Address the problem of FastJson circular references in springmvc

Let's start with an example:

package com.elong.bms; 
 
import java.io.OutputStream; 
import java.util.HashMap; 
import java.util.Map; 
 
import com.alibaba.fastjson.JSON; 
 
public class Test { 
 public static void main(String[] args) { 
 Map<String, Student> maps = new HashMap<String, Student>(); 
 Student s1 = new Student("s1", 16); 
 
 maps.put("s1", s1); 
 maps.put("s2", s1); 
 
 byte[] bytes = JSON.toJSONBytes(maps); 
 
 System.out.println(new String(bytes)); 
 } 
} 

Output:

{"s1":{"age":16,"name":"s1"},"s2":{"$ref":"$.s1"}} 

As you can see, this json cannot be used if sent to the front end. Fortunately, FastJson provides a solution. Let's take a look.

package com.elong.bms; 
 
import java.io.OutputStream; 
import java.util.HashMap; 
import java.util.Map; 
 
import com.alibaba.fastjson.JSON; 
import com.alibaba.fastjson.serializer.SerializerFeature; 
 
public class Test { 
 public static void main(String[] args) { 
 Map<String, Student> maps = new HashMap<String, Student>(); 
 Student s1 = new Student("s1", 16); 
 
 maps.put("s1", s1); 
 maps.put("s2", s1); 
  
 SerializerFeature feature = SerializerFeature.DisableCircularReferenceDetect; 
 
 byte[] bytes = JSON.toJSONBytes(maps,feature); 
 
 System.out.println(new String(bytes)); 
 } 
} 

The output is as follows:

{"s1":{"age":16,"name":"s1"},"s2":{"age":16,"name":"s1"}} 

The problem is if we're using spring mvc, we need to inject SerializerFeature into MessageConverter, FastJsonHttpMessageConverter

However, SerializerFeature is of type 1 enum and another array. Considering that most people are not familiar with this, we will go straight to the code.

<bean id="jsonConverter" 
  class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter"> 
  <property name="supportedMediaTypes" value="application/json;charset=UTF-8"/> 
  <property name="features"> 
  <array value-type="com.alibaba.fastjson.serializer.SerializerFeature"> 
   <value>DisableCircularReferenceDetect</value> 
  </array> 
  </property> 
 </bean> 
 <bean id="DisableCircularReferenceDetect" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean"> 
  <property name="staticField" value="com.alibaba.fastjson.serializer.SerializerFeature.DisableCircularReferenceDetect"></property> 
 </bean>