【设计模式】【第二章】【业务投放场景】【责任链模式】

package com.example.designdemo.controller;
import com.example.designdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:
 */
@RestController
public class UserController {
    @Autowired
    private UserService userService;
    @GetMapping("/suggest")
    public List<String> suggestRequirement(@RequestParam String username) {
        return userService.suggestRequirement(username);
    }
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:
 */
public abstract class AbstractSuggestRequirementHandler {
    abstract void processHandler(UserInfo userInfo, List<String> suggestLists);
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:用户所在城市是否满足业务投放城市
 */
public class CityCheckHandler extends AbstractSuggestRequirementHandler{
    @Override
    public void processHandler(UserInfo userInfo, List<String> suggestLists) {
        //通过获取 userinfo 的 city 属性
        String city = userInfo.getCity();
        // 通过city 和 之前保留的 4 个 业务信息进行对比。然后筛选出剩余的 3 个 业务投放
        suggestLists.remove("1");
    }
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import java.util.ArrayList;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:新用户首次购买投放指定业务
 */
public class NewCheckHandler extends AbstractSuggestRequirementHandler{
    @Override
    public void processHandler(UserInfo userInfo, List<String> suggestLists) {
        //通过获取 userinfo 的 buyProducts 属性
        boolean newUser = userInfo.isNewUser();
        if(newUser) {
            suggestLists = new ArrayList<>(); // 特定的新用户奖励
        }
    }
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:用户资质是否满足业务投放资质
 */
public class PersonnalCheckHandler extends AbstractSuggestRequirementHandler{
    @Override
    public void processHandler(UserInfo userInfo, List<String> suggestLists) {
        // 通过个人资质的check，我们找到了 4 个可以投放的业务。放到 suggestLists 中。
        suggestLists.add("1");
        suggestLists.add("2");
        suggestLists.add("3");
        suggestLists.add("4");
    }
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:用户近期购买的商品是否符合投放的人群
 */
public class RecentCheckHandler extends AbstractSuggestRequirementHandler{
    @Override
    public void processHandler(UserInfo userInfo, List<String> suggestLists) {
        //通过获取 userinfo 的 buyProducts 属性
        List<String> buyProducts = userInfo.getBuyProducts();
        // buyProducts 和 之前保留的 3 个 业务信息进行对比。然后筛选出剩余的 2 个 业务投放
        suggestLists.remove("2");
    }
}

package com.example.designdemo.handler;
import com.example.designdemo.pojo.UserInfo;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 19:26
 * @Description:
 */
@Component
public class SuggestRequirementHandlerProcess {
    @Value("#{'${suggest.requirement.handler}'.split(',')}")
    private List<String> handlers;
    public void process(UserInfo userInfo, List<String> suggestLists) {
        // 如果想要实时的进行顺序的调整或者是增减。那必须要使用配置中心进行配置。比如springcloud里边自带的 git 的这种配置中心； applo 配置中心；nacos配置中心。
        try {
            for(String handler : handlers) {
                AbstractSuggestRequirementHandler handle =
                        (AbstractSuggestRequirementHandler) Class.forName(handler).newInstance();
                handle.processHandler(userInfo, suggestLists);
            }
        } catch (Exception e) {
        }
    }
}

package com.example.designdemo.pojo;
import java.util.List;
public class UserInfo {
    private String username;
    private String city;
    private List<String> buyProducts;
    private boolean isNewUser;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getCity() {
        return city;
    }
    public void setCity(String city) {
        this.city = city;
    }
    public List<String> getBuyProducts() {
        return buyProducts;
    }
    public void setBuyProducts(List<String> buyProducts) {
        this.buyProducts = buyProducts;
    }
    public boolean isNewUser() {
        return isNewUser;
    }
    public void setNewUser(boolean newUser) {
        isNewUser = newUser;
    }
}

package com.example.designdemo.service;
import java.util.List;
/**
 * @Author: zhiwei Liao
 * @Date: 2022/9/25 9:28
 * @Description:
 */
public interface UserService {
    List<String> suggestRequirement(String username);
}

package com.example.designdemo.service.impl;
import com.example.designdemo.handler.SuggestRequirementHandlerProcess;
import com.example.designdemo.pojo.UserInfo;
import com.example.designdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private SuggestRequirementHandlerProcess suggestRequirementHandlerProcess;
    @Override
    public List<String> suggestRequirement(String username) {
        //获取用户信息。因为用户已经登录了，那么user的信息是保存在我们的缓存里的。
        UserInfo userInfo = getUserInfo(username);
        List<String> results = new ArrayList<>();
        //可以发现，调用方无需关心任何 handler。完全对其屏蔽的。而且是完全解耦
        suggestRequirementHandlerProcess.process(userInfo, results);
        return results;
    }
    //因为这部分是需要查询 缓存（如果缓存没有，需要查库）不应该写到 service层，但是为了代码书写简便
    //这部分我模拟在service 层。
    private UserInfo getUserInfo(String username) {
        return new UserInfo();
    }
}

# 应用名称
spring.application.name=design-demo
# 这里比喻成配置中心 先后顺序决定投放执行的逻辑
# 这里我们先执行PersonnalCheckHandler用户资质是否满足业务投放资质，为用户添加投放业务1,2,3,4.
# 然后再执行CityCheckHandler用户所在城市是否满足业务投放城市,移除用户投放业务1.
# 接着执行RecentCheckHandler用户近期购买的商品是否符合投放的人群，移除用户投放业务2。
# 最后执行NewCheckHandler新用户首次购买投放指定业务，给业务特定业务奖励。最终给用户投放业务3,4
suggest.requirement.handler=com.example.designdemo.handler.PersonnalCheckHandler,com.example.designdemo.handler.CityCheckHandler,com.example.designdemo.handler.RecentCheckHandler,com.example.designdemo.handler.NewCheckHandler