我们先来看一个例子：
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));
}
}
输出：
{"s1":{"age":16,"name":"s1"},"s2":{"$ref":"$.s1"}}
可以看到，这个json如果发到前端是无法使用的，幸好FastJson提供了解决办法，我们来看下，解决办法为禁用循环引用检测，代码如下：
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));
}
}
输出如下：
{"s1":{"age":16,"name":"s1"},"s2":{"age":16,"name":"s1"}}
问题是如果我们在spring mvc中使用的时候，需要将SerializerFeature注入到MessageConverter里面， FastJsonHttpMessageConverter
但是SerializerFeature是一个enum类型的，又是一个array，考虑到大部分人对这个不熟悉，直接上代码了。
<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>
