How does the backend take out the json data

In Java back-end development, JSON data can be taken from the request in different ways. Here are some common methods:

1. Servlet+JSON parsing library : If you use traditional servlet development, you can obtain the input stream of the request body and use JSON parsing libraries (such as Jackson, Gson, etc.) to convert JSON strings into Java objects. The example code is as follows:

 import com.fasterxml.jackson.databind.ObjectMapper; // ...

 protected  void  doPost (HttpServletRequest request,  HttpServletResponse response)  throws ServletException, IOException { //Get the input stream of the request body
     BufferedReader  reader  = request.getReader(); StringBuilder  jsonBuilder  =  new  StringBuilder (); String line; while ((line = reader.readLine()) != null ) { jsonBuilder.append(line); } reader.close(); //Parse JSON string
     ObjectMapper  objectMapper  =  new  ObjectMapper (); YourDTOObject  dtoObject  = objectMapper.readValue(jsonBuilder.toString(),  YourDTOObject.class); //Get Data
     String  name  = dtoObject.getName(); int  age  = dtoObject.getAge(); // ... }

2. Spring MVC : If you use the Spring MVC framework, you can use its annotations to automatically bind JSON data to Java objects. The example code is as follows:

 @RestController
 public  class  YourController { @PostMapping("/your-url")
     public  void  handleJsonRequest ( @RequestBody YourDTOObject dtoObject) { //Get Data
         String  name  = dtoObject.getName(); int  age  = dtoObject.getAge(); // ... } }

In this example, @RequestBody The annotation means to get the JSON string from the request body and automatically convert it to YourDTOObject Class. You can go directly from YourDTOObject Object.

No matter which way you use, you need to ensure that the fields between the JSON string and the target Java object match, so that they can be parsed and retrieved correctly.