Communications link failure-Mysql，网上一大推解决方法，还是不行的

问题描述：

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 1158 ms ago.
   at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
   at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
   at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
   at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
   at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
   at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:104)
   at com.mysql.jdbc.MysqlIO.negotiateSSLConnection(MysqlIO.java:4472)
   at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1319)
   at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2031)
   ... 12 more
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
   at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
   at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1946)
   at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:316)
   at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:310)
   at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1640)
   at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:223)
   at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1037)
   at sun.security.ssl.Handshaker.process_record(Handshaker.java:965)
   at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1064)
   at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367)
   at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395)
   at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379)
   at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:89)
   ... 15 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
   at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:450)
   at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:317)
   at sun.security.validator.Validator.validate(Validator.java:262)
   at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:330)
   at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:227)
   at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132)
   at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1622)
   ... 23 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
   at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
   at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
   at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
   at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:445)
   ... 29 more

答

mysql启动了吗？端口是什么？把连接字符串发出来看看。

答

遇到什么问题

答

R%P51B4JO)GE]OW9RKL[_LT.png

答


import java.sql.*;

public class JdbcFristDemo {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        //加载驱动
        Class.forName("com.mysql.jdbc.Driver");
        //用户信息和url
        String url="jdbc:mysql://localhost:3306/jdbcStudy?useUnicode=true&characterEncoding=utf8&useSSL=true";
        String username="root";
        String password="123456";

        //连接成功，数据库对象
        Connection connection = DriverManager.getConnection(url,username,password);
        Statement statement=connection.createStatement();
        //执行SQL的对象去执行SQL，可能存在结果，查看返回结果
        String sql="select * from users";
        ResultSet resultSet=statement.executeQuery(sql);
        while (resultSet.next()){
            System.out.println("id="+resultSet.getObject("id"));
            System.out.println("name="+resultSet.getObject("NAME"));
            System.out.println("pwd="+resultSet.getObject("PASSWORD"));
            System.out.println("email="+resultSet.getObject("email"));
            System.out.println("birth="+resultSet.getObject("birthday"));
        }
        //释放连接
        resultSet.close();
        statement.close();
        connection.close();

    }

答

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答

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答

找到问题的原因了-数据库连接驱动版本问题-换成8.0的jar包就好了已解决

Communications link failure-Mysql，网上一大推解决方法，还是不行的

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