Java jdbc：无法创建到数据库服务器的连接
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jdbc : Could not create connection to database server
提问by Ali ?.
I am trying to connect mysql database using jdbc. Here is my Database connection Class:
我正在尝试使用 jdbc 连接 mysql 数据库。这是我的数据库连接类：
public class Database {
String userName = "myUserName";
String password = "myPass";
String url = "jdbc:mysql://xxx.xxx.xxx.xxx:3306/database_Name?autoReconnect=true&useSSL=false";
public void connect()
{
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(url,userName,password);
Statement statement = conn.createStatement();
String queryString = "select * from users";
ResultSet rs = statement.executeQuery(queryString);
while (rs.next()) {
System.out.println(rs.getString(2));
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
For now, you can assume that I am calling that method like:
现在，您可以假设我正在调用该方法，例如：
new Database().connect();
And I get this exception:
我得到这个例外：
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
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:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
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 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:425)
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 Database.<init>(Database.java:17)
at ServerTest.main(ServerTest.java:8)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: 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:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:341)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2251)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
... 19 more
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:350)
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)
... 21 more
*I added % to access database from remote.
*我添加了 % 以从远程访问数据库。
*Java part working for localhost but when I try this remote database, it fails.
*Java 部分适用于本地主机，但是当我尝试这个远程数据库时，它失败了。
*The database and tables are created.(there is no problem about this.)
*数据库和表都创建好了。（这个没有问题。）
So where is the problem?
那么问题出在哪里呢？
回答by code
Java part working for localhost but when I try this remote database, it fails
Java 部分适用于本地主机，但是当我尝试使用此远程数据库时，它失败了
This means, your MySql server is bound to localhost and is not visible outside.
Please set bind-addressproperty in your MySql conf file to the actual IP addressof the host.
这意味着，您的 MySql 服务器绑定到本地主机并且在外部不可见。请将bind-addressMySql conf 文件中的属性设置为主机的实际 IP 地址。
Eg: bind-address=192.168.1.26
例如：绑定地址=192.168.1.26
By actual IP address, I mean whichever is visible to your client where java code is running. This could be intranet address or public IP. You might have to use some firewall if you are going to expose your public IP.
通过实际 IP 地址，我的意思是您的客户端可以看到运行 java 代码的任何地址。这可以是 Intranet 地址或公共 IP。如果您要公开您的公共 IP，您可能需要使用一些防火墙。
