blocks|key|1990668|text|使用日历的工具通过getTime()创建新的日期对象|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1990669|import+java.util.GregorianCalendar;
import+java.util.Date;

Calendar+cal+=+new+GregorianCalendar();
cal.add(Calendar.DAY_OF_MONTH,+-7);
Date+sevenDaysAgo+=+cal.getTime();|code-block|syntax|javascript|1990670|entityMap^0|9|9|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Use Calendar's facility to create new Date objects using <code>getTime()</code>:

<pre><code>import java.util.GregorianCalendar;
import java.util.Date;

Calendar cal = new GregorianCalendar();
cal.add(Calendar.DAY_OF_MONTH, -7);
Date sevenDaysAgo = cal.getTime();
</code></pre>

blocks|key|1990749|text|试一试|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1990750|+Date+sevenDay+=+new+Date(System.currentTimeMillis()+-+7L+*+24+*+3600+*+1000));|code-block|syntax|javascript|1990751|另一种方式是使用日历，但我自己不喜欢使用它。|1990752|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

try

<pre><code> Date sevenDay = new Date(System.currentTimeMillis() - 7L * 24 * 3600 * 1000));
</code></pre>

Another way is to use Calendar but I don't like using it myself.

blocks|key|1990777|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1990778|Calendar+c+=+Calendar.getInstance();
c.add(Calendar.DAY_OF_MONTH,+-7);
return+c.getTime();|code-block|syntax|javascript|1990779|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>Calendar c = Calendar.getInstance();
c.add(Calendar.DAY_OF_MONTH, -7);
return c.getTime();
</code></pre>

blocks|key|1777065|text|我不确定他们什么时候添加的，但是JasperReports有他们自己的一组可以操作日期的“函数”。下面是一个我还没有彻底测试过的例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1777066|DATE(YEAR(TODAY()),+MONTH(TODAY()),+DAY(TODAY())+-+7)|code-block|syntax|javascript|1777067|这将构建一个日期设置为从今天起7天的java.util.Date。如果你想使用一个不同的“锚”日期，只要用你想使用的日期替换TODAY()即可。|offset|length|style|CODE|1777068|entityMap^0|0|0|I|E|1Q|7|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

I'm not sure when they added these, but JasperReports has their own set of "functions" that can manipulate dates. Here is an example that I haven't tested thoroughly:

<pre><code>DATE(YEAR(TODAY()), MONTH(TODAY()), DAY(TODAY()) - 7)
</code></pre>

That builds a <code>java.util.Date</code> with the date set to 7 days from today. If you want to use a different "anchor" date, just replace <code>TODAY()</code> with whatever date you want to use.

blocks|key|1777167|text|确定的“天”需要一个时区。时区定义了“一天”开始的时间。时区包括处理夏令时和其他异常情况的规则。没有魔法可以让时区变得无关紧要。如果忽略该问题，则将应用JVM的默认时区。这往往会导致混乱和痛苦。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1777168|避免java.util.Date|1777169|java.util.Date和.Calendar类是出了名的麻烦。避开他们。它们太糟糕了，以至于Sun/Oracle同意用Java8中的新java.time+package来取代它们。|offset|length|1777170|Joda-Time|1777171|Joda-Time+2.3中的示例代码。|1777172|DateTimeZone+timeZone+=+DateTimeZone.forID(+"Europe/Paris"+);+//+Specify+or+else+the+JVM's+default+will+apply.
DateTime+dateTime+=+new+DateTime(+new+java.util.Date(),+timeZone+);+//+Simulate+passing+a+Date.
DateTime+weekAgo+=+dateTime.minusDays(+7+);|code-block|syntax|javascript|1777173|一天的第一个时刻|1777174|或者，您可能希望将一天中的时间调整为一天中的第一个时刻，以便捕获一整天的时间价值。调用该方法withTimeAtStartOfDay。请记住，这通常是00:00:00，但并非总是如此。|style|CODE|1777175|避免在Joda-Time中使用“午夜”方法和类。它们基于一个错误的概念，现在已被弃用。|1777176|DateTime+dateTimeStart+=+new+DateTime(+new+java.util.Date(),+timeZone+).withTimeAtStartOfDay();+//+Not+necessarily+the+time+"00:00:00".
DateTime+weekAgo+=+dateTime.minusDays(+7+).withTimeAtStartOfDay();+|1777177|转换为j.u.Date格式/从From格式转换|1777178|如上所述，要从java.util.Date转换为Joda-Time，只需将Date对象传递给DateTime的构造函数即可。请理解，j.u.Date没有时区，而DateTime有。因此，指定所需的/适当的时区来决定“天”是什么以及它们何时开始。|1777179|要使用另一种方法，DateTime+To+j.u.Date，只需调用toDate方法。|1777180|java.util.Date+date+=+dateTime.toDate();|1777181|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/8/docs/api/java/time/package-summary.html^0|0|0|1X|H|0|0|0|0|0|0|1A|K|23|8|0|0|0|0|0|Y|6|0|0^^$0|@$1|2|3|4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1H|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1I|8|@]|9|@$F|1J|G|1K|1|1L]]|A|$]]|$1|H|3|I|5|6|7|1M|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1N|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1O|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1P|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1Q|8|@$F|1R|G|1S|U|V]|$F|1T|G|1U|U|V]]|9|@]|A|$]]|$1|W|3|X|5|6|7|1V|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|N|7|1W|8|@]|9|@]|A|$O|P]]|$1|10|3|11|5|6|7|1X|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|14|3|15|5|6|7|1Z|8|@$F|20|G|21|U|V]]|9|@]|A|$]]|$1|16|3|17|5|N|7|22|8|@]|9|@]|A|$O|P]]|$1|18|3|-4|5|6|7|23|8|@]|9|@]|A|$]]]|19|$1A|$5|1B|1C|1D|A|$1E|1F]]]]

A determining "days" requires a time zone. A time zone defines when a "day" begins. A time zone includes rules for handling Daylight Saving Time and other anomalies. There is no magic to make time zones irrelevant. If you ignore the issue, the JVM's default time zone will be applied. This tends to lead to confusion and pain.

<h1>Avoid java.util.Date</h1>

The java.util.Date and .Calendar classes are notoriously troublesome. Avoid them. They are so bad that Sun/Oracle agreed to supplant them with the new <a href="http://docs.oracle.com/javase/8/docs/api/java/time/package-summary.html" rel="nofollow">java.time package</a> in Java 8. Use either that or <a href="http://www.joda.org/joda-time/" rel="nofollow">Joda-Time</a>.

<h1>Joda-Time</h1>

Example code in Joda-Time 2.3.

<pre><code>DateTimeZone timeZone = DateTimeZone.forID( "Europe/Paris" ); // Specify or else the JVM's default will apply.
DateTime dateTime = new DateTime( new java.util.Date(), timeZone ); // Simulate passing a Date.
DateTime weekAgo = dateTime.minusDays( 7 );
</code></pre>

<h1>First Moment Of Day</h1>

Or, you may want to adjust the time-of-day to the first moment of the day so as to capture an entire day's worth of time. Call the method <code>withTimeAtStartOfDay</code>. Keep in mind this is usually <code>00:00:00</code> but not always. 

Avoid the "midnight" methods and classes in Joda-Time. They are based on a faulty concept and are now deprecated.

<pre><code>DateTime dateTimeStart = new DateTime( new java.util.Date(), timeZone ).withTimeAtStartOfDay(); // Not necessarily the time "00:00:00".
DateTime weekAgo = dateTime.minusDays( 7 ).withTimeAtStartOfDay(); 
</code></pre>

<h1>Convert To/From j.u.Date</h1>

As seen above, to convert from java.util.Date to Joda-Time merely pass the Date object to constructor of DateTime. Understand that a j.u.Date has no time zone, a DateTime does. So assign the desired/appropriate time zone for deciding what "days" are and when they start.

To go the other way, DateTime to j.u.Date, simply call the <code>toDate</code> method.

<pre><code>java.util.Date date = dateTime.toDate();
</code></pre>

blocks|key|1990897|text|因为还没有人提到TimeUnit：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1990898|new+Date(System.currentTimeMillis()+-+TimeUnit.DAYS.toMillis(7))|code-block|syntax|javascript|1990899|entityMap^0|8|8|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Since no one has mentioned <code>TimeUnit</code> yet:

<pre><code>new Date(System.currentTimeMillis() - TimeUnit.DAYS.toMillis(7))
</code></pre>

blocks|key|1990920|text|我是这样做的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1990921|Date+oneWeekAgo+=+DateUtils.addDays(DateUtils.truncate(new+Date(),+java.util.Calendar.DAY_OF_MONTH),+-7);|code-block|syntax|javascript|1990922|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I'm doing it this way :

<pre><code>Date oneWeekAgo = DateUtils.addDays(DateUtils.truncate(new Date(), java.util.Calendar.DAY_OF_MONTH), -7);
</code></pre>

blocks|key|1777249|text|你可以试试这个，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1777250|++++Calendar+c+=+Calendar.getInstance();
++++c.add(Calendar.DAY_OF_MONTH,+-7);
++++System.out.println(new+java.sql.Date(c.getTimeInMillis()));|code-block|syntax|javascript|1777251|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can try this,

<pre><code> Calendar c = Calendar.getInstance();
 c.add(Calendar.DAY_OF_MONTH, -7);
 System.out.println(new java.sql.Date(c.getTimeInMillis()));
</code></pre>

blocks|key|1990944|text|基于Java+8的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1990945|new+Date(
+++++Instant.now().minus(7,+ChronoUnit.DAYS)
+++++.toEpochMilli()
)|code-block|syntax|javascript|1990946|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Java 8 based solution:
<pre><code>new Date(
 Instant.now().minus(7, ChronoUnit.DAYS)
 .toEpochMilli()
)
</code></pre>

I have a report created in Jasper Reports which ONLY recognizes java.util.Date's (not Calendar or Gregorian, etc).

Is there a way to create a date 7 days prior to the current date?

Ideally, it would look something like this:

<pre><code>new Date(New Date() - 7)
</code></pre>

UPDATE: I can't emphasize this enough: JasperReports DOES NOT RECOGNIZE Java Calendar objects.

java.util.Date: seven days ago

Java

我有一个在Jasper Reports中创建的报告，它只识别java.util.Date的(不能识别日历或公历等)。有没有办法在当前日期前7天创建一个日期？理想情况下，它应该是这样的：new Date(New Date() - 7)更新:我再怎么强调也不为过: JasperReports不能识别Java Calenda...

问java.util.Date:七天前
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问java.util.Date:七天前EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问java.util.Date:七天前
EN