eclipse jdbc连接数据库 Could not create connection to database server. Attempted reco

[weixin_41288181]

首先写上我的url="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&autoReconnect=true&failOverReadOnly=false"
实在不知道怎么改了
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:488)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
at com.mysql.jdbc.Util.getInstance(Util.java:387)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2163)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2088)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:488)
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/java.sql.DriverManager.getConnection(DriverManager.java:678)
at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:229)
at mysql209.mysql209.main(mysql209.java:17)
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2997)
at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1936)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1865)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1228)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
... 13 more

[weixin_41288181]

我的代码： package mysql209; import java.sql.*; public class mysql209 { static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&autoReconnect=true&failOverReadOnly=false"; static final String USER ="root"; static final String PASS = "123456"; public static void main(String[] args) { // TODO Auto-generated method stub Connection conn=null; Statement stmt=null; try { Class.forName("com.mysql.jdbc.Driver"); System.out.println("连接数据库......"); conn=DriverManager.getConnection(DB_URL,USER,PASS); System.out.println("实例化statement对象..."); stmt=conn.createStatement(); String sql; sql="select * from product"; ResultSet rs=stmt.executeQuery(sql); while(rs.next()){ // 通过字段检索 int rid = rs.getInt("id"); String pname = rs.getString("name"); String type = rs.getString("type"); // 输出数据 System.out.print("ID: " + rid); System.out.print(", 名称: " + pname); System.out.print(", 类型: " + type); System.out.print("\n"); } // 完成后关闭 rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ // 处理 JDBC 错误 se.printStackTrace(); }catch(Exception e){ // 处理 Class.forName 错误 e.printStackTrace(); }finally{ // 关闭资源 try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ }// 什么都不做 try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); } } } }

[yjsl__]

MySQL版本和驱动jar包版本请告知

[weixin_41288181]

mysql版本是5.7 的 jar包mysql-connector-java-5.1.39-bin

[Cathy313]

按你这个在我本地测试，没有报错，你看看是不是你本地数据库的问题

[stacksoverflow]

mysql是启动在3306端口吗？ netstat /oan 看一下

[yjsl__]

characterEncoding=UTF-8去掉试试 建表的时候设置了编码没

[oyljerry]

数据库连接字符串正确吗