如何修复 Spring MVC 中的“noHandlerFound”

Question

这是spring-mvc-demo-servlet.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- Step 3: Add support for component scanning -->
    <context:component-scan base-package="com.robert.springdemo" />

    <!-- Step 4: Add support for conversion, formatting and validation support -->
    <mvc:annotation-driven/>
    <!-- Step 5: Define Spring MVC view resolver -->
    <bean
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/view/" />
        <property name="suffix" value=".jsp" />
    </bean>

</beans>

这是web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    id="WebApp_ID" version="3.1">

    <display-name>spring-mvc-demo</display-name>

    <absolute-ordering />

    <!-- Spring MVC Configs -->

    <!-- Step 1: Configure Spring MVC Dispatcher Servlet -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-mvc-demo-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Step 2: Set up URL mapping for Spring MVC Dispatcher Servlet -->
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
</web-app>

这是控制器 java 文件

public class HelloWorldController {

    // need a controller method to show the initial HTML form
    @RequestMapping("/showForm")
    public String showForm() {
        return "helloworld-form";
    }
}

当我尝试在服务器上运行它时，我会收到此错误：

org.springframework.web.servlet.DispatcherServlet noHandlerFound
WARNING: No mapping for GET /spring-mvc-demo/showForm

我是 SpringMVC 的新手，我认为它与组件扫描有关，但我在 xml 文件中添加了组件扫描。

谢谢。

Answer 1

试试这个：

@RequestMapping("/spring-mvc-demo")
public class HelloWorldController {

    // need a controller method to show the initial HTML form
    @RequestMapping("/showForm")
    public String showForm() {
        return "helloworld-form";
    }
}

使用您当前的设置，您需要点击GET /showForm 然后它才能工作。

请同时查看其他映射方式，例如GetMapping、PostMapping、PutMapping、DeleteMapping、PatchMapping 等

Answer 2

在eclipse中将原来的JRE库改成JRE系统库