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;
}
}