Java取一年有多少周、某周的第一天和最后一天

[java] view plaincopy

1. import java.text.SimpleDateFormat;  
2. import java.util.Calendar;  
3. import java.util.Date;  
4. import java.util.GregorianCalendar;  
5. public class WeekUtils {  
6.   
7.  // 获取当前时间所在年的周数  
8.  public static int getWeekOfYear(Date date) {  
9.   Calendar c = new GregorianCalendar();  
10.   c.setFirstDayOfWeek(Calendar.MONDAY);  
11.   c.setMinimalDaysInFirstWeek(7);  
12.   c.setTime(date);  
13.   
14.   return c.get(Calendar.WEEK_OF_YEAR);  
15.  }  
16.   
17.  // 获取当前时间所在年的最大周数  
18.  public static int getMaxWeekNumOfYear(int year) {  
19.   Calendar c = new GregorianCalendar();  
20.   c.set(year, Calendar.DECEMBER, 31, 23, 59, 59);  
21.   
22.   return getWeekOfYear(c.getTime());  
23.  }  
24.   
25.  // 获取某年的第几周的开始日期  
26.  public static Date getFirstDayOfWeek(int year, int week) {  
27.   Calendar c = new GregorianCalendar();  
28.   c.set(Calendar.YEAR, year);  
29.   c.set(Calendar.MONTH, Calendar.JANUARY);  
30.   c.set(Calendar.DATE, 1);  
31.   
32.   Calendar cal = (GregorianCalendar) c.clone();  
33.   cal.add(Calendar.DATE, week * 7);  
34.   
35.   return getFirstDayOfWeek(cal.getTime());  
36.  }  
37.   
38.  // 获取某年的第几周的结束日期  
39.  public static Date getLastDayOfWeek(int year, int week) {  
40.   Calendar c = new GregorianCalendar();  
41.   c.set(Calendar.YEAR, year);  
42.   c.set(Calendar.MONTH, Calendar.JANUARY);  
43.   c.set(Calendar.DATE, 1);  
44.   
45.   Calendar cal = (GregorianCalendar) c.clone();  
46.   cal.add(Calendar.DATE, week * 7);  
47.   
48.   return getLastDayOfWeek(cal.getTime());  
49.  }  
50.   
51.  // 获取当前时间所在周的开始日期  
52.  public static Date getFirstDayOfWeek(Date date) {  
53.   Calendar c = new GregorianCalendar();  
54.   c.setFirstDayOfWeek(Calendar.MONDAY);  
55.   c.setTime(date);  
56.   c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek()); // Monday  
57.   return c.getTime();  
58.  }  
59.   
60.  // 获取当前时间所在周的结束日期  
61.  public static Date getLastDayOfWeek(Date date) {  
62.   Calendar c = new GregorianCalendar();  
63.   c.setFirstDayOfWeek(Calendar.MONDAY);  
64.   c.setTime(date);  
65.   c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6); // Sunday  
66.   return c.getTime();  
67.  }  
68.   
69.  public static void main(String[] args) {  
70.   int year = 2011;  
71.   int week = 1;  
72.   
73.   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
74.   Date today = new Date();  
75.   Calendar c = new GregorianCalendar();  
76.   c.setTime(today);  
77.   
78.   System.out.println("current date = " + sdf.format(today));  
79.   System.out.println("getWeekOfYear = " + getWeekOfYear(today));  
80.   System.out.println("getMaxWeekNumOfYear = " + getMaxWeekNumOfYear(year));  
81.   System.out.println("getFirstDayOfWeek = " + sdf.format(getFirstDayOfWeek(year, week)));  
82.   System.out.println("getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(year, week)));  
83.   System.out.println("getFirstDayOfWeek = " + sdf.format(getFirstDayOfWeek(today)));  
84.   System.out.println("getLastDayOfWeek = " + sdf.format(getLastDayOfWeek(today)));  
85.  }  
86. }  
87. 转自:http://blog.csdn.net/dragon1984456/article/details/7094473