java - 连接到 Cloud SQL 时出错

Question

我正在尝试使用 Google App Engine 连接到 Google 的 Cloud SQL Server。我已授权我的 IP，并且可以使用 MySQL Workbench 连接到 Cloud SQL 实例。

public static Connection connect(){
    if (SystemProperty.environment.value() ==
        SystemProperty.Environment.Value.Production) {
        // Connecting from App Engine.
        // Load the class that provides the "jdbc:google:mysql://"
        // prefix.
        try {
            System.out.println("Connecting from App Engine");
            Class.forName("com.mysql.jdbc.GoogleDriver");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        url = "jdbc:google:mysql://op-greek-755:greek3?user=root";
    } else {
         // Connecting from an external network.
        try {
            System.out.println("Connecting from Ext Network");
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        url = "jdbc:mysql://173.194.252.30:3306?user=root";
        }
        Connection conn;
        try {
            System.out.println("About to get Connection");
            conn = DriverManager.getConnection(url);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            conn = null;
        };
        return conn;
}

错误:

Connecting from Ext Network  
About to get Connection  
Nov 10, 2014 1:46:42 PM com.google.appengine.tools.development.ApiProxyLocalImpl log
SEVERE: javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.util.ArrayList com.greek.assassins.client.MySQLService.getAll()' threw an unexpected exception: java.lang.ExceptionInInitializerError
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:389)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:579)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:265)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:305)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:127)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)    
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:491)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: java.lang.ExceptionInInitializerError
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.greek.assassins.server.MySQLServiceImpl.connect(MySQLServiceImpl.java:56)
    at com.greek.assassins.server.MySQLServiceImpl.getAll(MySQLServiceImpl.java:66)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:561)
    ... 40 more
Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
    at java.security.AccessControlContext.checkPermission(Unknown Source)
    at java.security.AccessController.checkPermission(Unknown Source)
    at java.lang.SecurityManager.checkPermission(Unknown Source)
    at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkPermission(DevAppServerFactory.java:429)
    at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkAccess(DevAppServerFactory.java:454)
    at java.lang.ThreadGroup.checkAccess(Unknown Source)
    at java.lang.Thread.init(Unknown Source)
    at java.lang.Thread.init(Unknown Source)
    at java.lang.Thread.<init>(Unknown Source)
    at java.util.TimerThread.<init>(Unknown Source)
    at java.util.Timer.<init>(Unknown Source)
    at java.util.Timer.<init>(Unknown Source)
    at com.mysql.jdbc.Connection.<clinit>(Connection.java:1089)
    ... 51 more

Answer 1

App Engine 对 java 有安全限制，这意味着不能使用多线程。查看 com.google.appengine.api.rdbms.AppEngineDriver 而不是 com.mysql.jdbc.Driver。如果这不起作用，请尝试下载较新版本的 com.mysql.jdbc.Driver 并将其放入类路径中，同时确保也删除旧版本。