18 SpringMVC 文件上传和异常处理

1.文件上传的必要前提

(1)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
(2)method 属性取值必须是 Post
(3)提供一个文件选择域<input type=”file” />

2.文件上传环境搭建

(1)项目结构

18 SpringMVC 文件上传和异常处理-LMLPHP

(2)部分重要代码

<1>web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <!--配置前端控制器，让前端控制器去加载resources包下的springmvc.xml配置文件-->
  <servlet>
    <servlet-name>dispatcherServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--全局的初始化参数-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!--配置解决中文乱码的过滤器-->
  <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>

</web-app>

<2>spirngmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<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">

    <!-- 开启注解扫描 -->
    <context:component-scan base-package="lucky"/>

    <!-- 视图解析器对象 -->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--配置控制器方法中return返回的字符串对应的同名文件所在目录-->
        <property name="prefix" value="/WEB-INF/pages/"/>
        <!--配置文件的后缀名-->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!-- 开启SpringMVC框架注解的支持 -->
    <mvc:annotation-driven/>


</beans>

<3>index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>文件上传</h3>
    <form action="/day19_fileupload/user/fileUploadTest01" method="post" enctype="multipart/form-data">
        选择文件：<input type="file" name="upload"><br>
        <input type="submit" value="上传">
    </form>
</body>
</html>

3.传统方式上传文件

package lucky.controller;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.util.List;
import java.util.UUID;

@Controller
@RequestMapping(path = "/user")
public class UserController {
    //传统方式上传文件
    @RequestMapping(path = "/fileUploadTest01")
    public String fileUploadTest01(HttpServletRequest request, HttpServletResponse response) throws Exception{
        System.out.println("文件上传");
        // 使用fileupload组件完成文件上传
        // 上传的位置
        String path = request.getSession().getServletContext().getRealPath("/uploads/");
        System.out.println(path);  //查看文件上传的路径
        // 判断，该路径是否存在
        File file = new File(path);
        if(!file.exists()){
            // 创建该文件夹
            file.mkdirs();
        }

        // 解析request对象，获取上传文件项
        DiskFileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        // 解析request
        List<FileItem> items = upload.parseRequest(request);
        // 遍历
        for(FileItem item:items){
            // 进行判断，当前item对象是否是上传文件项
            if(item.isFormField()){
                // 说明普通表单向
            }else{
                // 说明上传文件项
                // 获取上传文件的名称
                String filename = item.getName();
                // 把文件的名称设置唯一值，uuid
                String uuid = UUID.randomUUID().toString().replace("-", "");
                filename = uuid+"_"+filename;
                // 完成文件上传
                item.write(new File(path,filename));
                // 删除临时文件
                item.delete();
            }
        }
        return "success";
    }
}

4.Springmvc方式文件上传

原理分析图：

18 SpringMVC 文件上传和异常处理-LMLPHP

package lucky.controller;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.util.List;
import java.util.UUID;

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

    /**
     * springmvc方式上传文件
     * 注意：请求参数MultipartFile upload 的名称upload必须与index.jsp中input标签的属性名一致，否则会造成空指针异常
     * @return
     */
    @RequestMapping(path = "/fileUploadTest02")
    public String fileUploadTest02(HttpServletRequest request, MultipartFile upload) throws Exception{
        System.out.println("springmvc文件上传");
        // 使用fileupload组件完成文件上传
        // 上传的位置
        String path = request.getSession().getServletContext().getRealPath("/uploads/");
        System.out.println(path);  //查看文件上传的路径
        // 判断，该路径是否存在
        File file = new File(path);
        if(!file.exists()){
            // 创建该文件夹
            file.mkdirs();
        }

        // 说明上传文件项
        // 获取上传文件的名称
        String filename = upload.getOriginalFilename();
        // 把文件的名称设置唯一值，uuid
        String uuid = UUID.randomUUID().toString().replace("-", "");
        filename = uuid+"_"+filename;
        // 完成文件上传
        upload.transferTo(new File(path,filename));
        return "success";
    }
}

5.Springmvc异常处理

原理分析图：

18 SpringMVC 文件上传和异常处理-LMLPHP

(1)项目结构

18 SpringMVC 文件上传和异常处理-LMLPHP

(2)部分重要代码

<1>控制器类：UserController.java

package lucky.controller;

import lucky.exception.CustomException;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping(path = "/user")
public class UserController {
    @RequestMapping(path = "/testException")
    public String testException() throws CustomException {
        System.out.println("testException执行了");
        try {
            //模拟异常
            int a=10/0;
        } catch (Exception e) {
            //抛出自定义异常
            throw new CustomException("被除数有问题");
        }
        return "success";
    }
}

<2>自定义异常类

package lucky.exception;

/**
 * 自定义异常类
 */
public class CustomException extends Exception{
    //存储提示信息
    private String message;

    public String getMessage() {
        return message;
    }

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

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

<3>异常处理器：CustomExceptionResolver.java

package lucky.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 CustomExceptionResolver implements HandlerExceptionResolver {

    /**
     *处理异常的业务逻辑
     */
    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
        //获取异常对象
        CustomException customException=null;
        if(e instanceof CustomException){
            customException= (CustomException) e;
        }else {
            customException=new CustomException("系统正在维护。。。");
        }
        //创建ModelAndView
        ModelAndView mv=new ModelAndView();
        mv.addObject("errormsg",e.getMessage());
        mv.setViewName("error");
        return mv;
    }
}

<4>springmvc.xml文件中配置异常处理器

<?xml version="1.0" encoding="UTF-8"?>
<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">

    <!-- 开启注解扫描 -->
    <context:component-scan base-package="lucky"/>

    <!-- 视图解析器对象 -->
    <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--配置控制器方法中return返回的字符串对应的同名文件所在目录-->
        <property name="prefix" value="/WEB-INF/pages/"/>
        <!--配置文件的后缀名-->
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--配置异常处理器-->
    <bean id="customExceptionResolver" class="lucky.exception.CustomExceptionResolver"/>

    <!-- 开启SpringMVC框架注解的支持 -->
    <mvc:annotation-driven/>



</beans>

<6>相关jsp页面

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>异常处理</h3>
    <a href="/day19_exception/user/testException">异常处理</a>
</body>
</html>

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h3>error.jsp</h3>
    ${errormsg}
</body>
</html>

(3)执行效果图

18 SpringMVC 文件上传和异常处理-LMLPHP

lblog_yg19sz9i

18 SpringMVC 文件上传和异常处理