責任鏈模式應(yīng)用
1. 責任鏈模式介紹
責任鏈模式（Chain of Responsibility Pattern）為請求創(chuàng)建了一個接收者對象的鏈徘键。這種模式給予請求的類型练对，對請求的發(fā)送者和接收者進行解耦。這種類型的設(shè)計模式屬于行為型模式吹害。在這種模式中螟凭，通常每個接收者都包含對另一個接收者的引用。如果一個對象不能處理該請求它呀，那么它會把相同的請求傳給下一個接收者螺男，依此類推。
2. 應(yīng)用場景
- 1). 有多個對象可以處理同一個請求纵穿，具體哪個對象處理該請求由運行時刻自動確定下隧。
- 2). 在不明確指定接收者的情況下，向多個對象中的一個提交一個請求谓媒。
- 3). 可動態(tài)指定一組對象處理請求淆院。
3. 實現(xiàn)(以創(chuàng)建訂單為例子)
步驟一
創(chuàng)建一個接口:
package com.example.demo.designmodel.chain3;
import org.springframework.core.Ordered;
/**
* @author: robin
* @date: 2020/8/6 4:44 PM
* @aphorism: "stay hungry, stay foolish"
*/
public interface AbstractOrderHandler extends Ordered {
/**
*
* provide abstract method
*
* @param stage
* @param ride
* @return
*/
Boolean doHandler(int stage, GreenChannelOrder ride);
}
步驟二
創(chuàng)建責任鏈處理器添加后繼處理器:
package com.example.demo.designmodel.chain3;
import com.google.common.collect.Maps;
import org.springframework.stereotype.Component;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
/**
* Chain of Responsibility Pattern
* Ensure link order
*/
@Component
public class OrderHandlerChain {
private List<AbstractOrderHandler> baseHandlers;
//private Map<String, AbstractOrderHandler> map2 = Maps.newHashMapWithExpectedSize(3);
public OrderHandlerChain(List<AbstractOrderHandler> baseHandlers) {
baseHandlers.sort(Comparator.comparing(AbstractOrderHandler::getOrder));
/* Map<String, AbstractOrderHandler> map = Maps.newHashMapWithExpectedSize(3);
for(AbstractOrderHandler handler:baseHandlers){
map.put(handler.handLerName(),handler);
}
*/
// this.map2=baseHandlers.stream().collect(Collectors.toMap(AbstractOrderHandler::handLerName, a -> a,(k1, k2)->k1));
this.baseHandlers = Collections.unmodifiableList(baseHandlers);
}
/* public AbstractOrderHandler getAbstractHandler(String handlerName){
return map2.get(handlerName);
}*/
public void handle(int stage, GreenChannelOrder ride) {
boolean handle = false;
for (AbstractOrderHandler baseHandler : baseHandlers) {
if (!handle) {
handle = baseHandler.doHandler(stage, ride);
}
}
}
}
步驟三
創(chuàng)建具體的職責處理類
1)預(yù)置訂單處理器
package com.example.demo.designmodel.chain3;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
/**
* @author: robin
* @date: 2020/8/6 4:46 PM
* @aphorism: "stay hungry, stay foolish"
*/
@Slf4j
@Component
public class PreOrderHandler implements AbstractOrderHandler {
@Override
public Boolean doHandler(int stage, GreenChannelOrder ride) {
if (stage <= 1) { //預(yù)置訂單處理職責
log.info("階段1");
System.out.println("階段1");
return false;
}
return false;//繼續(xù)傳遞
}
@Override
public int getOrder() {
return 0;
}
}
2)開始訂單處理器
package com.example.demo.designmodel.chain3;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
/**
* @author: robin
* @date: 2020/8/6 4:46 PM
* @aphorism: "stay hungry, stay foolish"
*/
@Slf4j
@Component
public class StartOrderHandler implements AbstractOrderHandler {
@Override
public Boolean doHandler(int stage, GreenChannelOrder ride) {
if (stage <= 2) {//開始訂單處理職責
log.info("階段2");
return true;
}
return false;
}
@Override
public int getOrder() {
return 1;
}
}
3)結(jié)束訂單處理器
package com.example.demo.designmodel.chain3;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
/**
* @author: robin
* @date: 2020/8/6 4:46 PM
* @aphorism: "stay hungry, stay foolish"
*/
@Slf4j
@Component
public class FinishOrderHandler implements AbstractOrderHandler {
@Override
public Boolean doHandler(int stage, GreenChannelOrder ride) {
if (stage <= 3) {//結(jié)束訂單處理職責
try {
log.info("階段3");
} catch (Exception e) {
}
}
return true;
}
@Override
public int getOrder() {
return 2;
}
}
