堆栈溢出时存在许多相关问题，但我仍然提出这个问题，因为我仍然没有明确的解决方案和我的问题的确切原因。我希望在这里我能完全解决我的问题并为所有人提供帮助
我在我的应用程序中使用 c3p0、MySQL、hibernate(J PA) 和 spring。我在我的应用程序中使用的主要 jar 文件列表是：
c3p0-0.9.2.jar
mchange-commons-java-0.2.3.3.jar
hibernate-commons-annotations-3.0.0.ga.jar
hibernate-entity manager.jar
hibernate-tools.jar
hibernate-validator-4.0.2.GA.jar
hibernate3.jar
mysql-connector-java-5.1.13-bin.jar
我的 persistent.XML 中的 c3p0 设置是这样的：
<property name="hibernate.c3p0.timeout" value="300"/>
<property name="hibernate.c3p0.max_statements" value="50"/>
<property name="hibernate.c3p0.idle_test_period" value="300"/>
在这里，我读到 hibernate.c3p0.idle_test_period 不能高于 hibernate.c3p0.timeout。就我而言，两者都是平等的。
我需要改变什么吗？我怎么解决这个问题 ？
服务器可以正常工作几个小时（可能不完全是 8 小时）并给出以下错误。错误日志是：
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException:
Communications link failure
The last packet successfully received from the server was 35,019,246 milliseconds
ago. The last packet sent successfully to the server was 0 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1118)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3055)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2941)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3489)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1959)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2113)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2113)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2275)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery
(NewProxyPreparedStatement.java:116)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1787)
at org.hibernate.loader.Loader.doQuery(Loader.java:674)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
at org.hibernate.loader.Loader.doList(Loader.java:2220)
... 39 more
Caused by: java.io.EOFException: Can not read response from server.
Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2502)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2952)
... 52 more
... 39 more
Caused by: java.net.SocketException: Broken pipe
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3302)
... 50 more
在这里，我展示了我的 persistent.xml 的快照：-
<properties>
<property name="hibernate.connection.username" value="****"/>
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.connection.password" value="***************"/>
<property name="hibernate.connection.url" value="jdbc:mysql://xxx.xxx.x.xx:3306/projectname?autoReconnect=true"/>
<!--Connection Pooling c3p0 configuration-->
<!--Minimum number of JDBC connections in the pool. Hibernate default: 1-->
<property name="hibernate.c3p0.min_size" value="5"/>
<!--Maximum number of JDBC connections in the pool. Hibernate default: 100-->
<property name="hibernate.c3p0.max_size" value="20"/>
<!--When an idle connection is removed from the pool (in second). Hibernate default: 0, never expire.-->
<property name="hibernate.c3p0.timeout" value="300"/>
<!--Number of prepared statements will be cached. Increase performance. Hibernate default: 0 , caching is disable.-->
<property name="hibernate.c3p0.max_statements" value="50"/>
<!--idle time in seconds before a connection is automatically validated. Hibernate default: 0-->
<property name="hibernate.c3p0.idle_test_period" value="300"/>
</properties>
我在我的应用程序中使用连接类的单例对象。
public static void createConnection()
{
if (em != null)
{
Connection.em.clear();
}
if (em == null) {
new Connection();
}
提前致谢。希望我能得到我的解决方案。
--嗡--