JSONUtil.bean2Json()报Property 'key' of class has no read method. SKIPPED的问题处理

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错误警告信息描述：

net.sf.json.JSONObject.defaultBeanProcessing(JSONObject.java:) 
Property 'handler' of class com.vrv.cems.mgr.domain.Manager_$$_javassist_182 has no read method. SKIPPED

问题分析：

JsonUtil.bean2Json(queryHistogramVO,new String[]{}));

将VO对象转换成JSON对象格式

jsonUtil包路径：

queryHistogramVO 对象的属性和方法：

public class HistogramVO {

    private Integer userNum;

    private Integer topCategory;

    private Integer lastUserNum;

    public Integer getCurrentUser() {

        return this.userNum;

    }

    public Integer getTopCategory() {

        return topCategory;

    }

    public void setTopCategory(Integer topCategory) {

        this.topCategory = topCategory;

    }

    public void setUserNum(Integer userNum) {

        this.userNum = userNum;

    }

    public Integer getLastUserNum() {

        return lastUserNum;

    }

    public void setLastUserNum(Integer lastUserNum) {

        this.lastUserNum = lastUserNum;

    }

 }

肉眼看上去这个类没有任何问题，仔细观察发现属性"userNum"的get方法为"getCurrentUser()"

详细分析：

1、jsonutil调用类图分析：

JsonUtil工具类是通过JSONObject.fromObject()方法转换的，查看源码，对fromObject详细分析发现代码：

　　　　　　//这一句话很关键下面详细讲解

         PropertyDescriptor[] pds = PropertyUtils.getPropertyDescriptors( bean );

         PropertyFilter jsonPropertyFilter = jsonConfig.getJsonPropertyFilter();

         Class beanClass = bean.getClass();

         for( int i = ; i < pds.length; i++ ){

            String key = pds[i].getName();

            if( exclusions.contains( key ) ){

               continue;

            }

            if( jsonConfig.isIgnoreTransientFields() && isTransientField( key, beanClass ) ){

               continue;

            }

            Class type = pds[i].getPropertyType();

            //判断如果类的get方法存在则设置属性值

            if( pds[i].getReadMethod() != null ){

              //--------------中间的代码省略掉

               setValue( jsonObject, key, value, type, jsonConfig );

            }else{

               //当get方法不存在报警告错误

               String warning = "Property '" + key + "' has no read method. SKIPPED";

               fireWarnEvent( warning, jsonConfig );

               log.warn( warning );

            }

         }

PropertyDescriptor[] pds = PropertyUtils.getPropertyDescriptors( bean );

这段代码是获取Bean所有的属性信息并将他封装成 PropertyDescriptor描述类。

深入 getPropertyDescriptors()分析：

　　　　　if (beanClass == null) {

            throw new IllegalArgumentException("No bean class specified");

        }

        // Look up any cached descriptors for this bean class

        PropertyDescriptor[] descriptors = null;

        descriptors =

                (PropertyDescriptor[]) descriptorsCache.get(beanClass);

        if (descriptors != null) {

            return (descriptors);

        }

        // Introspect the bean and cache the generated descriptors

        BeanInfo beanInfo = null;

        try {

            beanInfo = Introspector.getBeanInfo(beanClass);

        } catch (IntrospectionException e) {

            return (new PropertyDescriptor[]);

        }

        descriptors = beanInfo.getPropertyDescriptors();

        if (descriptors == null) {

            descriptors = new PropertyDescriptor[];

        }