В памяти встроенный сервер с помощью Apache Derby

Question

есть хороший пример того, как начать встроенный сервер (то есть. Сервер базы данных, который только в Интернете до тех пор, пока приложение находится в режиме онлайн)

Кроме того, можно для того, чтобы он был только в памяти?

Answer 1

Скачать Apache Derby и добавить ссылки в вашем проекте следующие файлы:

derby.jar 
derbynet.jar 
derbyclient.jar 

Используйте следующий код для запуска сервера и создать в памяти базы данных:

import java.net.InetAddress; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.PreparedStatement; 
import java.sql.SQLNonTransientConnectionException; 
import java.util.ArrayList; 
import java.util.List; 
import org.apache.derby.drda.NetworkServerControl; 

public class DerbyInMemoryEmbeddedServer { 

    public static void main(String[] args) throws Exception { 
     NetworkServerControl server = new NetworkServerControl(InetAddress.getByName("localhost"), 1528); 
     server.start(null); 

     String connectionString = "jdbc:derby://localhost:1528/memory:hello_world_database;create=true"; 
     Connection conn = DriverManager.getConnection(connectionString); 
     System.out.println("Server started"); 

     //create the database here. The following is an example: 

     //create the users table 
     try (PreparedStatement ps = conn.prepareStatement(
       "create table users (" 
       + "id int not null generated always as identity, " 
       + "username varchar(8000), " 
       + "first_name varchar(8000), " 
       + "surname varchar(8000), " 
       + "primary key (id), " 
       + "constraint uc_username unique (username)" 
       + ")")) { 
      ps.execute(); 
     } 

     //create an index 
     try (PreparedStatement ps = conn.prepareStatement(
       "create index ix_surname on users (surname)")) { 
      ps.execute(); 
     } 

     //add some users 
     List<String> names = new ArrayList<>(); 
     names.add("jhuff|Jeffrey|Huffines"); 
     names.add("woodsey223|Sherwood|Gurule"); 
     names.add("tim_w|Tim|Woods"); 
     try (PreparedStatement ps = conn.prepareStatement("insert into users (username, first_name, surname) values (?, ?, ?)")) { 

      for (String name : names) { 
       String[] tokens = name.split("\\|"); 

       ps.setString(1, tokens[0]); 
       ps.setString(2, tokens[1]); 
       ps.setString(3, tokens[2]); 
       ps.addBatch(); 
      } 

      ps.executeBatch(); 
     } 

     //create the team table 
     try (PreparedStatement ps = conn.prepareStatement(
       "create table team (" 
       + "id int not null generated always as identity, " 
       + "name varchar(8000), " 
       + "primary key (id)," 
       + "constraint uc_team_name unique (name)" 
       + ")")) { 
      ps.execute(); 
     } 

     //insert a team 
     try (PreparedStatement ps = conn.prepareStatement(
       "insert into team (name) values (?)")) { 
      ps.setString(1, "Wombats"); 
      ps.executeUpdate(); 
     } 

     //create a many-to-many table to link teams to users. (Since a user can belong to more than one team) 
     try (PreparedStatement ps = conn.prepareStatement(
       "create table team_member (" 
       + "id int not null generated always as identity, " 
       + "team_id int not null, " 
       + "user_id int not null," 
       + "constraint fk_team_member_team foreign key (team_id) references team(id), " 
       + "constraint fl_team_member_user foreign key (user_id) references users(id), " 
       + "primary key (id)" 
       + ")")) { 
      ps.execute(); 
     } 

     //create team members 
     List<String> teamMembers = new ArrayList<>(); 
     teamMembers.add("jhuff|Wombats"); 
     teamMembers.add("tim_w|Wombats"); 

     try (PreparedStatement ps = conn.prepareStatement("insert into team_member (team_id, user_id) values (" 
       + "(select id from team where name = ?)," 
       + "(select id from users where username = ?)" 
       + ")")) { 

      for (String teamMember : teamMembers) { 
       String[] tokens = teamMember.split("\\|"); 

       ps.setString(1, tokens[1]); 
       ps.setString(2, tokens[0]); 
       ps.addBatch(); 
      } 
      ps.executeBatch(); 
     } 

     System.out.println("Server ready"); 
     System.in.read(); 

     System.out.println("Disconnecting"); 
     String shutdownConnectionString = connectionString + ";shutdown=true"; 

     try { 
      DriverManager.getConnection(shutdownConnectionString); 
     } catch (SQLNonTransientConnectionException ex) { 
      //derby throws an exception on disconnection 
     } 

     System.out.println("Disconnected"); 
    } 
} 

Если вы в конечном счете, хотите, чтобы ваша база данных сохранялась между перезапусками приложений, вместо этого используйте эту строку подключения:

jdbc:derby://localhost:1528/jdbc:derby:C:\db_files\proof_of_concept;create=true;