如何在hibernate中使用属性文件读取数据库配置参数 [英] How to read database configuration parameter using properties file in hibernate

问题描述

在我的应用程序中，我使用hibernate连接数据库并创建会话。这是我的hibernate.cfg.xml文件。还行吧。它正常工作。

 <？xml version =1.0encoding =UTF-8？> 
<！DOCTYPE hibernate-configuration PUBLIC 
 -  // Hibernate / Hibernate配置DTD 3.0 // EN
http://www.hibernate.org/dtd/hibernate-configuration -3.0.dtd> 
 
< hibernate-configuration> 
 
< session-factory> 
 <！ - 数据库连接设置 - > 
< property name =connection.driver_class> com.mysql.jdbc.Driver< / property> 
< property name =connection.url> jdbc：mysql：// localhost：3306 / country< / property> 
< property name =connection.username> root< / property> 
< property name =connection.password>密码< / property> 
 
< / session-factory> 
 
< / hibernate-configuration> 
  

但是当我尝试使用 db.property文件读取数据库配置属性时使用这个 hibernate.cfg.xml ，它显示Exception，这是我的另一个 hibernate.cfg.xml file

 < util：properties id =dblocation =classpath：db.properties/> 
 
< hibernate-configuration> 
 
< session-factory> 
 <！ - 数据库连接设置 - > 
 < property name =urlvalue =＃{db ['url']}>< / property> 
< property name =usernamevalue =＃{db ['username']}>< / property> 
< property name =passwordvalue =＃{db ['password']}>< / property> 
 
< / session-factory> 
 
< / hibernate-configuration> 
  

这是错误

  org.dom4j.DocumentException：文档第8行的错误：元素util：properties的前缀util未绑定。嵌套异常：未绑定元素util：properties的前缀util。 
 at org.dom4j.io.SAXReader.read（SAXReader.java:482）
 at org.hibernate.cfg.Configuration.doConfigure（Configuration.java:2155）
 > 
 
 
这是我的属性文件，名称为 db.properties  
  driverClassName = com.mysql.jdbc.Driver 
 
 url = jdbc：mysql：// localhost：3306 / country 
 
 username = root 
 
 password =密码
  
什么是问题在那里？ 
如何正确地做到这一点 
 
解决方案
  util：properties 不是在 hibernate.cfg.xml 文件中使用的有效标记。如果你想把所有的数据库配置细节放​​在一个属性文件中，那么你可以把它们放在 hibernate.properties 文件中，并从 hibernate.cfg .xml 文件。以这种方式，DB详细信息将保存在属性文件中。
 
 
 
如果您想要维护一个单独的文件而不是使用hibernate.properties文件，那么您可以试试这个：
  java.util.Properties properties = new Properties（）; 
 properties.load（new FileInputStream（db.properties））; 
 
配置配置=新配置（）; 
 
 configuration.configure（hibernate.cfg.xml）。addProperties（properties）;; 
 
 ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder（）
 .applySettings（configuration.getProperties（））。build（）; 
 
 SessionFactory sessionFactory =配置
 .buildSessionFactory（serviceRegistry）; 
  
 
In my apps I am using hibernate, to connect a with database and create a session. this is my hibernate.cfg.xml file. This is ok. It working properly.
<?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/country</property>
        <property name="connection.username">root</property>
        <property name="connection.password">password</property>

    </session-factory>

</hibernate-configuration>
But when I try to read the DB configuration properties using db.property file using this hibernate.cfg.xml, it showing Exception, this is my another hibernate.cfg.xml file


     
<util:properties id="db" location="classpath:db.properties" />

<hibernate-configuration>

    <session-factory>
        <!-- Database connection settings -->
        <property name="driverClassName" value="#{db['driverClassName']}"></property>
        <property name="url" value="#{db['url']}"></property>
        <property name="username" value="#{db['username']}"></property>
        <property name="password" value="#{db['password']}"></property>

    </session-factory>

</hibernate-configuration>
this is the error 
 org.dom4j.DocumentException: Error on line 8 of document  : The prefix "util" for       element "util:properties" is not bound. Nested exception: The prefix "util" for element   "util:properties" is not bound.
    at org.dom4j.io.SAXReader.read(SAXReader.java:482)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2155)
this is my properties file named db.properties
driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://localhost:3306/country

username=root

password=password
what is the problem is there?
how to do that properly
解决方案
util:properties is not a valid tag to use in hibernate.cfg.xml file. If you want to place all the DB configuration details in a properties file then you can place them in hibernate.properties file and remove those from hibernate.cfg.xml file. In this way the DB details will be maintained in properties file.

If you want to maintain a separate file instead of using hibernate.properties file then you can try this:
java.util.Properties properties = new Properties();
properties.load(new FileInputStream("db.properties"));

Configuration configuration = new Configuration();

configuration.configure("hibernate.cfg.xml").addProperties(properties);;

ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();

SessionFactory sessionFactory = configuration
.buildSessionFactory(serviceRegistry);


                        
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