java 文件指针复位

 1 BufferedReader br = new BufferedReader(new InputStreamReader(
 2                 new FileInputStream("userremain.log")));
 3 String msg = null;
 4         String mail = null;
 5         String newDateString=null;    //用户激活后第day天的存留率，先得到那天的日期
 6         //要查看的某一天的新激活用户的存留率，先获得那天的所有的用户email
 7         while (true) {
 8             msg = br.readLine();
 9             if (msg == null) {
10                 break; // 为空文件或者是读到最后，跳出循环
11             }
12             if ("".equals(msg))
13                 continue;
14             
15 //            System.out.println("createTime:" + dateString);
16             if (msg.contains("createTime:"+ dateString)) {
17                 mail = msg.split(" ")[0].split(":")[1];
18                 userSet.add(mail);
19             }
20         }
21 
22 //用户激活后第day天的存留率，先得到那天的日期
23         newDateString=newDate(dateString, day);
24         //获得某一天新激活的用户在第day天的留存用户
25         while (true) {
26             System.out.println("1111111111111111");
27             msg = br.readLine();
28             if (msg == null) {
29                 break; // 为空文件或者是读到最后，跳出循环
30             }
31             if ("".equals(msg))
32                 continue;
33             System.out.println("222222222222222222222");
34             System.out.println(msg.contains("activeTime:" + newDateString));
35             if (msg.contains("activeTime:" + newDateString)) {
36                 mail = msg.split(" ")[0].split(":")[1];
37                 if(userSet.contains(mail)){
38                     userRemainSet.add(mail);
39                 }
40             }
41         }
42         
43         br.close();