spring日期类型转Json时转换为时间戳的处理与使用

当数据库字段为date类型时，@ResponseBody注解在转换日期类型时会默认把日期转换为时间戳（例如： date：2017-10-25  转换为 时间戳：15003323990）。

配置

我们在使用springmvc中的 @ResponseBody 注解返回JSON时可以配置Json转换器如下:

<!-- 日期处理时间类 -->
  <bean id="jsonUtils" class="com.utils.JsonUtil" lazy-init="false"/>
  <!--避免IE执行AJAX时，返回JSON出现下载文件 -->
  <bean id="mappingJacksonHttpMessageConverter"
    class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    <property name="objectMapper" value="#{jsonUtils.mapper}"/>   <!-- 用于日期输出格式转换 -->
    <property name="supportedMediaTypes">
      <list>
        <value>text/html;charset=UTF-8</value>
        <value>*; charset=UTF-8</value>
      </list>
    </property>
  </bean>
  <!-- 启动SpringMVC的注解功能，完成请求和注解POJO的映射 -->
  <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
      <list>
        <ref bean="mappingJacksonHttpMessageConverter" /> <!-- JSON转换器 -->
      </list>
    </property>
  </bean>

  <!-- 日期处理时间类 -->
  <bean id="jsonUtils" class="com.platform.utils.JsonUtil" lazy-init="false"/>

JsonUtil

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
import java.io.IOException;
import java.lang.reflect.AnnotatedElement;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.stereotype.Component;

@Component
public class JsonUtil
{
  private static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
  private static final ObjectMapper mapper;
  
  public ObjectMapper getMapper()
  {
    return mapper;
  }
  
  static
  {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    
    mapper = new ObjectMapper();
    mapper.setDateFormat(dateFormat);
    mapper.setAnnotationIntrospector(new JacksonAnnotationIntrospector()
    {
      public Object findSerializer(Annotated a)
      {
        if ((a instanceof AnnotatedMethod))
        {
          AnnotatedElement m = a.getAnnotated();
          DateTimeFormat an = (DateTimeFormat)m.getAnnotation(DateTimeFormat.class);
          if ((an != null) && 
            (!"yyyy-MM-dd HH:mm:ss".equals(an.pattern()))) {
            return new JsonUtil.JsonDateSerializer(an.pattern());
          }
        }
        return super.findSerializer(a);
      }
    });
  }
  
  public static String toJson(Object obj)
  {
    try
    {
      return mapper.writeValueAsString(obj);
    }
    catch (Exception e)
    {
      throw new RuntimeException("转换json字符失败!");
    }
  }
  
  public <T> T toObject(String json, Class<T> clazz)
  {
    try
    {
      return mapper.readValue(json, clazz);
    }
    catch (IOException e)
    {
      throw new RuntimeException("将json字符转换为对象时失败!");
    }
  }
  
  public static class JsonDateSerializer
    extends JsonSerializer<Date>
  {
    private SimpleDateFormat dateFormat;
    
    public JsonDateSerializer(String format)
    {
      this.dateFormat = new SimpleDateFormat(format);
    }
    
    public void serialize(Date date, JsonGenerator gen, SerializerProvider provider)
      throws IOException, JsonProcessingException
    {
      String value = this.dateFormat.format(date);
      gen.writeString(value);
    }
  }
}