Android: generic mapping analysis of gson and JSON in kotlin

background ：

stay Android in ,kotlin Use , It can greatly beautify the code and bring simplicity to the code , however kotlin Before ,android The main language is Java.

stay android in , Parsing data is a common technique .JavaBean,GSON,JSONOBJECT, These three members are partners , But in kotlin This is still supported in , however kotlin Of data GSON,JSONOBJECT, And Java Parsing is different

Java：

People{

private String name="";

private String sex="";

public void setName(String name)

{

this.name=name

}

public void setSex(String sex){

this.sex=sex;

}

public String getName(){

return name;

}

public String getSex()

{

return sex;

}

}

Json:{"name":"zhangshan","sex":" male "}
 

The analysis is as follows

People people=new Gson().fromJson(json,People.class);

This is a Java Parsing .

kotlin：

kotlin Analysis and Java Different ,JavaBean stay kotlin Middle call data data

data class People(var name:String="",var sex:String="");

Or directly define a class Class is OK

class People{

var name:String=""

var sex:String=""

}

analysis GSON：

When we are doing parsing, we'd better be generic , So it's a little different to do parsing tools , as follows

object GsonUtil {

    public inline fun <reified T> getGsonObject(json: String): T? {
        val result = Gson().fromJson<T>(json)
        return result

    }
//type  Generic extension 
    inline fun <reified T> Gson.fromJson(json: String) = this.fromJson<T>(json, object : TypeToken<T>() {}.type)


}

GSON stay kotlin The biggest generic handling of is type part , So we use the extension function internally , Yes Gson.fromJson Expand , In this way, we can use method parameter generic parsing directly .

This is different from Java Function generics of ,kotlin Support method generics .

summary ：

Difference is that bean The definition of ,kotlin It's called in Chinese data class