集合转字符串

调用接口时输入数据为List<>集合，可利用Joiner.on(",").join(ids);转化为字符串（以“，”分割）

 /*  依赖 <!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
      <version>28.0-jre</version>
    </dependency>*/
    @Test
    public void testJoiner(){
        List ids=new ArrayList<String>();
        ids.add("1");
        ids.add("2");
        String idStr = Joiner.on(",").join(ids);
        System.out.println(idStr);
    }

更多详解：https://blog.csdn.net/wwwdc1012/article/details/82228458