springboot 利用configureMessageConverters add FastJsonHttpMessageConverter 实现返回JSON值 null to ""

/*
*
 * 文件名：@WebConfiguration.java <br/>
 * @author tomas <br/>

import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.actuate.health.ApplicationHealthIndicator;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import java.util.ArrayList;
import java.util.List;

import static com.alibaba.fastjson.serializer.SerializerFeature.*;

/**
 * 类名：WebConfiguration  <br />
 *
 * 功能：Web相关配置
 *
 * @author tomas <br />
 * 创建时间：2016年7月27日 下午3:57:19  <br />
 * @version 2016年7月27日*/
@Configuration
@EnableWebMvc
public class FrontConfiguration extends WebMvcConfigurerAdapter implements EnvironmentAware {
   // 日志记录器
 private static final Logger logger = LoggerFactory.getLogger(FrontConfiguration.class);

 // 当前的环境对象
 protected Environment environment;


   @Override
 public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
      super.configureMessageConverters(converters);
 //1.需要先定义一个 convert 转换消息的对象;
 FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();

 //2、添加fastJson 的配置信息，比如：是否要格式化返回的json数据;
 FastJsonConfig fastJsonConfig = new FastJsonConfig();
 // 不忽略对象属性中的null值
 fastJsonConfig.setSerializerFeatures(
            PrettyFormat,
 WriteNullListAsEmpty,
 WriteNullStringAsEmpty);
 //3、在convert中添加配置信息.
 fastConverter.setFastJsonConfig(fastJsonConfig);
 //4、将convert添加到converters当中.
 converters.add(fastConverter);
 }


   public void addResourceHandlers(ResourceHandlerRegistry registry) {
      registry.addResourceHandler("swagger-ui.html")
            .addResourceLocations("classpath:/META-INF/resources/");
 registry.addResourceHandler("favicon.ico")
            .addResourceLocations("classpath:/static/favicon.ico");
 registry.addResourceHandler("/webjars/**")
            .addResourceLocations("classpath:/META-INF/resources/webjars/");
 }
   /**
    * Set the {@code Environment} that this object runs in.
    *
    * @param environment
 */
 @Override
 public void setEnvironment(Environment environment) {
      this.environment = environment;
 }
}
























@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
   super.configureMessageConverters(converters);
 //1.需要先定义一个 convert 转换消息的对象;
 FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
 List<MediaType> supportedMediaTypes = new ArrayList<>();
 supportedMediaTypes.add(MediaType.APPLICATION_JSON);
 supportedMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
 supportedMediaTypes.add(MediaType.APPLICATION_ATOM_XML);
 supportedMediaTypes.add(MediaType.APPLICATION_FORM_URLENCODED);
 supportedMediaTypes.add(MediaType.APPLICATION_OCTET_STREAM);
 supportedMediaTypes.add(MediaType.APPLICATION_PDF);
 supportedMediaTypes.add(MediaType.APPLICATION_RSS_XML);
 supportedMediaTypes.add(MediaType.APPLICATION_XHTML_XML);
 supportedMediaTypes.add(MediaType.APPLICATION_XML);
 supportedMediaTypes.add(MediaType.IMAGE_GIF);
 supportedMediaTypes.add(MediaType.IMAGE_JPEG);
 supportedMediaTypes.add(MediaType.IMAGE_PNG);
 supportedMediaTypes.add(MediaType.TEXT_EVENT_STREAM);
 supportedMediaTypes.add(MediaType.TEXT_HTML);
 supportedMediaTypes.add(MediaType.TEXT_MARKDOWN);
 supportedMediaTypes.add(MediaType.TEXT_PLAIN);
 supportedMediaTypes.add(MediaType.TEXT_XML);
 fastConverter.setSupportedMediaTypes(supportedMediaTypes);
 //2、添加fastJson 的配置信息，比如：是否要格式化返回的json数据;
 FastJsonConfig fastJsonConfig = new FastJsonConfig();
 // 不忽略对象属性中的null值
 fastJsonConfig.setSerializerFeatures(
         PrettyFormat,
 WriteNullListAsEmpty,
 WriteNullStringAsEmpty);
 //3、在convert中添加配置信息.
 fastConverter.setFastJsonConfig(fastJsonConfig);
 //4、将convert添加到converters当中.
 converters.add(fastConverter);
}