Java如何利用策略模式替代if/else语句

public class MainStart {

  public static void main(String[] args) {
    String msgid = "MS066";
    if(message.equals("MS066")){
      System.out.println("MS066");
    }else if (message.equals("MS034")){
      System.out.println("MS034");
    }else if (message.equals("MS064")){
      System.out.println("MS064");
    }else{
      System.out.println("no msgid!");
    }
  }
}

public class MainStart {

  public static void main(String[] args) {　　　　 OrderDictController controller=new OrderDictController();
    String msgid = "MS066";
    MsgInterface msgInterface=MsgContext.getInstance(msgId);　　　　 msgInterface.manage(msg,controller);
  }
}

import java.sql.SQLException;

import org.dom4j.DocumentException;

import com.huc.controller.OrderDictController;

public interface MsgInterface {
  public void manage(String msg, OrderDictController controller) throws DocumentException, SQLException;
}

package com.huc.msg.imp;

import java.sql.SQLException;

import org.dom4j.DocumentException;

import com.huc.controller.OrderDictController;
import com.huc.msg.MsgInterface;

public class MS003 implements MsgInterface{
  @Override
  public void manage(String msg, OrderDictController controller) throws DocumentException, SQLException {
    controller.manageMs003(msg);
  }
}

package com.huc.msg.imp;

import java.sql.SQLException;

import org.dom4j.DocumentException;

import com.huc.controller.OrderDictController;
import com.huc.msg.MsgInterface;

public class MS028 implements MsgInterface{
  @Override
  public void manage(String msg, OrderDictController controller) throws DocumentException, SQLException {
    controller.manageMs028(msg);
  }
}

package com.huc.msg;

import java.util.Map;

public class MsgContext {
  public static MsgInterface getInstance(String msgId){
    MsgInterface inter=null;
    Map<String, String> allClazz = MsgEnum.getAllClazz();
    String clazz = allClazz.get(msgId);
    if (msgId!=null&&msgId.trim().length()>0) {
      try {
        try {
          inter = (MsgInterface) Class.forName(clazz).newInstance();//调用无参构造器创建实例
        } catch (InstantiationException e) {
          e.printStackTrace();
        } catch (IllegalAccessException e) {
          e.printStackTrace();
        }
      } catch (ClassNotFoundException e) {
        e.printStackTrace();
      }
    }
    return inter;
  }
}

package com.huc.msg;

import java.util.HashMap;
import java.util.Map;

public enum MsgEnum {

  MS066("MS066", "com.huc.msg.imp.MS066"),
  MS034("MS034", "com.huc.msg.imp.MS034"),
  MS064("MS064", "com.huc.msg.imp.MS064"),
  MS028("MS028", "com.huc.msg.imp.MS028"),
  MS003("MS003", "com.huc.msg.imp.MS003"),
  MS062("MS062", "com.huc.msg.imp.MS062"),
  MS154("MS154", "com.huc.msg.imp.MS154"),
  MS153("MS153", "com.huc.msg.imp.MS153"),
  MS033("MS033", "com.huc.msg.imp.MS033");
  private String msgid;
  private String clazz;

  public static Map<String, String> getAllClazz() {
    Map<String, String> map = new HashMap<String, String>();
    for (MsgEnum msgEnum : MsgEnum.values()) {
      map.put(msgEnum.getMsgid(), msgEnum.getClazz());
    }
    return map;
  }


  MsgEnum(String msgid, String clazz) {
    this.msgid = msgid;
    this.clazz = clazz;
  }


  public String getMsgid() {
    return msgid;
  }


  public void setMsgid(String msgid) {
    this.msgid = msgid;
  }


  public String getClazz() {
    return clazz;
  }

  public void setClazz(String clazz) {
    this.clazz = clazz;
  }

}