在J2SE应用程序中从persistence.xml外部化凭据 [英] Externalize credentials from persistence.xml in J2SE app

问题描述

我正在编写一个使用JPA进行持久化的J2SE应用程序（无企业容器）。这是我的 persistence.xml ：

 < persistence xmlns = http://java.sun.com/xml/ns/persistence
 xmlns：xsi =http://www.w3.org/2001/XMLSchema-instance
 xsi：schemaLocation = http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd
 version =2.0> 
 
< persistence-unit name =dbstats> 
 
 <！ -  TODO：为什么需要？ - > 
< class> dreambear.stats.data.GamePlayedEvent< / class> 
< class> dreambear.stats.data.HyveMemberCountPoll< / class> 
< class> dreambear.stats.data.ProfileCountPoll< / class> 
< class> dreambear.stats.data.UserSession< / class> 
< class> dreambear.stats.data.UsersOnlinePoll< / class> 
 
<属性> 
 
< property name =hibernate.dialectvalue =org.hibernate.dialect.MySQLDialect/> 
< property name =hibernate.max_fetch_depthvalue =3/> 
< property name =hibernate.hbm2ddl.autovalue =update/> 
 
< property name =javax.persistence.jdbc.drivervalue =com.mysql.jdbc.Driver/> 
 
 <！ -  TODO：外部化信息 - > 
< property name =javax.persistence.jdbc.uservalue =dbstats/> 
< property name =javax.persistence.jdbc.passwordvalue =*****/> 
< property name =javax.persistence.jdbc.urlvalue =jdbc：mysql：//example.com/dbstats/> 
 
< / properties> 
 
< / persistence-unit> 
 
< /持久性> 
  

这是一个静态文件，编译到应用程序中。但是，我需要提取证书，以便我可以在运行时从配置参数加载它们，因为它们与例如

我以默认方式加载持久性设置：

  emf = Persistence.createEntityManagerFactory（dbstats）; 
  

如何在此设置中外部化凭据？我可以在运行时生成persistence.xml文件，但这有点不好。

解决方案

创建 EntityManagerFactory ：

  Map< String，String> properties = new HashMap< String，String>（）; 
 properties.put（javax.persistence.jdbc.user，...）; 
 ... 
 
 emf = Persistence.createEntityManagerFactory（dbstats，properties）; 
  

I'm writing a J2SE app (no enterprise container) that uses JPA for persistence. Here is my persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">

    <persistence-unit name="dbstats">

    <!-- TODO: why is this needed? -->
    <class>dreambear.stats.data.GamePlayedEvent</class>
    <class>dreambear.stats.data.HyveMemberCountPoll</class>
    <class>dreambear.stats.data.ProfileCountPoll</class>
    <class>dreambear.stats.data.UserSession</class>
    <class>dreambear.stats.data.UsersOnlinePoll</class>

    <properties>

        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
        <property name="hibernate.max_fetch_depth" value="3" />
        <property name="hibernate.hbm2ddl.auto" value="update" />

        <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />

        <!-- TODO: externalize information -->
        <property name="javax.persistence.jdbc.user" value="dbstats" />
        <property name="javax.persistence.jdbc.password" value="*****" />
        <property name="javax.persistence.jdbc.url" value="jdbc:mysql://example.com/dbstats" />

    </properties>

    </persistence-unit>

</persistence>

It's a static file, "compiled" into the application. However, I need to extract the credentials so I can load them from config parameters at runtime, because they're different for e.g. the development and live version of the app.

I load the persistence setup in the default way:

emf = Persistence.createEntityManagerFactory("dbstats");

How can I externalize the credentials in this setup? I could generate the persistence.xml file at runtime, but that's a bit hacky.

解决方案

You can provide additional properties when creating EntityManagerFactory:

Map<String, String> properties = new HashMap<String, String>();
properties.put("javax.persistence.jdbc.user", ...);
...

emf = Persistence.createEntityManagerFactory("dbstats", properties); 

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