1 SpringMVC中拦截器

1.1 作用

作用:类似于javaweb中的Filter,用来对请求进行拦截,可以将多个Controller中执行的共同代码放入拦截器中执行,减少Controller类中代码的冗余.

1.2 特点

• 拦截器器只能拦截Controller的请求,不能拦截jsp。

• 拦截器可中断用户的请求轨迹。

• 请求先经过拦截器,之后之后还会经过拦截器。

1.3开发拦截器

如图所示：
1.引入依赖的代码如下：

<?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>com.txw</groupId><artifactId>springmvc_03</artifactId><version>1.0-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><!--相关的依赖--><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aop</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-expression</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aspects</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-tx</artifactId><version>4.3.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>4.3.2.RELEASE</version></dependency><!--springmvc核心依赖--><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.3.2.RELEASE</version></dependency><!--servlet-api--><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><!--文件上传的依赖--><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3</version></dependency><!--json依赖--><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.9.0</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.11</version><scope>test</scope></dependency></dependencies><build><finalName>springmvc_03</finalName></build>
</project>

如图所示：
2.编写MyInterceptor的代码如下：

package com.txw.interceptor;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/*** 自定义拦截器* @author Adair* E-mail: 1578533828@qq.com*/
@SuppressWarnings("all")  // 注解警告信息
public class MyInterceptor implements HandlerInterceptor {/*** 前置处理 请求到达拦截器后会优先执行指定内容* 返回值:代表是否执行 false:不执行 中断请求   true:放行 执行后续Controller* @param httpServletRequest* @param httpServletResponse* @param o* @return* @throws Exception*/@Overridepublic boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {System.out.println("-------------1-------------------");return true;}/*** 请求后的处理 在Controller返回后执行指定内容 类似:AOP中的后置通知* postHandler执行完成之后开始给客户端进行响应* @param httpServletRequest* @param httpServletResponse* @param o* @param modelAndView* @throws Exception*/@Overridepublic void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {System.out.println("-------------3-------------------");}/*** 响应处理  当Controller响应完客户端之后会执行指定内容 Controller发生异常之后也会执行指定内容。类似:finlly{}* @param httpServletRequest* @param httpServletResponse* @param o* @param e* @throws Exception*/@Overridepublic void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {System.out.println("-------------4-------------------");}
}

如图所示：
3.编写springmvc.xml的代码如下：

<?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.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"><!--开启注解扫描--><context:component-scan base-package="com.txw"/><!--配置处理器映射器 和处理器适配器--><mvc:annotation-driven/><!--注册视图解析器 注入 前缀 后缀--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"><property name="prefix" value="/"/><property name="suffix" value=".jsp"/></bean><!--放行静态资源--><mvc:default-servlet-handler/><bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"><!--控制文件上传大小单位字节 默认没有大小限制 这里是2--><property name="maxUploadSize" value="2097152"/></bean><!--配置拦截器--><bean id="myInterceptor" class="com.txw.interceptor.MyInterceptor"></bean><!--指定拦截器要拦截哪些Controller--><mvc:interceptors><!--单个拦截器的配置--><mvc:interceptor><!--要拦截的Controller--><mvc:mapping path="/test/*"/><!--不要拦截的Controller--><mvc:exclude-mapping path="/test/test1"/><!--指定当前使用哪个拦截器--><ref bean="myInterceptor"/></mvc:interceptor></mvc:interceptors>
</beans>

如图所示：
/*``: 代表拦截所有请求路径。
4.编写TestController的代码如下：

package com.txw.controller;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
/*** @author Adair* E-mail: 1578533828@qq.com*/
@Controller
@RequestMapping("/test")
public class TestController {@RequestMapping("test1")public String test1(){System.out.println("-------------2-------------------");return "index";}@RequestMapping("test2")public String test2(){System.out.println("-------------2-------------------");return "index";}
}

如图所示：
6.通过浏览器访问：http://localhost:8080/test/test1，如图所示：
控制台打印结果，如图所示：
6.通过浏览器访问：http://localhost:8080/test/test2，如图所示：
控制台打印结果，如图所示：
7.编写error.jsp的代码如下：

%@ page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" isELIgnored="false" %>
<html>
<head><title>登录页面</title><meta charset="UTF-8">
</head>
<body><h1>输入用户名</h1><h1>输入密码</h1>
</body>
</html>

如图所示：
8.编写User的代码如下：

package com.txw.entity;import java.util.Date;
/*** @author Adair* E-mail: 1578533828@qq.com*/
public class User {private String name;private Integer age;private Double salary;private Boolean sex;private Date birthday;public User() {}public User(String name, Integer age, Double salary, Boolean sex, Date birthday) {this.name = name;this.age = age;this.salary = salary;this.sex = sex;this.birthday = birthday;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public Double getSalary() {return salary;}public void setSalary(Double salary) {this.salary = salary;}public Boolean getSex() {return sex;}public void setSex(Boolean sex) {this.sex = sex;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}@Overridepublic String toString() {return "User{" +"name='" + name + '\'' +", age=" + age +", salary=" + salary +", sex=" + sex +", birthday=" + birthday +'}';}
}

如图所示：
9.编写MyInterceptor的代码如下：

package com.txw.interceptor;import com.txw.entity.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/*** 自定义拦截器* @author Adair* E-mail: 1578533828@qq.com*/
@SuppressWarnings("all")  // 注解警告信息
public class MyInterceptor implements HandlerInterceptor {/*** 前置处理 请求到达拦截器后会优先执行指定内容* 返回值:代表是否执行 false:不执行 中断请求   true:放行 执行后续Controller* @param request 请求响应对象* @param response 请求响应对象* @param o 要访问的目标Controller服务方法* @return* @throws Exception*/@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {System.out.println("-------------1-------------------");System.out.println(o);// 模拟登录验证 session获取用户对象 进行判断/*  User user = (User) request.getSession().getAttribute("user");if (user != null){return true;}// 跳转登录页面 error.jspresponse.sendRedirect(request.getContextPath() + "/error.jsp");*/// request.getRequestDispatcher("/error.jsp").forward(request,response);return true;}/*** 请求后的处理 在Controller返回后执行指定内容 类似:AOP中的后置通知* postHandler执行完成之后开始给客户端进行响应* @param request* @param response* @param o* @param modelAndView* @throws Exception*/@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object o, ModelAndView modelAndView) throws Exception {System.out.println("-------------3-------------------");System.out.println("name: " + modelAndView.getModel().get("name"));System.out.println("即将跳转的位置为：" + modelAndView.getViewName());}/*** 响应处理  当Controller响应完客户端之后会执行指定内容 Controller发生异常之后也会执行指定内容。类似:finlly{}* @param httpServletRequest* @param httpServletResponse* @param o* @param e* @throws Exception 封装的是Controller中出现的异常对象*/@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object o, Exception e) throws Exception {System.out.println("-------------4-------------------");System.out.println(e.getMessage());}
}

如图所示：
10.编写TestController的代码如下：

package com.txw.controller;import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
/*** @author Adair* E-mail: 1578533828@qq.com*/
@Controller
@RequestMapping("/test")
public class TestController {@RequestMapping("test1")public String test1(Model model){System.out.println("-------------2-------------------");int i = 1 / 0;model.addAttribute("name","Adair");// SpringMVC自动将request作用域和返回值封装为ModelAndViewreturn "index";}@RequestMapping("test2")public String test2(){System.out.println("-------------2-------------------");return "index";}
}

如图所示：
拦截器运行顺序，如图所示：

2 SpringMVC全局异常处理

如图所示：

2.1 作用

​ `当控制器中某个方法在运行过程中突然发生运行时异常时,为了增加用户体验对于用户不能出现500错误代码,应该给用户良好展示错误界面,全局异常处理就能更好解决这个问题.。

2.2 全局异常处理开发

1.编写CustomerHanlderExceptionResolver的代码如下：

package com.txw.exception;import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.net.URLEncoder;
/*** 全局异常处理类* @author Adair* E-mail: 1578533828@qq.com*/
@SuppressWarnings("all")   // 注解警告信息
public class CustomerHanlderExceptionResolver implements HandlerExceptionResolver {/*** 方法功能：一旦程序出现异常的处理方案* @param request 请求响应对象* @param response 请求响应对象* @param o 发生异常的Controller访问方法对象* @param e 发生的异常对象* @return*/@Overridepublic ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object o, Exception e) {ModelAndView modelAndView = new ModelAndView();// 发生异常跳转到专门准备的异常处理页面 /error.jsp  等价于 return ""try {modelAndView.setViewName("redirect:/error.jsp?message=" + URLEncoder.encode(e.getMessage(),"UTF-8"));} catch (Exception exception) {exception.printStackTrace();}return modelAndView;}
}

如图所示：
2.编写springmvc.xml的代码如下：

<!--配置全局异常处理类-->
<bean class="com.txw.exception.CustomerHanlderExceptionResolver"/>

如图所示：
3.编写TestController的代码如下：

package com.txw.controller;import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
/*** @author Adair* E-mail: 1578533828@qq.com*/
@Controller
@RequestMapping("test")
public class TestController {@RequestMapping("test1")public String test1(Model model){System.out.println("-------------2-------------------");int i = 1 / 0;model.addAttribute("name","Adair");// SpringMVC自动将request作用域和返回值封装为ModelAndViewreturn "index";}@RequestMapping("test2")public String test2(){System.out.println("-------------2-------------------");return "index";}
}

如图所示：
4.编写error.jsp的代码如下：

<%@ page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8" isELIgnored="false" %>
<html>
<head><title>登录页面</title><meta charset="UTF-8">
</head>
<body>异常信息:${param.massage}<h1>当前网络环境较差，请刷新重试！<a href="">刷新</a> </h1>
</body>
</html>

如图所示：
5.通过浏览器访问：http://localhost:8080/test/test1，跳转到如图所示：

3 父子容器问题

如图所示：