java 分批次读取java.util.List 数据

java 功能源代码：

 @RequestMapping({"/batchupdate"})
  @ResponseBody
  public String batchUpdate(){
	  String result = "";
	  try{
	  List<Account> list = accountService.batchUpdate();
	  List<Account> batch = new ArrayList<Account>();
	  
	 
	  //密码修改
	  if(list !=null && list.size()>0){
		  for(int i=0;i<list.size();i++){
			  Account account =list.get(i);
			  String oldpassword = account.getPassword();
			  account.setPassword(EncryptUtils.encodeBase64String(oldpassword));
			  batch.add(account);
		  }
	  }
	  //一次处理数据量
	  int  init = 1000;// 每隔1000条循环一次  =1000;
	  //总数
	  int nums = batch.size();
	  //批次数
	  int batchnum = nums / init;  
	  if (nums % init != 0) {  
		  batchnum += 1;  
          if (nums < init) {  
              init = list.size();  
          }  
      } 
	  
	   for (int i = 0; i < batchnum; i++) {  
           System.out.println("------" + i + "保存"+init+"条数据到数据库....");  
           List<Account> a = new ArrayList<Account>();
           if (i == batchnum - 1) {  
               int size = (i + 1) * init;  
               for (int j = size - init; j < nums; j++) {  
            	   if (batch.get(j) == null) {  
                       break;  
                   } 
            	   a.add(batch.get(j));  
               }  
              
           } else {  
               int size = (i + 1) * init;  
               for (int j = size - init; j < size; j++) { 
            	   if (batch.get(j) == null) {  
                       break;  
                   }  
            	   a.add(batch.get(j));  
               }  
             
           }  
           accountService.updateBatch(a);
          
       }  
	  
	 
	
	  
	  }catch(Exception e){
		  System.out.println(e.getMessage());
		  return "false";
	  }
	  result = "true";
	  return result;
	  
  }

待补充