OSGi上的PostgreSQL连接器 [英] PostgreSQL connector on OSGi
问题描述
我正在使用Karaf开发OSGi应用程序。
此应用程序使用Hibernate 4.3连接到postgresql数据库。
我的应用程序在我使用hibernate default连接池,但JBoss建议不要在prod系统上使用它。所以我试图使用c3p0连接池。
我使用以下包:
< bundle wrap =yes> hibernate-jpa-2.1-api-1.0.0.Final< / bundle>
< bundle wrap =no> hibernate-core-4.3.7.Final< / bundle>
< bundle wrap =no> hibernate-entitymanager-4.3.7.Final< / bundle>
< bundle wrap =no> hibernate-c3p0-4.3.7.Final< / bundle>
< bundle wrap =no> hibernate-envers-4.3.7.Final< / bundle>
< bundle wrap =no> hibernate-osgi-4.3.7.Final< / bundle>
为了使用c3p0,我还添加了请求的第三方库:
< bundle wrap =yes> c3p0-0.9.2.1< / bundle>
wrap
选项设置为yes
,因为它是一个简单的jar文件。
所有这些包都由karaf正确加载。
现在我的问题是添加PostgreSQL驱动程序:我有 postgresql-9.3-1102.jdbc41.jar
,这不是一个包没有manifest.mf文件)。
我试过:
- 将它添加到classpath中
- 在<$ c中使用
< bundle wrap =no> postgresql-9.3-1102.jdbc41.jar< / bundle>
$ c> bundles.xml - 使用本教程 将
- 变成一个片段,由我的dao-layer包托管
但没有任何效果。每次c3p0都会启动连接池,当找到正确的驱动程序时,它会失败并显示以下消息:
java.sql .SQLException:在java.sql.DriverManager.getDriver(DriverManager.java:278)[:1.7.0_67]
处没有合适的驱动
。com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource。 java:240)[98:wrap_file_D_container_karaf_bundles_c3p0-0.9.2.1.jar:0]
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:146)[98:wrap_file_D_trunk_container_karaf_bundles_c3p0-0.9.2.1.jar :0]
寻找这样的问题,我发现有两个原因可能会增加:
- hibernate.connection.url可能是错误的。但那不是我的情况。
- postgresql驱动程序未加载
是否有任何魔法在OSGi环境中使用c3p0和hibernate?
Postgresql现在提供了一个兼容OSGi的驱动程序。它可以从maven central下载:mvn:org.postgresql / postgresql / 9.4-1203-jdbc41
在Apache karaf中,它可以安装在
功能:安装pax-jdbc-postgresql
该包提供了一个DataSourceFactory作为OSGi。这可用于以编程方式创建数据源。
使用 service:list
来查看此DataSourceFactory的属性。
或者,您可以使用pax-jdbc-config从配置中使用 pax-jdbc-config 。使用 osgi.jdbc.driver.class = org.postgresql.Driver
来识别配置中的Postgresql驱动程序。如果可以正确处理配置,将会有一个DataSource类型的服务,您可以在您的代码中参考。
我有一个完整的使用derby和hibernate的例子应该很容易适应postgresql。
I'm working on an OSGi application using Karaf.
This application connects to a postgresql database using Hibernate 4.3.
My application works when I use the hibernate default connection pool but JBoss advices not to use it on a prod system. So I'm trying to use a c3p0 connection pool.
I use the following bundles:
<bundle wrap="yes">hibernate-jpa-2.1-api-1.0.0.Final</bundle>
<bundle wrap="no">hibernate-core-4.3.7.Final</bundle>
<bundle wrap="no">hibernate-entitymanager-4.3.7.Final</bundle>
<bundle wrap="no">hibernate-c3p0-4.3.7.Final</bundle>
<bundle wrap="no">hibernate-envers-4.3.7.Final</bundle>
<bundle wrap="no">hibernate-osgi-4.3.7.Final</bundle>
In order to use c3p0, I also add the requiered third party library:
<bundle wrap="yes">c3p0-0.9.2.1</bundle>
wrap
option is set to "yes"
as it's a simple jar file.
All those bundles are correctly loaded by karaf.
Now my problem is to add the PostgreSQL driver: I have postgresql-9.3-1102.jdbc41.jar
, which is not a bundle (no manifest.mf file).
I tried to:
- add it to the classpath
- wrap it using
<bundle wrap="no">postgresql-9.3-1102.jdbc41.jar</bundle>
inbundles.xml
- wrap it throught eclipse using this tutorial
- make it into a fragment, hosted by my dao-layer bundle
But nothing works. Each times c3p0 start the connexion pool and when it comes to find the right driver, it fails with this message:
java.sql.SQLException: No suitable driver
at java.sql.DriverManager.getDriver(DriverManager.java:278)[:1.7.0_67]
at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:240)[98:wrap_file_D_container_karaf_bundles_c3p0-0.9.2.1.jar:0]
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:146)[98:wrap_file_D_trunk_container_karaf_bundles_c3p0-0.9.2.1.jar:0]
Looking for this kind of problem, I found there are 2 reasons this may append:
- the hibernate.connection.url may be wrong. But that's not my case. I checked it multiple times.
- The postgresql driver is not loaded
Is there any magical trick to use c3p0 with hibernate on a OSGi environment?
Postgresql now delivers an OSGi compatible driver. It can be downloaded from maven central: mvn:org.postgresql/postgresql/9.4-1203-jdbc41 In Apache karaf it can be installed with
feature:install pax-jdbc-postgresql
The bundle offers a DataSourceFactory as an OSGi. This can be used to create a DataSource programmatically.
Use service:list
to see the properties of this DataSourceFactory.
Alternatively you can use pax-jdbc-config to create a DataSource from a config using pax-jdbc-config. Use osgi.jdbc.driver.class=org.postgresql.Driver
to identify the Postgresql driver in the config. If the config can be processed correctly there will be a service of type DataSource that you can refer to in your code.
I got a complete example using derby and hibernate that should be quite easy to adapt to postgresql.
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