错误案例
约 699 字大约 2 分钟
错误案例
问题
我们是否中了 Spring 的毒，代码编程模式变成了 Controller -> Service -> Dao (1:1:1)编写。 贫血模型案例代码布局如下:
.
├── service
│ ├── OtherService.java
│ └── impl
│ └── OtherServiceImpl.java
└── web
├── OtherController.http
└── OtherController.java
- 先看一眼 dto
@Data
public class HelloRequest {
private String policy;
private String name;
}
- 在看一下 Controller 代码
@RequestMapping("/other")
@RestController
public class OtherController {
@Autowired
private OtherService otherService;
@GetMapping("/hello")
public String hello(HelloRequest request) {
return otherService.print(request);
}
}
- 看一下 Service 代码:
public interface OtherService {
String print(HelloRequest helloRequest);
}
@Service
public class OtherServiceImpl implements OtherService {
@Override
public String print(HelloRequest helloRequest) {
if ("hello".equalsIgnoreCase(helloRequest.getPolicy())) {
return helloRequest.getName() + "hello";
}
return helloRequest.getName() + "world";
}
}
然后进行测试，完全符合预期，测试结果如下:
Testing started at 10:01 ...
// 进行测试
GET http://localhost:8080/other/world?name=ren&policy=hello
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 8
Date: Mon, 20 Apr 2020 02:01:50 GMT
Keep-Alive: timeout=60
Connection: keep-alive
> 2020-04-20T100150.200.txt > renhello
###
GET http://localhost:8080/other/hello?name=ren&policy=world
Response code: 200; Time: 54ms; Content length: 8 bytes
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 8
Date: Mon, 20 Apr 2020 02:01:50 GMT
Keep-Alive: timeout=60
Connection: keep-alive
> 2020-04-20T100150-1.200.txt > renworld
Response code: 200; Time: 56ms; Content length: 8 bytes
注意 Service 的实现，这里如果请求的 policy 为 hello，则进行 hello 处理，如果这里为 world 处理，则进行 world 返回， 未来进行扩展业务，我们也就编程了下面这个样子:
// 这段代码完全违背了OCP原则，扩展和测试增加了很大的难度。
if ("hello".equalsIgnoreCase(helloRequest.getPolicy())) {
return helloRequest.getName() + "hello";
} else if () {
// dosomething
} else if () {
// dosomething ....
}
return helloRequest.getName() + "world";
我怎么把 Java 的多态丢了，好像是这个样子，然后你进行了重构。
.
├── service
│ ├── SimpleService.java
│ └── impl
│ ├── HelloSimpleServiceImpl.java
│ └── WorldSimpleServiceImpl.java
└── web
├── SimpleController.http
└── SimpleController.java
- 让我们来看一下一个 Controller:
@RequestMapping("/simple")
@RestController
public class SimpleController {
// Resource = Autowired+Qualifier
/**
* style1 Autowired+Qualifier
*/
@Autowired
@Qualifier("helloSimpleServiceImpl")
private SimpleService helloService;
/**
* style2 Resource = Autowired+Qualifier
*/
@Resource(name = "worldSimpleServiceImpl")
private SimpleService worldService;
@GetMapping("/hello")
public String hello(HelloRequest request) {
return helloService.print(request);
}
@GetMapping("/world")
public String world(HelloRequest request) {
return worldService.print(request);
}
}
- 然后看一下 Service:
public interface SimpleService {
/**
* @param helloRequest 请求
*/
String print(HelloRequest helloRequest);
}
@Service(value = "helloSimpleServiceImpl")
public class HelloSimpleServiceImpl implements SimpleService {
@Override
public String print(HelloRequest helloRequest) {
return helloRequest.getName() + "hello";
}
}
@Service(value = "worldSimpleServiceImpl")
public class WorldSimpleServiceImpl implements SimpleService {
@Override
public String print(HelloRequest helloRequest) {
return helloRequest.getName() + "world";
}
}
- 进行测试:
Testing started at 10:08 ...
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 8
Date: Mon, 20 Apr 2020 02:08:36 GMT
Keep-Alive: timeout=60
Connection: keep-alive
> 2020-04-20T100836.200.txt > renworld
Response code: 200; Time: 19ms; Content length: 8 bytes
HTTP/1.1 200
Content-Type: text/plain;charset=UTF-8
Content-Length: 8
Date: Mon, 20 Apr 2020 02:08:36 GMT
Keep-Alive: timeout=60
Connection: keep-alive
> 2020-04-20T100836-1.200.txt > renhello
Response code: 200; Time: 53ms; Content length: 8 bytes
但是我们发现好像问题没有解决，只是把 Service 问题转移到了 Controller，添加一个策略我们都需要添加一个控制器，无法根据数据进行动态选择策略。 下一章我们将用策略(多态)+享元模式解决这个问题。