FastJson对Object对象的解析问题

雨点打透心脏的1/2处 2022-03-16 00:38 405阅读 0赞

## 问题描述 ##

ActivityRuleBase 基础类，ActivityRuleUserVo,ActivityRulePayTypeVo 继承ActivityRuleBase 类

public class Activity implements Serializable {
    
    	private Long id;  //
    	private String name;  //活动名称
    	private List<Object> ActivityRuleList;//实际可能是多个不同类实例,eg:cRule,dRule
    //setting,getting
    }

Activity 数据json字符串解析成对象实例数据时，如下是无法实现的，即便是加上了TypeReference子类的特有数据仍然会丢失

Activity sv2 = JSON.parseObject(text, Activity.class);
            System.out.println(JSON.toJSONString(sv2));

[{"condition":"11111","ruleType":"USER_RULE"},{"payType":"22222","ruleType":"PAY_TYPE_RULE"}]
    USER_RULE={"condition":"11111","ruleType":"USER_RULE"}
    PAY_TYPE_RULE={"payType":"22222","ruleType":"PAY_TYPE_RULE"}
    json解析结果----------------------------------------------------
    {"activityRuleList":[{"condition":"11111","ruleType":"USER_RULE"},{"payType":"22222","ruleType":"PAY_TYPE_RULE"}],"name":"ces","status":1}
    USER_RULE={"ruleType":"USER_RULE"}
    PAY_TYPE_RULE={"ruleType":"PAY_TYPE_RULE"}
    {"activityRuleList":[{"ruleType":"USER_RULE"},{"ruleType":"PAY_TYPE_RULE"}],"name":"ces","status":1}

看解析的结果，子类的自有属性值并没有解析处来，只有父类的属性值。

## 解决办法 ##

fastJson源码可以看到对于ArrayList的默认的反序列化器是CollectionCodec，另外fastjson还提供了@JSONField注解对field可以有一些自定义的处理，其deserializeUsing属性可以指定具体的反序列化器。我们要做的就很简单了。

public class ActivitiyRuleVoDeserializer extends CollectionCodec {
    
        @Override
        public <T> T deserialze(DefaultJSONParser parser, Type type, Object fieldName) {
            T list = super.deserialze(parser, type, fieldName);
            JSONArray jsonArray = JSON.parseArray(JSON.toJSONString(list));
            ArrayList<ActivityRuleBase> debtVOs = new ArrayList<>();
    
            for(int i=0;i<jsonArray.size();i++){
                // 遍历 jsonarray 数组，把每一个对象转成 json 对象
                JSONObject jsob = jsonArray.getJSONObject(i);
                // 得到 每个对象中的属性值
                System.out.println(jsob.get("ruleType")+"="+JSON.toJSONString(jsob)) ;
    
                switch (RuleType.valueOf(jsob.get("ruleType").toString())) {
                    case USER_RULE://USER_RULE 用户限制规则
                        ActivityRuleUserVo activityRuleUser = JSON.parseObject(JSON.toJSONString(jsob),ActivityRuleUserVo.class);
                        debtVOs.add(activityRuleUser);
                        break;
                    case PAY_TYPE_RULE://PAY_TYPE_RULE支付方式
                        ActivityRulePayTypeVo activityRulePayProm = JSON.parseObject(JSON.toJSONString(jsob),ActivityRulePayTypeVo.class);
                        debtVOs.add(activityRulePayProm);
                        break;
                    case DISCOUNT_RULE://打折活动
                        ActivityRuleDiscountVo activityRuleDiscount = JSON.parseObject(JSON.toJSONString(jsob),ActivityRuleDiscountVo.class);
                        debtVOs.add(activityRuleDiscount);
                        break;
                	// 其他活动规则省略
                    default:
                        ActivityRuleBase activityRuleBase  = JSON.parseObject(JSON.toJSONString(jsob),ActivityRuleBase.class);
                        debtVOs.add(activityRuleBase);
                }
    
    
            }
    
    
    
       /*     if (jsonArray != null && jsonArray.size()>0){
    
                for (:
                jsonArray) {
    
                }
    
    
                if (jsonArray.getJSONObject(0).get("totalEarning")!=null){
                    ArrayList<CreditorDebtVO> creditorDebtVOList = (ArrayList<CreditorDebtVO>)JSON.parseArray(JSON.toJSONString(list),CreditorDebtVO.class);
                    return (T)creditorDebtVOList;
                } else if (jsonArray.getJSONObject(0).get("overdueOtherFee")!=null){
                    ArrayList<ObligorDebtVO> obligorDebtVOList = (ArrayList<ObligorDebtVO>)JSON.parseArray(JSON.toJSONString(list),ObligorDebtVO.class);
                    return (T)obligorDebtVOList;
                }
            } else {
                return list;
            }*/
    
            return (T)debtVOs;
        }
    }

在要解析的类的setting方法上加上如下注解

@JSONField(deserializeUsing = ActivitiyRuleVoDeserializer.class)
        public void setActivityRuleList(List<Object> activityRuleList) {
            ActivityRuleList = activityRuleList;
        }

测试方法

public static void main(String[] args) {
    
            ActivityVo sv = new ActivityVo();
            sv.setStatus(1).setName("ces");
            List<ActivityRuleBase> activityRuleList = Lists.newArrayList();//实际可能是多个
    
    
            ActivityRuleUser activityRuleUser1 = new ActivityRuleUser();
            activityRuleUser1.setRuleType("USER_RULE");
            activityRuleUser1.setCondition("11111");
    
            ActivityRulePayType activityRulePayProm1 = new ActivityRulePayType();
            activityRulePayProm1.setRuleType("PAY_TYPE_RULE");
            activityRulePayProm1.setPayType("22222");
    
    
            activityRuleList.add(activityRuleUser1);
            activityRuleList.add(activityRulePayProm1);
    
            sv.setActivityRuleList(activityRuleList);
    
            ParserConfig parserConfig = new ParserConfig() {
                @Override
                public ObjectDeserializer getDeserializer(Type type) {
                    if (type == ActivityRuleUser.class) {
                        return super.getDeserializer(ActivityRuleUser.class);
                    }
                    return super.getDeserializer(type);
                }
            };
    
    
            String text1 = JSON.toJSONString(activityRuleList);
            System.out.println(text1);
    
            JSONArray jsonArray = JSON.parseArray(text1);
    
            for(int i=0;i<jsonArray.size();i++){
                // 遍历 jsonarray 数组，把每一个对象转成 json 对象
                JSONObject jsob = jsonArray.getJSONObject(i);
                // 得到 每个对象中的属性值
                System.out.println(jsob.get("ruleType")+"="+JSON.toJSONString(jsob)) ;
            }
            System.out.println("json解析结果----------------------------------------------------") ;
    
    
            String text = JSON.toJSONString(sv);
            System.out.println(text);
    
            Activity sv2 = JSON.parseObject(text, Activity.class);
            System.out.println(JSON.toJSONString(sv2));
    
    
        }

打印出来的数据

[{"condition":"11111","ruleType":"USER_RULE"},{"payType":"22222","ruleType":"PAY_TYPE_RULE"}]
    USER_RULE={"condition":"11111","ruleType":"USER_RULE"}
    PAY_TYPE_RULE={"payType":"22222","ruleType":"PAY_TYPE_RULE"}
    json解析结果----------------------------------------------------
    {"activityRuleList":[{"condition":"11111","ruleType":"USER_RULE"},{"payType":"22222","ruleType":"PAY_TYPE_RULE"}],"name":"ces","status":1}
    USER_RULE={"condition":"11111","ruleType":"USER_RULE"}
    PAY_TYPE_RULE={"payType":"22222","ruleType":"PAY_TYPE_RULE"}
    {"activityRuleList":[{"condition":"11111","ruleType":"USER_RULE","toAllUser":false},{"payType":"22222","ruleType":"PAY_TYPE_RULE"}],"name":"ces","status":1}

### 参考资料 ###

FastJson对泛型解析问题  
[https://blog.csdn.net/u011535541/article/details/80492091][https_blog.csdn.net_u011535541_article_details_80492091]  
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[https_blog.csdn.net_u011535541_article_details_80492091]: https://blog.csdn.net/u011535541/article/details/80492091