.net C# jdbc 驱动程序连接器异常

Question

I'm trying to connect to a hyperSQL database (HSQLDB) on my local machine from ac# application in visual studio.

I've ran through the steps to create the .net JDBC driver to build the dll, and also downloading the demo console application in the "download" section from the following url: http://nikolaiklimov.de/query-java-HyperSQL-database-with-csharp/

The demo application works!! i can connect to the database and query its contents . Next I have converted the console app into a class library then call the class library to query the DB but this is where it falls over and I get initialization errors of System.TypeInitializationException. any idea why the project falls over after converting to a class library. (if i convert the class library straight back a console app it works again).

The code and connection string are:

namespace HyperSQL
{
public static class sqlconnector
{
             readonly static string CONNECTION_STRING =   
  ConfigurationManager.ConnectionStrings["HyperSQL"].ConnectionString;
             const string SQL = "SELECT * FROM meeting";

    public static void getdata()
    {
        try
        {


        java.sql.DriverManager.registerDriver(new org.hsqldb.jdbcDriver());
        using (java.sql.Connection conn = java.sql.DriverManager.getConnection(CONNECTION_STRING))
        {
            java.sql.PreparedStatement ps = conn.prepareStatement(SQL);
            using (java.sql.ResultSet rs = ps.executeQuery())
            {
                while (rs.next())
                {
                    Console.WriteLine($"MEETING_NO={rs.getInt("MEETING_NO")}");

                    Console.WriteLine("------------------");
                }
            }
        }
        }
        catch (Exception ex)
        {

        }

        Console.ReadLine();
    }
}
}

jdbc:hsqldb:hsql://localhost:3458/elitedb;crypt_key=DADADADADAADDADAD;crypt_type=AES;shutdown=true;write_delay=false;user=****;password=****

Ive added a console app to my solution after the conversion to a class libary. The console app code is below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                HyperSQL.sqlconnector.getdata();
            }
            catch (Exception ex)
            {

            }
        }
    }
}

Here is a link to download my solution created in visual studio. It contains a console application that calls a function in a class library. The class library (HyperSQL) itself is simply converted from a console application and can be converted back. You will need a running instance of HyperSQL on your machine to be able to connect successfully. http://eliteservicedev.azurewebsites.net/DemoHyperSQL.zip

Answer 1

Have you seen the error listed in the original site you posted?

If your forget to add runtime dependencies to the build folder of your project then you can get these errors: Could not load file or assembly 'IKVM.OpenJDK.Util, Version=8.1.5717.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' or one of its dependencies. The system cannot find the file specified. TypeInitializationException: The type initializer for 'org.hsqldb.jdbc.JDBCDriver' threw an exception: FileNotFoundException: Could not load file or assembly 'IKVM.Runtime, Version=8.1.5717.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' or one of its dependencies. 'The type initializer for 'sun.util.locale.provider.LocaleProviderAdapter' threw an exception.' FileNotFoundException: Could not load file or assembly 'IKVM.OpenJDK.Text, Version=8.1.5717.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58' or one of its dependencies. 'The type initializer for 'org.hsqldb.HsqlDateTime' threw an exception.' InvalidCastException: Unable to cast object of type 'java.util.PropertyResourceBundle' to type 'sun.util.resources.OpenListResourceBundle'.

***** UPDATE With the source project i see an error, looking in the bin\\debug folder i see that non all the referenced file are copied to ConsoleApp1.exe bin folder: this is the compare result:

Confronto in corso dei file consoleapp1.txt e DEMOCSHARPTHYPERSQL.TXT
***** consoleapp1.txt
ConsoleApp1.exe
ConsoleApp1.exe.config
ConsoleApp1.pdb
hsqldb.dll
HyperSQL.dll
***** DEMOCSHARPTHYPERSQL.TXT
hsqldb.dll
HyperSQL.dll
*****

***** consoleapp1.txt
IKVM.OpenJDK.Jdbc.dll
IKVM.OpenJDK.Text.dll
***** DEMOCSHARPTHYPERSQL.TXT
IKVM.OpenJDK.Jdbc.dll
IKVM.OpenJDK.Localedata.dll --> Missing in ConsoleApp1.exe folder
IKVM.OpenJDK.Text.dll
*****

If i manually copy the missing dll on ConsoleApp1.exe folder the program run correctly. I think that is a visual studio bug

Answer 2

Seems VS is not copying all IKVM DLLs to output folder due to not resolving they are needed. Please see this SourceForge issue and this GitHub issue , the later one with my comments.