優雅的借助Spring使用策略模式
策略模式(Strategy Pattern)
一個類的行為或其算法可以在運行時更改。這種類型的設計模式屬於行為型模式。
在策略模式中，我們創建表示各種策略的對象和一個行為隨着策略對象改變而改變的 context 對象。策略對象改變 context 對象的執行算法。
example
策略接口
public interface Strategy {
public int doOperation(int num1, int num2);
}
實現策略接口
// +
public class OperationAdd implements Strategy{
@Override
public int doOperation(int num1, int num2) {
return num1 + num2;
}
}
// -
public class OperationSubstract implements Strategy{
@Override
public int doOperation(int num1, int num2) {
return num1 - num2;
}
}
// *
public class OperationMultiply implements Strategy{
@Override
public int doOperation(int num1, int num2) {
return num1 * num2;
}
}
創建 Context 類
public class Context {
private Strategy strategy;
public Context(Strategy strategy){
this.strategy = strategy;
}
public int executeStrategy(int num1, int num2){
return strategy.doOperation(num1, num2);
}
public static void main(String[] args) {
Context context = new Context(new OperationAdd());
System.out.println("10+5="+context.executeStrategy(10, 5));
context = new Context(new OperationSubstract());
System.out.println("10-5="+context.executeStrategy(10, 5));
context = new Context(new OperationMultiply());
System.out.println("10*5="+context.executeStrategy(10, 5));
}
}
執行結果
10+5=15
10-5=5
10*5=50
使用場景
我們看下面這個例子
public String event(){
if("level 0"){
return "do this";
}
if("level 1"){
return "do that";
}
if("level 2"){
return "do where";
}
if("level 3"){
return "do what";
}
if("level 4"){
if("allen is handsome"){
return "do you like me?";
}
return "do you know?Where is the hospital?";
}
}
這里只是舉個例子, 真實業務場景可能比這個復雜的多, 顯然使用策略模式重構這套邏輯更適合程序的維護和開發.
那有些機靈的觀客老爺就會問了, 那Spring里面怎么用才會更優雅呢?
Spring 實現策略模式
策略接口
public interface LevelRank {
String doEvent(String face);
}
策略實現
@Component("AnyValue")
@Order(4)
public class Level0 implements LevelRank {
@Override
public String doEvent(String face) {
return "do this";
}
}
@Component
@Order(3)
public class Level1 implements LevelRank {
@Override
public String doEvent(String face) {
return "do that";
}
}
@Component
@Order(2)
public class Level2 implements LevelRank {
@Override
public String doEvent(String face) {
return "do where";
}
}
@Component
@Order(1)
public class Level3 implements LevelRank {
@Override
public String doEvent(String face) {
return "do what";
}
}
@Component
@Order(0)
public class Level4 implements LevelRank {
@Override
public String doEvent(String face) {
if(StringUtils.equals(face, "handsome")){
return "do you like me?";
}
return "do you know?Where is the hospital?";
}
這里注意
- @Component的value 值是隨意的, 但要有實際意義
- @Order可以覺得該Bean的加載順序
Context的實現
@Slf4j
@RestController
public class LevelController {
// 展示一下list的用法
@Resource
private List<LevelRank> list;
@Resource
private Map<String, LevelRank> map;
@GetMapping("level")
public void doEvent(String level, String face){
log.info(String.valueOf(map));
LevelRank levelRank = map.get(level);
log.info(levelRank.doEvent(face));
//// 展示一下list的用法
log.info("===========================");
for (LevelRank rank : list) {
log.info(rank.doEvent(face));
}
}
}
我們看下結果:
ok, 差不多就這些了.歡迎評論,交流點贊
