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Yyds dry goods inventory springboot JSON format processing

2022-01-27 02:48:25 Chasing dreams_ Picking stars

Era of separation of front and back ends

Back end deployment , Provide the interface , Provide data

Front end independent deployment , Responsible for rendering back-end data

take javascrapt Object conversion to Json object

       
       
<script type="text/javascript>
var user={
name:" Pick stars ",
age:3,
sex:" male "
}

// take js Object conversion json object
var us=JSON.stringify(user);
console.log(us)


// It is also possible to json Convert characters to js
var obj=JSON.parse(json)
console.log(obj);
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Back end Json Handle

Need to import dependency

stay springboot in , Recommended springboot default jackson

       
       
<!-- This is spring-mvc Default used in , But we also need to import dependencies -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.8</version>
</dependency>
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When you need to go back json Data time , Just add one... To the method @ResponseBody annotation , Then return the object directly , You can return a Json Data.

       
       
@RequestMapping("/t1")
@ResponseBody
public List<User> t1(){
List<user> users=t.t1();
return users;
}
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Here's a special case . When an object is returned , It's automatically converted to a string , If the returned string is already a string , Add this note , Then the response is a string data , in other words , When we return to a page , You can't add this annotation , Otherwise, you will misunderstand .


You can add a to the class @RestController such All methods under this class , All default to return json data , You don't have to add... To every method @ResponseBody , also RestController Contains Controller



Advanced operations ( Is to operate on entity class attributes )

1、 Date formatting : Add... To the attribute @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss") Date formatting ,


2、 Add... To the attribute @JsonIgnore annotation , Then this attribute will not be passed in the past , That is to say, excluding


3、 Exclude null values : Add... To the attribute @JsonInclude(JsonInclude.Include.NON_NULL) If this property is null , Will not be excluded


4、 Solve the problem of different names Add... To the attribute JsonProperty(" name ") : In this way, the name is used ;



Java operation json

1、 take java Object conversion to json character string

First create ObjectMapper object , Use it writeValueAsString() Method ,

       
       
ObjectMapper mapper=new ObjectMapper();
// Pass in the object to be converted
System.out.println(mapper.writeValueAsString(ajaxResponse));
System.out.println(mapper.writeValueAsString(ajaxResponse1));
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json String rotation java

Use ObjectMapper Object's readValue() Method , Pass in two parameters ,, The first is to be converted json character string , The second is The name of the object to be converted .class Need to pay attention to when , Converted java On the object , Be sure to add construction methods , Full participation No arguments Both

       
       
System.out.println( mapper.readValue(k2,AjaxResponse.class));
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