fastjson把对象转化成json避免$ref

港控/mmm° 2022-08-23 13:47 196阅读 0赞

转：http://blog.csdn.net/mephistodemon1/article/details/19118493

DisableCircularReferenceDetect来禁止循环引用检测：

JSON.toJSONString(..., SerializerFeature.DisableCircularReferenceDetect)

当进行toJSONString的时候，默认如果重用对象的话，会使用引用的方式进行引用对象。

"颜色": [
          {
            "$ref": "$.itemSkuList[0].itemSpecificationList[0]"
          }, 
          {
            "$ref": "$.itemSkuList[1].itemSpecificationList[0]"
          }
        ]

### 循环引用 ###

很多场景中，我们需要序列化的对象中存在循环引用，在许多的json库中，这会导致stackoverflow。在功能强大的fastjson中，你不需要担心这个问题。例如：

A a = new A();
    B b = new B(a);
    a.setB(b);
    String text = JSON.toJSONString(a); //{"b":{"a":{"$ref":".."}}}
    A a1 = JSON.parseObject(text, A.class);
    Assert.assertTrue(a1 == a1.getB().getA());

引用是通过"$ref"来表示的

<table style="font-size:10pt; line-height:13pt; color:rgb(51,51,51); clear:left; margin:5px 0px; border-collapse:collapse; padding:0px; background-color:initial"> 
 <tbody> 
  <tr style="font-size:10pt; line-height:13pt; background-color:initial"> 
   <th style="font-size:10pt; line-height:13pt; color:rgb(0,0,0); padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:rgb(240,240,240)"> 引用</th> 
   <th style="font-size:10pt; line-height:13pt; color:rgb(0,0,0); padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:rgb(240,240,240)"> 描述</th> 
  </tr> 
  <tr style="font-size:10pt; line-height:13pt; background-color:initial"> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> "$ref":".."</td> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> 上一级</td> 
  </tr> 
  <tr style="font-size:10pt; line-height:13pt; background-color:initial"> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> "$ref":"@"</td> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> 当前对象，也就是自引用</td> 
  </tr> 
  <tr style="font-size:10pt; line-height:13pt; background-color:initial"> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> "$ref":"$"</td> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> 根对象</td> 
  </tr> 
  <tr style="font-size:10pt; line-height:13pt; background-color:initial"> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> "$ref":"$.children.0"</td> 
   <td style="font-size:10pt; line-height:13pt; padding:5px; border:1px solid rgb(221,221,221); vertical-align:top; min-width:0.6em; background-color:initial"> 基于路径的引用，相当于 root.getChildren().get(0)</td> 
  </tr> 
 </tbody> 
</table>