JSONObject.toBean转换出错

Exception in thread "main" net.sf.json.JSONException: java.lang.NoSuchMethodException: com.lsxy.framework.mq.events.ussd.DelaySendEvent.<init>()
    at net.sf.json.JSONObject.toBean(JSONObject.java:288)
    at net.sf.json.JSONObject.toBean(JSONObject.java:233)
    at com.lsxy.framework.mq.ons.OnsMessageParser.parse(OnsMessageParser.java:37)
    at com.lsxy.framework.mq.ons.OnsMessageParser.main(OnsMessageParser.java:55)
Caused by: java.lang.NoSuchMethodException: com.lsxy.framework.mq.events.ussd.DelaySendEvent.<init>()
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.getDeclaredConstructor(Class.java:2178)
    at net.sf.json.util.NewBeanInstanceStrategy$DefaultNewBeanInstanceStrategy.newInstance(NewBeanInstanceStrategy.java:55)
    at net.sf.json.JSONObject.toBean(JSONObject.java:282)
    ... 3 more

要将json字符创转换成类。需要类提供空构造函数。如果

net.sf.json.JSONException: java.lang.NoSuchMethodException:

这个错的话，大家就检查一下是否是少了构造函数。