fastjson枚举转换

http://zhidao.baidu.com/link?url=buRL8gjIT75xDZgYJG7SwyB5EzES8cgiNPDCPLNMPXLVYyNR9tPbklmxOYWVzmTT0G1V1ewdcLmaTvTwnqTSF9ZS_hl8gC_Ed4iNdYD1XYu

看fastjson源码，SerializeWriter

public void writeEnum(Enum value, char c) {
　if (value == null) {
	　writeNull();
　write(',');
　return;
　}
 
　if (isEnabled(SerializerFeature.WriteEnumUsingToString)) {
　if (isEnabled(SerializerFeature.UseSingleQuotes)) {
　write('\'');
　write(value.name());
　write('\'');
　write(c);
 
　} else {
　write('\"');
　write(value.name());
　write('\"');
　write(c);
　}
　return;
　}
 
　writeIntAndChar(value.ordinal(), c);
　}

可以看出SerializeWriter在初始化的时候，features不要设置SerializerFeature.WriteEnumUsingToString


因为JSON.DEFAULT_PARSER_FEATURE是enable了SerializerFeature.WriteEnumUsingToString，也就是说是读枚举的value值而不是int值

public static int    DEFAULT_GENERATE_FEATURE;
　　static {
　　int features = 0;
　　features |= com.alibaba.fastjson.serializer.SerializerFeature.QuoteFieldNames.getMask();
　　features |= com.alibaba.fastjson.serializer.SerializerFeature.SkipTransientField.getMask();
　　features |= com.alibaba.fastjson.serializer.SerializerFeature.WriteEnumUsingToString.getMask();
　　features |= com.alibaba.fastjson.serializer.SerializerFeature.SortField.getMask();
　　// features |=
　　// com.alibaba.fastjson.serializer.SerializerFeature.WriteSlashAsSpecial.getMask();
　　DEFAULT_GENERATE_FEATURE = features;
　　}

所以，解决你这个问题的方法就是
之前调用下
JSONSerializer.config(SerializerFeature.WriteEnumUsingToString,false);

我的实体类里面有一个熟悉是枚举类型的，但是我在转换的时候我不希望取它的name，而且她的索引值0,1,2,3,搜索一番后发现这个回答.
但是JSONSerializer.config不是一个静态方法，不能直接调用

而且如果直接调用JSON.toJSON把实体类转为json，这里还有另外一句代码

if (clazz.isEnum()) {
    return ((Enum) javaObject).name();
}

如果是枚举类型，不管你怎么改配置都不会给你转成索引值的情况，所以我们这里就先想把实体转成jsonString，再把jsonString转成JSONObject。

再继续看fastjson的源码
在JOSN.toJSONString中

public static final String toJSONString(Object object, SerializerFeature... features) {
        SerializeWriter out = new SerializeWriter();

        try {
            JSONSerializer serializer = new JSONSerializer(out);
            for (com.alibaba.fastjson.serializer.SerializerFeature feature : features) {
                serializer.config(feature, true);
            }

            serializer.write(object);

            return out.toString();
        } finally {
            out.close();
        }
    }

他这里也是用的serializer.config来配置的，干脆我们自己写个工具方法吧，同时把WriteEnumUsingToString禁用掉

private static final SerializerFeature[] CONFIG = new SerializerFeature[]{
            SerializerFeature.WriteNullBooleanAsFalse,//boolean为null时输出false
            SerializerFeature.WriteMapNullValue, //输出空置的字段
            SerializerFeature.WriteNonStringKeyAsString,//如果key不为String 则转换为String 比如Map的key为Integer
            SerializerFeature.WriteNullListAsEmpty,//list为null时输出[]
            SerializerFeature.WriteNullNumberAsZero,//number为null时输出0
            SerializerFeature.WriteNullStringAsEmpty//String为null时输出""
    };

    public static JSONObject toJSON(Object javaObject) {

        SerializeWriter out = new SerializeWriter();
        String jsonStr;
        try {
            JSONSerializer serializer = new JSONSerializer(out);

            for (com.alibaba.fastjson.serializer.SerializerFeature feature : CONFIG) {
                serializer.config(feature, true);
            }
            serializer.config(SerializerFeature.WriteEnumUsingToString, false);
            serializer.write(javaObject);

            jsonStr =  out.toString();
        } finally {
            out.close();
        }
        JSONObject jsonObject = JSON.parseObject(jsonStr);
        return jsonObject;
    }

这样转换出来的结果，就是我们想要的数字了。