我正在尝试在被Web项目引用的Java项目中运行Hibernate。这很简单，但是我无法让Hibernate连接到我的数据库。有很多人描述了这个问题并得到了很多答案，但是似乎没有一个对我起作用。
这是我的hibernate.cfg.xml的样子：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql//localhost:3306/dbname</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">commander</property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">50</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Enable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.EhCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<mapping resource="com/amakena/profile/mapping/Credentials.hbm.xml"/>
<mapping resource="com/amakena/profile/mapping/Profile.hbm.xml"/>
<mapping resource="com/amakena/profile/mapping/City.hbm.xml"/>
<mapping resource="com/amakena/profile/mapping/Country.hbm.xml"/>
<mapping resource="com/amakena/profile/mapping/Gender.hbm.xml"/>
</session-factory>
</hibernate-configuration>
我调试了代码到 DriverManagerConnectionProvider 类，异常是在尝试调用 getConnection() 方法时抛出的。
Connection conn = DriverManager.getConnection(url, connectionProps);
我检查了url和connectionProps，它们都是hibernate.cfg.xml中的内容。
我在tomcat的\lib文件夹中添加了< i >mysql-connector-java-3.1.14-bin，并且在eclipse的库中可以看到它：Libraries>Apache Tomcat v6.0>。我也将其添加到了%Javahome%\lib\ext以及我的CLASSPATH变量中（尽管我知道这样做可能没用）。
在session.beginTransaction()之前，我通过运行以下代码来确保驱动程序已正确安装，这将引导DriverManagerConnectionProvider.getConnection()。
Class.forName("com.mysql.jdbc.Driver");
Properties connectionProperties = new Properties();
connectionProperties.put("user", "root");
connectionProperties.put("password", "root");
DriverManager.getConnection("jdbc:mysql://localhost:3306/dbname", connectionProperties);
我注意到发出第一行会导致相同的异常。
抛出异常。
WARNING: Method execution failed:
org.hibernate.exception.JDBCConnectionException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:160)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:81)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1473)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:345)
at $Proxy0.beginTransaction(Unknown Source)
at com.amakena.profile.dao.CredentialsDao.hydrate(CredentialsDao.java:45)
at com.amakena.profile.ProfileManager.login(ProfileManager.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.directwebremoting.impl.ExecuteAjaxFilter.doFilter(ExecuteAjaxFilter.java:34)
at org.directwebremoting.impl.DefaultRemoter$1.doFilter(DefaultRemoter.java:428)
at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:431)
at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:283)
at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:52)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.SQLException: No suitable driver found for jdbc:mysql//localhost:3306/dbname
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
... 37 more
WARNING: --Erroring: batchId[24] message[org.hibernate.exception.JDBCConnectionException: Cannot open connection]
感谢您提供的所有帮助。预先致谢。
使用的版本：Tomcat v6.0 - Hibernate 3.6.6 - Java 6 - Eclipse 3.5.2 R35x
Class#forName()调用上没有处理异常，导致出现了抑制。 - BalusC