1、在 pom.xml 導包 （必須高於 1.2.10 版本）

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.15</version>
        </dependency>

2、在 Spring boot 啟動類配置 Json解析。（配置方法有兩種）
第一種 （繼承 WebMvcConfigurerAdapter 重寫 configureMessageConverters方法 新增 FastJson 到 converters中）

@SpringBootApplication
public class App extends WebMvcConfigurerAdapter{

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        super.configureMessageConverters(converters);
        //建立 FastJson
        FastJsonHttpMessageConverter fastConverter = new
 
 FastJsonHttpMessageConverter();
        FastJsonConfig fastConfig = new FastJsonConfig();

    //配置 FastJson   基本設定    fastConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
        fastConverter.setFastJsonConfig(fastConfig);

        //配置 FastJson 到 Spring boot中。
        converters.add(fastConverter);
    }

    public
 
 static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

方法二 @Bean 注入方式：（簡單，直接注入 FastJson 到 HttpMessageConverters 中）

@SpringBootApplication
public class App{

    @Bean
    public HttpMessageConverters fastJsonHttpMessageConverter(){
        FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastConfig = new FastJsonConfig();
        fastConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
        fastConverter.setFastJsonConfig(fastConfig);

        return new HttpMessageConverters((HttpMessageConverter)fastConverter);
    }
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}