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By Leo II

Source: r6d. Cn/tEvn

In the mobile Internet, distributed, microservices prevailing today, now the vast majority of projects have adopted the microservice framework, the front and back end separation method, (aside: the front and back end work responsibilities are more and more clear, now the front end is called the big front end, technology stack and ecosystem have been very mature; The back end used to look down on the front end, but now the back end has to rethink the front end, which is well established).

The general architecture of the general system is as follows:

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To be clear, some people will reply that this architecture is too simple, too low, there is no gateway, cache, message middleware, etc. Since this article mainly introduces the API interface, we will focus on the other module partners to supplement.

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The interface interaction

The front end and the back end interact. The front end requests the URL path according to the convention and passes in relevant parameters. The back end server receives the request, processes services and returns data to the front end.

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The restful style of the URL path, as well as the requirements of the common request header (such as: app_version, API_version,device, etc.) of the passed parameters, are not introduced here.

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How do back-end servers return data to the front end?

Returns the format

The back end returns to the front end in JSON body mode, which is defined as follows:

{# Return status code:integer, # return information description message:string, # return value data:object}Copy the code

CODE status CODE

Code returns the status code, which is used to add whatever is needed during development.

If the interface wants to return a user permission exception, we add a status code of 101, and the next time we add a data parameter exception, we add a status code of 102. This satisfies business as usual, but the status code is too cluttered

We should refer to the status code returned by the HTTP request

301 - Resource (web page etc.) permanently transferred to another URL 404 - Requested resource (web page etc.) did not exist 500 - Internal server errorCopy the code

We can refer to this design, and the benefit of this is to classify the error type into some interval, and if the interval is not enough, we can design it into four digits.

The value ranges from 1000 to 1999. The value ranges from 2000 to 2999. The value ranges from 3000 to 3999Copy the code

In this way, the front-end developer, after receiving the return value, can know what the error is based on the status code, and can quickly locate the error based on the description of the message related information.

Message

This field is relatively simple to understand, is the error occurs, how to friendly prompt. The general design is designed with the code status code, such as

Define the status code in the enumeration

The status code and the information will correspond one to one, which is easier to maintain.

Data

Returns the data body in JSON format, which varies according to the business.

We’re going to design a return body class Result

Control layer Controller

We will process the business request at the Controller layer and return it to the front end, for example the Order order

We see that after we get the Order object, we wrap the assignment with the Result constructor and then return it. Do you find that the constructor wrapper is not troublesome, we can optimize it.

Beautiful and optimization

We can add static methods to the Result class, just to make sense

So let’s change the Controller

The code is not more concise, also beautiful.

Elegant optimization

We saw above that static methods were added to the Result class, making the business processing code simpler. But have you noticed that there are several problems with this?

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2. In business code, we call result. success on success and result.failure on exception. Hibernate Validate = null; hibernate validate = null; hibernate Validate = null; hibernate Validate = null

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Our best approach is to return the real business object directly, preferably without changing the previous business approach, as shown below

This is the same as our usual code, very intuitive, directly return the order object, isn’t it perfect.

So what’s the implementation?

Implementation scheme

Do you have any ideas on how to achieve it? In this process, we need to do several things

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Define a @responseresult annotation to indicate that the value returned by this interface needs to be wrapped. [ResponseBodyAdvice] [ResponseResult] [ResponseBodyAdvice] [ResponseBodyAdvice] [ResponseBodyAdvice] Override the return value of the Controller interface.

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Annotation class

To mark the return value of a method, whether wrapping is required

The interceptor

Intercepting the request, whether the value returned by the request needs to be wrapped, is essentially parsing the @responseresult annotation at runtime

The core idea of this code is to get this request, whether you need to return the value wrapper, set an attribute tag.

Overwrite return body

The code above is to determine whether return value wrapping is required, and if so, to wrap it directly. Here we only deal with normal successful wrapping, what if the method body reports an exception? Handling exceptions is also easy, as long as you determine whether the body is an exception class.

How to do global exception processing, space reasons, old care here will not be introduced, as long as the idea is clear, on the line of their own transformation.

Rewrite the Controller

Put an @responseresult annotation on your controller class or on your method body, and you’re done. Simple. The design idea that returns to this is completed, is not concise again, elegant again.

conclusion

Is there room for further optimization in this scheme? Of course there is. For example, each request needs to be reflected, whether the method to get the request needs to be wrapped, in fact, can do a cache, do not need to be resolved every time. Of course, the overall idea of understanding, partners can expand on this basis. Thanks!!

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