导入servlet、springmvc、Jackson的依赖,编译插件、tomcat
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>springmvc</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<name>springmvc Maven Webapp</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<!--必要的servlet依赖 -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<!--springmvc的核心依赖 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.0.5.RELEASE</version>
</dependency>
<!--jackson依赖,用来方便数据转java格式 -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.5</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.5</version>
</dependency>
</dependencies>
<build>
<finalName>springmvc</finalName>
<pluginManagement>
<plugins>
<!--jdk的编译插件,用1.8的版本 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<!--tomcat插件 -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
先在web.xml上注册中央调度器,这是最关键的
<!--配置DispqtcherServlet -->
<servlet>
<!--自定义名称,就当个id吧, -->
<servlet-name>springmvc</servlet-name>
<!--全限定类名,固定 -->
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<!--大于零代表启动时创建servlet-->
<load-on-startup>1</load-on-startup>
<init-param>
<param-name>contextConfigLocation</param-name>
<!--springmvc配置文件的路径 -->
<param-value>classpath:springmvc.xml</param-value>
</init-param>
</servlet>
<!--配置地址映射,将请求映射到对应的Servlet -->
<servlet-mapping>
<servlet-name>springmvc</servlet-name><!--上面的中央调度器的名称 -->
<url-pattern>*.do</url-pattern>
<!--一般情况不要写/*,这样的话,所有的请求将全部由Spring的DispatcherServlet来处理,显然是不合适的,jsp文件还是应该由Tomcat配置的JSP Servlet来处理 -->
<!--大概感觉有点像过滤器的作用,代表这个形式的访问地址才经过中央调度器 -->
</servlet-mapping>
接下来就在resources目录里写springmvc的配置文件
当然这里的配置文件的路径就是你在web.xml里指定的
<?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">
<!-- 声明组件扫描器 -->
<context:component-scan base-package="top.changtong1819.controller"/>
<!--mvc的注解驱动 -->
<mvc:annotation-driven/>
<!--注册视图解析器,用来帮我们自动在文件路径上添加前后缀 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp"/>
</bean>
</beans>
那么组件扫描器的作用是什么呢
组件扫描(component scanning):
Spring能够从指定的classpath下自动扫描,侦测和实例化具有特定注解的bean。
Spring提供了一下几个注解来标注需要被扫描到的bean:
@Component
:标注一个普通的Spring Bean类
@Controller
:标注一个控制器组件类
@Service
:标注一个业务逻辑组件类
@Repository
:标注一个Dao组件类
有了组件扫描器之后,相当于不需要再写bean标签去实例化某个类了,扫描到注解会自动实例化
@Controller//表示当前类是处理类
public class MyController {
@RequestMapping(value = "/some.do")//表示当前方法为处理器方法,value属性指定URl地址
public ModelAndView doSome(){
ModelAndView mv = new ModelAndView();
mv.addObject("name","changtong");
mv.addObject("age","21");
mv.setViewName("show");
return mv;
}
}
要返回自定义对象,需要在方法上使用@ResponseBody
注解,这里要在springmvc的配置文件上先注册注解驱动,前面已经注册了
@Controller//表示当前类是处理类
public class MyController {
@RequestMapping(value = "/ajax.do")
@ResponseBody
public Student doAjax(HttpServletRequest req, HttpServletResponse resp,int age,String name) throws IOException {
Student stu = new Student();
stu.setAge(age);
stu.setName(name);
/* ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(stu);
resp.getWriter().write(json);*/ //不需要再写这些了
return stu;//直接返回对象就是json格式
}
}
使用过滤器,在web.xml里注册
<!--注册过滤器,解决请求乱码的问题 -->
<filter>
<filter-name>characterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<!-- 声明字符集 -->
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
<!-- 强制request请求使用encoding格式-->
<init-param>
<param-name>forceRequestEncoding</param-name>
<param-value>true</param-value>
</init-param>
<!-- 强制response请求使用encoding格式-->
<init-param>
<param-name>forceResponseEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<!--过滤器所过滤的地址 -->
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
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