Java的部分问题和小结

2015/9/6

ThreadLocal:该类提供了线程局部变量，这样可以生成对每个线程唯一的局部标识符。

 

2015/9/18
 1.乱码问题：
  js:xdata = encodeURI(encodeURI(xdata));
  java:fUrl = URLDecoder.decode(URLDecoder.decode(fUrl,"utf-8"),"utf-8");

 2.数据库查询返回的resultSet的处理：
  ResultSet rs = stmt.executeQuery(sql);
  while(rs.next()){
  String aa = rs.getString("DNS");
  ...
  }

 

2015/9/23
 1.TreeMap中的键值对会进行自然排序，HaspMap则不会

 

2015/11/10
 1.车辆：两年，如查封开始时间为2015-10-27，查封结束时间为2017-10-26的设置；
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
  Calendar cal = Calendar.getInstance();
  String jssj = null;
  int gap = 0;
  try {
   Date date = sdf.parse(kssj);
   cal.setTime(date);
   cal.add(Calendar.YEAR, gap);
   cal.add(Calendar.DAY_OF_MONTH, -1);
   date = cal.getTime();
   jssj = sdf.format(date);
  } catch (ParseException e) {
   Logger.logger.error("获取冻结结束时间失败：",e);
  }
  return jssj;
 <另一相似例子：添加年份>
  （<select id="NF" name="nf" class="Bordered" style="width:70px">
   <%
    Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR)+1;
    for(int i=year;i>=(year-9);i--){
     %>
     <option value="<%=i%>" <%if(i==year-1){%>selected<%} %>><%=i%></option>
     <%
    }
   %>
  </select>）

 

2015/12/8
 1..EL表达式，可以取出域中的数据,如${requestScope.id}

 

2015/12/21 
 1.SQL语句：date_format(CJSJ,'%Y') = date_format(now(),'%Y') //本年新录用总人数
 2.保留小数点后几位： round(avg(A.NL),3)保留小数点后3位(mysql)
   java : (1)Math.round();(2)DecimalFormat("#.##%");(3)。。。

2015/12/31
 1.迭代获取数据
 public String getNodeValue(List list, String Node) {
  Iterator it = list.iterator();
  if (it.hasNext()) {
      Element styleElement = (Element) it.next();
      Iterator memo = styleElement.elementIterator(Node);
      if (memo.hasNext()) {
   Element memostring = (Element) memo.next();
   return memostring.getTextTrim();
      } else {
   return "";
      }
  } else {
      return "";
  }
 }

 

2016/2/3
 1.获取编号，如LY-1501-1111?
   public static String getNewRkdNum(String rkdNum) {
  Date date = new Date();
  SimpleDateFormat sdf = new SimpleDateFormat("yyMM");
  String d = sdf.format(date);
  String mon = d.substring(2,4);
  if (isEmptyOrNull(rkdNum)) {
   rkdNum =  d + "-"
     + "00001";
  } else {
   String rkMon = rkdNum.substring(rkdNum.indexOf("-")+1,rkdNum.lastIndexOf("-"));
   if(rkMon.endsWith(mon)){
    String rknum = rkdNum.substring(rkdNum.lastIndexOf("-") + 1,
      rkdNum.length());
    int n = Integer.parseInt(rknum);
    int num = n + 1;
    if (num < 10) {
     rknum = "0000" + num;
    } else if (num < 100 && num >= 10) {
     rknum = "000" + num;
    } else if (num < 1000 && num >= 100) {
     rknum = "00" + num;
    } else if (num < 10000 && num >= 1000) {
     rknum = "0" + num;
    } else {
     rknum = "" + num;
    }
    rkdNum = rkdNum.substring(0, rkdNum.indexOf("-") + 1) + d + "-"
      + rknum;
   }else{
    rkdNum = rkdNum.substring(0, rkdNum.indexOf("-") + 1) + d + "-" + "00001";
   }
   
  }
  return rkdNum;
   }
 2.JAVA设置登录密码(相关md5的知识，java自带...)
   String encodePwd = new MD5().getMD5ofStr(newPwd);