c3p0 ThreadLocal 报错too many Connection

[NCS123456]

public class DBUtil {
        private static final ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>();
	
	/**
	 * 取得数据库连接
	 * @return
	 */
	public static Connection getConnection() {
		Connection conn = null;
		conn = threadLocal.get();
		if(conn==null) {
			conn = ConnectionManager.getInstance().getConn();
			threadLocal.set(conn);
		}
		return conn;
	}

	public static void closeConn() {
		Connection conn = threadLocal.get();
		try {
			if(conn!=null && !conn.isClosed()) {
				conn.close();
				threadLocal.remove();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	 
	 public static void main(String args[]) {
		 for(int i=0;i<30;i++) {
			 Connection conn = getConnection();
			 closeConn();
			 System.out.println(i+"="+conn);
		 }
	 }
}

public class ConnectionManager {
	private static ConnectionManager instance;
	private ConnectionManager(){}
	
	public synchronized Connection getConn() {
		Connection conn = null;
		ComboPooledDataSource ds = new ComboPooledDataSource("userApp");
		
		try {
			conn = ds.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
	
	public static ConnectionManager getInstance() {
		if(instance==null) {
			instance = new ConnectionManager();
		}
		return instance;
	}
	
}

c3p0配置：
[code=text]<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/examtest?useUnicode=true&characterEncoding=utf-8</property>
<property name="user">root</property>
<property name="password">root</property>
<property name="acquireIncrement">10</property>
<property name="acquireRetryAttempts">30</property>
<property name="initialPoolSize">10</property>
<property name="minPoolSize">10</property>
<property name="maxPoolSize">40</property>
<property name="maxStatements">100</property>
<property name="maxStatementsPerConnection">5</property>
<property name="checkoutTimeout">1000</property>
<property name="idleConnectionTestPeriod">18000</property>
<property name="maxIdleTime">25000</property>code]


一运行就只能取得10次连接，11以后就报错
java.sql.SQLException: Data source rejected establishment of connection, message from server: "Too many connections"
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1018)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2568)
at com.mysql.jdbc.Connection.<init>(Connection.java:1485)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.initializeAutomaticTestTable(C3P0PooledConnectionPoolManager.java:772)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.createPooledConnectionPool(C3P0PooledConnectionPoolManager.java:696)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.getPool(C3P0PooledConnectionPoolManager.java:257)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.getPool(C3P0PooledConnectionPoolManager.java:271)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at com.tom.util.ConnectionManager.getConn(ConnectionManager.java:17)
at com.tom.util.DBUtil.getConnection(DBUtil.java:19)
at com.tom.util.DBUtil.main(DBUtil.java:115)29=null