Question

我有一个带有mysql的XAMPP（所以localhost），我可以通过mysql workbench或phpymadmin连接到它，没有任何问题。我有一个使用hibernate的webapp（也尝试了简单和丑陋的方式连接到我的数据库）

Class.forName("com.mysql.jdbc.Driver");
Connection cn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/testlink", "testlink", "testlink");
Statement st = cn.createStatement();
String query = "INSERT INTO `cfield_testprojects` (`field_id`, `testproject_id`, `display_order`, `location`, `active`, `required`, `required_on_design`, `required_on_execution`";
                    st.executeUpdate(query);

我尝试了localhost：3306并没有端口...我一直得到同样的错误：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packet
s from the server.
        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:526)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1038)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
        at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2237)
        at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2270)
        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2069)
        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
        at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
        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:526)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:389)
        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
        at java.sql.DriverManager.getConnection(DriverManager.java:571)
        at java.sql.DriverManager.getConnection(DriverManager.java:215)
        at BuildProject.doPost(BuildProject.java:148)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
        at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:283)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2463)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2452)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.SocketException: Unknown proxy type : HTTP
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:396)
        at java.net.Socket.connect(Socket.java:579)
        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:213)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:297)
        ... 39 more

我在stackoverflow和其他地方都关注了这个问题。我在0.0.0.0上绑定了mysql ...我使用useSystemProxies = false（或类似的东西）没有工作。我只是想让jdbc直接连接到我的localhost DB ...请帮助我疯狂

没有工作： MySQL Connect via proxy in Java

Answer 1

这个问题在我之前发生过，但我当时没有解决，但是在我改变方法之后，它从未发生过，几点要记下来，看看它是否可以解决你的问题：

尝试将Connection对象，PreparedStatement / Statement（如果有）对象，ResultSet对象（如果有）作为全局变量（我更喜欢私有）。初始化连接以及构造函数中的Driver（使用class.forName（））的初始化。如果需要，可以在单独的方法中或在主要内部对查询进行编码。
查看将localhost更改为127.0.0.1是否有帮助
确保在mysql配置文件（my.ini）中注释skip-networking（即在它之前放＃）
不要在查询字符串中引用您的表名
不要犹豫更新jdk / jre / mysql-connector jar，他们或许可以解决这个问题。

强制JDBC不使用代理

1 个答案: