基础使用 - 墨码山河

摘要：本文学习了SpringMVC的基础使用，包括环境搭建和快速入门。

环境

Windows 10 企业版 LTSC 21H2
Java 1.8
Tomcat 8.5.50
Maven 3.6.3
Spring 5.2.25.RELEASE

1 环境准备

1.1 依赖管理

创建Maven项目，并创建pom.xml文件：

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>

  <groupId>com.example</groupId>
  <artifactId>demo-springmvc</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <!-- Spring MVC -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.2.25.RELEASE</version>
    </dependency>
    <!-- Servlet -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
    <!-- JSP -->
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.1</version>
      <scope>provided</scope>
    </dependency>
    <!-- JSTL -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <!-- Maven Compiler Plugin -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <!-- Maven WAR Plugin -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>3.2.3</version>
        <configuration>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

1.2 项目结构

标准的项目结构如下：

code

demo-springmvc/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/
│   │   │       └── controller/
│   │   │           └── DemoController.java
│   │   ├── resources/
│   │   │   └── spring-mvc.xml
│   │   └── webapp/
│   │       ├── WEB-INF/
│   │       │   ├── views/
│   │       │   │   └── demo.jsp
│   │       │   └── web.xml
│   │       └── index.jsp
└── pom.xml

2 快速入门

2.1 创建配置文件

在WEB-INF目录下创建web.xml配置文件，配置前端控制器：

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app 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"
         version="3.1">
  <!-- 配置DispatcherServlet前端控制器 -->
  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- 指定配置文件的位置 -->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring-mvc.xml</param-value>
    </init-param>
    <!-- 在应用启动时立即加载 -->
    <load-on-startup>1</load-on-startup>
  </servlet>

  <!-- 配置DispatcherServlet映射URL -->
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!-- 解决POST请求中文乱码问题 -->
  <filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

在resources目录下创建spring-mvc.xml配置文件：

spring-mvc.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
  <!-- 配置控制器 -->
  <bean id="demoController" class="com.example.controller.DemoController"/>

  <!-- 配置控制器映射 -->
  <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
      <props>
        <prop key="/demo">demoController</prop>
      </props>
    </property>
  </bean>

  <!-- 配置视图解析器 -->
  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/views/"/>
    <property name="suffix" value=".jsp"/>
    <property name="contentType" value="text/html;charset=UTF-8"/>
  </bean>
</beans>

2.2 创建控制器

创建前端控制器，实现控制器接口：

java

public class DemoController implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) {
        // 创建模型视图对象
        ModelAndView mav = new ModelAndView();
        // 设置视图名称
        mav.setViewName("demo");
        // 添加模型数据
        mav.addObject("message", "欢迎");
        // 返回模型视图对象
        return mav;
    }
}

2.3 创建页面

创建首页，在webapp目录下创建index.jsp页面：

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
  <title>首页</title>
</head>
<body>
  <div>
    <a href="${pageContext.request.contextPath}/demo">请求接口</a>
  </div>
</body>
</html>

创建视图，在views目录下创建demo.jsp页面：

demo.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta charset="UTF-8">
  <title>信息</title>
</head>
<body>
  <div>
    <p><strong>查看消息：</strong>${message}</p>
  </div>
  <div>
    <a href="${pageContext.request.contextPath}/">返回首页</a>
  </div>
</body>
</html>

2.4 运行测试

使用Maven编译打包项目：

cmd

1	mvn clean package

将生成的WAR文件部署到Tomcat服务器。

启动Tomcat并访问首页：
http://localhost:8080/demo-springmvc