对于一个POJO,可以使用Apahche Commons Lang 包来重写equals()和hashCode()方法，

maven导入包：

        <dependency>

                <groupId>org.apache.commons</groupId>                 <artifactId>commons-lang3</artifactId>                  <version>3.4</version>            </dependency>

示例：

@Override

public boolean equals(Object that){

   return EqualsBuilder.reflectionEquals(this, that, "id","time");

}

@Override

    public int hashCode() {         return HashCodeBuilder.reflectionHashCode(this, "id","time");     }