SpringMVC 上传下载异常处理

冷不防 2022-08-20 15:25 185阅读 0赞

SpringMVC 上传下载 异常处理

上一章节对[SpringMVC的表单验证][SpringMVC]进行了详细的介绍，本章节介绍SpringMVC文件的上传和下载（重点），国际化以及异常处理问题。这也是SpringMVC系列教程中的最后一节，文章底部会提供该系列的源码地址。

首先看效果图（文件上传，下载和异常处理）

![20171009150443572][]

pom.xml，文件上传和下载是需要两个jar包： commons-fileupload.jar 和 commons-io.jar

<?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.springmvc</groupId>
      <artifactId>springmvc</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <packaging>war</packaging>
      
      
      <build>
    	<plugins>
    		<plugin>
    			<artifactId>maven-compiler-plugin</artifactId>
    			<configuration>
    				<source>1.7</source>
    				<target>1.7</target>
    				<encoding>UTF-8</encoding>
    			</configuration>
    		</plugin>
    	</plugins>
      </build>
      
      <properties>  
        <spring.version>4.1.3.RELEASE</spring.version>  
      </properties> 
      <dependencies>
          
        <dependency>  
            <groupId>org.springframework</groupId>  
            <artifactId>spring-webmvc</artifactId>  
            <version>${spring.version}</version>  
        </dependency>  
      
        <dependency>  
            <groupId>org.springframework</groupId>  
            <artifactId>spring-context</artifactId>  
            <version>${spring.version}</version>  
        </dependency>  
      
        <dependency>  
            <groupId>org.springframework</groupId>  
            <artifactId>spring-aop</artifactId>  
            <version>${spring.version}</version>  
        </dependency>  
      
        <dependency>  
            <groupId>org.springframework</groupId>  
            <artifactId>spring-core</artifactId>  
            <version>${spring.version}</version>  
        </dependency> 
         
        <dependency>  
            <groupId>org.springframework</groupId>  
            <artifactId>spring-web</artifactId>  
            <version>${spring.version}</version>  
        </dependency>  
      
        
    	<dependency>
    	    <groupId>javax.servlet</groupId>
    	    <artifactId>javax.servlet-api</artifactId>
    	    <version>4.0.0</version>
    	    <scope>provided</scope>
    	</dependency>
    	<dependency>
    	    <groupId>javax.servlet</groupId>
    	    <artifactId>jstl</artifactId>
    	    <version>1.2</version>
    	</dependency>
    	<dependency>
    	    <groupId>taglibs</groupId>
    	    <artifactId>standard</artifactId>
    	    <version>1.1.2</version>
    	</dependency>
    	
    	<dependency>
    	    <groupId>javax.servlet.jsp</groupId>
    	    <artifactId>jsp-api</artifactId>
    	    <version>2.2</version>
    	    <scope>provided</scope>
    	</dependency>
        
    	<dependency>
    	    <groupId>org.hibernate</groupId>
    	    <artifactId>hibernate-validator</artifactId>
    	    <version>5.4.1.Final</version>
    	</dependency>
    	<dependency>
    	    <groupId>javax.validation</groupId>
    	    <artifactId>validation-api</artifactId>
    	    <version>1.1.0.Final</version>
    	</dependency>
        
        
    	<dependency>
    	    <groupId>commons-fileupload</groupId>
    	    <artifactId>commons-fileupload</artifactId>
    	    <version>1.3.1</version>
    	</dependency>
    	<dependency>
    	    <groupId>commons-io</groupId>
    	    <artifactId>commons-io</artifactId>
    	    <version>2.4</version>
    	</dependency>
    	
    		
      </dependencies> 
    </project>

SpringMVC配置文件

<?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/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
    		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
    
    	
    	<context:component-scan base-package="com.itdragon.springmvc" />
    
    	
    	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    		<property name="prefix" value="/WEB-INF/views/"></property>
    		<property name="suffix" value=".jsp"></property>
    	</bean>
    	
    	
    	<mvc:annotation-driven />
    
    	
    	<bean class="org.springframework.web.servlet.view.BeanNameViewResolver">
    		<property name="order" value="100"></property>
    	</bean>
    	
    	
    	<mvc:view-controller path="/index" view-name="index"/>
    	
    	<mvc:default-servlet-handler/>
    	
    	
    	<bean id="messageSource"
    		class="org.springframework.context.support.ResourceBundleMessageSource">
    		<property name="basename" value="i18n"></property>
    	</bean>
    	
    	
    	<bean id="localeResolver" 
    		class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean>
    		
    	
    	<mvc:interceptors>
    		<bean id="localeChangeInterceptor"
    			class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor"></bean>
    	</mvc:interceptors>
    	
    	
    	<bean id="multipartResolver"
    		class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    		<property name="defaultEncoding" value="UTF-8"></property>
    		<property name="maxUploadSize" value="2048000"></property>
    	</bean>
    	
    	
    	<bean id="simpleMappingExceptionResolver"
    		class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    		
    		<property name="exceptionAttribute" value="exception"></property>
    		<property name="exceptionMappings">
    			<props>
    				
    				<prop key="java.lang.ArrayIndexOutOfBoundsException">exception</prop>
    			</props>
    		</property>
    	</bean>
    </beans>

FileUploadController.java 文件上传，下载和国际化知识点

**国际化步骤**

第一步，在SpringMVC配置文件中配置 SessionLocaleResolver（bean的id必须是localeResolver） 和 LocaleChangeInterceptor（bean放在mvc:interceptors 拦截器中）两个bean。

第二步，视图页面引入 fmt 标签，并用 <fmt:message key="xxx" /> 设置值。

第三步，语言切换的链接，其格式：<a href="链接?locale=en\_US" class="btn" >English</a>。

第四步，创建链接的目标方法，其参数为Locale 类型参数。

第五步，准备语言文件，i18n\_en\_US.properties 和 i18n\_zh\_CN.properties，配置xxx的对应语言。

**文件上传和下载**

第一步，在SpringMVC配置文件中配置 CommonsMultipartResolver，并设置默认编码格式和最大尺寸

第二步，视图页面创建一个form表单，并设置 enctype="multipart/form-data"

第三步，目标方法接收参数的类型为 MultipartFile ，然后是文件流的操作。

第四步，看代码吧！

import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.util.Locale;
    import java.util.Map;
    import javax.servlet.ServletContext;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.support.ResourceBundleMessageSource;
    import org.springframework.http.HttpHeaders;
    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.multipart.MultipartFile;
    
    @Controller
    public class FileUploadController {
    
    	@Autowired
    	private ResourceBundleMessageSource messageSource;
    	
    	/**
    	 * 国际化
    	 * 第一步，在SpringMVC配置文件中，配置 SessionLocaleResolver 和 LocaleChangeInterceptor
    	 * 第二步，准备语言文件，i18n_en_US.properties 和 i18n_zh_CN.properties
    	 * 第三步，目标方法中，参数加入Locale对象。
    	 */
    	@RequestMapping("/fileUpload")
    	public String fileUpload(Locale locale) {
    //		String val = messageSource.getMessage("file", null, locale);
    //		System.out.println(val);
    		return "fileUpload";
    	}
    	
    	// MultipartFile 上传文件必用的变量类型
    	@RequestMapping("/testFileUpload")
    	public String testFileUpload(@RequestParam("desc") String desc, @RequestParam("file") MultipartFile file,
    			Map<String, Object> map, HttpServletRequest request) {
    		InputStream in = null;
    		OutputStream out = null;
    		String fileName = file.getOriginalFilename(); // 获取文件名
    		try {
    			String realPath = request.getServletContext().getRealPath("uploads/");
    			in = file.getInputStream();
                byte[] buffer = new byte[1024];
                String filePath = realPath + "/" + fileName; // 文件上传路径
                out = new FileOutputStream(filePath);  
                int len = 0;  
                while ((len = in.read(buffer)) != -1) {  
                    out.write(buffer, 0, len);
                }  
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				if (null != out) {
    					out.close();
    				}
    				if (null != in) {
    					in.close();
    				}
    			} catch (IOException e) {
    				e.printStackTrace();
    			}  
    		}
    		map.put("fileName", fileName);
    		return "fileUpload";
    	}
    	
    	// 不适合大文件的下载，适用于简单的下载场景。
    	@RequestMapping("/downLoadFile")
    	public ResponseEntity<byte[]> downLoadFile(@RequestParam("fileName") String fileName, HttpSession session) {
    		byte [] body = null;
    		ServletContext servletContext = session.getServletContext();
    		InputStream in = null;
    		ResponseEntity<byte[]> response = null;
    		try {
    			in = servletContext.getResourceAsStream("/uploads/"+fileName);
    			body = new byte[in.available()];
    			in.read(body);
    			HttpHeaders headers = new HttpHeaders();
    			headers.add("Content-Disposition", "attachment;filename="+fileName);
    			HttpStatus statusCode = HttpStatus.OK;
    			response = new ResponseEntity<byte[]>(body, headers, statusCode);
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				if (null != in) {
    					in.close();
    				}
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    		return response;
    	}
    	
    }

fileUpload.jsp 文件上传下载前端页面

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
    <%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
        
    <!DOCTYPE>
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>SpringMVC 快速入门</title>
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    </head>
    <body>
    	
    	<div class="container">
    	   <div class="row">
    	      <div class="col-sm-6">
    			<div class="panel panel-info" style="margin-top:10px;">
    			    <div class="panel-heading">
    			        <h3 class="panel-title"><fmt:message key="file.upload" /></h3>
    			    </div>
    			    <div class="panel-body">
    			    	
    			    	<form action="${pageContext.request.contextPath }/testFileUpload" method="POST"  enctype="multipart/form-data">
    			    			<div class="form-group">
    								<label class="col-sm-2 control-label"><fmt:message key="file" /></label>
    								<div class="col-sm-10">
    									<input type="file" name="file" class="form-control" />
    								</div>
    							</div>
    			    			<div class="form-group">
    								<label class="col-sm-2 control-label"><fmt:message key="desc" /></label>
    								<div class="col-sm-10">
    									<input type="text" name="desc" class="form-control" />
    								</div>
    							</div>
    							<input type="submit" value="Submit" class="btn btn-success" />
    			    	</form>
    					<a href="fileUpload?locale=zh_CN" class="btn" >中文</a>
    					<a href="fileUpload?locale=en_US" class="btn" >English</a>
    			    </div>
    			</div>
    	      </div>
    	      <hr />
    	      <a href="downLoadFile?fileName=${fileName}" >${fileName}</a>
    	      <hr />
    	   </div>
    	</div>
    </body>
    </html>

常用的三种异常处理

**@ExceptionHandler 注解**

第一步，创建一个用注解@ControllerAdvice 修饰的切面类（也可以是普通类）。

第二步，创建一个目标方法，并用注解@ExceptionHandler 修饰，value值是一个数组，值是异常类。

第三步，目标方法的的参数必须有Exception 类型的参数，用于获取运行时发生的异常。

第四步，目标方法若想把异常返回给页面，可以用ModelAndView 类型作为返回值，而不能用Map作为参数返回。

**@ResponseStatus 注解**

第一步，创建一个被注解@ResponseStatus 修饰的自定义异常类，value值是状态码，reason值是字符串。

第二步，在目标方法执行时抛出自定义异常。

**SimpleMappingExceptionResolver Bean**

第一步，在SpringMVC的配置文件中 配置Bean SimpleMappingExceptionResolver 。

第二步，设置exceptionAttribute 模型Model，必须和页面上的值一致。

第三步，设置exceptionMappings 视图View，只有当异常触发时跳转到视图页面。

注意细节，看代码

StudyExceptionHandlerAdvice.java 切面类

import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.servlet.ModelAndView;
    
    /**
     * 1 @ExceptionHandler 注解修饰的方法可以放在普通类中，也可以放在切面类中(@ControllerAdvice 注解修饰的类)。前者表示只处理当前类的异常，后者表示处理全局的异常。
     * 2 @ExceptionHandler 注解修饰的方法参数中，不能有Map，否则会提示：。若希望把异常信息返回给前端，可以使用ModelAndView
     * 3 @ExceptionHandler 注解修饰的多个方法中，优先级原则是就近原则(和异常精度越近的异常，优先执行)。
     */
    @ControllerAdvice
    public class StudyExceptionHandlerAdvice {
    	
    	@ExceptionHandler({ArithmeticException.class})
    	public ModelAndView handleArithmeticException(Exception exception){
    		System.out.println("ArithmeticException 出异常了: " + exception);
    		ModelAndView mv = new ModelAndView("exception");
    		mv.addObject("exception", "ArithmeticException 出异常了: " + exception);
    		return mv;
    	}
    	
    	/*@ExceptionHandler({RuntimeException.class})
    	public ModelAndView handleRuntimeException(Exception exception){
    		System.out.println("RuntimeException 出异常了: " + exception);
    		ModelAndView mv = new ModelAndView("exception");
    		mv.addObject("exception", "RuntimeException 出异常了: " + exception);
    		return mv;
    	}*/
    	
    }

ResponseStatusException.java 自定义异常类

import org.springframework.http.HttpStatus;
    import org.springframework.web.bind.annotation.ResponseStatus;
    
    @ResponseStatus(value = HttpStatus.BAD_REQUEST, reason = "ResponseStatusException : 自定义异常原因")
    public class ResponseStatusException extends RuntimeException{
    
    }

StudyExceptionController.java 异常处理测试类

import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    @Controller
    public class StudyExceptionController {
    	
    	@RequestMapping("/exception")
    	public String exception(){
    		return "exception";
    	}
    	
    	@RequestMapping("/simpleMappingExceptionResolver")
    	public String simpleMappingExceptionResolver(@RequestParam("num") int num){
    		String [] args = new String[10];
    		System.out.println("通过配置bean，来处理某一种异常导致的所有问题。" + args[num]);
    		return "exception";
    	}
    	
    	@RequestMapping(value="/testResponseStatus")
    	public String testResponseStatus(@RequestParam("num") Integer num){
    		System.out.println("@ResponseStatus 自定义异常");
    		if (0 == num) {
    			throw new ResponseStatusException();
    		}
    		return "exception";
    	}
    	
    	@RequestMapping("/testExceptionHandler")
    	public String testExceptionHandler(@RequestParam("num") Integer num){
    		System.out.println("@ExceptionHandler - result: " + (10 / num));
    		return "exception";
    	}
    
    }

exception.jsp 异常处理前端页面

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
        
    <!DOCTYPE>
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>SpringMVC 快速入门</title>
    <link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
    </head>
    <body>
    	
    	<div class="container">
    	   <div class="row">
    	   		<h2>SpringMVC 异常处理</h2>
    			<hr/>
    			@ExceptionHandler : <a href="testExceptionHandler?num=0" class="btn" >testExceptionHandler?num=0</a>
    			<hr/>
    			SimpleMappingExceptionResolver : <a href="simpleMappingExceptionResolver?num=20" class="btn" >simpleMappingExceptionResolver?num=20</a>
    			<hr/>
    			@ResponseStatus : <a href="testResponseStatus?num=0" class="btn" >testResponseStatus?num=0</a>
    			<hr/>
    			${exception}
    	   </div>
    	</div>
    </body>
    </html>

到这里，SpringMVC的教程就结束了，有什么好的建议和问题，可以提出来。大家一起成长！

SpringMVC源码地址：[https://gitee.com/itdragon/springmvc][https_gitee.com_itdragon_springmvc]

[SpringMVC]: http://blog.csdn.net/qq_19558705/article/details/50127611
[20171009150443572]: /images/20220731/7b4e364d1d0f4173a14b322b015217d3.png
[https_gitee.com_itdragon_springmvc]: https://gitee.com/itdragon/springmvc