hutool 常用工具類 ---（有空看看-含驗證碼）前端流文件生成圖片展示的方法

https://www.hutool.cn/docs/#/

 

 <dependency>
                <groupId>cn.hutool</groupId>
                <artifactId>hutool-all</artifactId>
                <version>5.4.1</version>
            </dependency>

 

 

驗證碼

后端代碼

    @PostMapping("/no2")
    //獲取用戶信息的方法 用Authentication類
    public void NO2(HttpServletResponse response) throws IOException {
//        HttpHeaders headers = new HttpHeaders();
////        //生成驗證碼圖片
        LineCaptcha lineCaptcha = CaptchaUtil.createLineCaptcha(200, 100);
        //輸出code,這里可以存到redis，前端給個隨機碼 +這個驗證碼
        Console.log("輸出驗證碼code: "+lineCaptcha.getCode());
        //指定響應頭給瀏覽器
        response.setContentType("image/png");//告訴瀏覽器輸出內容為圖片
        response.setHeader("Pragma", "No-cache");//禁止瀏覽器緩存
        response.setHeader("Cache-Control", "no-cache");
        //輸出流文件給前端
        lineCaptcha.write(response.getOutputStream());
    }

 

前端代碼

<template>
  <div>
    <img :src="src" alt="圖像的替代文本">
    <button @click="post">更新驗證碼</button>
  </div>
</template>
<script>
import {photo} from "../../api/index";
import {photo2} from "../../api/index";
export default {
  data() {
    return {
        type:'1',
        src:'https://emoji.cdn.bcebos.com/yunque/hejirukou.jpg',
  }
},
  methods: {

//下載驗證碼
   async post(){
       try {
          let { response } = await photo();
          const objectUrl = window.URL.createObjectURL(new Blob([response], {type: "image/png"}));
          this.src = objectUrl;     //到這步已經實現圖片展示了 
          const a = document.createElement('a');  //模擬生成一個a標簽 點就下載
          a.href = objectUrl;
          a.download = '2023.png';
          a.click();
          a.remove();
        } catch (e) {
          console.log(e);
        }
}

}}
</script>
<style>
</style>

 

 

 

 

常用api

//把one實體類 復制到 userDTO 實體類 ，相同字段會自動賦值過去
import cn.hutool.core.bean.BeanUtil;
BeanUtil.copyProperties(one, userDTO, true);

 

//判斷變量是否為空
import cn.hutool.core.util.StrUtil;
StrUtil.isBlank(username)

 

import cn.hutool.core.date.DateUtil;
//當前時間加20秒后的時間
DateUtil.offsetSecond(new Date(), 20)
當前時間加2小時后的時間    
DateUtil.offsetHour(new Date(), 2)
    
//輸出結果: 2022-06-14 17:28:26

 

//格式化
import cn.hutool.core.util.StrUtil;
String template = "{}愛{}，就像老鼠愛大米";
String str = StrUtil.format(template, "我", "你"); //str -> 我愛你，就像老鼠愛大米

 

//字符轉json
import cn.hutool.json.JSONUtil;
String html = "{\"name\":\"Something must have been changed since you leave\"}";
JSONObject jsonObject = JSONUtil.parseObj(html);
jsonObject.getStr("name");
System.out.println(jsonObject);


//List轉Json，maps是List類型的參數
String json = JSONUtil.toJsonStr(maps);
System.out.println("這是json字符串: "+json);

//Json轉List 
//例子: {
//    "items": [
//        {
//            "id": "62f64658923314000118f4f6",
//           "phoneNumber": "15994727178",
//          "captcha": "247743",
//          "state": "SUCCESS",
//            "sendTime": 1660307032
//        }]
//        }
JSONArray objects =JSONUtil.parseArray(json);
List<Map> maps1 = JSONUtil.toList(objects, Map.class);
System.out.println("這是list集合: "+maps1);



String ss="{'items': [{'id':'62f64658923314000118f4f6'}]}";
JSONObject jsonObject = JSONUtil.parseObj(ss);
System.out.println(jsonObject);  //{"items":[{"id":"62f64658923314000118f4f6"}]}
List<Map> maps1 = JSONUtil.toList(jsonObject.getJSONArray("items"), Map.class);
System.out.println("這是list集合: "+maps1);  //這是list集合: [{id=62f64658923314000118f4f6}]--類型 java.util.ArrayList

 

json轉java對象

場景: 接收前端100多個字段的json，直接映射到實體類里面，然后通過Mongo傳實體類分別把字段插入到數據庫

AcceptCancelationApplyReq req = JSONUtil.toBean(request, AcceptCancelationApplyReq.class);