This issue recommends a Ali open source high-performance JSON library – FASTJSON2.

FASTJSON2 is an important upgrade to the FASTJSON project, with the goal of providing a high-performance JSON library for the next decade. Through the same API,

• Supports both JSON/JSONB protocols
• Support full and partial parsing
• Support Java server, client Android, big data scenarios
• Kotlin
• Support for Android (2.0.3.android)
• Support Graal Native Image (2.0.3.graal)

Preparation

Add dependencies

Maven:

< dependency> 

< groupId> com.alibaba.fastjson2< /groupId> 

< artifactId> fastjson2< /artifactId> 

< version> 2.0.3< /version> 

< /dependency> 

Gradle:

dependencies {

implementation  'com. Alibaba. Fastjson2: fastjson2:2.0.3' < / span >

}

Other modules

• Fastjson v1 compatible module

If you used fastjson 1.2.x version, you can use the compatibility package, the compatibility package cannot guarantee 100% compatibility, please carefully test and verify, and please timely feedback if you find any problems.

Maven：

<dependency>

<groupId>com.alibaba</groupId>

<artifactId>fastjson</artifactId>

<version>2.0.3</version>

</dependency>

Gradle：

dependencies {

implementation 'com.alibaba:fastjson:2.0.3'

}

• Kotlin Integration module

If the project uses Kotlin, you can use the fastjson-kotlin module, which uses the characteristics of kotlin.

Maven:

< dependency> 

< groupId> com.alibaba.fastjson2< /groupId> 

< artifactId> fastjson2-kotlin< /artifactId> 

< version> 2.0.3< /version> 

< /dependency> 

Gradle:

dependencies {

implementation(<span ">" class = "HLJS - string com. Alibaba. Fastjson2: fastjson2 - kotlin: 2.0.3" < / span >)

}

Simple use

In fastjson v2, the package is not the same as 1.x, it is com.alibaba.fastjson2. If you were using fastjson1, in most cases you can simply change the package name.

Parse JSON to JSONObject

String text = "..." ;
JSONObject data = JSON.parseObject(text);

byte[] bytes = ... ;
JSONObject data = JSON.parseObject(bytes); 

Parse JSON to JSONArray

String text = "..." ;
JSONArray data = JSON.parseArray(text); 

Parsing JSON into Java objects

String text = "..." ;
User data = JSON.parseObject(text,  User.class); 

Serializes Java objects to JSON

Object data = "..." ;
String text = JSON.toJSONString(data);
byte[] text = JSON.toJSONBytes(data); 

Use JSONObject, JSONArray

Get simple properties

String text = "{\"id\": 2,\"name\": \"fastjson2\"}";
JSONObject obj = JSON.parseObject(text);

int id = obj.getIntValue("id");
String name = obj.getString("name"); 

Read JavaBean

JSONArray array = ...
JSONObject obj = ...

User user = array.getObject(0, User.class);
User user = obj.getObject("key", User.class);

转为JavaBean

JSONArray array = ...
JSONObject obj = ...

User user = obj.toJavaObject(User.class);
List<User> users = array.toJavaList(User.class);

Serializes JavaBean objects to JSON

class User {
public int id;
public String name;
}

User user = new User();
user.id = 2;
user.name = "FastJson2";

String text = JSON.toJSONString(user);
byte[] bytes = JSON.toJSONBytes(user); 

Serialization result

{

"id" : 2,

"name" : "FastJson2"

}

Advanced use

Use JSONB

Serializing a JavaBean object JSONB

User user = ... ;
byte[] bytes = JSONB.toBytes(user);
byte[] bytes = JSONB.toBytes(user, JSONWriter.Feature.BeanToArray); 

Parsing JSONB data to JavaBean

byte[] bytes = ...
User user = JSONB.parseObject(bytes, User.class);
User user = JSONB.parseObject(bytes, User.class,  JSONReader.Feature.SupportBeanArrayMapping); 

Use JSONPath

Read some data using JSONPath

String text = ... ;

JSONPath path = JSONPath.of("$.id");  // Caching and reuse improves performance 

JSONReader parser = JSONReader.of(text);

Object result = path.extract(parser); 

Read part of byte[] using JSONPath

byte[] bytes = ... ;

JSONPath path = JSONPath.of("$.id");  // Caching and reuse can improve performance

JSONReader parser = JSONReader.of(bytes);

Object result = path.extract(parser); 

Read part of byte[] data using JSONPath

byte[] bytes = ... ;

JSONPath path = JSONPath.of("$.id");  // Caching and reuse improves performance 

JSONReader parser = JSONReader.ofJSONB(bytes);  // Note that the ofJSONB method is used here 

Object result = path.extract(parser); 

—END—

Open source protocol: Apache2.0