关于数据序列化(5),定制FastJSON序列化解决Java大Long类型js的Number接收丢失数据的问题，不序列化某些属性

1. 指定某个类型序列化

问题描述：
JavaScript使用IEEE 754标准

1位用来表示符号位
11位用来表示指数
52位表示尾数

javaScript对于整形只能识别52位。遇到Long大整数可能会丢失数据
因为后台是Java写的难免有属性的类型是long。本来项目的做法是手动写每个类的toString();方法要拼接很多双引号。比较费劲也容易出错。
后来我使用了FastJson定制序列化遇到Long就写字符串来解决返回给客户端的JSON。
主要代码如下：

定制Long类型的序列化
    public final static SerializeConfig resultJsonConfig = new SerializeConfig();
    static{
        resultJsonConfig.put(Long.class,new ObjectSerializer() {
            @Override
            public void write(JSONSerializer serializer,Object object,Object fieldName,Type fieldType,int features)
                    throws IOException {
                SerializeWriter out = serializer.getWriter();
                out.writeString(Objects.toString(object,null));
            }
        });
    }

使用：
    protected <T> String getResult(T value) {
        JSONObject json = new JSONObject();
        json.put("state",state.getState());
        json.put("desc",state.getDesc());
        json.put("value",value);
        return JSON.toJSONString(json,resultJsonConfig,SerializerFeature.DisableCircularReferenceDetect);
    }

2.如果要让这个策略全局生效

SerializeConfig.getGlobalInstance().put(Long.class,int features)
                    throws IOException {
                SerializeWriter out = serializer.getWriter();

                if (fieldType == long.class || fieldType == Long.class) {
                    out.writeString(Objects.toString(object,null));
                }
                // if (numberValue == null) {
                // if (out.isEnabled(SerializerFeature.WriteNullNumberAsZero)) {
                // out.write('0');
                // } else {
                // out.writeNull();
                // }
                // return;
                // }

            }
        });

2. 对某些属性不序列化

2.1 定义一个注解

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD})
public @interface ResultNotSerialize {

}

2.2 将注解加在属性上

public class MemberVO {
    private String memberId;
    private String memberName;

    @ResultNotSerialize
    private String password;

2.3 定义一个过滤器

public static final PropertyFilter controllerResultJsonFilter = new PropertyFilter() {
        @Override
        public boolean apply(Object object,String key,Object value) {
            try {
                Field field = object.getClass().getDeclaredField(key);
                if(null !=field && null != field.getAnnotation(ResultNotSerialize.class)){
                    return false;
                }
                return true;
            } catch (Exception e) {
                return true;
            }
        }
    };

2.4 如何使用

SON.toJSONString(obj,controllerResultJsonFilter);

3. Java长ID，js接收丢失数据问题最终的解决办法

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD})
public @interface SerializeAsSting {

}

public class MemberVO {
    @SerializeAsSting
    private Long id = 0L;//long type id

public static final PropertyFilter resultJsonPropertyFilter = new PropertyFilter() {
        @Override
        public boolean apply(Object object,Object value) {
            try {
                Field field = object.getClass().getDeclaredField(key);
                if (null != field && null != field.getAnnotation(NotSerialize.class)) {
                    return false;
                }
                return true;
            } catch (Exception e) {
                return true;
            }
        }
    };

    public static final ValueFilter resultValueFilter = new ValueFilter() {
        @Override
        public Object process(Object object,String name,Object value) {
// LogCore.BASE.info("object={},name={},value={}",object,name,value);
            if(value == null){
                return value;
            }
            try {
                Field field = object.getClass().getDeclaredField(name);
                if (null != field && null != field.getAnnotation(SerializeAsSting.class)) {
                    return value.toString();
                }
                return value;
            } catch (Exception e) {
                return value;
            }
        }
    };
    public final static SerializeFilter[] resultJsonFilters = new SerializeFilter[]{resultJsonPropertyFilter,resultValueFilter};

protected <T> String getResult(ErrorState state,T value) {
        JSONObject json = new JSONObject();
        json.put("state",state.getState());
        json.put("desc",state.getDesc());
        json.put("value",value);
        return JSON.toJSONString(json,resultJsonFilters,SerializerFeature.WriteMapNullValue,SerializerFeature.DisableCircularReferenceDetect);
    }

其他的序列化见这篇文章fastjson使用@JSONField、@JSONType、SerializeFilter定制序列化