Question

我正在尝试使用以下代码从java连接到MySQL数据库：

Connection connection = null;
try {
    connection = DriverManager
    .getConnection("jdbc:mysql://localhost:3306/database","user", "password");
} catch (SQLException e) {
    System.out.println("Connection Failed! Check output console");
    e.printStackTrace();
    return;
}

如果我用Java 7编译它，我会收到以下错误：

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 packets 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:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:355)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2479)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2516)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2301)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    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:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:317)
    at java.sql.DriverManager.getConnection(DriverManager.java:579)
    at java.sql.DriverManager.getConnection(DriverManager.java:221)
    at jobimtext.util.db.DatabaseConnection.openConnection(DatabaseConnection.java:44)
    at jobimtext.util.db.DatabaseResource.connect(DatabaseResource.java:154)
    at jobimtext.thesaurus.distributional.DatabaseThesaurusDatastructure.connect(DatabaseThesaurusDatastructure.java:83)
    at jobimtext.example.demo.IThesaurusDatastructureSimpleDistSimProb.<init>(IThesaurusDatastructureSimpleDistSimProb.java:36)
    at jobimtext.example.demo.DistThresaurus.inizializeDT(DistThresaurus.java:49)
    at jobimtext.example.demo.HolingInput$4.actionPerformed(HolingInput.java:544)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:682)
    at java.awt.EventQueue$3.run(EventQueue.java:680)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:696)
    at java.awt.EventQueue$4.run(EventQueue.java:694)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:693)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
Caused by: java.net.SocketException: Malformed reply from SOCKS server
    at java.net.SocksSocketImpl.readSocksReply(SocksSocketImpl.java:128)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:459)
    at java.net.Socket.connect(Socket.java:579)
    at java.net.Socket.connect(Socket.java:528)
    at java.net.Socket.<init>(Socket.java:425)
    at java.net.Socket.<init>(Socket.java:241)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:305)
    ... 56 more

如果我将编译环境更改为Java 6，一切正常。有人知道Java 7和JDBC之间是否存在不兼容性？我使用JDBC连接器的最新版本：mysql-connector-java-5.1.29-bin.jar

先谢谢你，西尔维娅

Answer 1

加载jdbc驱动程序并再次尝试。

Connection connection = null;
try {
    Class.forName("com.mysql.jdbc.Driver"); 
    connection = DriverManager
    .getConnection("jdbc:mysql://localhost:3306/database","user", "password");
} catch (SQLException e) {
    System.out.println("Connection Failed! Check output console");
    e.printStackTrace();
    return;
} catch (ClassNotFoundException e) {
    System.out.println("Drive Class Not Found.");
    e.printStackTrace();
    return;
}

Answer 2

使用此：

Connection conn = null;
Statement stmt = null;
try {
   Class.forName("com.mysql.jdbc.Driver");
   conn = DriverManager.getConnection("DB_URL", "USER", "PASSWORD");
   stmt = conn.createStatement();
   String sql = "ANY_QUERY";
   stmt.executeUpdate(sql);
} catch (SQLException se) {
   se.printStackTrace();
} catch (Exception e) {
   e.printStackTrace();
}

从Java 7连接到MySQL

2 个答案: