Fastjason handles generics

Ali's FastJson It's always good to use , It is very simple to deal with object transformation mapping . But today I found that I have been using it blindly .

Resolve before Map This is the way :

Map map = JSON.parseObject("{'name':'zhangsan','address':'hangzhou'}", Map.class);

That's what we got Map There is no generic information ,FastJson If it is impossible to judge, the default processing is Map<String,Object> The format of , We still need to do some conversion in actual use .

At this time, we can pass in generic information through type parameters , such FastJ You can convert according to the generic type we provide .

String str = "{'name':'zhangsan','address':'hangzhou'}";
#  Notice that an inner class is created here , The difference is that there is a pair of braces at the end 
Map map = JSON.parseObject(str, new TypeReference<Map<String,String>>(){
    });

After knowing this skill , You can steal a lot of laziness , Like this ：

String str = "{'name': [1,2,3,4,5]}";
Map<String, List<Integer>> map = JSON.parseObject(str, new TypeReference<Map<String, List<Integer>>>() {
    });

Or the type is specified by the input parameter ：

public static <T> void main(Class<T> clz) {
    
    String str = "{'name': [1,2,3,4,5]}";
    T instance = JSON.parseObject(str, new TypeReference<T>() {
    });
}

Of course , These are just fur , How to apply depends on how you design .

Reference material

FastJson Parsing multilevel generics
fastjson Use generics to convert objects
fastJson Deserialization handles generics