Spring Rest HelloWorld应用程序没有SpringBoot的Gradle

Question

如何使Spring应用程序在不使用Spring的情况下工作呢？

在Eclipsetomcat8.5中运行此项目时，我希望url "localhost:8080/hello“显示"HelloWorld"，而不是显示404

src/main/java/com.package/HelloController.java

@RestController
public class HelloController {

    @RequestMapping("/hello")
    public String helloWorld() {
        return "Hello World";
    }

}

src/main/java/com.package/HelloConfig.java

public class HelloConfig {

    @Bean
    public HelloController helloController() {
        return new HelloController();
    }

    public static void main(String[] args) {
        ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(HelloConfig.class);
        context.getBean(HelloController.class);
    }
}

build.gradle

plugins {
    id 'java'
    id 'war'
    id 'eclipse-wtp'
}

dependencies {
    compile 'org.springframework:spring-context:5.0.3.RELEASE'
    compile 'org.springframework:spring-web:5.0.3.RELEASE'
    testCompile 'junit:junit:4.12'
}

repositories {
    mavenCentral()
}

Answer 1

回答我自己的问题:缺失的位是DispatcherServlet，它是负责将http请求委托给控制器的逻辑，就像我的例子中的HelloController。

基于Spring (https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-servlet)，有三种配置DispatcherServlet的方法：

1. 在web.xml中
2. 覆盖WebApplicationInitializer
3. 扩展(推荐应用程序使用基于Java的配置，比如我的)

src/main/java/com.package/ServletInitializer：

public class ServletInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class<?>[] { HelloConfig.class };
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }
}

注:为什么投反对票？

Answer 2

您可能需要WebApplicationInitializer和AnnotationConfigWebApplicationContext on start up.In onStartup方法，您可以提到应用程序的根上下文，并访问相应的控制器映射。

public class CustomWebAppInitializer implements WebApplicationInitializer {

 @Override
 public void onStartup(ServletContext container) {
  AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
  rootContext.register(RootConfiguration.class);
  ContextLoaderListener contextLoaderListener = new ContextLoaderListener(rootContext);
  container.addListener(contextLoaderListener);

  AnnotationConfigWebApplicationContext webContext = new AnnotationConfigWebApplicationContext();
  webContext.register(MvcConfiguration.class);
  DispatcherServlet dispatcherServlet = new DispatcherServlet(webContext);
  ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", dispatcherServlet);
  dispatcher.addMapping("/");
 }
}

Answer 3

我不确定您是否检查了web应用程序的web.xml，是否正确地设置了以下配置

<servlet>
        <servlet-name>springDispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:pathToYourSpringBeanConfig/channel-application-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Map all requests to the DispatcherServlet for handling -->
    <servlet-mapping>
        <servlet-name>springDispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <!-- needed for ContextLoaderListener -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath: pathToYourSpringBeanConfig/channel-application-context.xml</param-value>
    </context-param>

    <!-- Bootstraps the root web application context before servlet initialization -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

此外，您还需要提供上下文xml应用程序的位置，在其中您需要告诉上下文，如下所示：

<mvc:annotation-driven></mvc:annotation-driven>
    <context:component-scan base-package="group.*"></context:component-scan>

PS :如果您想访问没有war名称的URL，您可能需要检查这个Deploy war on Tomcat without the war name in the URL