【Spring MVC】之 DispatcherServlet【一】

不念不忘少年蓝@ 2023-06-29 02:56 15阅读 0赞

### 初始化一个零xml配置的springmvc项目(版本5.2.1.RELEASE) ###

[Spring MVC 官方文档][Spring MVC]

#### 1.添加pom文件 ####

<artifactId>good-mvc</artifactId>
        <packaging>war</packaging>
    
        <properties>
            <tomcat.version>7.0.86</tomcat.version>
        </properties>
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.1.0</version>
                <scope>provided</scope>
            </dependency>
        </dependencies>
        <build>
            <pluginManagement>
                <plugins>
                    <plugin>
                        <artifactId>maven-compiler-plugin</artifactId>
                        <version>3.7.0</version>
                        <configuration>
                            <source>1.8</source>
                            <target>1.8</target>
                        </configuration>
                    </plugin>
                    <plugin>
                        <groupId>org.apache.tomcat.maven</groupId>
                        <artifactId>tomcat7-maven-plugin</artifactId>
                        <version>2.2</version>
                        <configuration>
                            <path>/</path>
                            <port>8087</port>
                        </configuration>
                        <dependencies>
                            <dependency>
                                <groupId>org.apache.tomcat.embed</groupId>
                                <artifactId>tomcat-embed-core</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-util</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-coyote</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-api</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-jdbc</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-dbcp</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-servlet-api</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-jsp-api</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-jasper</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-jasper-el</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-el-api</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-catalina</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-tribes</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-catalina-ha</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-annotations-api</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat</groupId>
                                <artifactId>tomcat-juli</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat.embed</groupId>
                                <artifactId>tomcat-embed-logging-juli</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                            <dependency>
                                <groupId>org.apache.tomcat.embed</groupId>
                                <artifactId>tomcat-embed-logging-log4j</artifactId>
                                <version>${tomcat.version}</version>
                            </dependency>
                        </dependencies>
                    </plugin>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-war-plugin</artifactId>
                        <version>2.3</version>
                        <configuration>
                            <failOnMissingWebXml>false</failOnMissingWebXml>
                        </configuration>
                    </plugin>
                </plugins>
            </pluginManagement>
        </build>

这里面解释一下，关于`tomcat7-maven-plugin`属性里面添加那么多dependency的原因，如果不添加这些dependency，则在启动的时候会抛出`org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 19`错误， 网上搜了一大圈，最终采用这个方案，原文链接地址找不到了。

#### 2.添加AppConfig ####

@Configuration
    @ComponentScan(basePackages = { "com.good.mvc"})
    public class AppConfig { 
    }

#### 3.添加AppInitializer ####

/** * 等同于 * <web-app> * * <listener> * <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> * </listener> * * <context-param> * <param-name>contextConfigLocation</param-name> * <param-value>/WEB-INF/root-context.xml</param-value> * </context-param> * * <servlet> * <servlet-name>app1</servlet-name> * <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> * <init-param> * <param-name>contextConfigLocation</param-name> * <param-value>/WEB-INF/app1-context.xml</param-value> * </init-param> * <load-on-startup>1</load-on-startup> * </servlet> * * <servlet-mapping> * <servlet-name>app1</servlet-name> * <url-pattern>/app1/*</url-pattern> * </servlet-mapping> * * </web-app> * @author sunhan */
    public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { 
    
        @Override
        protected Class<?>[] getRootConfigClasses() { 
            return null;
        }
    
        @Override
        protected Class<?>[] getServletConfigClasses() { 
            return new Class[]{ AppConfig.class};
        }
    
        @Override
        protected String[] getServletMappings() { 
            return new String[]{ "/"};
        }
    }

#### 4.添加MyWebApplicationInitializer，可选 ####

/** * 代替web.xml中 * <web-app> * * <listener> * <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> * </listener> * * <context-param> * <param-name>contextConfigLocation</param-name> * <param-value>/WEB-INF/app-context.xml</param-value> * </context-param> * * <servlet> * <servlet-name>app</servlet-name> * <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> * <init-param> * <param-name>contextConfigLocation</param-name> * <param-value></param-value> * </init-param> * <load-on-startup>1</load-on-startup> * </servlet> * * <servlet-mapping> * <servlet-name>app</servlet-name> * <url-pattern>/app/*</url-pattern> * </servlet-mapping> * * </web-app> * * @author sunhan */
    public class MyWebApplicationInitializer implements WebApplicationInitializer { 
    
        @Override
        public void onStartup(ServletContext servletCxt) { 
    
            // Load Spring web application configuration
            AnnotationConfigWebApplicationContext ac = new AnnotationConfigWebApplicationContext();
            ac.register(AppConfig.class);
            ac.refresh();
    
            // Create and register the DispatcherServlet
            DispatcherServlet servlet = new DispatcherServlet(ac);
            ServletRegistration.Dynamic registration = servletCxt.addServlet("app", servlet);
            registration.setLoadOnStartup(1);
            registration.addMapping("/app/*");
        }
    }

最基本的功能，大功告成了，还有其他的功能，可自行看官方文档。在命令行里面输入mvn clean install tomcat7:run 通过mvn插件的形式进行启动

[Spring MVC]: https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html