- 最后一次出现"."的位置
String fileName = "hahaha.java";int lastIndexOf = originalFilename.lastIndexOf(".");
- 查找文件的后缀名
String fileName = "hahaha.java";String suffix = fileName.substring(lastIndexOf);
String fileName = "hahaha.java";int lastIndexOf = originalFilename.lastIndexOf(".");
String fileName = "hahaha.java";String suffix = fileName.substring(lastIndexOf);