It is always good to use Design Pattern in your application, although it is not required, in order to avoid spaghetti. One of popular design pattern is Factory pattern. The concept is similar to DI (Dependency Injection). In this example, I use Static Factory pattern.

With Factory pattern, you can instantiate a class with “new” (Source Code)

@RequestMapping("/cUrlValSubLine01Jsp/{rmaNum}")
public ModelAndView goToSubLine01Jsp(@PathVariable("rmaNum") String rmaNum,	Model model, HttpServletRequest req) {
	List<RmaLineModel> rmaLineModelList = RmaDtlBL.getRmaLineListWithCdTblNm(rmaNum, null);
	return getMVSubLine01(rmaNum, rmaLineModelList, req);
}

This method is being called to set ModelAndView object, and one of them is the list of code for auto-complete feature

private ModelAndView getMVSubLine01(String rmaNum, List<RmaLineModel> rmaLinsList, HttpServletRequest req) {

	RmaLineListModel newModel = new RmaLineListModel(rmaNum, rmaLinsList);

	ModelAndView modelAndView = new ModelAndView(VIEW.SUB_LINE_01.getVal());
	modelAndView.addObject(CONST.FORM_KEY.getVal(), newModel);
	// For item detail list
	modelAndView.addObject(CONST.LINE_LIST_MODEL.getVal(), newModel);
	// Setup Status drop down line the item list
	modelAndView.addObject(CONST.HDR_STS_LIST.getVal(), getList(CONST.HDR_STS_LIST.getVal()));
	// Item list for AJAX Auto complete
	req.getSession().setAttribute(CONST.MDSE_LIST.getVal(), getList(CONST.MDSE_LIST.getVal()));
	return modelAndView;
}

Above line 12 calls this method:

private List<?> getList(String key) {
	BLFactory fact = BLFactory.getInstance(key);
	return fact.getList();
}

Above line 12 calls this method:

package com.ns.spring.common.gen;

import java.util.List;

import com.ns.spring.constant.RtrnConstant;

public class BLFactory implements RtrnConstant {

	private BLService svc;

	private BLFactory(String param) {
		if (CONST.HDR_STS_LIST.getVal().equals(param)) {
			this.svc = new RtrnCommonBL();
		} else if (CONST.TP_LIST.getVal().equals(param)) {
			this.svc = new TpCommonBL();
		} else if (CONST.MDSE_LIST.getVal().equals(param)) {
			this.svc = new MdseCommonBL();
		}
	}

	// static factory
	public static BLFactory getInstance(String param) {
		return new BLFactory(param);
	}

	public List<?> getList() {
		return this.svc.getList();
	}
}

This factory class returns static instance via interface BLService.

package com.ns.spring.common.gen;

import java.util.List;

public interface BLService {
	public List<?> getList();
}

package com.ns.spring.common.gen;

import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.ns.spring.common.CommonBL;
import com.ns.spring.constant.RtrnConstant.CONST;
import com.ns.spring.model.MDSE;
import com.ns.spring.model.RMA_HDR_STS;
import com.ns.spring.model.RTRN_TP;
import com.ns.spring.model.ui.MdseModel;
import com.ns.spring.model.ui.RmaHdrStsModel;
import com.ns.spring.model.ui.RtrnTpModel;
import com.ns.spring.service.template.MdseService;
import com.ns.spring.service.template.RmaHdrStsService;
import com.ns.spring.service.template.RtrnTpService;

@Component
public class MdseCommonBL implements BLService {

	private static MdseService mdseSvc;
	
	@Autowired(required = true)
	public void setMdseSvc(MdseService mdseSvc) {
		this.mdseSvc = mdseSvc;
	}

	@Override
	public List<MdseModel> getList() {
		List<MdseModel> mdseModelList = new ArrayList<>();
		List<MDSE> mdseList = mdseSvc.findAll();
		if (!CommonBL.isEmpty(mdseList)) {
			for (int i = 0; i < mdseList.size(); i++) {
				MDSE obj = (MDSE) mdseList.get(i);
				mdseModelList.add(new MdseModel(i, obj.getMdseCd()));
			}
		}
		return mdseModelList;
	}
}

getList() eventually calls findAll() that returns all record from MDSE table.