Connect to Minecraft servers while running Forge or MCP inside of your IDE

MinecraftLogin.java

package net.minecraft.client;

import com.mojang.authlib.Agent;
import com.mojang.authlib.UserAuthentication;
import com.mojang.authlib.exceptions.AuthenticationException;
import com.mojang.authlib.minecraft.MinecraftSessionService;
import com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService;
import net.minecraft.util.Session;

import java.net.Proxy;
import java.util.UUID;

/**
 * Place this class in the net.minecraft.client package or wherever you see fit
 *
 * Make sure you remember to remove the login when you are done developing
 * This was made so you can easily join legit minecraft servers while working from your IDE
 * It just makes modding minecraft a lot easier as you don't have to build everytime you want to test something
 *
 * In Minecraft.java replace these two lines:
 *
 * this.sessionService = (new YggdrasilAuthenticationService(gameConfig.userInfo.proxy, clientToken)).createMinecraftSessionService();
 * this.session = gameConfig.userInfo.session;
 *
 * With this:
 *
 * MinecraftLogin login = new MinecraftLogin("example@email.com", "password123");
 * this.sessionService = login.getSessionService();
 * this.session = login.getSession();
 *
 * Only tested on 1.8.8 MCP
 *
 * @author Nicbo
 */

public class MinecraftLogin {
    private final MinecraftSessionService sessionService;
    private final Session session;

    public MinecraftLogin(String email, String password) {
        YggdrasilAuthenticationService authService = new YggdrasilAuthenticationService(Proxy.NO_PROXY, UUID.randomUUID().toString());
        this.sessionService = authService.createMinecraftSessionService();

        UserAuthentication auth = authService.createUserAuthentication(Agent.MINECRAFT);
        auth.setUsername(email);
        auth.setPassword(password);

        // Attempts to login
        try {
            auth.logIn();
        } catch (AuthenticationException e) {
            System.out.println("Could not login");
            e.printStackTrace();
        }

        // Gets the session from the login
        this.session = new Session(
                auth.getSelectedProfile().getName(),
                auth.getSelectedProfile().getId().toString().replace("-", ""),
                auth.getAuthenticatedToken(),
                auth.getUserType().getName()
        );
    }

    public MinecraftSessionService getSessionService() {
        return sessionService;
    }
    
    public Session getSession() {
        return session;
    }
}