使用Java应用程序远程连接到H2数据库 [英] Connect remotely to an H2 Database using a Java Application
问题描述
我遇到以下问题：
当我尝试使用我的外部IP地址创建TCP服务器时（PC的IP而不是我的本地IP =我们在cmd.exe中运行ipconfig后看到的输出）发生以下错误：
I'm having the following problem: When I try to createTcpServer with my external IP address (the PC's IP and not my local IP = the one we see as an output after running ipconfig in cmd.exe) the following error occurs:
服务器出错：异常打开端口9092（端口可能正在使用中），原因：java.net.BindException：无法分配请求地址：JVM_Bind[90061-169]
Error with Server: Exception opening port "9092" (port may be in use), cause: "java.net.BindException: Cannot assign requested address: JVM_Bind" [90061-169]
但是，该端口未被使用。我已经使用netstat -a -n检查过了。
我启用了外部IP，并且已从路由器禁用了防火墙。我的外部IP现在可以被ping。
However, the port is not in use. I've checked that using netstat -a -n . I have enabled my external IP and I have disabled the firewall from the router. My external IP can now be pinged.
请帮助我。
更新：这是我的代码开始tcp服务器。
Update: Here is my code to start the tcp server.
package businessApp;
import org.h2.tools.Server; //imports the server utility
public class startTcpServerForH2 {
Server server; //the server's instance variable
private static final String SERVER_IP = "192.168.1.101"; //fixed IP of the server
private static final String SERVER_PORT = "9092"; //fixed port the server is listening to
public void tcpServer() { //method responsible to create the tcp server
optionPane optPane = new optionPane(); //option pane for debugging purposes, shows the server's status
try { //catches any server related errors, if the connection is broken etc.
//server uses the IP and port defined earlier, allows other computers in the LAN to connect and implements the secure socket layer (SSL) feature
server = Server.createTcpServer( //create tcp server
new String[] { "-tcpPort" , SERVER_PORT , "-tcpAllowOthers" , "-tcpSSL" }).start();
System.out.println(server.getStatus()); //prints out the server's status
optPane.checkServerStatus(server.getStatus()); //prints out the server's status on the option pane as well
} catch(Exception ex){
System.out.println("Error with Server: " + ex.getMessage());
}
}
public static void main(String[] args){
startTcpServerForH2 tcpServ = new startTcpServerForH2(); //create a new server object
tcpServ.tcpServer(); //starts the tcp server
}
}
第二次更新：这里是h2Connection代码。
Second Update: here is the h2Connection code.
package businessApp;
package businessApp;
import java.sql。*; //导入sql功能
import java.sql.*; //imports sql features
//负责连接H2数据库引擎的类
公共类h2Connection {
//Class responsible for connection with H2 Database Engine public class h2Connection {
Connection conn; //connection variable
DatabaseMetaData dbmd; /** Metadata variable which include methods such as the following:
* 1) Database Product Name
* 2) Database Product Version
* 3) URL where the database files are located (in TCP mode)
*/
Statement stm; //statements variable
ResultSet rst; //result sets variable
private static final String SERVER_IP = "..."; //here I enter my WAN_IP
private static final String SERVER_PORT = "9092";
public Connection connectionToH2(Connection connt) {
optionPane optPane = new optionPane(); //create new option pane object
String outputConn = null; //declare & initialize string which will hold important messages
try {
Class.forName("org.h2.Driver"); //Driver's name
/** The String URL is pertained of the following:
* 1) jdbc which java implements so that it can take advantage of the SQL features
* 2) Which Database Engine will be used
* 3) URL where the files will be stored (as this is a TCP connection)
* 4) Schema: businessApp
* 5) Auto server is true means that other computers can connect with the same databse at any time
* 6) Port number of the server is also defined
*/
String url = "jdbc:h2:tcp://" + SERVER_IP + ":" + SERVER_PORT + "/C:/Databases/businessApp;IFEXISTS=TRUE";
System.out.println(url); //prints out the url the database files are located as well as the h2 features used (SSL)
connt = DriverManager.getConnection(url, "sa", ""); //Driver Manager defines the username & password of the database
System.out.println(connt.getCatalog()); //prints out the database schema
optPane.checkServerStatus(connt.getCatalog()); //prints out the database schema on the option pane as well
connt.setAutoCommit(false); //set AutoCommit to false to control commit actions manually
//outputs H2 version and the URL of the database files which H2 is reading from, for confirmation
dbmd = connt.getMetaData(); //get MetaData to confirm connection
outputConn = "Connection to "+dbmd.getDatabaseProductName()+" "+
dbmd.getDatabaseProductVersion()+ " with the URL " + dbmd.getURL()+" was successful.\n";
System.out.println(outputConn); //outputs the message on the system (NetBeans compiler)
optPane.checkH2Connection(outputConn); //outputs the message on top of the frame
} catch (ClassNotFoundException ex){ //In case there is an error for creating the class for the Driver to be used
System.out.println("Error creating class: " + ex.getMessage());
} catch(SQLException ex){ //Any error associated with the Database Engine
System.out.println("SQL error: " + ex.getMessage());
optPane.checkServerStatus("SQL error: " + ex.getMessage());
}
return connt; //As the method is not void, a connection variable must be returned
}
}
当我想连接到h2数据库时，我创建了一个新的h2Connection对象并用它来连接。我一字一句地跟着H2手册。你还需要什么？
When I want to connect to the h2 database, I make a new h2Connection object and use it to connect. I have followed the H2 manual word by word. What more do you need?
推荐答案
正如下面显示的命令行帮助所示，针对远程访问的保护 建议如下：
As suggested in the command line help shown below, Protection against Remote Access advises the following:
默认情况下，此数据库在启动H2控制台，TCP服务器或PG服务器时不允许来自其他计算机的连接。可以使用命令行选项
-webAllowOthers，-tcpAllowOthers，-pgAllowOthers启用远程访问。
请参阅重要文件caveats 。
附录：只要我重新开始<$ c $ 打开防火墙后，c>服务器 ;你根本不需要 setProperty（）行;您的 WAN_IP 转发端口9092的 LAN IP 应该是您的主机IP地址;然后你可以通过 WAN_IP 打开一个shell：
Addendum: Works for me, as long as I restart the Server after opening the firewall; you don't need the setProperty() line at all; the LAN IP to which your WAN_IP forwards port 9092 should be your host IP address; then you can open a shell via your WAN_IP:
java -cp h2.jar org.h2.tools.Shell -url
jdbc:h2:tcp://WAN_IP/~/path/to/test;ifexists=true"
命令行帮助：
$ java -cp .:/opt/h2/bin/h2.jar org.h2.tools.Shell -?
Interactive command line tool to access a database using JDBC.
Usage: java org.h2.tools.Shell
Options are case sensitive. Supported options are:
[-help] or [-?] Print the list of options
[-url ""] The database URL (jdbc:h2:...)
[-user ] The user name
[-password ] The password
[-driver ] The JDBC driver class to use (not required in most cases)
[-sql ""] Execute the SQL statements and exit
[-properties ""] Load the server properties from this directory
If special characters don't work as expected, you may need to use
-Dfile.encoding=UTF-8 (Mac OS X) or CP850 (Windows).
See also http://h2database.com/javadoc/org/h2/tools/Shell.html
$ java -cp /opt/h2/bin/h2.jar org.h2.tools.Server -?
Starts the H2 Console (web-) server, TCP, and PG server.
Usage: java org.h2.tools.Server
When running without options, -tcp, -web, -browser and -pg are started.
Options are case sensitive. Supported options are:
[-help] or [-?] Print the list of options
[-web] Start the web server with the H2 Console
[-webAllowOthers] Allow other computers to connect - see below
[-webDaemon] Use a daemon thread
[-webPort ] The port (default: 8082)
[-webSSL] Use encrypted (HTTPS) connections
[-browser] Start a browser connecting to the web server
[-tcp] Start the TCP server
[-tcpAllowOthers] Allow other computers to connect - see below
[-tcpDaemon] Use a daemon thread
[-tcpPort ] The port (default: 9092)
[-tcpSSL] Use encrypted (SSL) connections
[-tcpPassword ] The password for shutting down a TCP server
[-tcpShutdown ""] Stop the TCP server; example: tcp://localhost
[-tcpShutdownForce] Do not wait until all connections are closed
[-pg] Start the PG server
[-pgAllowOthers] Allow other computers to connect - see below
[-pgDaemon] Use a daemon thread
[-pgPort ] The port (default: 5435)
[-properties ""] Server properties (default: ~, disable: null)
[-baseDir ] The base directory for H2 databases (all servers)
[-ifExists] Only existing databases may be opened (all servers)
[-trace] Print additional trace information (all servers)
The options -xAllowOthers are potentially risky.
For details, see Advanced Topics / Protection against Remote Access.
See also http://h2database.com/javadoc/org/h2/tools/Server.html
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