JDBC连接池c3p0的问题
测试CP30连接池，怎么报这样的异常？



import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public final class ConnectionManager {

private static ConnectionManager instance;
private static ComboPooledDataSource dataSource;

private ConnectionManager() throws SQLException, PropertyVetoException {
dataSource = new ComboPooledDataSource();

dataSource.setUser("root");
dataSource.setPassword("root");
dataSource.setJdbcUrl("jdbc:mysql://loachost:3306/test");
dataSource.setDriverClass("com.mysql.jdbc.Driver");
dataSource.setInitialPoolSize(5);
dataSource.setMinPoolSize(1);
dataSource.setMaxPoolSize(10);
dataSource.setMaxStatements(50);
dataSource.setMaxIdleTime(60);
}

public static final ConnectionManager getInstance() {
if (instance == null) {
try {
instance = new ConnectionManager();
} catch (Exception e) {
e.printStackTrace();
}
}
return instance;
}

public synchronized final Connection getConnection() {
Connection conn = null;
try {
conn = dataSource.getConnection();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
}


import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class ConnectionDemo {

public static void main(String[] args) {
System.out.println("使用连接池................................");
for (int i = 0; i < 20; i++) {
long beginTime = System.currentTimeMillis();
Connection conn = ConnectionManager.getInstance().getConnection();
try {
PreparedStatement pstmt = conn.prepareStatement("SELECT * FROM t_fmscpy200");
ResultSet rs = pstmt.executeQuery();
while (rs.next()) {
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

long endTime = System.currentTimeMillis();
System.out.println("第" + (i + 1) + "次执行花费时间为:" + (endTime - beginTime));
}

}
}


2010-7-4 21:12:52 com.mchange.v2.log.MLog <clinit>
信息: MLog clients using java 1.4+ standard logging.
2010-7-4 21:12:53 com.mchange.v2.c3p0.C3P0Registry banner
信息: Initializing c3p0-0.9.2-pre1 [built 27-May-2010 01:00:49 -0400; debug? true; trace: 10]

Exception in thread "main" java.lang.NoSuchMethodError: com.mchange.v2.async.ThreadPoolAsynchronousRunner.<init>(IZLjava/util/Timer;Ljava/lang/String;)V
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.createTaskRunner(C3P0PooledConnectionPoolManager.java:132)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.poolsInit(C3P0PooledConnectionPoolManager.java:143)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.<init>(C3P0PooledConnectionPoolManager.java:262)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getPoolManager(AbstractPoolBackedDataSource.java:508)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at ConnectionManager.getConnection(ConnectionManager.java:39)
at ConnectionDemo.main(ConnectionDemo.java:14)

结果报这样的异常，jar用到的是cp300.9.1.2.jar


[解决办法]
重新打包，或是在MANIFEST.MF这个文件里指定Main-Class,应该可以解决你的问题.