Java web项目创建笔记3 之《springmvc基础配置—xml配置文件》
1、springmvc配置应用上下文有两种方式:
1)第一种是配置一个Servlet WebApplicationContext和Root WebApplicationContext
Servlet WebApplicationContext是springmvc使用
Root WebApplicationContext是全局配置,比如:事务管理、数据源
2)第二种是配置Root WebApplicationContext对单个DispatcherServlet
2、配置web.xml
这里使用第一种配置方法
<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">
<display-name>Archetype Created Web Application</display-name>
<!--配置spring前端控制器 -->
<servlet>
<servlet-name>dispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- 配置初始化root WebApplicationContext -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- 字符编码过滤器 统一编码UTF-8 -->
<filter>
<filter-name>encodingFilter</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>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</filter-mapping>
</web-app>
3、web.xml解析过程
1)web项目启动,容器(tomcat)创建ServletContext————由tomcat代码实现
2)容器开始读取web.xml文件
3)读取<context-param></context-param>作为键值对存到ServletContext中
4)触发ServletContextEvent事件
spring的ContextLoaderListener监听器继承ContextLoader类,实现ServletContextListener接口
ServletContextListener接口监听ServletContextEvent事件
public class ContextLoaderListener extends ContextLoader implements ServletContextListener {
...
}
5)ContextLoaderListener执行初始化方法
创建root WebApplicationContext,并以键值对放入ServletContext中
6)web.xml的加载顺序是:context-param -> listener -> filter -> servlet ,而同个类型之间的实际程序启动的顺序是根据对应的mapping定义的顺序进行启动的
4、配置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"
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-4.1.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">
<!-- 基于注解的自动装配 -->
<context:annotation-config />
<!-- 只扫描Controller -->
<context:component-scan base-package="com.study.resources">
<context:include-filter type="annotation"
expression="org.springframework.stereotype.Controller" />
</context:component-scan>
<!-- 开启注解驱动 -->
<mvc:annotation-driven />
<!-- 使用默认的Servlet来响应静态文件 -->
<mvc:default-servlet-handler />
<!-- 配置视图解析器 -->
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver"
id="internalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/jsp/" />
<!-- 后缀 -->
<property name="suffix" value=".jsp" />
</bean>
</beans>
5、spring-mvc.xml说明
1)<context:annotation-config />
打开自动装配
2)<context:component-scan></context:component-scan>
打开自动扫描,此处只扫描Controller注解
3)<mvc:annotation-driven />
开启mvc的注解驱动,自动注册默认处理请求,参数和返回值的类
4)<mvc:default-servlet-handler />
静态页面,如html、css、js、images可以访问
6、配置applicationContext.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"
xmlns:context="http://www.springframework.org/schema/context"
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-4.1.xsd">
<!-- 注解bean扫描,spring扫描排除Controller -->
<context:annotation-config />
<context:component-scan base-package="com.study">
<context:exclude-filter type="annotation"
expression="org.springframework.stereotype.Controller" />
</context:component-scan>
<!-- 下面可以导入其他spring配置文件 -->
</beans>
7、在src下建立测试controller
package com.study.resources;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("mvc")
public class TestController {
@RequestMapping("hello")
private String hello() {
return "hello";
}
}
8、在WEB-INF下新建jsp文件夹,新建hello.jsp文件
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
Hello!
</body>
</html>
9、启动tomcat,访问测试页面:http://127.0.0.1:8080/webapp/mvc/hello
10、其他注意事项
<servlet-mapping>
<servlet-name>dispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
这段url-pattern如果写成 /* 会拦截jsp页面,导致浏览器不能正确解析jsp页面,直接显示源代码
参考资料:
1)总结下ServletContext和ApplicationContext
https://blog.csdn.net/bai_bug/article/details/80218202
2)web.xml 中的listener、 filter、servlet 加载顺序及其详解
https://www.cnblogs.com/Kevin-mao/p/5664056.html