </property>
        </activation>
        <properties>
            <spring.profile>prod</spring.profile>
        </properties>
    </profile>

</profiles>

您可以通过-D传递个人资料选择参数，例如：mvn -Dprod clean compile test install

修改

在application.properties以下属性中选择个人资料：

spring.profiles.active=${spring.profile}

如何在applicationContext.xml中有条件地使用数据源

2 个答案: