springboot整合thymeleaf，href失效

我用thymeleaf提交表单数据，总是提示路径找不到，然后我单独试了一下href，发现用thymeleaf后直接无跳转了，请问这是为什么啊，我看依赖也没有问题啊


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

index.html页面


<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<a th:href="@{/user}">实验</a>
</body>
</html>


    @RequestMapping("/user")
    public String index(){

        return "add";

img

默认前缀 private String prefix = "classpath:/templates/";
默认后置 private String suffix = ".html";