Fastjson V2 simple user manual

Preface

In daily life  Java  In enterprise development , May not be able to avoid  

JSON

  This format . 

JSON

  From the  1999  Year of  

JS

  language norm  

ECMA262

  A subset of , And then in  2003  Year as a data format  

ECMA404

  Release , here we are  2006  year , Again  

rfc4627

  Release . Until now, ,

JSON

  Has been widely used .

JSON

  Based on plain text , So it's easy to read , And the specification is simple , Easy to handle , It can be used out of the box , The most important thing is ,

JSON

  It's not about the platform , So it can be used as a transmission format protocol between different systems .

JSON

  Yes  7  Large basic value , Namely ：

false

、

null

、

true

、

object

、

array

、

number

、

string

. Its structure is also very simple , There are only two structures ： One is  

Array

, One is

The set of key values in the object

. among , Object use  

{}

  To express , Its interior is  

key:value

  form , The array uses  

[]

  To express , Use commas between different values  

,

  Separate .

Here is a  

JSON

  Simple example ：

{
 "baseInfo": {
 "name": "cunyu1943",
 "wepublic": " Village Yuyao ",
 "wechat": "cunyu1024",
 "platform": ["juejin", "CSDN", "Github", "zhihu"]
 }
}


And in the  Java  in , Mainstream  

JSON

  The library only has the following three ：

• Fastjson
  ： Developed by domestic Alibaba company  
  JSON
    library , Superior performance and speed .

• Jackson
  ：
  Spring
    default  
  JSON
    library , The community is very active , Update iteration fast .

• Gson
  ： From Google  
  JSON
    library , At present, it is the most versatile  
  JSON
    The library .

Thanks to the  

Fastjson

  Super high performance , Most domestic companies have chosen Alibaba products  

Fastjson

  As a handle  

JSON

  The tool library . Let's take a look at ,

Fastjson

  Some common usage skills of .

Using skills

First , We create a  

Maven

  project , For demonstration  

Fastjson

  Use , It is also convenient for us to manage dependencies . meanwhile , Choose here  

Fastjson v2

  As the protagonist of today's demonstration .

Of course , The first job is to create a  

Maven

  project , If you're still a little confused , Then you can take a look at the previous knowledge ：

Maven  Introduction Manual ： Use  IDEA  establish  Maven  project

When we create a  

Maven

  After the project , The first job is in the project  

pom.xml

  Add  

Fastjson V2

  Dependence .

<dependency>
 <groupId>com.alibaba.fastjson2</groupId>
 <artifactId>fastjson2</artifactId>
 <version>2.0.6</version>
</dependency>


Then we create a  

Hero

  class , It is convenient for use in the subsequent process .

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Hero {
 private String sex;
 private String name;
 private String profession;
}


Java  Object serialization to  JSON

Create a in our main class  

Hero

  object , And then use it  

toJSONString()

  Method to convert it to  

JSON

  character string , You can see that the result is converted correctly .

public class MainApplication {
 public static void main(String[] args) {
 // Java  Object turn  JSON
 Hero hero = new Hero(" Woman ", " concubine ", " striker ");
 String heroJson = JSON.toJSONString(hero);
 System.out.println(heroJson);
 }
}


JSON  It can be interpreted as  Java  object

Let's say I have a  

JSON

  character string , We want to convert it into  Java  object , You can use  

parseObject()

  Method .

public class MainApplication {
 public static void main(String[] args) {
 // JSON  String rotation  Java  object
 String shooter = "{"name":" Galois ","profession":" striker ","sex":" Woman "}";
 Hero hero = JSON.parseObject(shooter, Hero.class);
 System.out.println(hero.toString());
 }
}


JSON  It can be interpreted as  JSONObject

take  

JSON

  It can be interpreted as  

JSONObject

  Method and will  

JSON

  Convert to  Java  The method of an object is similar to , But one parameter is missing , Here we need to pay attention to .

public class MainApplication {
 public static void main(String[] args) {
 // JSON  It can be interpreted as  JSONObject
 String shooter = "{"name":" Huang Zhong ","profession":" striker ","sex":" male "}";
 JSONObject heroJson = JSON.parseObject(shooter);
 System.out.println(heroJson.toJSONString());
 }
}


JSON  It can be interpreted as  JSONArray

To put  

JSON

  It can be interpreted as  

JSONArray

, You can use  

parseArray()

  Method .

public class MainApplication {
 public static void main(String[] args) {
 // JSON  It can be interpreted as  JSONArray
 String platform = "[{"name":"CSDN","id":" Village Yuyao "},{"name":"Juejin","id":" Village Yuyao "}]";
 JSONArray platformArray = JSON.parseArray(platform);
 System.out.println(platformArray.toJSONString());
 }
}


summary

These are common in daily development  4  Other formats and  

JSON

  The conversion process between formats , among , The most commonly used should be  

JSON

  and  Java  The conversion between objects , Be sure to master ！ About  

Fastjson V2

  That's all for the simple use of , About more  

Fastjson V2

  Advanced use skills of , Wait for our follow-up articles to see you ！