SpringMVC 作为 Spring 框架的核心模块之一,是构建 Java Web 应用的主流技术。本文将从拦截器、文件上传、全局异常处理器三个核心功能入手,最终完成 SSM(Spring+SpringMVC+MyBatis)的整合实战,帮助开发者掌握 SpringMVC 进阶用法与企业级项目的整合思路。
一、拦截器(interceptor)
1.1 拦截器概述
Spring MVC 中的拦截器(Interceptor)类似于 Servlet 中的过滤器(Filter),主要用于拦截用户请求并做针对性处理(如权限验证、登录状态校验)。拦截器依赖 Web 框架,基于 Java 反射机制实现,是 AOP(面向切面编程)的典型应用。
1.2 自定义基础拦截器
1.2.1 编写拦截器类
实现HandlerInterceptor接口,重写核心方法:
java
package com.hg.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 CustomHandlerInterceptor implements HandlerInterceptor {
/**
* 控制器方法调用前执行,返回true继续执行,false中断
*/
@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object object) throws Exception {
System.out.println("HandlerInterceptor preHandle ....");
return true;
}
/**
* 控制器方法调用后、视图解析前执行,可修改视图/模型
*/
@Override
public void postHandle(HttpServletRequest request,HttpServletResponse response,
Object object, ModelAndView modelAndView) throws Exception {
System.out.println("HandlerInterceptor postHandle ....");
}
/**
* 整个请求完成(视图渲染后)执行,用于资源清理、日志记录
*/
@Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response,Object object, Exception e) throws Exception {
System.out.println("HandlerInterceptor afterCompletion ....");
}
}
1.2.2 配置拦截器
在 SpringMVC 配置文件中注册拦截器:
XML
<!--配置拦截器 -->
<mvc:interceptors>
<mvc:interceptor>
<!-- 匹配所有URL -->
<mvc:mapping path="/**"></mvc:mapping>
<bean class="com.hg.interceptor.CustomHandlerInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
1.2.3 测试拦截器
编写 Controller 和页面超链接:
java
@Controller
@RequestMapping("/account")
public class AccountController {
@RequestMapping("/findAccount12")
public String findAccount12(Model model) {
model.addAttribute("msg", "欢迎你 springmvc");
System.out.println("controller的方法执行了......");
return "success";
}
}
1.3 实战:登录状态拦截器
1.3.1 编写登录拦截逻辑
java
package com.hg.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object object) throws Exception {
// 从Session获取用户信息
String user = (String) request.getSession().getAttribute("user_session");
if (user != null) {// 已登录,放行
System.out.println("获得用户信息:"+user);
return true;
} else {// 未登录,跳转登录页
response.sendRedirect(request.getContextPath() +"/login.jsp");
return false;
}
}
}
1.3.2 配置登录拦截器
XML
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"></mvc:mapping>
<bean class="com.hg.interceptor.LoginInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
1.3.3 测试登录拦截
java
@RequestMapping("/findAccount13")
public String findAccount13(Model model) {
model.addAttribute("msg", "欢迎你 springmvc");
System.out.println("controller的方法执行了......");
return "success";
}
html
<%
// 模拟登录(实际场景从登录接口存入Session)
session.setAttribute("user_session","User{name:张二狗,age:18}");
%>
<a href="/account/findAccount13">登录拦截器</a>
二、文件上传
2.1 添加依赖
XML
<!--文件上传依赖-->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.1</version>
</dependency>
2.2 配置文件上传解析器
注意:id 必须为 multipartResolver
XML
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 最大上传大小:5MB -->
<property name="maxUploadSize" value="5242880" />
<!-- 编码格式 -->
<property name="defaultEncoding" value="UTF-8" />
</bean>
2.3 静态资源映射(可选)
XML
<!-- 映射静态资源:/head/** 对应 /head/ 目录 -->
<mvc:resources mapping="/head/**" location="/head/"/>
2.4 编写文件上传接口
java
@Controller
@RequestMapping("/account")
public class AccountController {
@RequestMapping(path="/upload")
public String upload(HttpServletRequest request,
MultipartFile head,Model model) throws IOException {
System.out.println("springmvc方式的文件上传");
// 获取上传目录(服务器端)
String path = request.getSession().getServletContext().getRealPath("/uploads");
// 创建目录(不存在则创建)
File file = new File(path);
if(!file.exists()){
file.mkdirs();
}
// 获取文件名并上传
String filename = head.getOriginalFilename();
head.transferTo(new File(path,filename));
model.addAttribute("msg", "文件上传成功");
return "success";
}
}
2.5 编写上传页面
html
<form action="/account/upload" method="post" enctype="multipart/form-data">
文件: <input type="file" name="head"></input>
<input type="submit" value="提交">
</form>
三、全局异常处理器
3.1 异常处理思路
系统中 DAO、Service、Controller 层的异常统一向上抛出,最终由 SpringMVC 前端控制器交给自定义异常处理器处理,避免错误信息直接暴露给前端。
3.2 编写全局异常处理器
java
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 CustomExceptionResolver implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex) {
ModelAndView modelAndView = new ModelAndView();
// 封装异常信息
modelAndView.addObject("message", ex.toString());
// 跳转错误页面
modelAndView.setViewName("error");
return modelAndView;
}
}
3.3 测试异常处理
java
@RequestMapping("/findAccount14")
public String findAccount14(Model model) {
model.addAttribute("msg", "欢迎你 springmvc");
// 模拟算术异常
int i = 10/0;
return "success";
}
html
<a href="/account/findAccount14">异常处理器</a>
四、SSM 整合实战
4.1 环境准备
4.1.1 建库建表
sql
CREATE TABLE `account` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(20) DEFAULT NULL,
`money` double DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
4.1.2 依赖配置(pom.xml)
XML
<?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.hg</groupId>
<artifactId>ssm</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<properties>
<spring.version>5.2.8.RELEASE</spring.version>
<slf4j.version>1.6.6</slf4j.version>
<log4j.version>1.2.12</log4j.version>
<mysql.version>8.0.29</mysql.version>
<mybatis.version>3.4.5</mybatis.version>
<druid.version>1.1.0</druid.version>
</properties>
<dependencies>
<!-- Spring核心 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- MyBatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.3.0</version>
</dependency>
<!-- 数据库 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>${druid.version}</version>
</dependency>
<!-- Web -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- 日志 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Tomcat插件 -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
<configuration>
<port>8080</port>
<path>/</path>
</configuration>
</plugin>
</plugins>
<!-- 资源扫描 -->
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
<resource>
<directory>src/main/resources</directory>
</resource>
</resources>
</build>
</project>
4.2 核心配置文件
4.2.1 日志配置(log4j.properties)
XML
log4j.rootLogger=DEBUG,A1
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss}【{%5p}】 - %c%m%n
4.2.2 数据库配置(db.properties)
XML
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=UTF-8
jdbc.username=root
jdbc.password=1111
4.2.3 DAO 层配置(applicationContext-dao.xml)
XML
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 加载数据库配置 -->
<context:property-placeholder location="classpath:db.properties" />
<!-- 德鲁伊连接池 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
destroy-method="close">
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="driverClassName" value="${jdbc.driver}" />
<property name="maxActive" value="10" />
<property name="minIdle" value="5" />
</bean>
<!-- SqlSessionFactory配置 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<!-- 实体类别名扫描 -->
<property name="typeAliasesPackage" value="com.hg.pojo"></property>
</bean>
<!-- Mapper扫描 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.hg.mapper"></property>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
</bean>
</beans>
4.2.4 事务配置(applicationContext-tx.xml)
XML
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/aop
https://www.springframework.org/schema/aop/spring-aop.xsd">
<!-- 事务管理器 -->
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!-- 事务通知 -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="insert*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="select*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="get*" propagation="SUPPORTS" read-only="true"/>
</tx:attributes>
</tx:advice>
<!-- 事务切面 -->
<aop:config>
<aop:advisor advice-ref="txAdvice"
pointcut="execution(* com.hg.service.*.*(..))" />
</aop:config>
</beans>
4.2.5 Service 层配置(applicationContext-service.xml)
XML
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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">
<!-- 扫描Service包 -->
<context:component-scan base-package="com.hg.service"></context:component-scan>
</beans>
4.2.6 SpringMVC 配置(springmvc.xml)
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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 扫描Controller -->
<context:component-scan base-package="com.hg.controller"></context:component-scan>
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/pages/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
</beans>
4.2.7 Web 配置(web.xml)
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_4_0.xsd"
version="4.0">
<!-- Spring容器监听器 -->
<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>
<!-- 解决POST乱码 -->
<filter>
<filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- SpringMVC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:springmvc.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>
4.3 业务代码编写
4.3.1 实体类(Account.java)
java
package com.hg.pojo;
public class Account {
private Integer id;
private String name;
private Double money;
// Getter & Setter
public Integer getId() { return id; }
public void setId(Integer id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
public Double getMoney() { return money; }
public void setMoney(Double money) { this.money = money; }
@Override
public String toString() {
return "Account{" +
"id=" + id +
", name='" + name + '\'' +
", money=" + money +
'}';
}
}
4.3.2 Mapper 层
- 接口(AccountMapper.java):
java
package com.hg.mapper;
import com.hg.pojo.Account;
import java.util.List;
public interface AccountMapper {
List<Account> selectAccount();
}
XML 映射(AccountMapper.xml):
java
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hg.mapper.AccountMapper">
<select id="selectAccount" resultType="Account">
select * from account
</select>
</mapper>
4.3.3 Service 层
java
package com.hg.service;
import com.hg.mapper.AccountMapper;
import com.hg.pojo.Account;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class AccountServiceImpl implements AccountService {
@Autowired
private AccountMapper accountMapper;
@Override
public List<Account> selectAccount() {
return accountMapper.selectAccount();
}
}
4.3.4 Controller 层
java
package com.hg.controller;
import com.hg.pojo.Account;
import com.hg.service.AccountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import java.util.List;
@Controller
@RequestMapping("/account")
public class AccountController {
@Autowired
private AccountService accountService;
@RequestMapping("/selectAccount")
public String selectAccount(Model model){
List<Account> list = accountService.selectAccount();
model.addAttribute("list",list);
return "select_account";
}
}
4.3.5 前端页面(select_account.jsp)
XML
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>账户列表</title>
</head>
<body>
<h2>查询所有账户</h2>
<table width="30%" border="1" cellspacing="0" cellpadding="0">
<tr>
<th>id</th>
<th>name</th>
<th>money</th>
</tr>
<c:forEach var="account" items="${list}">
<tr>
<td>${account.id}</td>
<td>${account.name}</td>
<td>${account.money}</td>
</tr>
</c:forEach>
</table>
</body>
</html>
4.4 测试 SSM 整合
启动 Tomcat,访问http://localhost:8080/account/selectAccount,即可查询数据库中的账户列表。
总结
本文从 SpringMVC 核心功能(拦截器、文件上传、异常处理)入手,逐步完成了 SSM 整合的全流程实战。掌握这些知识点后,开发者可基于此框架快速构建企业级 Java Web 应用,后续可进一步学习分页、多表关联、Redis 缓存等进阶技术,丰富项目功能。