Hibernate 可编程的配置方式

org.hibernate.cfg.Configuration 实例代表了一个应用程序中 Java 类型到SQL数据库映射的完整集合。org.hibernate.cfg.Configuration 被用来构建一个（不可变的（immutable））org.hibernate.SessionFactory。映射定义则由不同的 XML 映射定义文件编译而来。

你可以直接实例化 org.hibernate.cfg.Configuration 来获取一个实例，并为它指定 XML 映射定义文件。如果映射定义文件在类路径（classpath）中，请使用 addResource（)。例如：

<a id="configuration-programmatic" style="text-decoration:none"><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_plain" style="color:rgb(0,0,0)"> cfg </span><span class="java_operator" style="color:rgb(0,0,0)">=</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">new</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_separator" style="color:rgb(0,0,0)">()</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addResource</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_literal" style="color:rgb(42,0,255)">"Item.hbm.xml"</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addResource</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_literal" style="color:rgb(42,0,255)">"Bid.hbm.xml"</span><span class="java_separator" style="color:rgb(0,0,0)">);</span></a>  
一个替代方法（有时是更好的选择）是，指定被映射的类，让 Hibernate 帮你寻找映射定义文件：

[JAVA] view plaincopy
<a id="configuration-programmatic" style="text-decoration:none"><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_plain" style="color:rgb(0,0,0)"> cfg </span><span class="java_operator" style="color:rgb(0,0,0)">=</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">new</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_separator" style="color:rgb(0,0,0)">()</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addClass</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_plain" style="color:rgb(0,0,0)">org</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">hibernate</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">auction</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_type" style="color:rgb(0,0,0)">Item</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">class</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addClass</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_plain" style="color:rgb(0,0,0)">org</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">hibernate</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">auction</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_type" style="color:rgb(0,0,0)">Bid</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">class</span><span class="java_separator" style="color:rgb(0,0,0)">);</span></a>  
Hibernate 将会在类路径（classpath）中寻找名字为 /org/hibernate/auction/Item.hbm.xml 和/org/hibernate/auction/Bid.hbm.xml 映射定义文件。这种方式消除了任何对文件名的硬编码（hardcoded）。

org.hibernate.cfg.Configuration > 也允许你指定配置属性。例如：

[JAVA] view plaincopy
<a id="configuration-programmatic" style="text-decoration:none"><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_plain" style="color:rgb(0,0,0)"> cfg </span><span class="java_operator" style="color:rgb(0,0,0)">=</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">new</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_type" style="color:rgb(0,0,0)">Configuration</span><span class="java_separator" style="color:rgb(0,0,0)">()</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addClass</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_plain" style="color:rgb(0,0,0)">org</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">hibernate</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">auction</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_type" style="color:rgb(0,0,0)">Item</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">class</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">addClass</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_plain" style="color:rgb(0,0,0)">org</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">hibernate</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">auction</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_type" style="color:rgb(0,0,0)">Bid</span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_keyword" style="font-weight:bold; color:rgb(127,27,85)">class</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">setProperty</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_literal" style="color:rgb(42,0,255)">"hibernate.dialect"</span><span class="java_separator" style="color:rgb(0,0,0)">,</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_literal" style="color:rgb(42,0,255)">"org.hibernate.dialect.MySQLInnoDBDialect"</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">setProperty</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_literal" style="color:rgb(42,0,255)">"hibernate.connection.datasource"</span><span class="java_separator" style="color:rgb(0,0,0)">,</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_literal" style="color:rgb(42,0,255)">"java:comp/env/jdbc/test"</span><span class="java_separator" style="color:rgb(0,0,0)">)</span>  
<span class="java_plain" style="color:rgb(0,0,0)">    </span><span class="java_separator" style="color:rgb(0,0,0)">.</span><span class="java_plain" style="color:rgb(0,0,0)">setProperty</span><span class="java_separator" style="color:rgb(0,0,0)">(</span><span class="java_literal" style="color:rgb(42,0,255)">"hibernate.order_updates"</span><span class="java_separator" style="color:rgb(0,0,0)">,</span><span class="java_plain" style="color:rgb(0,0,0)"> </span><span class="java_literal" style="color:rgb(42,0,255)">"true"</span><span class="java_separator" style="color:rgb(0,0,0)">);</span></a>

当然这不是唯一的传递 Hibernate 配置属性的方式，其他可选方式还包括：

传一个 java.util.Properties 实例给 Configuration.setProperties()。
将 hibernate.properties 放置在类路径（classpath）的根目录下（root directory）。
通过 java -Dproperty=value 来设置系统（System）属性。
在 hibernate.cfg.xml 中加入元素 <property>

Hibernate 可编程的配置方式

猜你喜欢