关于通过Date.getTime()得到1970年01月1日0点零分问题验证

本文通过实例纠正了一个常见的误解:即Java中Date.getTime()方法返回的并非从1970年1月1日0点开始的毫秒数,而是考虑了时区差异后的值。深入探讨了系统时间和本地时间的区别。

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我的博客:通常认为Date.getTime()可以得到得到1970年01月1日0点零分以来的毫秒数,经过实践证明是错误的

实际上通过Date.getTime()的到的是1970年01月01日8点中以来的毫秒数,

实践代码如下

 public static String getTimestamp_1970() throws Exception {
  java.text.SimpleDateFormat formater = new SimpleDateFormat(
  "yyyy-MM-dd HH:mm:ss");
  java.util.Date   date=   formater.parse("1970-01-01 08:00:00");  
  return Long.toString(date.getTime());
 }

如果调用上面的函数,返回值为0

但是如果调用

 public static String getTimestamp_1970() throws Exception {
  java.text.SimpleDateFormat formater = new SimpleDateFormat(
  "yyyy-MM-dd HH:mm:ss");
  java.util.Date   date=   formater.parse("1970-01-01 00:00:00");  
  return Long.toString(date.getTime());
 }

返回-28800000

作为一个软件测试者要相信:只有测过的才是可信的!

yhntgbty 发表于2009-03-15 17:23:23  IP: 125.33.197.*

 

看到这篇文章,忍不住要说几句。
朋友你错了!
你没有理解时间的计算机制。计算机系统里面的时间有两个,
一个叫做系统时间,一个叫做本地时间。
什么是系统时间?就是跟那个什么子午线的地方一致的时间,计算机如果运行正常的话,世界上所有的计算机的系统时间都应该是相同的。但是问题来了,我们有一个时区的概念,虽然所有的计算机的系统时间相同,但是他们的本地时间不一样,比如在那个子午线上的时间是1970-01-01 00:00:00的系统时间的时候,他的本地时间也是1970-01-01 00:00:00。但是在这个时候的中国,处在东八区,它的本地时间比那个时间快八个小时,也就是1970-01-01 08:00:00。注意这只是本地时间不一致,这时候在中国的计算机的系统时间,仍然是1970-01-01 00:00:00。 现在你明白为什么了么?
你就没想一下为什么是八个小时,而不是七个小时或者九个小时么? 好累。。。

 

非常感谢yhntgbty的回复,特将回复剪切到文章中来,一方面免得其他读者被我糊弄

二来激励自己以后除了测试验证之外,再多问个为什么,进一步研究。加油!!!

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'取消关注' : '关注'}} </div> </div> </div> <div class="blog-text" v-html="blog.content"> </div> <div class="shop-basic"> <div class="shop-icon"> <img :src="shop.image" alt="店铺图片"> </div> <div style="width: 80%"> <div class="name">{{shop.name}}</div> <div> <el-rate v-model="shop.score/10"> </el-rate> </div> <div class="shop-avg">¥{{shop.avgPrice}}/人</div> </div> </div> <div class="zan-box"> <div> <svg t="1646634642977" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="2187" width="20" height="20"> <path d="M160 944c0 8.8-7.2 16-16 16h-32c-26.5 0-48-21.5-48-48V528c0-26.5 21.5-48 48-48h32c8.8 0 16 7.2 16 16v448zM96 416c-53 0-96 43-96 96v416c0 53 43 96 96 96h96c17.7 0 32-14.3 32-32V448c0-17.7-14.3-32-32-32H96zM505.6 64c16.2 0 26.4 8.7 31 13.9 4.6 5.2 12.1 16.3 10.3 32.4l-23.5 203.4c-4.9 42.2 8.6 84.6 36.8 116.4 28.3 31.7 68.9 49.9 111.4 49.9h271.2c6.6 0 10.8 3.3 13.2 6.1s5 7.5 4 14l-48 303.4c-6.9 43.6-29.1 83.4-62.7 112C815.8 944.2 773 960 728.9 960h-317c-33.1 0-59.9-26.8-59.9-59.9v-455c0-6.1 1.7-12 5-17.1 69.5-109 106.4-234.2 107-364h41.6z m0-64h-44.9C427.2 0 400 27.2 400 60.7c0 127.1-39.1 251.2-112 355.3v484.1c0 68.4 55.5 123.9 123.9 123.9h317c122.7 0 227.2-89.3 246.3-210.5l47.9-303.4c7.8-49.4-30.4-94.1-80.4-94.1H671.6c-50.9 0-90.5-44.4-84.6-95l23.5-203.4C617.7 55 568.7 0 505.6 0z" p-id="2188" :fill="blog.isLike ? 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'#ff6633' : '#82848a'"></path> </svg> <span :class="{liked: blog.isLike}">{{blog.liked}}</span> </div> </div> <div style="width: 40%"> </div> <div class="foot-box"> <div class="foot-view" @click="showCommentBox"> <i class="el-icon-chat-square"></i> </div> </div> </div> <!-- 评论输入框 --> <div class="comment-container" ref="commentContainer"> <div class="comment-header"> <button class="cancel-btn" @click="hideCommentBox">取消</button> <h3>评论</h3> <button class="send-btn" @click="sendComment" :disabled="!commentText.trim()">发送</button> </div> <div class="comment-content"> <textarea class="comment-input" v-model="commentText" placeholder="输入评论内容..." ref="commentInput"></textarea> </div> </div> </div> <script src="./js/vue.js"></script> <script src="./js/axios.min.js"></script> <!-- 引入组件库 --> <script src="./js/element.js"></script> <script src="./js/common.js"></script> <script> let each = function (ary, callback) { for (let i = 0, l = ary.length; i < l; i++) { if (callback(ary[i], i) === false) break } } const app = new Vue({ el: "#app", data: { util, blog: {}, shop: {}, likes: [], user: {}, // 登录用户 followed: false, // 是否关注了 _width: 0, duration: 300, container: null, items: [], active: 0, start: { x: 0, y: 0 }, move: { x: 0, y: 0 }, sensitivity: 60, resistance: 0.3, commentText: '', // 评论内容 commentContainer: null, // 评论相关数据 comments: [], // 当前页评论列表 totalComments: 0, // 评论总数 currentPage: 1, // 当前页码 pageSize: 10, // 每页大小 hasMore: false, // 是否有更多数据 isLoading: false, // 是否正在加载 }, created() { let id = util.getUrlParam("id"); this.queryBlogById(id); this.fetchComments(id); }, mounted() { this.commentContainer = this.$refs.commentContainer; }, methods: { init() { // 获得父容器节 this.container = this.$refs.swiper // 获得所有的子节 this.items = this.container.querySelectorAll('.swiper-item') this.updateItemWidth() this.setTransform() this.setTransition('none') }, goBack() { history.back(); }, toOtherInfo(){ if(this.blog.userId === this.user.id){ location.href = "/info.html" }else{ location.href = "/other-info.html?id=" + this.blog.userId } }, queryBlogById(id) { axios.get("/blog/" + id) .then(({data}) => { data.images = data.images.split(",") this.blog = data; this.$nextTick(this.init); this.queryShopById(data.shopId) this.queryLikeList(id); this.queryLoginUser(); }) .catch(this.$message.error) }, queryShopById(shopId) { axios.get("/shop/" + shopId) .then(({data}) => { data.image = data.images.split(",")[0] this.shop = data }) .catch(this.$message.error) }, queryLikeList(id){ axios.get("/blog/likes/" + id) .then(({data}) => this.likes = data) .catch(this.$message.error) }, addLike(){ axios.put("/blog/like/" +this.blog.id) .then(({data}) => { axios.get("/blog/" + this.blog.id) .then(({data}) => { data.images = data.images.split(",") this.blog = data; this.queryLikeList(this.blog.id); }) .catch(this.$message.error) }) .catch(err => { this.$message.error(err) }) }, isFollowed(){ axios.get("/follow/or/not/" + this.blog.userId) .then(({data}) => this.followed = data) .catch(this.$message.error) }, follow(){ axios.put("/follow/" + this.blog.userId + "/" + !this.followed) .then(() => { this.$message.success(this.followed ? "已取消关注" : "已关注") this.followed = !this.followed }) .catch(this.$message.error) }, formatTime(b) { return b.getFullYear() + "" + (b.getMonth() + 1) + "月" + b.getDate() + " "; }, formatMinutes(m) { if (m < 10) m = "0" + m return m; }, queryLoginUser(){ // 查询用户信息 axios.get("/user/me") .then(({ data }) => { // 保存用户 this.user = data; if(this.user.id !== this.blog.userId){ this.isFollowed(); } }) .catch(console.log) }, // 轮播图相关方法 updateItemWidth() { this._width = this.container.offsetWidth || document.documentElement.offsetWidth }, setTransform(offset) { offset = offset || 0 each(this.items, (item, i) => { let distance = (i - this.active) * this._width + offset let transform = `translate3d(${distance}px, 0, 0)` item.style.webkitTransform = transform item.style.transform = transform }) }, setTransition(duration) { duration = duration || this.duration duration = typeof duration === 'number' ? (duration + 'ms') : duration each(this.items, (item) => { item.style.webkitTransition = duration item.style.transition = duration }) }, moveStart(e) { this.start.x = e.changedTouches[0].pageX this.start.y = e.changedTouches[0].pageY this.setTransition('none') }, moving(e) { e.preventDefault() e.stopPropagation() let distanceX = e.changedTouches[0].pageX - this.start.x let distanceY = e.changedTouches[0].pageY - this.start.y if (Math.abs(distanceX) > Math.abs(distanceY)) { this.isMoving = true this.move.x = this.start.x + distanceX this.move.y = this.start.y + distanceY if ((this.active === 0 && distanceX > 0) || (this.active === (this.items.length - 1) && distanceX < 0)) { distanceX = distanceX * this.resistance } this.setTransform(distanceX) } }, moveEnd(e) { if (this.isMoving) { e.preventDefault() e.stopPropagation() let distance = this.move.x - this.start.x if (Math.abs(distance) > this.sensitivity) { if (distance < 0) { this.next() } else { this.prev() } } else { this.back() } this.reset() this.isMoving = false; } }, next() { let index = this.active + 1 this.go(index) }, prev() { let index = this.active - 1 this.go(index) }, reset() { this.start.x = 0 this.start.y = 0 this.move.x = 0 this.move.y = 0 }, back() { this.setTransition() this.setTransform() }, destroy() { this.setTransition('none') }, go(index) { this.active = index if (this.active < 0) { this.active = 0 } else if (this.active > this.items.length - 1) { this.active = this.items.length - 1 } this.$emit('change', this.active) this.setTransition() this.setTransform() }, // 评论相关方法 showCommentBox() { if (!this.user.id) { this.$message.warning("请先登录"); return; } this.commentContainer.classList.add('active'); setTimeout(() => { this.$refs.commentInput.focus(); }, 300); }, hideCommentBox() { this.commentContainer.classList.remove('active'); this.commentText = ''; }, sendComment() { const content = this.commentText.trim(); if (content) { // 使用FormData格式,与后端接口参数匹配 const formData = new FormData(); formData.append('comment', content); formData.append('blogId', this.blog.id); axios.post("/blog-comments", formData) .then(() => { this.$message.success("评论发送成功"); this.hideCommentBox(); this.commentText = ''; // 刷新第一页评论 this.fetchComments(this.blog.id, 1); }) .catch(err => { this.$message.error("评论发送失败: " + err.response?.data?.message || err.message); console.error(err); }); } else { this.$message.warning("请输入评论内容"); } }, // 获取评论列表 - 适配后端分页接口 fetchComments(blogId, page = 1) { // 如果是加载第一页,清空现有评论 if (page === 1) { this.comments = []; } this.isLoading = true; axios.get(`/blog-comments/${blogId}`, { params: { page: page, size: this.pageSize } }) .then((response) => { // 确保响应数据存在 if (!response.data) { this.$message.warning("评论数据为空"); this.hasMore = false; this.isLoading = false; return; } const pageResult = response.data; // 验证必要字段存在 if (pageResult.records === undefined || pageResult.totalRecords === undefined) { this.$message.warning("评论数据格式异常,缺少必要字段"); this.hasMore = false; this.isLoading = false; return; } // 更新评论列表 if (page === 1) { this.comments = pageResult.records || []; } else { this.comments = [...this.comments, ...(pageResult.records || [])]; } // 更新分页信息 this.totalComments = pageResult.totalRecords || 0; this.currentPage = pageResult.currentPage || page; this.pageSize = pageResult.pageSize || this.pageSize; // 判断是否还有更多数据 this.hasMore = this.comments.length < this.totalComments; }) .catch(err => { this.$message.error('评论加载失败: ' + err.response?.data?.message || '网络错误'); console.error(err); }) .finally(() => { this.isLoading = false; }); }, // 加载更多评论 loadMoreComments() { if (!this.isLoading && this.hasMore) { this.fetchComments(this.blog.id, this.currentPage + 1); } }, // 格式化评论时间(最终修复版) formatCommentTime(timestamp) { if (!timestamp) return ''; // 尝试将时间戳转换为数字 let timeValue; // 处理字符串类型的时间戳 if (typeof timestamp === 'string') { // 移除所有非数字字符 const cleanTimestamp = timestamp.replace(/[^\d]/g, ''); // 如果清理后为空字符串,尝试其他解析方法 if (!cleanTimestamp) { // 尝试直接解析原始字符串 try { timeValue = Number(timestamp); } catch (e) { console.error('Failed to parse timestamp:', timestamp); return '未知时间'; } } else { timeValue = Number(cleanTimestamp); } } else if (typeof timestamp === 'number') { timeValue = timestamp; } else { console.error('Unsupported timestamp type:', typeof timestamp); return '未知时间'; } // 验证转换后的时间戳是否为有效数字 if (isNaN(timeValue)) { console.error('Invalid timestamp value:', timestamp); return '未知时间'; } // 处理零值或负值时间戳 if (timeValue <= 0) { return '未知时间'; } // 根据时间戳范围智能判断(优化处理超长时间戳) let commentDate; // 特殊处理:如果时间戳大于当前时间的2倍,可能是前端时间戳生成问题 const currentTime = Date.now(); if (timeValue > currentTime * 2) { // 尝试将超长时间戳除以10的幂,直到合理范围 let adjustedTimestamp = timeValue; while (adjustedTimestamp > currentTime * 2 && adjustedTimestamp > 1e15) { adjustedTimestamp = Math.floor(adjustedTimestamp / 10); } // 使用调整后的时间戳 commentDate = new Date(adjustedTimestamp); } else { // 默认作为毫秒级时间戳处理 commentDate = new Date(timeValue); } // 验证期有效性 if (isNaN(commentDate.getTime())) { console.error('Invalid date from timestamp:', timestamp); return '未知时间'; } // 计算与当前时间的差值(毫秒) const now = new Date(); const diffMs = now - commentDate; // 处理未来时间(diffMs为负数) if (diffMs < 0) { // 未来时间显示完整期 return commentDate.toISOString().slice(0, 10); } // 计算差值(分钟、小时、天) const diffMinutes = Math.floor(diffMs / 60000); const diffHours = Math.floor(diffMs / 3600000); const diffDays = Math.floor(diffMs / 86400000); // 相对时间显示 if (diffMinutes < 1) return '刚刚'; if (diffMinutes < 60) return `${diffMinutes}分钟前`; if (diffHours < 24) return `${diffHours}小时前`; if (diffDays < 7) return `${diffDays}天前`; // 超过7天,显示完整期 return commentDate.toISOString().slice(0, 10); } } }) </script> </body> </html>时间显示错了,传进来的"createTime": 1749989266662,后端System.currentTimeMillis()产生的,时间显示错了
06-16
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