策略模式,工厂模式,InitializingBean相结合解决多条件筛选

编码中面对日益繁多的if else,switch导致代码越来越臃肿,可读性,可维护性也会急剧下降,这里我们先用策略模式去解决:

策略模式代码:

接口IDemoService

public interface IDemoService {
           String getServiceName();    }

实现类Demo1ServiceImpl,Demo2ServiceImpl

@Servicepublic class Demo1ServiceImpl implements IDemoService {
       @Override    public String getServiceName() {
           return "Demo1ServiceImpl";    }}@Servicepublic class Demo2ServiceImpl implements IDemoService {
       @Override    public String getServiceName() {
           return "Demo2ServiceImpl";    }}

控制器

@RestController@RequestMapping("demo")public class DemoController {
       @PostMapping("/getServiceName")    public String getServiceName(@RequestParam("num") int num) {
           IDemoService demoService;        if (num == 1) {
               demoService = new Demo1ServiceImpl();        } else if (num==2) {
               demoService = new Demo2ServiceImpl();        } else {
               return null;        }        return demoService.getServiceName();    }}

结果:

参数num=1时,返回Demo1ServiceImpl;参数num=2时,返回Demo2ServiceImpl;

这样看,随着业务提升还是会有大量的if else;

结合工厂模式,InitializingBean:

接口IDemoService

public interface IDemoService extends InitializingBean {
       String getServiceName();    }

工厂类DemoServiceFactory

public class DemoServiceFactory {
       private static Map
   
     services = new ConcurrentHashMap<>();    public static IDemoService getByNum(int type) {
           return services.get(type);    }    public static void register(int type, IDemoService demoService) {
           Assert.notNull(type, "type can't be null");        services.put(type, demoService);    }}

实现类Demo1ServiceImpl,Demo2ServiceImpl

@Servicepublic class Demo1ServiceImpl implements IDemoService {
       @Override    public String getServiceName() {
           return "Demo1ServiceImpl";    }    @Override    public void afterPropertiesSet() throws Exception {
           DemoServiceFactory.register(1, this);    }}@Servicepublic class Demo2ServiceImpl implements IDemoService {
       @Override    public String getServiceName() {
           return "Demo2ServiceImpl";    }    @Override    public void afterPropertiesSet() throws Exception {
           DemoServiceFactory.register(2, this);    }}

控制器

@RestController@RequestMapping("demo")public class DemoController {
       @PostMapping("/getServiceName")    public String getServiceName(@RequestParam("num") int num) {
           IDemoService demoService = DemoServiceFactory.getByNum(num);        return demoService.getServiceName();    }}

结果:

参数num=1时,返回Demo1ServiceImpl;参数num=2时,返回Demo2ServiceImpl;

这样通过工厂的方法将实现类存储在map中，根据传入的值为key，取出对应的实现类，大大减少了代码，后期业务增加的时候也只需要增加对应的实现类即可，无需修改之前的代码！

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