页面效果:
一、文件下载
1.访问资源时相应头如果没有设置 Content-Disposition,浏览器默认按照 inline 值进行处理
1.1 inline 能显示就显示,不能显示就下载.
2.只需要修改响应头中 Context-Disposition=”attachment;filename=文件名”
2.1 attachment
下载,以附件形式下载.
2.2 filename=值
就是下载时显示的下载文件名
3.实现步骤
3.1 导入apache 的两个jar
3.2 在 jsp 中添加超链接,设置要下载文件
<a href="download?fileName=a.rar">下载</a>
3.2.1 在 springmvc.xml 中放行静态资源 files 文件夹
<!-- 静态资源 -->
<mvc:resources location="/js/" mapping="/js/**"></mvc:resources>
<mvc:resources location="/css/" mapping="/css/**"></mvc:resources>
<mvc:resources location="/images/" mapping="/images/**"></mvc:resources>
<mvc:resources location="/files/" mapping="/files/**"></mvc:resources>
3.3 编写控制器方法
Java示例
@Controller
public class DemoDownload {
@RequestMapping("download")
public void download(String filename, HttpServletResponse res, HttpServletRequest req) throws IOException {
// 设置响应流中文件进行下载
// attachment是以附件的形式下载,inline是浏览器打开
// bbb.txt是下载时显示的文件名
res.setHeader("Content-Disposition", "attachment;filename=bbb.txt"); // 下载
// res.setHeader("Content-Disposition", "inline;filename=bbb.txt"); // 浏览器打开
// 把二进制流放入到响应体中
ServletOutputStream os = res.getOutputStream();
System.out.println("here download");
String path = req.getServletContext().getRealPath("files");
System.out.println("path is: " + path);
System.out.println("fileName is: " + filename);
File file = new File(path, filename);
byte[] bytes = FileUtils.readFileToByteArray(file);
os.write(bytes);
os.flush();
os.close();
}
}
JSP示例
<a href="download?filename=a.txt">点击下载</a><br/>
二、文件上传
1. 基于apache 的commons-fileupload.jar 完成文件上传.
2. MultipartResovler 作用:
2.1 把客户端上传的文件流转换成MutipartFile 封装类.
2.2 通过MutipartFile 封装类获取到文件流
3. 表单数据类型分类
3.1 在的enctype 属性控制表单类型
3.2 默认值 application/x-www-form-urlencoded,普通表单数据.(少量文字信息)
3.3 text/plain 大文字量时使用的类型.邮件,论文
3.4 multipart/form-data
表单中包含二进制文件内容.(重要)
4. 实现步骤:
4.1 导入springmvc 包和apache 文件上传 commons-fileupload 和 commons-io 两个jar
4.2 编写JSP 页面
<h3>文件上传</h3>
<form action="upload" enctype="multipart/form-data" method="post">
姓名:<input type="text" name="name"/><br/>
文件:<input type="file" name="file"/><br/>
<input type="submit" value="提交"/>
</form>
4.3 配置 springmvc.xml
<!-- MultipartResovler解析器 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置文件最大字节数 -->
<property name="maxUploadSize" value="1024"></property>
</bean>
<!-- 异常解析器 -->
<bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<property name="exceptionMappings">
<props>
<prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">/error.jsp</prop>
</props>
</property>
</bean>
4.4 编写控制器类
4.4.1 MultipartFile 对象名必须和的name 属性值相同
@Controller
public class DemoUpload {
@RequestMapping("upload")
public String upload(MultipartFile file,String name) throws IOException{
String fileName = file.getOriginalFilename();
String suffix = fileName.substring(fileName.lastIndexOf("."));
// 限制上传文件类型
if(suffix.equalsIgnoreCase(".png")||suffix.equalsIgnoreCase(".txt")){
String uuid = UUID.randomUUID().toString();
FileUtils.copyInputStreamToFile(file.getInputStream(), new File("C:/picture/"+uuid+suffix));
return "index.jsp";
}else{
return "error.jsp";
}
}
}
附:springmvc.xml 完整配置
<?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:mvc="http://www.springframework.org/schema/mvc"
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
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- 扫描注解 -->
<context:component-scan
base-package="cn.hanquan.controller"></context:component-scan>
<!-- 注解驱动,相当于配置了以下两个类 -->
<!-- org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping -->
<!-- org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter -->
<mvc:annotation-driven></mvc:annotation-driven>
<!-- 放行静态资源 -->
<!-- 访问示例:http://localhost:8080/springmvc_test/test/jquery.js -->
<mvc:resources location="/js/" mapping="/test/**"></mvc:resources>
<mvc:resources location="/js/" mapping="/js/**"></mvc:resources>
<mvc:resources location="/css/" mapping="/css/**"></mvc:resources>
<mvc:resources location="/images/" mapping="/images/**"></mvc:resources>
<mvc:resources location="/images/" mapping="/files/**"></mvc:resources>
<!-- MultipartResovler解析器 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置文件最大字节数 -->
<property name="maxUploadSize" value="1024"></property>
</bean>
<!-- 异常解析器 -->
<bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<property name="exceptionMappings">
<props>
<prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">/error.jsp</prop>
</props>
</property>
</bean>
<!-- 自定义视图解析器 -->
<!-- 当跳转语句添加前缀(比如forward:)时,自定义视图解析器无效,走默认视图解析器 -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 添加前缀后,写相对路径不用加/ -->
<property name="prefix" value="/"></property>
<!-- 后缀没配,与不写相同,可以配成jsp -->
<property name="suffix" value=""></property>
</bean>
</beans>
附:web.xml 完整配置
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<!-- 配置前端控制器 -->
<servlet>
<servlet-name>abc</servlet-name>
<!-- servlet分发器 -->
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- 初始化参数名 -->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc.xml</param-value>
</init-param>
<!-- 自启动 -->
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>abc</servlet-name>
<!-- '/'表示除了jsp都拦截 -->
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- 字符编码过滤器 -->
<!-- 配置文件无关顺序问题,加载时就被实例化,等待tomcat回调 -->
<filter>
<filter-name>encoding</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>encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>