Java框架-SpringMVC统一异常处理、ssm框架整合
1. SpringMVC中异常处理
1.1 各层处理异常原则即实现方法
1.1.1 各层处理异常原则
dao：不处理，抛异常；
service：不处理，抛异常；
controller/servlet：必须处理，否则错误信息将直接在浏览器显示给用户看。
1.1.2 异常处理实现方法
- 方法1：控制层的方法中写try…catch。异常处理信息一多，控制层方法就会十分冗余，而且每个控制器都有可能有异常，即每个控制器都要写；
- 方法2：使用异常过滤器，拦截所有请求。在过滤器中对异常进行处理；
- 方法3：使用框架自带的异常处理机制。
1.2 异常处理
- 使用异常处理器统一对dao、service、controller的异常进行处理
- SpringMVC提供了HandlerExceptionResolver异常处理器接口
1.3 SpringMVC异常处理实现
1.3.1 环境准备
1.3.1.1 创建项目、添加依赖
<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.azuregroupId>
<artifactId>day57projects_SpringMVC_ssmartifactId>
<version>1.0-SNAPSHOTversion>
<dependencies>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webmvcartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>servlet-apiartifactId>
<version>2.5version>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>jsp-apiartifactId>
<version>2.0version>
dependency>
<dependency>
<groupId>log4jgroupId>
<artifactId>log4jartifactId>
<version>1.2.17version>
dependency>
dependencies>
project>
1.3.1.2 springMVC.xml配置
<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">
<context:component-scan base-package="com.azure">context:component-scan>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/pages/">property>
<property name="suffix" value=".jsp">property>
bean>
<mvc:annotation-driven>mvc:annotation-driven>
<mvc:resources mapping="/pages/**" location="/pages/">mvc:resources>
<mvc:resources mapping="/js/**" location="/pages/">mvc:resources>
beans>
1.3.1.3 web.xml配置
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<servlet>
<servlet-name>dispatcherServletservlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
<init-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:springMVC.xmlparam-value>
init-param>
<load-on-startup>1load-on-startup>
servlet>
<servlet-mapping>
<servlet-name>dispatcherServletservlet-name>
<url-pattern>/url-pattern>
servlet-mapping>
web-app>
1.3.2 控制类模拟异常
@Controller
public class ExpController {
/**
* 模拟异常
*/
@RequestMapping("/save")
public String save(){
int i = 1/0;
return "success";
}
}
1.3.3 使用方法1手动捕获异常
1.3.3.1 error.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
error
出错啦~系统繁忙~
1.3.3.2 控制类调整
@Controller
public class ExpController {
/**
* 模拟异常
*/
@RequestMapping("/save")
public String save(ModelMap modelMap){
try {
int i = 1/0;
} catch (Exception e) {
e.printStackTrace();
//将异常信息发送给error.jsp页面，error页面获取并显示错误信息
modelMap.addAttribute("errorMsg","出错啦~系统繁忙~");
return "error";
}
return "success";
}
}
1.3.3.3 总结
- 每个请求方法都要写异常代码，都要手动捕获异常处理，效率低。
1.3.4 使用方法3自定义异常处理器
- 使用SpringMVC提供的异常处理接口（HandlerExceptionResolver）实现类
1.3.4.1 设置自定义异常处理器
public class CustomerExceptionResolver implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
//1.打印异常信息
e.printStackTrace();
//2.保存异常信息并跳转到错误页面
ModelAndView mv = new ModelAndView();
mv.addObject("errorMsg", "出错啦~系统繁忙~");
mv.setViewName("error");
return mv;
}
}
1.3.4.2 springMVC.xml配置异常处理器
- 除了在springMVC.xml配置，也可以在自定义异常处理器类上使用@Component注解创建对象
<bean class="com.azure._01exception.CustomerExceptionResolver">
1.3.4.3 测试控制类
@Controller
public class HERController {
/**
* 模拟异常
*/
@RequestMapping("/saved")
public String saved(ModelMap modelMap) {
int i = 1 / 0;
return "success";
}
}
2. SpringMVC中的拦截器
2.1 拦截器的作用
- SpringMVC的处理器拦截类似于 的处理器拦截类似于Servlet开发中的过滤器Filter，用于对处理器进行预处理和后处理。
- 拦截器链：多个拦截器按一定的顺序连接成链，访问被拦截方法或字段时，按定义的顺序调用拦截器
2.1.1 拦截器与过滤器的异同
相同点：
- 都可以对请求进行拦截：过滤器拦截所有请求、拦截器只拦截控制器请求；
- 请求处理前可以做一些前期操作，在请求处理完毕后，也可以做后续的操作。
区别：
- 过滤器是servlet规范中的一部分，任何java web工程都可以使用；而拦截器只能在SpringMVC框架的工程内使用。
- 过滤器可以通过在url-pattern属性中配置
/*实现拦截所有访问请求；而拦截器只会拦截访问控制器方法的请求，不会对网页资源（html、jsp等）进行拦截。 - 过滤器应用范围更广，拦截器只应用在SpringMVC项目。
2.2 自定义拦截器使用
2.2.1 编写控制器
@Controller
public class HIDemoController {
//构造函数
public HIDemo1Controller(){
System.out.println("1.实例UserController");
}
@RequestMapping("/interceptor")
public ModelAndView testInterceptor(){ //存入数据并跳转页面
System.out.println("4.执行控制器的testInterceptor方法");
ModelAndView mv = new ModelAndView();
mv.addObject("username", "JoJo");
mv.setViewName("success");
return mv;
}
}
2.2.2 编写拦截器类实现HandlerInterceptor接口
- 除了在springMVC.xml配置，也可以在自定义异常处理器类上使用@Component注解创建对象
public class HandlerInterceptor1 implements HandlerInterceptor {
//构造函数
public HandlerInterceptor1(){
System.out.println("2.实例拦截器1号");
}
/**
* 编写请求拦截方法，包含业务逻辑控制校验代码
* 返回值为true：放行，进入拦截器链的下一个拦截器，如果是最后一个，则执行控制器的方法
* 返回值为false：不放行，请求不被处理
*/
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("3.拦截器1号的preHandle方法已执行");
return true;
}
/**
* 编写响应拦截方法，在请求处理完返回响应前调用
*/
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("5.拦截器1号的postHandle方法已执行");
}
/**
* 编辑资源清理方法，在preHandle返回true就会被调用
*/
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("6.拦截器1号的afterCompletion方法已执行");
}
}
2.2.3 springMVC.xml配置拦截器
<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">
<context:component-scan base-package="com.azure">context:component-scan>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/pages/">property>
<property name="suffix" value=".jsp">property>
bean>
<mvc:annotation-driven>mvc:annotation-driven>
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**" />
<bean class="com.azure._02Interceptor.HandlerInterceptor1">bean>
mvc:interceptor>
mvc:interceptors>
beans>
2.3 多拦截器使用
2.3.1 新增一个拦截器2
@Component
public class HandlerInterceptor2 implements HandlerInterceptor {
//构造函数
public HandlerInterceptor2(){
System.out.println("实例拦截器2号");
}
/**
* 编写请求拦截方法，包含业务逻辑控制校验代码
* 返回值为true：放行，进入拦截器链的下一个拦截器，如果是最后一个，则执行控制器的方法
* 返回值为false：不放行，请求不被处理
*/
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("拦截器2号的preHandle方法已执行");
return true;
}
/**
* 编写响应拦截方法，在请求处理完返回响应前调用
*/
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("拦截器2号的postHandle方法已执行");
}
/**
* 编辑资源清理方法，在preHandle返回true就会被调用
*/
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("拦截器2号的afterCompletion方法已执行");
}
}
2.3.2 springMVC.xml配置拦截器2
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**" />
<bean class="com.azure._02Interceptor.HandlerInterceptor1">bean>
mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<ref bean="handlerInterceptor2">ref>
mvc:interceptor>
mvc:interceptors>
2.3.3 运行结果
2.3.3.1 服务器启动
2.3.3.2 请求访问
3. SSM整合（重点*3）
3.1 整合原则
-
xml和注解组合使用
-
配置方式的选择：
- Spring：自己编写的类使用注解，jar包的类用xml，事务用xml；
- SpringMVC：控制器配置用注解，使用xml有：扫描包、视图解析器开启、注解支持开启、静态资源不过滤等；
- mybatis：SqlMapConfig.xml整合到spring配置文件中，接口映射使用注解配置
-
Spring整合Mybatis关键点：把Mybatis的SqlSessionFactory对象的创建交给Spring管理。
3.2 整合步骤
- 构建单独Spring环境
- 构建单独SpringMVC环境
- Spring与SpringMVC整合
- 构建单独Mybatis环境
- Spring整合Mybatis
- ssm 整合，页面，测试
- 为确保整合成功，每步都会单独测试检查是否有误
3.3 构建Spring环境
3.3.1 创建项目，添加依赖
<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.azuregroupId>
<artifactId>day57projects_SSMartifactId>
<version>1.0-SNAPSHOTversion>
<packaging>warpackaging>
<dependencies>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>org.aspectjgroupId>
<artifactId>aspectjweaverartifactId>
<version>1.8.9version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-webmvcartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-txartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-jdbcartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>org.mybatisgroupId>
<artifactId>mybatis-springartifactId>
<version>1.3.1version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-testartifactId>
<version>5.0.2.RELEASEversion>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.12version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>5.1.30version>
dependency>
<dependency>
<groupId>com.alibabagroupId>
<artifactId>druidartifactId>
<version>1.1.10version>
dependency>
<dependency>
<groupId>org.mybatisgroupId>
<artifactId>mybatisartifactId>
<version>3.4.5version>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>servlet-apiartifactId>
<version>2.5version>
dependency>
<dependency>
<groupId>javax.servletgroupId>
<artifactId>jsp-apiartifactId>
<version>2.0version>
dependency>
<dependency>
<groupId>jstlgroupId>
<artifactId>jstlartifactId>
<version>1.2version>
dependency>
<dependency>
<groupId>log4jgroupId>
<artifactId>log4jartifactId>
<version>1.2.17version>
dependency>
dependencies>
project>
3.3.2 spring配置文件
- 创建applicationContext.xml文件
<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.xsd">
<context:component-scan base-package="com.azure.service">context:component-scan>
beans>
3.3.3 创建实体类
public class Account {
private int accountId;
private int uid;
private double money;
...
}
3.3.4 service层
3.3.4.1 service层接口
public interface IAccountService {
/*实现查询功能*/
List<Account> findAll();
}
3.3.4.2 service接口实现类
@Service
public class AccountServiceImpl implements IAccountService {
@Override
public List<Account> findAll() {
System.out.println("测试。。。调用service的findAll查询全部账户");
return null;
}
}
3.3.5 测试类
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml") //指定容器类
public class TestDemo01 {
//注入service
@Autowired
private IAccountService accountService;
@Test
public void find(){
accountService.findAll();
}
}
3.4 构建单独SpringMVC环境
3.4.1 配置web.xml
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<servlet>
<servlet-name>DispatcherServletservlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
<init-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:springMVC.xmlparam-value>
init-param>
<load-on-startup>1load-on-startup>
servlet>
<servlet-mapping>
<servlet-name>DispatcherServletservlet-name>
<url-pattern>/url-pattern>
servlet-mapping>
web-app>
3.4.2 配置springMVC.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.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:component-scan base-package="com.azure.controller"/>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/pages/">property>
<property name="suffix" value=".jsp">property>
bean>
<mvc:annotation-driven>mvc:annotation-driven>
beans>
3.4.3 控制类
@Controller
public class AccountController {
@RequestMapping("/findAll")
public ModelAndView findAll(HttpServletRequest request) {
ModelAndView mv = new ModelAndView();
mv.addObject("name", "JoJo");
mv.setViewName("success");
return mv;
}
}
3.4.4 测试页面
- 增加success.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
success
success~~
3.5 Spring整合SpringMVC
- 思路：
- 1、SpringMVC负责controller层，需要注入service
- 2、在web.xml中加载applicationContext.xml配置
3.5.1 控制器类注入service
@Controller
@RequestMapping("/account") //设置第一级目录，方便区分findAll方法
public class AccountController {
//注入service
@Autowired
private IAccountService accountService;
@RequestMapping("/findAll")
public ModelAndView findAll(HttpServletRequest request) {
List<Account> list = accountService.findAll();
ModelAndView mv = new ModelAndView();
mv.addObject("list", list);
mv.setViewName("success");
return mv;
}
}
3.5.2 在web.xml配置ServletContext的监听器加载applicationContext.xml
- 服务器启动的时候会创建ServletContext，通过监听ServletContext，在创建ServletContext时加载配置，就能实现服务器启动后加载配置。
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class>
listener>
<context-param>
<param-name>contextConfigLocationparam-name>
<param-value>classpath:applicationContext.xmlparam-value>
context-param>
3.6 配置单独mybatis环境
3.6.1 配置sqlMapConfig.xml
<configuration>
<properties resource="jdbc.properties"/>
<environments default="mysql">
<environment id="mysql">
<transactionManager type="JDBC">transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
dataSource>
environment>
environments>
<mappers>
<package name="com.azure.dao">package>
mappers>
configuration>
3.6.2 dao层
public interface IAccountDao {
/**
* 查询功能
*/
@Select("select * from account") //使用注解方式实现查询
List<Account> findAll();
}
3.6.3 测试类
public class TestDemo02 {
@Test
public void findAll() throws IOException {
InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(is);
SqlSession session = factory.openSession();
//创建Dao实现类
IAccountDao accountDao = session.getMapper(IAccountDao.class);
List<Account> list = accountDao.findAll();
System.out.println(list);
session.close();
is.close();
}
}
3.7 Spring整合mybatis
思路：
- 将SqlMapConfig.xml整合到applicationContext.xml中，包括
- 加载数据库配置文件
- 配置数据库连接池
- 增加Spring声明式事务；
- 将SqlSessionFactoryBean交由Spring创建，配置SqlSessionFactoryBean
- 开启dao接口扫描
- service注入dao
3.7.1 applicationContext.xml整合SqlMapConfig.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:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
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/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<context:component-scan base-package="com.azure.service">context:component-scan>
<context:property-placeholder location="classpath:jdbc.properties"/>
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
bean>
<bean class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.azure.dao"/>
bean>
<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
bean>
<tx:advice id="txadvice" transaction-manager="txManager">
<tx:attributes>
<tx:method name="find*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="*" propagation="REQUIRED" read-only="false"/>
tx:attributes>
tx:advice>
<aop:config>
<aop:pointcut id="pt" expression="execution(* com.azure.service.*.*(..))">aop:pointcut>
aop:config>
beans>
3.7.2 service注入dao
@Service
public class AccountServiceImpl implements IAccountService {
//注入Dao
@Autowired
private IAccountDao accountDao;
@Override
public List<Account> findAll() {
return accountDao.findAll();
}
}
3.7.3 测试
分两部分：
- 测试service在整合后是否有误；
- 从controller开始走完整的流程，看最终页面是否正常返回数据
3.7.3.1 service测试
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml") //指定容器类
public class TestDemo03 {
//注入service
@Autowired
private IAccountService accountService;
@Test
public void find(){
List<Account> accounts = accountService.findAll();
System.out.println(accounts);
}
}
3.7.3.2 启动服务器测试
- 配置返回的页面，将获取的结果打印
success.jsp:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
success
查询所有账户
success~~
序号
账号编号
用户编号
账户余额
<%--遍历结果获取每个元素并打印--%>
<%--varStatus相当于遍历的i--%>
${num.count}
${account.accountId}
${account.uid}
${account.money}