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import com.alibaba.fastjson2.JSONWriter;
import com.alibaba.fastjson2.support.config.FastJsonConfig;
import com.alibaba.fastjson2.support.spring.http.converter.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

/**
 * @Description 重写configureMessageConverters转换器对返回值内容进行转换
 * @Author WangKun
 * @Date 2023/4/10 16:27
 * @Version
 */
@Configuration
public class FastJson2Config implements WebMvcConfigurer {


    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        //字符串转换
        StringHttpMessageConverter strConverter = new StringHttpMessageConverter(StandardCharsets.UTF_8);
        converters.add(strConverter);
        //定义一个convert转换消息的对象
        FastJsonHttpMessageConverter fastConverter=new FastJsonHttpMessageConverter();
        //添加fastjson的配置信息，比如是否要格式化返回的json数据；
        FastJsonConfig config = new FastJsonConfig();
        config.setWriterFeatures(
                //是否输出值为null的字段,默认为false
                JSONWriter.Feature.WriteMapNullValue,
                //将Collection类型字段的字段空值输出为[]
                JSONWriter.Feature.WriteNullListAsEmpty,
                //将字符串类型字段的空值输出为空字符串
                JSONWriter.Feature.WriteNullStringAsEmpty,
                // 将Number类型的null转成0
                JSONWriter.Feature.WriteNullNumberAsZero,
                // 将Boolean类型的null转成false
                JSONWriter.Feature.WriteNullBooleanAsFalse
        );
        config.setDateFormat("yyyy-MM-dd HH:mm:ss");
        //在convert中添加配置信息
        fastConverter.setFastJsonConfig(config);
        //设置支持的媒体类型
        fastConverter.setSupportedMediaTypes(Collections.singletonList(MediaType.APPLICATION_JSON));
        //设置默认字符集
        fastConverter.setDefaultCharset(StandardCharsets.UTF_8);
        //将convert添加到converters
        converters.add(fastConverter);

    }
}