java - @RequestMapping 找不到 Jsp 页面

Question

我尝试在 spring-boot 中构建一个小应用程序，它的结构如下。我在使用 @RequestMapping 时遇到了一个奇怪的问题，它可以找到除一个之外的所有资源。
这是web.xml文件

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

以下是 applicationContext.xml文件

<?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.example.*" />

    <!-- 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/views/" />
        <property name="suffix" value=".jsp" />
    </bean>

</beans>

在 com.example.controller包我有两个文件 FrontController.java和 FormController.java .
这就是他们的样子。 FrontController.java

package com.example.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class FrontController {

    public FrontController() {
        // TODO Auto-generated constructor stub
    }
    
    @RequestMapping("/")
    public String showHomePage() {
        System.out.println("Reached In");
        return "home";
        
    }
    
    @RequestMapping("/spring")
    public String spring() {
        
        return "spring";
        
    }

}

FormController.java

package com.example.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class FormController {

    public FormController() {
        // TODO Auto-generated constructor stub
    }

    @RequestMapping("/showform")
    public String showForm() {
        return "showForm";
        
    }
    
    @RequestMapping("/formResp")
    public String formResp() {
        return "formResp";
        
    }
}

现在在服务器中加载我的项目时，我得到的默认页面是 home.jsp使用以下堆栈跟踪成功显示。

09:21:49.390 [http-nio-8080-exec-3] DEBUG org.springframework.web.servlet.view.InternalResourceView - View name 'home', model {}
09:21:49.392 [http-nio-8080-exec-3] DEBUG org.springframework.web.servlet.view.InternalResourceView - Forwarding to [/WEB-INF/views/home.jsp]
09:21:49.427 [http-nio-8080-exec-3] DEBUG org.springframework.web.servlet.DispatcherServlet - Completed 200 OK

同样的事情发生在 showForm.jsp页面和 formResp.jsp页面在 FormController.java ，它们会成功显示。下面的堆栈跟踪。

09:21:57.107 [http-nio-8080-exec-4] DEBUG org.springframework.web.servlet.DispatcherServlet - GET "/WebAppDemo/showform", parameters={}
09:21:57.107 [http-nio-8080-exec-4] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped to com.example.controller.FormController#showForm()
09:21:57.108 [http-nio-8080-exec-4] DEBUG org.springframework.web.servlet.view.InternalResourceView - View name 'showForm', model {}
09:21:57.108 [http-nio-8080-exec-4] DEBUG org.springframework.web.servlet.view.InternalResourceView - Forwarding to [/WEB-INF/views/showForm.jsp]
09:21:57.302 [http-nio-8080-exec-4] DEBUG org.springframework.web.servlet.DispatcherServlet - Completed 200 OK
09:22:02.378 [http-nio-8080-exec-5] DEBUG org.springframework.web.servlet.DispatcherServlet - GET "/WebAppDemo/formResp?name=jony", parameters={masked}
09:22:02.379 [http-nio-8080-exec-5] DEBUG org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped to com.example.controller.FormController#formResp()
09:22:02.380 [http-nio-8080-exec-5] DEBUG org.springframework.web.servlet.view.InternalResourceView - View name 'formResp', model {}
09:22:02.380 [http-nio-8080-exec-5] DEBUG org.springframework.web.servlet.view.InternalResourceView - Forwarding to [/WEB-INF/views/formResp.jsp]
09:22:02.621 [http-nio-8080-exec-5] DEBUG org.springframework.web.servlet.DispatcherServlet - Completed 200 OK

但是一旦我尝试显示 spring.jsp页面在 FrontController.java我遇到了 404 Error .下面的堆栈跟踪。

09:22:09.179 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.DispatcherServlet - GET "/WebAppDemo/spring", parameters={}
09:22:09.187 [http-nio-8080-exec-6] WARN org.springframework.web.servlet.PageNotFound - No mapping for GET /WebAppDemo/spring
09:22:09.187 [http-nio-8080-exec-6] DEBUG org.springframework.web.servlet.DispatcherServlet - Completed 404 NOT_FOUND

不知道为什么找不到 spring.jsp页面位于 WEB-INF/views文件夹以及其他 JSP 文件。将深深地感谢这方面的一些帮助。提前致谢。

Answer 1

首先，我在我解决的项目中发现了很多配置问题和缺少的类。
获取新代码:https://github.com/anish-fullstack/WebDemoApp
更新的项目结构:

从 web.xml 中删除所有内容。更新的 web.xml :

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

添加了一个缺少的类，从应用程序的启动位置。

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ImportResource;

@SpringBootApplication
@ImportResource("WEB-INF/applicationContext.xml")
public class WebAppDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebAppDemoApplication.class, args);
    }

}

更新 application.properties。

spring.main.allow-bean-definition-overriding=true

你需要jasper依赖和jSTL来支持jsp解析和jSTL支持。更新 pom.xml :

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>WebAppDemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>WebAppDemo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>11</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

运行应用程序日志:

 .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.3.4.RELEASE)

2020-10-03 13:27:01.494  INFO 7738 --- [           main] com.example.WebAppDemoApplication        : Starting WebAppDemoApplication on Anishs-MacBook-Pro.local with PID 7738 (/Users/anish/Downloads/WebDemoApp-master/WebAppDemo/target/classes started by anish in /Users/anish/Downloads/WebDemoApp-master/WebAppDemo)
2020-10-03 13:27:01.495  INFO 7738 --- [           main] com.example.WebAppDemoApplication        : No active profile set, falling back to default profiles: default
2020-10-03 13:27:01.955  INFO 7738 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-10-03 13:27:01.959  INFO 7738 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-10-03 13:27:01.959  INFO 7738 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.38]
2020-10-03 13:27:02.066  INFO 7738 --- [           main] org.apache.jasper.servlet.TldScanner     : At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
2020-10-03 13:27:02.071  INFO 7738 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2020-10-03 13:27:02.071  INFO 7738 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 553 ms
2020-10-03 13:27:02.242  INFO 7738 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-10-03 13:27:02.301  INFO 7738 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2020-10-03 13:27:02.309  INFO 7738 --- [           main] com.example.WebAppDemoApplication        : Started WebAppDemoApplication in 0.992 seconds (JVM running for 1.353)
2020-10-03 13:27:11.354  INFO 7738 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2020-10-03 13:27:11.354  INFO 7738 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2020-10-03 13:27:11.358  INFO 7738 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 4 ms

此外，您正在访问错误的网址。映射网址如下:

http://localhost:8080/showform - 这将打开 showForm.jsp .

http://localhost:8080/formResp - 这将打开 formResp.jsp .

http://localhost:8080/ - 这将打开 home.jsp .

http://localhost:8080/spring -/spring - 这将打开 spring.jsp