搭建SpringMVC项目

搭建SpringMVC

1. 使用idea快速创建webapp项目

2. 在pom.xml中添加依赖

<!-- spring-mvc 依赖-->
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc</artifactId>
  <version>5.3.2</version>
</dependency>

<!-- 非必填, 为演示过滤器, 如在idea中启动报错 将默认provided改为compile-->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>4.0.1</version>
  <scope>compile</scope>
</dependency>

3. 创建 java 和 resources 目录

4. 创建controller

@RestController
public class HelloController {

    @GetMapping("/hello")
    public Object hello() {
        return "hello world";
    }
}

5. 编辑WEB-INF目录下的web.xml文件

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

  <display-name>Archetype Created Web Application</display-name>

  <!--  第一步: 配置 Spring MVC Dispatcher Servlet-->
  <servlet>
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

    <!-- init-param是Servlet范围内的参数，只能在Sercvlet的init()的方法中取得-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springContext.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <!--  第二步: 设置 URL mapping for Spring MVC Dispatcher-->
  <servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!-- 非必填: context-param是应用范围内的参数, 存放在ServletContext中, 通过ServletContext对象获取参数-->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:springContext.xml</param-value>
  </context-param>

  <!-- 非必填: 监听器-->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <!-- 非必填: 过滤器-->
  <filter>
    <description>演示过滤器的注入</description>
    <filter-name>TestFilter</filter-name>
    <filter-class>cn.idea360.mvc.filter.TestFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>TestFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

</web-app>

6. 创建 springContext.xml

根据 web.xml 中的配置，我们在 resources 目录下创建 springContext.xml , 当然也可以根据
<param-value>/WEB-INF/springContext.xml</param-value> 在WEB-INF下创建

<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">

    <!-- 修改名称  修改名称去适配 base-package -->
    <context:component-scan base-package="cn.idea360.mvc"/>
    <mvc:annotation-driven/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp" />
    </bean>

    <!-- bean在这里注入-->

</beans>

7. 配置 tomcat 并启动, 如果没有 tomcat 可以在插件中添加

8. 测试api请求

curl http://localhost:8080/hello

过滤器示例

public class TestFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
    }
}

有参构造bean注入

定义bean1

public class UserService {

    private String name;

    public UserService(String name) {
        this.name = name;
    }

    public void show() {
        System.out.println("name=" + name);
    }
}

定义bean2

public class KafkaClient {

    private String servers;
    private String topic;

    /**
     * @param configs Map类型构造参数
     */
    public KafkaClient(Map<String, Object> configs) {
        this.servers = String.valueOf(configs.get("bootstrap.servers"));
    }

    /**
     * @param properties Properties类型构造参数
     */
    public KafkaClient(Properties properties) {
        this.servers = properties.getProperty("bootstrap.servers");
    }

    /**
     * @param kafkaConfig 对象参数
     */
    public KafkaClient(KafkaConfig kafkaConfig) {
        this.servers = kafkaConfig.getServers();
    }

    public void setTopic(String topic) {
        this.topic = topic;
    }

    public void show() {
        System.out.println("servers=" + servers + "; topic=" + topic);
    }
}

对象参数

public class KafkaConfig {

    private String servers;

    public String getServers() {
        return servers;
    }

    public void setServers(String servers) {
        this.servers = servers;
    }
}

在springContext.xml中注入bean

<!-- bean在这里注入-->

<!-- 根据参数名注入, 有参构造方法 -->
<bean id="userService" class="cn.idea360.mvc.service.UserService">
    <!-- 有参构造方式1-->
    <constructor-arg name="name" value="admin"/>
</bean>

<!-- Map构造参数-->
<bean id="kafkaProducerProperties1" class="java.util.HashMap">
    <constructor-arg>
        <map>
            <entry key="bootstrap.servers" value="localhost:9092"/>
        </map>
    </constructor-arg>
</bean>

<!-- Properties构造参数-->
<bean id="kafkaProducerProperties2" class="java.util.HashMap">
    <constructor-arg>
        <props>
            <prop key="bootstrap.servers">127.0.0.1:9092</prop>
        </props>
    </constructor-arg>
</bean>

<!-- 对象构造参数-->
<bean id="kafkaConfig" class="cn.idea360.mvc.service.KafkaConfig">
    <property name="servers" value="127.0.0.1"/>
</bean>

<!-- 有参注入-->
<bean id="kafkaClient" class="cn.idea360.mvc.service.KafkaClient">
    <!-- 有参构造方式2-->
    <constructor-arg ref="kafkaConfig"/>
    <!--设置对应 topic-->
    <property name="topic" value="topic-test"/>
</bean>

测试

public class BeanTest {

    public static void main(String[] args) {
        // 当类上标注 @Component 等注解时可以基于使用 new AnnotationConfigApplicationContext("cn.idea360.mvc") 上下文获取bean
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("springContext.xml");

        // 有参构造1 name=admin
        UserService userService = context.getBean("userService", UserService.class);
        userService.show();

        // 有参构造2 servers=127.0.0.1:9092; topic=topic-test
        KafkaClient kafkaClient = context.getBean(KafkaClient.class);
        kafkaClient.show();
    }
}

最后

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参考

• https://medium.com/@yuntianhe/create-a-web-project-with-maven-spring-mvc-b859503f74d7
• https://mkyong.com/maven/how-to-create-a-web-application-project-with-maven/
• https://github.com/yinjihuan/monkey-api-encrypt/tree/master/monkey-api-encrypt-springmvc-example
• https://gitbook.cn/books/5d6b2b9d84721b61db4432b5/index.html
• https://medium.com/panchalprogrammingacademy/create-a-spring-mvc-project-with-maven-and-intellij-idea-community-edition-1d31b3efe078