JavaWeb 获取应用根路径的实践指南

protected void doGet(HttpServletRequest request, HttpServletResponse response) {
    // 获取上下文路径（带斜杠）
    String contextPath = request.getContextPath();
    // 示例: "/myapp"
    // 构建完整URL
    String homeUrl = contextPath + "/index.html";
    // 示例: "/myapp/index.html"
}

<!-- 推荐：EL表达式 -->
<link rel="stylesheet" href="${pageContext.request.contextPath}/css/style.css" rel="external nofollow" >
<!-- 传统脚本 -->
<script>
  const basePath = '<%= request.getContextPath() %>';
</script>
<!-- 超链接示例 -->
<a href="${pageContext.request.contextPath}/user/profile" rel="external nofollow" >个人资料</a>

// 在Servlet的init()方法中
public void init(ServletConfig config) {
    String contextPath = config.getServletContext().getContextPath();
}
// 在自定义工具类中
public class PathUtils {
    public static String getContextPath() {
        return WebApplicationContextUtils
               .getRequiredWebApplicationContext()
               .getServletContext()
               .getContextPath();
    }
}

// 获取Web根目录物理路径
String realPath = request.getServletContext().getRealPath("/");
// Linux: "/usr/tomcat/webapps/myapp/"
// Windows: "C:\\tomcat\\webapps\\myapp\\"
// 获取资源物理路径
String imgPath = getServletContext().getRealPath("/images/logo.png");

# application.yml
server:
  servlet:
    context-path: /myapp

// 注入上下文路径
@Value("${server.servlet.context-path}")
private String contextPath;

@GetMapping("/path")
public String getPath(HttpServletRequest request) {
    return "Context Path: " + request.getContextPath();
}

<!-- 直接使用语法 -->
<a th:href="@{/user/profile}" rel="external nofollow" >Link</a> 
<!-- 自动添加context path -->
<!-- 显式获取 -->
<p th:text="${#request.getContextPath()}"></p>

// 安全拼接路径（避免双斜杠）
public static String buildPath(String base, String... parts) {
    StringBuilder path = new StringBuilder(base.endsWith("/") ? 
        base.substring(0, base.length() - 1) : base);
    for (String part : parts) {
        if (part.startsWith("/")) part = part.substring(1);
        if (!part.isEmpty()) {
            path.append("/").append(part);
        }
    }
    return path.toString();
}
// 使用示例
String fullPath = buildPath(contextPath, "api", "v1", "user");
// 输出: "/myapp/api/v1/user"

// 检查是否部署在ROOT应用
if (contextPath.isEmpty()) {
    contextPath = "/"; // 或保持空字符串
}

// 规范化路径
if (contextPath.endsWith("/")) {
    contextPath = contextPath.substring(0, contextPath.length() - 1);
}

String contextPath = request.getContextPath();
String basePath = request.getScheme() + "://" 
                + request.getServerName() + ":" 
                + request.getServerPort() 
                + contextPath;
// 输出: "http://localhost:8080/myapp"

@WebListener
public class AppContextListener implements ServletContextListener {
    public void contextInitialized(ServletContextEvent sce) {
        // 存储上下文路径
        sce.getServletContext().setAttribute("ctx", 
            sce.getServletContext().getContextPath());
    }
}

<!-- JSP中直接使用 -->
<link href="${ctx}/css/style.css" rel="external nofollow"  rel="stylesheet">

// 在base.jsp中
<script>
  window.APP_CONFIG = {
    contextPath: '${pageContext.request.contextPath}'
  };
</script>
// 其他JS中使用
axios.get(APP_CONFIG.contextPath + '/api/data');

// 防止路径遍历攻击
public static String safePath(String inputPath) {
    return Paths.get(inputPath)
                .normalize()
                .toString()
                .replaceAll("\\.\\.", ""); // 移除上级目录引用
}