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当我在寡妇中运行我的应用程序时，当我想连接到 MySQL 数据库时，myeclipse IDE 给了我以下错误。端口没问题（3306），IP 127.0.0.1，我已经安装驱动了。

如何连接到 MySQL 数据库？

    `String driver = "com.mysql.jdbc.Driver";



        String url ="jdbc:mysql://locahost:3306/registrationdb";
        String dbusername = "root";
        String dbpassword = "root";
        try{
            Class.forName(driver);
        Connection con = DriverManager.getConnection(url, dbusername, dbpassword);

        System.out.println("dbconnected");

        String insert = "insert into registrationdetails values(?,?,?,?,?,?,?)";

        PreparedStatement pstmt=con.prepareStatement(insert);

        pstmt.setString(1,username);
        pstmt.setString(2,password);
        pstmt.setString(3,address);
        pstmt.setString(4,DateofBirth);
        pstmt.setString(5,civilstatus);
        pstmt.setString(6,sex);
        pstmt.setString(7,telephone);

            int i = pstmt.executeUpdate();

            if (i<0){
            out.println("Registration Success");
             }else{
            out.println("Registration Fail");
             }


        }catch (Exception e){
            e.printStackTrace();
            out.println("Some Exception occur please return to the    registration page");



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:1117)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:350)

    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2408)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2230)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
    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:399)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
    at java.sql.DriverManager.getConnection(DriverManager.java:579)
    at java.sql.DriverManager.getConnection(DriverManager.java:221)

    at com.sqlite.registration.RegistrationServlet.doPost(RegistrationServlet.java:51)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:931)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)

    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.net.UnknownHostException: locahost
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:866)
    at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1258)
    at java.net.InetAddress.getAllByName0(InetAddress.java:1211)
    at java.net.InetAddress.getAllByName(InetAddress.java:1127)
    at java.net.InetAddress.getAllByName(InetAddress.java:1063)

    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:249)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
    ... 33 more
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