SpringMVC文件上传、异常处理、拦截器
SpringMVC文件上传、异常处理、拦截器
基本配置准备：maven项目模块
application.xml
<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-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
<context:component-scan base-package="com.etime">context:component-scan>
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping">bean>
<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">bean>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/">property>
<property name="suffix" value=".jsp">property>
bean>
<mvc:annotation-driven/>
<mvc:default-servlet-handler>mvc:default-servlet-handler>
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">bean>
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/interceptor/test02"/>
<bean class="com.etime.interceptor.MyInterceptor">bean>
mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/interceptor/test02"/>
<bean class="com.etime.interceptor.SecondInterceptor">bean>
mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/loginController/login"/>
<bean class="com.etime.interceptor.LoginInterceptor">bean>
mvc:interceptor>
mvc:interceptors>
beans>
web.xml
<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_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>dispatcherServletservlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
<init-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:application.xmlparam-value>
init-param>
servlet>
<servlet-mapping>
<servlet-name>dispatcherServletservlet-name>
<url-pattern>/url-pattern>
servlet-mapping>
<filter>
<filter-name>characterEncodingfilter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
<init-param>
<param-name>encodingparam-name>
<param-value>utf-8param-value>
init-param>
filter>
<filter-mapping>
<filter-name>characterEncodingfilter-name>
<url-pattern>/*url-pattern>
filter-mapping>
<filter>
<filter-name>hiddenMethodFilterfilter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilterfilter-class>
filter>
<filter-mapping>
<filter-name>hiddenMethodFilterfilter-name>
<url-pattern>/*url-pattern>
filter-mapping>
web-app>
pom.xml
<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>4.0.0modelVersion>
<groupId>com.etimegroupId>
<artifactId>day08artifactId>
<version>1.0-SNAPSHOTversion>
<properties>
<spring.version>5.2.5.RELEASEspring.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webmvcartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>javax.servlet-apiartifactId>
<version>3.1.0version>
<scope>providedscope>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>jsp-apiartifactId>
<version>2.0version>
<scope>providedscope>
dependency>
<dependency>
<groupId>com.fasterxml.jackson.coregroupId>
<artifactId>jackson-databindartifactId>
<version>2.9.9version>
dependency>
<dependency>
<groupId>commons-fileuploadgroupId>
<artifactId>commons-fileuploadartifactId>
<version>1.3.1version>
dependency>
dependencies>
project>
SpringMVC的文件上传
文件上传需要做的准备
form表单的enctype取值必须是：multipart/form-data(默认值是：application/x-www-form-urlencoded)enctype:是表单请求正文的类型
method属性取值必须是Post
提供一个文件选择域< input type="file"/>
文件上传原理
当form表单的enctype取值不是默认值后，request.getParameter()将失效。enctype="application/x-www-form-urlencoded"时，form表单的正文内容是：key=value&key=value&key=value;
当form表单的enctype 取值Mutilpart/form-data时，请正文内容就变成：每一部都是MIME类型描述的正文：
enctype="application/x-www-form-urlencoded"
key=value&key=value&key=value;
request.getParameter();
底层：form表单是一个大的请求体：
每一个组件都是一个小的请求体：
enctype=Mutilpart/form-data
request.getParameter();失效
每一组都是一个小的请求体：
username = lisi
age = 21
file = xxx.jpg
SpringMVC的文件上传
构建maven工程添加相关依赖
<dependency>
<groupId>commons-fileuploadgroupId>
<artifactId>commons-fileuploadartifactId>
<version>1.3.1version>
dependency>
commons-fileupload 依赖了commons-io Apache提供的
编写jsp页面
index.jsp
//多文件上传
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
<%--测试--%>
控制器
UploadController.java
package com.etime.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.IOException;
@Controller
@RequestMapping("upload")
public class UploadController {
@PostMapping("test")
public String test(MultipartFile[] photo){
String path = "D:\\test";
File file = new File(path);
if (!file.exists()){
file.mkdirs();
}
// //获取文件名
// String fileName = photo.getOriginalFilename();
// //上传
// try {
// photo.transferTo(new File(file, fileName));
// } catch (IOException e) {
// e.printStackTrace();
// }
for (MultipartFile f:photo) {
String fileName = f.getOriginalFilename();
try {
f.transferTo(new File(file,fileName));
} catch (IOException e) {
e.printStackTrace();
}
}
return "main";
}
}
配置文件解析器
注意： id必须固定~
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">bean>
运行结果：
SpringMVC的异常处理
项目开发中异常处理的方式
系统中异常包括两类：预期异常和运行时异常 RuntimeException，前者通过捕获异常从而获取异常信息，后者主要通过规范代码开发、测试等手段减少运行时异常的发生。
异常处理的设计思路
系统的dao、service、controller 出现都通过 throws Exception 向上抛出，最后由 springmvc 前端控制器交由异常处理器进行异常处理。
异常处理的步骤
编写异常类和错误页面
package com.etime.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("exception")
public class ExceptionController {
@GetMapping("test")
public String test(){
System.out.println("进啦");
int num = 7/0;
return "main";
}
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
臭宝~前路不通！！！
</body>
</html>
自定义异常处理器
package com.etime.util;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@Component
public class MyException implements HandlerExceptionResolver {
//只是掩盖了异常，该处理的异常还是得处理
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("error");
return modelAndView;
}
}
运行结果：当该异常出现时，捕获到异常然后接连的通过跳转到提示页面，将该页面出现的页面掩饰，但是异常依然存在，仍然要处理
SpringMVC的拦截器
拦截器的介绍和作用
SpringMVC的处理器拦截器类似于 Servlet 开发中的过滤器Filter，用于处理器进行预处理和后处理。用户可以自己定义一些拦截器来实现特定的功能。还要向大家提到一个词为Interceptor Chain。拦截器就是将拦截器按一定的顺序联结成一条链。在访问被拦截的方法或字段时，拦截器链中的拦截器就会按其之前定义的顺序被调用。
拦截器与过滤器的区别
过滤器是servlet规范中的一部分，任何java web 工程可以使用。拦截器是SpringMVC框架自己的，只有使用了SpringMVC框架的工程才能用。
过滤器在web.xml中的url-pattern 标签中配置了/*之后，可以对所有要访问的资源拦截。html js css image
拦截器它是只会拦截访问的控制器方法，如果访问的是 jsp 是不会进行拦截的。它也是AOP思想的具体应用。
我们要想自定义拦截器，要求必须实现：HandlerInterceptor接口
过滤器：/* : js css html
拦截器： /** :只是拦截控制器方法。
自定义拦截器
jsp:
package com.etime.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("interceptor")
public class InterceptorController {
@GetMapping("test01")
public String test01(){
System.out.println("test01真的进来了");
return "main";
}
@GetMapping("test02")
public String test02(){
System.out.println("test02真的进来了");
return "main";
}
}
编写一个普通类实现HandlerInterceptor接口
package com.etime.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyInterceptor implements HandlerInterceptor {
//Controller方法运行前运行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("Controller方法运行前");
//返回值为false拦截器Controller方法不执行
//返回值为true拦截器Controller方法执行
return false;
}
//Controller方法返回值时
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("Controller方法返回值时");
//return;
}
//Controller方法运行后
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("Controller方法运行后");
//return;
}
}
配置拦截器
application.xml
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/interceptor/test02"/>
<bean class="com.etime.interceptor.MyInterceptor">bean>
mvc:interceptor>
mvc:interceptors>
拦截器的注意事项
拦截器的放行
拦截器中的放行指的是：如果下一个拦截器就执行下一个，如果该拦截器处于拦截器链的最后一个，则执行控制器中的方法。
public boolean preHandle(HttpServletRequest request , HttpServletResponse response,Object handler)方法返回true表示继续执行控制层执行器方法，返回false表示方法结束，不会执行控制层执行器方法。
多个拦截器的执行顺序
拦截器1；
package com.etime.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyInterceptor implements HandlerInterceptor {
//Controller方法运行前运行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("Controller方法运行前");
//返回值为false拦截器Controller方法不执行
//返回值为true拦截器Controller方法执行
return false;
}
//Controller方法返回值时
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("Controller方法返回值时");
//return;
}
//Controller方法运行后
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("Controller方法运行后");
//return;
}
}
拦截器2：
package com.etime.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SecondInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("第二个拦截器，Controller方法执行前");
return true;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("第二个拦截器，Controller方法返回数据");
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("第二个拦截器，Controller方法执行后");
}
}
配置：
application.xml
<mvc:interceptor>
<!-- 拦截器路径-->
<mvc:mapping path="/**"/>
<!-- 放行路径-->
<mvc:exclude-mapping path="/interceptor/test01"/>
<!-- 指定前配置的拦截器-->
<bean class="com.etime.interceptor.SecondInterceptor"></bean>
</mvc:interceptor>
运行结果：
拦截器综合案例
实现思路分析：
1、定义登录页面，并定义请求映射。
2、判断用户名密码是否正确
3、如果正确 向 session 中写入用户信息
4、返回登录成功。
5、拦截用户请求，判断用户是否登录
6、如果用户已经登录。放行
7、如果用户未登录，跳转到登录页面
示例代码：
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="loginController/login" method="post" >
账号：<input type="text" name="username" >
密码：<input type="password" name="password">
<input type="submit" value="登录">
</form>
</body>
</html>
控制器：
package com.etime.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping("/loginController")
public class LoginController {
@PostMapping("login")
public ModelAndView login(String username, String password, ModelMap modelMap){
boolean res=true;
ModelAndView modelAndView = new ModelAndView();
if (res){
modelMap.addAttribute("username",username);
modelAndView.setViewName("success");
}
return modelAndView;
}
}
拦截器：
package com.etime.interceptor;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@Controller
@RequestMapping("/loginInterceptor")
public class LoginInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//登录过滤，未登录的情况，某些功能不能使用
HttpSession session = request.getSession();
if (session.getAttribute("username")==null){
//未登录
System.out.println("未登录");
response.sendRedirect("../login.jsp");
return false;
}else {
System.out.println("已登录");
return true;
}
}
}
application.xml
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/loginController/login"/>
<bean class="com.etime.interceptor.LoginInterceptor"></bean>
</mvc:interceptor>
运行结果：
