1：一定要加入依赖,否则不生效：
 <!--日期格式化依赖-->

    <dependency>

      <groupId>com.fasterxml.jackson.core</groupId>

      <artifactId>jackson-databind</artifactId>

      <version>${jackson.version}</version>

    </dependency>

  </dependencies>

2：在实体类get方法上加入注解：

private Date createTime;

@JsonFormat(pattern = "yyyy年MM月dd日 HH:mm:ss", timezone = "GMT+8")

public Date getCreateTime() {

  return createTime;

}

public void setCreateTime(Date createTime) {

  this.createTime = createTime;

}