mysql connection refused

2016-05-19 11:42:40 478 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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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:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:988)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:341)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2251)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
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:408)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.hibernate.TestMysql.main(TestMysql.java:35)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
... 15 more
Exception in thread "main" java.lang.NullPointerException

...全文

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切换为时间正序

zhu19774279 2016-05-20

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把代码用论坛自带的代码工具贴出来，你上面说35行报错，我都找不到35行是哪一行。另外把conn输出一下，看看是不是null

qq_24853685 2016-05-19

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不知道怎么处理这个问题，哪位大神帮忙看一下

qq_24853685 2016-05-19

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public class TestMysql { public static void main(String[] args) { Connection conn = null; Statement stmt = null; ResultSet rs = null; String url = null; String user = null; String password ; String sql = null; try { Class.forName("com.mysql.jdbc.Driver"); //加载mysq驱动 } catch (ClassNotFoundException e) { System.out.println("驱动加载错误"); e.printStackTrace();//打印出错详细信息 } try { url = "jdbc:mysql://localhost/mydb"; user = "root"; password = "123456"; conn = DriverManager.getConnection(url,user,password); } catch (SQLException e) { System.out.println("数据库链接错误"); e.printStackTrace(); } try { stmt = conn.createStatement(); sql = "select * from dept";//dept这张表有deptno，deptname和age这三个字段 rs = stmt.executeQuery(sql);//执行sql语句 while(rs.next()) { System.out.print(rs.getInt("deptno") + " "); System.out.print(rs.getString("deptname") + " "); System.out.println(rs.getInt("age") + " "); } } catch (SQLException e) { System.out.println("数据操作错误"); e.printStackTrace(); } //关闭数据库 try { if(rs != null) { rs.close(); rs = null; } if(stmt != null) { stmt.close(); stmt = null; } if(conn != null) { conn.close(); conn = null; } } catch(Exception e) { System.out.println("数据库关闭错误"); e.printStackTrace(); } } }

qq_24853685 2016-05-19

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自带的客户端可以连接，代码如2楼我看了很多遍，也找不到问题，驱动我换了2个版本了，都不行！

qq_24853685 2016-05-19

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我在cmd中试了一下mysql -u <root> -p 显示系统找不到指定的文件

qq_24853685 2016-05-19

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自带的客户端可以连接，代码如2楼我看了很多遍，也找不到问题，驱动我换了2个版本了，都不行！

ACMAIN_CHM 2016-05-19

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先尝试直接用MYSQL自带的MYSQL客户端工具连接一下试试。可能的原因有很多。如果MYSQL自带工具可以，则需要检查程序代码和以驱动参考下贴中的检查方法并贴出你的检查结果(#43楼) http://topic.csdn.net/u/20090920/22/14d4f597-b7d4-4c24-b0db-abb2956e66c3.html [收集]mysql 无法联接故障现象及原因

gikod 2016-05-19

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这就是原因：


Caused by: java.net.ConnectException: Connection refused: connect

Socket连不上，具体原因有可能是 1 MySQL服务没启动 2 MySQL连接信息不对 3 网络有问题首先用mysql -u <username> -p 连接试试，看看服务器和网络是否正常

mysql connection refused

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