Java框架_SpringMVC_day06_异常处理

目录

七、SpringMVC 的异常处理

7.1 异常处理思路

7.2 SpringMVC 的异常处理

7.2.1 数据准备

7.2.2 编写自定义异常类

7.2.3 编写异常处理器

7.2.4 配置异常处理器

7.2.5 Controller

7.2.6 error.jsp

---

七、SpringMVC 的异常处理

7.1 异常处理思路

       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、测试通过手段减少运行时异常的发生。 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

7.2 SpringMVC 的异常处理

7.2.1 数据准备

导入坐标

<!-- 版本锁定 -->
<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>
  <spring.version>5.0.2.RELEASE</spring.version>
</properties>

<dependencies>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>${spring.version}</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>${spring.version}</version>
  </dependency>

  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>${spring.version}</version>
  </dependency>

  <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>
</dependencies>

web.xml

<!-- SpringMVC的核心控制器 -->
<servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- 配置Servlet的初始化参数，读取springmvc的配置文件，创建spring容器 -->
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springmvc.xml</param-value>
    </init-param>
    <!-- 配置servlet启动时加载对象 -->
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

<!--配置解决中文乱码过滤器-->
<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.xml

<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:mvc="http://www.springframework.org/schema/mvc"
           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/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">
        <context:component-scan base-package="com.cpz"/>

        <!--视图解析器-->
        <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/pages/"></property>
            <property name="suffix" value=".jsp"></property>
        </bean>

        <mvc:annotation-driven></mvc:annotation-driven>

        <!-- 设置静态资源不过滤 -->
        <mvc:resources location="/js/" mapping="/js/**"/>  <!-- javascript -->

</beans>

index.jsp

<a href="user/testException">异常处理</a>

Controller

@Controller
@RequestMapping(value = "/user")
public class UserController {

    @RequestMapping(value = "/testException")
    public String testException(){
        System.out.println("执行了 testException 方法 ！！！ ");
        int a = 10 / 0;
        return "success";
    }
}

测试结果

7.2.2 编写自定义异常类

package com.cpz.exception;

// 自定义异常类
public class MySysException extends Exception {
    // 异常提示信息
    private String message;

    public MySysException(String message){
        this.message = message;
    }

    @Override
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

7.2.3 编写异常处理器

package com.cpz.exception;

import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// 异常处理器
public class MySysExceptionResolver implements HandlerExceptionResolver {
    // 跳转到具体的错误页面的方法
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {

        MySysException mySysException = null;
        // 如果这个异常是我们自定义的异常类型，就强转成自定义的类型
        if (ex instanceof MySysException){
            mySysException = (MySysException) ex;
        }else {
            // 如果不是自定义类型，利用有参构造，存入一个错误信息
            mySysException = new MySysException("请联系管理员！！！！");
        }

        ModelAndView mv = new ModelAndView();
        // 存入错误信息
        mv.addObject("message",mySysException.getMessage());
        // 确定跳转的页面
        mv.setViewName("error");

        return mv;
    }
}

7.2.4 配置异常处理器

<!-- 配置异常处理器 -->
<bean id="mySysExceptionResolver" class="com.cpz.exception.MySysExceptionResolver"></bean>

7.2.5 Controller

    @RequestMapping(value = "/testException")
    public String testException() throws MySysException {
        System.out.println("执行了 testException 方法 ！！！ ");
        try{
            int a = 10 / 0;
        }catch (Exception e){
            throw new MySysException("页面出现问题啦，请稍后重试");
        }
        return "success";
    }

7.2.6 error.jsp

<h1>访问失败！！！</h1>
${message}<br>