20201121千锤百炼软工人

今天是JAVA课上的一个选课系统

其中比较有心得的是一个时间的使用

这部分如下

public static String change(String date)
{
Date parse = null;
String dateString = "";
try {
parse = new SimpleDateFormat("yyyyMMdd").parse(date);
dateString = new SimpleDateFormat("yyyy-MM-dd").format(parse);
} catch (ParseException e) {
dateString=null;
}

return dateString;
}

一个转换格式的一个函数

public static List<Book> booklist2(String idc) throws Exception {
String sql = "select * from chosestudent where idc like '%" + idc + "%'";
List<Book> list = new ArrayList<>();
Connection conn = DBUtil.getConn();
Statement state = null;
ResultSet rs = null;

try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
String date = rs.getString("date");
String book = rs.getString("book");
int renewalsdata = 3;
SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");
Date sd=df.parse(date);
Calendar calendar = Calendar.getInstance();
calendar.setTime(sd);
int month = calendar.get(Calendar.MONTH) + 1;
if(month>9)
{
calendar.add(Calendar.YEAR, 1);
}
calendar.add(Calendar.MONTH, renewalsdata);
String NOW = df.format(new Date());
Integer i=NOW.compareTo(df.format(calendar.getTime()));
if(i>0)
{
list.add(getbyid3(book));
}
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtil.close(rs, state, conn);
}

return list;
}