重现 fastjson filter bug

StringUtils.java

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.parser.deserializer.ExtraProcessor;
import com.alibaba.fastjson.serializer.NameFilter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import org.apache.commons.lang3.Validate;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

/**
 * @author <a href="mailto:wuzhiqiang@ucfgroup.com">wuzhiqiang</a>
 * @version Revision: 1.0
 * @date 15/12/23 下午3:19
 */
public class StringUtils {
    /**
     * Convert a name in camelCase to an underscored name in upper case. Any
     * upper case letters are converted to lower case with a preceding
     * underscore.
     * <p>
     * 主要的作用是把java的字段转化为数据库字段.数字会被当成一个大写字母,在前面添加下划线,<br>
     * 如果连续两个字符都是数字,会当成一个整体.处理完毕后会返回小写格式
     *
     * <pre>
     * StringUtils.underscore(&quot;userNameLast10&quot;) = &quot;update_name_last_10&quot;;
     * StringUtils.underscore(&quot;xx2&quot;) = &quot;xx_2&quot;;
     * </pre>
     *
     * @param name
     *            the string containing original name
     * @return the converted name toLowerCase
     */
    public static String underscore(String name) {
        StringBuilder result = new StringBuilder();
        if (name != null && name.length() > 0) {
            result.append(name.substring(0, 1).toLowerCase());
            for (int i = 1; i < name.length(); i++) {
                String s = name.substring(i, i + 1);
                String b = name.substring(i - 1, i);
                // 如果这个字符是大写,或者前一个字符不是数字,那么添加一个下划线
                if (s.equals(s.toUpperCase()) && !Character.isDigit(b.charAt(0))) {
                    result.append('_');
                    result.append(s);
                } else {
                    result.append(s);
                }
            }
        }
        return result.toString().toLowerCase();
    }

    /**
     * 和underscore相反，这个方法用来把数据库字段转化为java字段
     *
     * <pre>
     * StringUtils.camelcase(&quot;user_name_last&quot;) = &quot;userNameLast&quot;;
     * StringUtils.camelcase(&quot;USER&quot;) = &quot;user&quot;;
     * </pre>
     *
     * @see StringUtils#underscore(String)
     * @param name
     * @return
     */
    public static String camelcase(String name) {
        StringBuilder result = new StringBuilder();
        boolean nextIsUpper = false;
        if (name != null && name.length() > 0) {
            if (name.length() > 1 && name.substring(1, 2).equals("_")) {
                result.append(name.substring(0, 1).toUpperCase());
            } else {
                result.append(name.substring(0, 1).toLowerCase());
            }
            for (int i = 1; i < name.length(); i++) {
                String s = name.substring(i, i + 1);
                if (s.equals("_")) {
                    nextIsUpper = true;
                } else {
                    if (nextIsUpper) {
                        result.append(s.toUpperCase());
                        nextIsUpper = false;
                    } else {
                        result.append(s.toLowerCase());
                    }
                }
            }
        }
        return result.toString();
    }

    public static void main(String[] args) {
        //序列化通过 NameFilter 来处理
        NameFilter underscoreFilter=new NameFilter() {
            @Override
            public String process(Object object, String name, Object value) {
                return underscore(name);
            }
        };
        Vo vo=new Vo();
        vo.setMpsRegistrationRecord("value1");
        vo.setIntellectualPropertyPledge("value2");
        //使用 filter，WriteMapNullValue不生效
        String json= JSON.toJSONString(vo,underscoreFilter, SerializerFeature.PrettyFormat,SerializerFeature.WriteMapNullValue,SerializerFeature.WriteNullStringAsEmpty);
        System.out.println("设置了 filter 和 WriteMapNullValue\n"+json);
        //不使用 filter，WriteMapNullValue生效
        String json2= JSON.toJSONString(vo, SerializerFeature.PrettyFormat,SerializerFeature.WriteMapNullValue,SerializerFeature.WriteNullStringAsEmpty);
        System.out.println("不设置filter 只设置WriteMapNullValue\n"+json2);


        //反序列化通过processor 处理
        ExtraProcessor processor = new ExtraProcessor() {
            public void processExtra(Object object, String key, Object value) {
                String camelKey=camelcase(key);
                setFieldValue(object,camelKey,value);
            }
        };
        Vo tmp=JSON.parseObject(json,Vo.class,processor);
        System.out.println(tmp.getMpsRegistrationRecord());
        System.out.println(tmp.getIntellectualPropertyPledge());
    }

    /**
     * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
     */
    public static void setFieldValue(final Object obj, final String fieldName,
                                     final Object value) {
        Field field = getAccessibleField(obj, fieldName);

        if (field == null) {
            throw new IllegalArgumentException("Could not find field ["
                    + fieldName + "] on target [" + obj + "]");
        }

        try {
            field.set(obj, value);
        } catch (IllegalAccessException e) {
            //eat it
        }
    }
    /**
     * 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问.
     * <p>
     * 如向上转型到Object仍无法找到, 返回null.
     */
    public static Field getAccessibleField(final Object obj,
                                           final String fieldName) {
        Validate.notNull(obj, "object can't be null");
        Validate.notNull(fieldName, "fieldName can't be blank");
        for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass
                .getSuperclass()) {
            try {
                Field field = superClass.getDeclaredField(fieldName);
                makeAccessible(field);
                return field;
            } catch (NoSuchFieldException e) {// NOSONAR
                // Field不在当前类定义,继续向上转型
            }
        }
        return null;
    }

    /**
     * 改变private/protected的成员变量为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
     */
    public static void makeAccessible(Field field) {
        if ((!Modifier.isPublic(field.getModifiers())
                || !Modifier.isPublic(field.getDeclaringClass().getModifiers()) || Modifier
                .isFinal(field.getModifiers())) && !field.isAccessible()) {
            field.setAccessible(true);
        }
    }
    static class Vo{
        private String mpsRegistrationRecord;
        private String intellectualPropertyPledge;
        private String testStringNullAsEmpty;

        public String getMpsRegistrationRecord() {
            return mpsRegistrationRecord;
        }

        public void setMpsRegistrationRecord(String mpsRegistrationRecord) {
            this.mpsRegistrationRecord = mpsRegistrationRecord;
        }

        public String getIntellectualPropertyPledge() {
            return intellectualPropertyPledge;
        }

        public void setIntellectualPropertyPledge(String intellectualPropertyPledge) {
            this.intellectualPropertyPledge = intellectualPropertyPledge;
        }

        public String getTestStringNullAsEmpty() {
            return testStringNullAsEmpty;
        }

        public void setTestStringNullAsEmpty(String testStringNullAsEmpty) {
            this.testStringNullAsEmpty = testStringNullAsEmpty;
        }
    }
}