文件上传
- form表单
- form表单的enctype取值必须是multipart/form-data, 默认是application/x-www-form-urlencoded
- 请求方式是post
- 文件选择域<input type="file" />
- 文件上传原理分析
enctype为application/x-www-form-urlencoded时，form表单的正文内容是key=value&key=value
enctype为multipart/form-data时，form表单的正文内容是:
-----------------------------7de1a433602ac 分界符
Content-Disposition: form-data; name="username" 协议头
lisi 协议的正文
-----------------------------7de1a433602ac
Content-Disposition: form-data; name="file";
filename="C:\test.txt"
Content-Type: text/plain 协议的类型（MIME 类型）
testeststetestsett
-----------------------------7de1a433602ac--
- 传统方式文件上传
传统方式的文件上传，指的是我们上传的文件和访问的应用存在于同一台服务器上
# 依赖
commons-fileupload-1.3.1.jar
commons-io-2.4.jar
a.jsp
<form action="/fileUpload" method="post" enctype="multipart/form-data">
<input type="text" name="name"/><br/>
<input type="file" name="file"/><br/>
<input type="submit" value="上传"/>
</form>
FileUploadController.class
@RequestMapping("/fileUpload")
public String fileupload(String name, MultipartFile multipartFile, HttpServletRequest request) throws Exception{
//1. 原始文件名
String uploadFileName = multipartFile.getOriginalFilename();
//2. 截取后缀
String extName = uploadFileName.substring(uploadFileName.lastIndexOf(".")+1, uploadFileName.length());
//3. 生成新的文件名
String fileName = "";
String uuid = UUID.randomUUID().toString().replace("-", "").toUpperCase();
if(!StringUtils.isEmpty(name)){
fileName = uuid + "_" + name + "." + extName;
}else {
fileName = uuid + "_" + uploadFileName;
}
//4.获取文件路径
ServletContext context = request.getServletContext();
String basePath = context.getRealPath("/uploads");
//通过日期解决同一文件夹文件过多的问题
String datePath = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
File file = new File(basePath + "/" + datePath);
if(!file.exists()){
file.mkdirs();
}
//5.上传
multipartFile.transferTo(new File(file, fileName));
return "success";
}
配置文件解析器
<!-- 配置文件上传解析器 -->
<bean id="multipartResolver" <!-- id 的值是固定的-->
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置上传文件的最大尺寸为 5MB -->
<property name="maxUploadSize">
<value>5242880</value>
</property>
</bean>
- 跨服务器上传文件
# 依赖
commons-fileupload-1.3.1.jar
commons-io-2.4.jar
jersey-client-1.81.1.jar
jersey-core-1.18.1.jar
UploadFileController.class
@RequestMapping("/fileUpload")
public String fileupload(String name, MultipartFile multipartFile, HttpServletRequest request) throws Exception{
//1. 原始文件名
String uploadFileName = multipartFile.getOriginalFilename();
//2. 截取后缀
String extName = uploadFileName.substring(uploadFileName.lastIndexOf(".")+1, uploadFileName.length());
//3. 生成新的文件名
String fileName = "";
String uuid = UUID.randomUUID().toString().replace("-", "").toUpperCase();
if(!StringUtils.isEmpty(name)){
fileName = uuid + "_" + name + "." + extName;
}else {
fileName = uuid + "_" + uploadFileName;
}
//4.上传
Client client = Client.create();
WebResource resource = client.resource("url");
String result = resource.put(String.class, multipartFile.getBytes());
System.out.println(result);
return "success";
}
异常处理
public class CustomException extends Exception {
private String message;
public CustomException(String message) {
this.message = message;
}
public String getMessage() {
return message;
}
}
public class CustomExceptionResolver implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
e.printStackTrace();
CustomException customException = null;
if(e instanceof CustomException){
customException = (CustomException)e;
}else {
customException = new CustomException("系统错误");
}
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("message", customException.getMessage());
modelAndView.setViewName("error");
return modelAndView;
}
}
# 配置自定义异常处理类
<bean id="handlerExceptionResolver" class="com.sn511.controller.CustomExceptionResolver"/>
拦截器
SpringMVC中的拦截器类似于Servlet中的过滤器Filter，用于对处理器进行预处理和后处理
过滤器是Servlet规范中的一部分，任何java web项目都可以使用，通过配置url-pattern，对要访问的资源进行过滤
拦截器是SpringMVC框架的，只有SpringMVC框架的工程才可以使用，只会拦截处理器的方法。
是AOP思想的具体应用
public class MyHandlerInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("MyHandlerInterceptor preHandle ......");
return true; //true就是放行
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("MyHandlerInterceptor postHandle .....");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("MyHandlerInterceptor afterCompletion ......");
}
}
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/> <!--指定拦截的url-->
<!--<mvc:exclude-mapping path=""/>排除的url-->
<bean id="myHandlerInterceptor" class="com.sn511.controller.MyHandlerInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
