springmvc基础（基于xml配置）
开发环境：IDEA
spring版本：5.1.3.RELEASE
本部分内容官方文档链接：Web Servlet
一、搭建hello spring工程
1.1 项目搭建
1.新建maven web工程，并引入相应的依赖
<properties>
<spring-base-version>5.1.3.RELEASE</spring-base-version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring-base-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring-base-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring-base-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring-base-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring-base-version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>4.0.1</version>
<scope>provided</scope>
</dependency>
</dependencies>
2.配置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spring前端控制器-->
<servlet>
<servlet-name>springMvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springApplication.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springMvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
3.在resources下新建springApplication.xml文件，文件内容如下:
<?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">
<!-- 开启注解包扫描-->
<context:component-scan base-package="com.heibaiying.*"/>
<!--使用默认的Servlet来响应静态文件 详见 1.2 -->
<mvc:default-servlet-handler/>
<!-- 开启注解驱动 详见 1.2 -->
<mvc:annotation-driven/>
<!-- 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>
4.在src 下新建controller用于测试
package com.heibaiying.controller;
import com.heibaiying.exception.NoAuthException;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
/**
* @author : heibaiying
* @description : hello spring
*/
@Controller
@RequestMapping("mvc")
public class HelloController {
@RequestMapping("hello")
private String hello() {
return "hello";
}
}
5.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 Spring MVC!
</body>
</html>
6.启动tomcat服务，访问localhost:8080/mvc/hello
1.2 相关配置讲解
1.<mvc:default-servlet-handler/>
在web.xml配置中，我们将DispatcherServlet的拦截路径设置为“\”，则spring会捕获所有web请求，包括对静态资源的请求，为了正确处理对静态资源的请求，spring提供了两种解决方案：
-
配置<mvc:default-servlet-handler/> ： 配置<mvc:default-servlet-handler />后，会在Spring MVC上下文中定义一个org.springframework.web.servlet.resource.DefaultServletHttpRequestHandler，它会对进入DispatcherServlet的URL进行筛查，如果发现是静态资源的请求，就将该请求转由Web应用服务器默认的Servlet处理，如果不是静态资源的请求，才由DispatcherServlet继续处理。
-
配置<mvc:resources /> ：指定静态资源的位置和路径映射：
<mvc:resources location="/img/" mapping="/img/**"/> <mvc:resources location="/js/" mapping="/js/**"/> <mvc:resources location="/css/" mapping="/css/**"/>
2.<mvc:annotation-driven/>
<mvc:annotation-driven /> 会自动注册DefaultAnnotationHandlerMapping与AnnotationMethodHandlerAdapter 两个bean,用以支持@Controllers分发请求。并提供了数据绑定、参数转换、json转换等功能，所以必须加上这个配置。
二、配置自定义拦截器
1.创建自定义拦截器，实现接口HandlerInterceptor（这里我们创建两个拦截器，用于测试拦截器方法的执行顺序）
package com.heibaiying.interceptors;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @author : heibaiying
* @description : spring5 中 preHandle，postHandle，afterCompletion 在接口中被声明为默认方法
*/
public class MyFirstInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
System.out.println("进入第一个拦截器preHandle");
return true;
}
// 需要注意的是，如果对应的程序报错，不一定会进入这个方法 但一定会进入afterCompletion这个方法
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
System.out.println("进入第一个拦截器postHandle");
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
System.out.println("进入第一个拦截器afterCompletion");
}
}
package com.heibaiying.interceptors;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @author : heibaiying
* @description : spring5 中 preHandle，postHandle，afterCompletion 在接口中被声明为默认方法
*/
public class MySecondInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
System.out.println("进入第二个拦截器preHandle");
return true;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
System.out.println("进入第二个拦截器postHandle");
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
System.out.println("进入第二个拦截器afterCompletion");
}
}
2.在springApplication.xml中注册自定义拦截器
<!--配置拦截器-->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/mvc/**"/>
<mvc:exclude-mapping path="/mvc/login"/>
<bean class="com.heibaiying.interceptors.MyFirstInterceptor"/>
</mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/mvc/**"/>
<bean class="com.heibaiying.interceptors.MySecondInterceptor"/>
</mvc:interceptor>
</mvc:interceptors>
3.关于多个拦截器方法执行顺序的说明
拦截器的执行顺序是按声明的先后顺序执行的，先声明的拦截器中的preHandle方法会先执行，然而它的postHandle方法和afterCompletion方法却会后执行。
三、全局异常处理
1.定义自定义异常
package com.heibaiying.exception;
/**
* @author : heibaiying
* @description : 自定义无权限异常
*/
public class NoAuthException extends RuntimeException {
public NoAuthException() {
super();
}
public NoAuthException(String message) {
super(message);
}
public NoAuthException(String message, Throwable cause) {
super(message, cause);
}
public NoAuthException(Throwable cause) {
super(cause);
}
}
2.实现自定义异常处理器
package com.heibaiying.exception;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @author : heibaiying
* @description : 无权限异常处理机制
*/
public class NoAuthExceptionResolver implements HandlerExceptionResolver {
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
if (ex instanceof NoAuthException && !isAjax(request)) {
return new ModelAndView("NoAuthPage");
}
return new ModelAndView();
}
// 判断是否是Ajax请求
private boolean isAjax(HttpServletRequest request) {
return "XMLHttpRequest".equalsIgnoreCase(request.getHeader("X-Requested-With"));
}
}
3.在springApplication.xml注册自定义异常处理器
<!--配置全局异常处理器-->
<bean class="com.heibaiying.exception.NoAuthExceptionResolver"/>
4.定义测试controller，抛出自定义异常
@Controller
@RequestMapping("mvc")
public class HelloController {
@RequestMapping("hello")
private String hello() {
return "hello";
}
@RequestMapping("auth")
private void auth() {
throw new NoAuthException("没有对应的访问权限！");
}
}
注：调用这个controller时，同时也可以验证在拦截器部分提到的：如果对应的程序报错，拦截器不一定会进入postHandle这个方法 但一定会进入afterCompletion这个方法