java 分批次读取java.util.List 数据

本是古典何须时尚 2023-10-17 10:24 36阅读 0赞

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;
    	  
      }

业务流程分解：

待补充