h2 - 如何从java代码中查找h2数据库服务器是否正在运行

Question

我需要从java代码中查找h2数据库服务器是否正在运行。我尝试过 getStatus().isRunning(args) 方法，但即使服务器正在运行，它也始终显示服务器未运行。下面是我的代码:

        Server server = Server.createTcpServer(args);

        // Find whether is server is on or not using "isRunning()" method
        if (server.isRunning(false)) {
            System.out.println("server is running");
        } else {
            System.out.println("server is not running");
        }

        // Find whether is server is on or not using "getStatus()" method

        String statVariable = server.getStatus();

        System.out.println("STATUS=" + statVariable);

        System.out.println("SERVER GONNA START");

        server.start();

Answer 1

也许您可以将请求发送到有问题的端口，假设它是 WebServer 或 TCP 服务器(默认端口分别为 8082 或 9092)。你知道这个电话

drewmac:bin Drawpierce$ java -cp h2*.jar org.h2.tools.Server

创建 3 个服务器并输出如下内容:

TCP 服务器运行于 tcp://192.168.1.3:9092(仅限本地连接)

PG 服务器运行于 pg://192.168.1.3:5435(仅限本地连接)

Web 控制台服务器在 http://192.168.1.3:8082 上运行(仅限本地连接)

然后，如果您调用例程来显示服务器上带有监听套接字的端口 我的电话是 drewmac:~drewpierce$ sudo lsof -i -P | sudo lsof -i -P | sudo lsof -i -P | sudo lsof -i -P | grep -i“听”

java 81339 Drawpierce 19u IPv6 0xffffff800b782ac0 0t0 TCP *:9092(监听)

java 81339 Drawpierce 22u IPv6 0xffffff800b781bc0 0t0 TCP *:5435(监听)

java 81339 Drawpierce 24u IPv6 0xffffff8015620800 0t0 TCP *:8082(监听)

现在，如果您想测试 Web 服务器(http 和 html 流到端口 80、8082，无论您做什么，您都可以发出 Chunk A。如果您想测试 TCP 服务器，您可以发出 Chunk B。

调用 block A，如java GreetingClient localhost 8082

或类似java GreetingClient ec2-1-2-3-4-amaz-aws-ec2.amazon.com 8082

不要忘记这个测试中的2个参数，否则会呕吐

block A:

import java.io.*;
import java.net.*;
public class GreetingClient {
    public static void main(String[] args) {
// declaration section:
// mySocket: our client socket pretending to be a browser
// os: output stream
// is: input stream
        Socket mySocket = null;  
        DataOutputStream os = null;
        DataInputStream is = null;

        String serverName = args[0];
        int port = Integer.parseInt(args[1]);
// Initialization section:
// btw make sure parameters are passed noting that this quick code is NOT
// Try to open input and output streams
        System.out.println("*1");
        try {
            mySocket = new Socket(serverName,port);
            os = new DataOutputStream(mySocket.getOutputStream());
            is = new DataInputStream(mySocket.getInputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: hostname");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: hostname");
        }
        System.out.println("*2");
// If everything has been initialized then we want to write some data
// to the socket we have opened a connection to on port 80, 8082, whatever 
// (what the server is listening on)
    if (mySocket != null && os != null && is != null) {
            try {
// pretend to be a browser and do a GET against a resource
        System.out.println("*3");
        os.writeBytes("GET /index.html HTTP/1.0\r\n\r\n");    
        System.out.println("*4");
// wait for response from webserver, dump out response for sanity check
                String responseLine;
                while ((responseLine = is.readLine()) != null) {
                    System.out.println("Server: " + responseLine);
                    if (responseLine.indexOf("Ok") != -1) {
                      break;
                    }
                }
// clean up:
// close the output stream
// close the input stream
// close the socket
        System.out.println("*5");
        os.close();
                is.close();
                mySocket.close();   
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
        System.out.println("*6");
    }           
}

block A输出(至少对我来说):

*1
*2
*3
*4
Server: HTTP/1.1 200 OK
Server: Content-Type: text/html
Server: Cache-Control: no-cache
Server: Content-Length: 937
Server: 
Server: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Server: <!--
Server: Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
Server: and the EPL 1.0 (http://h2database.com/html/license.html).
Server: Initial Developer: H2 Group
Server: -->
Server: <html><head>
Server:     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
Server:     <title>H2 Console</title>
Server:     <link rel="stylesheet" type="text/css" href="stylesheet.css" />
Server: <script type="text/javascript">
Server: location.href = 'login.jsp?jsessionid=f3d05d9b68f4c5407054628f096ffccb';
Server: </script>
Server: </head>
Server: <body style="margin: 20px;">
Server: 
Server: <h1>Welcome to H2</h1>
Server: <h2>No Javascript</h2>
Server: If you are not automatically redirected to the login page, then
Server: Javascript is currently disabled or your browser does not support Javascript.
Server: For this application to work, Javascript is essential.
Server: Please enable Javascript now, or use another web browser that supports it.
Server: 
Server: </body></html>
*5
*6

有一些事情，显然这是 H2 输出。 block 源代码可以缩减到大约 10 行。

block B(与 TCP jdbc 服务器对话 jdbc)

//STEP 1. Import required packages
import java.sql.*;
import org.h2.Driver;

public class JdbcTrial {
   // JDBC driver name and database URL

   //static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   //static final String DB_URL = "jdbc:mysql://127.0.0.1/test";

   static final String JDBC_DRIVER = "org.h2.Driver";  
   static final String DB_URL = "jdbc:h2:tcp://localhost/~/test";

   //  Database credentials
   static final String USER = "sa";
   static final String PASS = "";

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //STEP 2: Register JDBC driver
      System.out.println("***** 1");
      Class.forName(JDBC_DRIVER);
      System.out.println("***** 2");

      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);

      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      sql = "SELECT id, FirstName, LastName from people";
      ResultSet rs = stmt.executeQuery(sql);

      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve by column name
         int id  = rs.getInt("id");
         String first = rs.getString("FirstName");
         String last = rs.getString("LastName");

         //Display values
         System.out.print("ID: " + id);

         System.out.print(", First: " + first);
         System.out.println(", Last: " + last);
      }
      //STEP 6: Clean-up environment
      rs.close();
      stmt.close();
      conn.close();
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            stmt.close();
      }catch(SQLException se2){
      }// nothing we can do
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end FirstExample

block B 输出:

drewmac:~ drewpierce$ java JdbcTrial
***** 1
***** 2
Connecting to database...
Creating statement...
ID: 1, First: joan, Last: london
ID: 2, First: Sgt., Last: Corholio
Goodbye!

只需修改 jdbc_driver 和 db_url，就可以在 mysql、mariadb 和 H2 上正常工作

您可以只进行套接字连接，而不发出数据检索调用，并真正修剪它。

至于如何使用 H2 getStatus 执行此操作，我不知道。祝你好运。