Hibernate+PostgreSQL throws JDBCConnectionException: Cannot open connection

Question

I write an Test Java APP and it works right BUt this Web app throws an exception like that with to same cfg.xml file

<property name="hibernate.bytecode.use_reflection_optimizer">false</property>
<property name="hibernate.connection.autocommit">true</property>
<property name="hibernate.connection.release_mode">auto</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
<property name="hibernate.connection.password">1234</property>
<property name="hibernate.connection.url">jdbc:postgresql://localhost/postgres</property>
<property name="hibernate.connection.username">postgres</property>
<property name="hibernate.default_schema">public</property>
<property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>

<property name="hibernate.ejb.discard_pc_on_close">false</property>
<property name="hibernate.query.jpaql_strict_compliance">true</property>
<property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>
<property name="hibernate.transaction.flush_before_completion">false</property>
<property name="hibernate.show_sql">false</property>
<property name="hibernate.generate_statistics">false</property>
<property name="hibernate.use_sql_comments">false</property>
<property name="hibernate.connection.pool_size">100</property>

When I press "Save" button I get the following exception:

javax.servlet.ServletException: org.hibernate.exception.JDBCConnectionException: Cannot open connection
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:325)

root cause

javax.faces.el.EvaluationException: org.hibernate.exception.JDBCConnectionException: Cannot open connection
 javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
 com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
 javax.faces.component.UICommand.broadcast(UICommand.java:315)
 javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775)
 javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267)
 com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
 com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
 com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)

root cause

org.hibernate.exception.JDBCConnectionException: Cannot open connection
 org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:98)
 org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
 org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
 org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
 org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
 org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
 org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
 org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463)
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 java.lang.reflect.Method.invoke(Unknown Source)
 org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344)
 $Proxy108.beginTransaction(Unknown Source)
 com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52)
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 java.lang.reflect.Method.invoke(Unknown Source)
 org.apache.el.parser.AstValue.invoke(AstValue.java:196)
 org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
 com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98)
 javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
 com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
 javax.faces.component.UICommand.broadcast(UICommand.java:315)
 javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775)
 javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267)
 com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
 com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
 com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)

root cause

java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost/postgres
 java.sql.DriverManager.getConnection(Unknown Source)
 java.sql.DriverManager.getConnection(Unknown Source)
 org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133)
 org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
 org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
 org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
 org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
 org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1463)
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 java.lang.reflect.Method.invoke(Unknown Source)
 org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344)
 $Proxy108.beginTransaction(Unknown Source)
 com.yemex.beans.CompanyBean.saveOrUpdate(CompanyBean.java:52)
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 java.lang.reflect.Method.invoke(Unknown Source)
 org.apache.el.parser.AstValue.invoke(AstValue.java:196)
 org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
 com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:98)
 javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
 com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
 javax.faces.component.UICommand.broadcast(UICommand.java:315)
 javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:775)
 javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1267)
 com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
 com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
 com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
 javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)

Blockquote

Answer 1

When encountering an exception, it's worth to check the bottommost root cause in the stacktrace. In this case it's the following:

java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost/postgres

This just means that either the URL is wrong or that the desired driver is not present in the current runtime classpath. Since the URL looks fine as per the PostgreSQL JDBC documentation, it'll be that the driver is missing in the current runtime classpath.

So, to fix this problem, you need put the JDBC driver JAR file in the webapp's runtime classpath. The /WEB-INF/lib is one of the folders which is covered by the webapp's default runtime classpath. Just drop the PostgreSQL JDBC driver JAR file in there and redeploy.

Answer 2

What's the question here?

The exception is pretty explicit:

org.hibernate.exception.JDBCConnectionException: Cannot open connection

Make sure you can connect to the database you are connected to, that the configuration is correct, that you do not have network issues preventing the connection, etc.