Javaweb-Spring mvc 文件上传
文件上传
三要素
- 表单
- 提交方式为post
- 表单enctype时多部分表单形式
范例
项目结构
单文件步骤
- 创建测试表单upload.jsp
<%--
Created by IntelliJ IDEA.
User: Zsy
Date: 2020/8/9
Time: 14:01
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/user/upload" method="post" enctype="multipart/form-data">
<input type="text" name="username"> <br>
<input type="file" name="file"><br>
<input type="submit" value="submit">
</form>
</body>
</html>
- 在spring mvc xml配置文件上传解析器
<!--配置文件上传解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="UTF-8"/>
<property name="maxUploadSize" value="500000"/>
</bean>
- 编写控制层代码
@RequestMapping(value="/upload")
@ResponseBody
public void testFileUpload(String username, MultipartFile file) throws IOException {
System.out.println(username);
file.transferTo(new File("F:\\test\\"+file.getOriginalFilename()));
}
- 测试
多文件上传
步骤
- 在原先的jsp文件添加一个表单
<form action="${pageContext.request.contextPath}/user/upload2" method="post" enctype="multipart/form-data">
<input type="text" name="username"> <br>
<input type="file" name="uploadFile"><br>
<input type="file" name="uploadFile"><br>
<input type="submit" value="submit">
</form>
- 添加多文件上传控制器
@RequestMapping(value="/upload2")
@ResponseBody
public void testMultiFileUpload(String username, MultipartFile[] uploadFile) throws IOException {
System.out.println(username);
for (MultipartFile file : uploadFile) {
System.out.println(file.getOriginalFilename());
file.transferTo(new File("F:\\test\\"+file.getOriginalFilename()));
}
}
spring mvc拦截器
作用
用于预处理和后处理，即将拦截器按一定顺序结成一条链，这条链称为拦截器链。在访问拦截器方法或字段时，拦截器中的拦截器就会按照顺序被调用，拦截器也是AOP思想的具体实现
与传统过滤器的区别
拦截器入门案例
步骤
- 编写测试网页
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false"%>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>hello ${username}</h1>
</body>
- 编写拦截器
代码如下所示，这里控制器做了个判断，若请求的user为root则返回true，即这个请求可以通过，若为false则跳转到error页面
postHandle在目标方法执行之后 视图对象返回之前执行，所以笔者在这里修改了username的值，最后响应的usernmae是rose而不是jack
package com.study.interceptor;
/**
* Created by Zsy on 2020/8/9.
*/
public class myInterceptor implements HandlerInterceptor {
//在目标方法执行之前 执行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle。。。。。");
String param = request.getParameter("user");
if ("root".equals(param))
return true;
request.getRequestDispatcher("/error.jsp").forward(request, response);
return false;
}
//在目标方法执行之后 视图对象返回之前执行
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
modelAndView.addObject("username", "rose");
System.out.println("postHandle........");
}
//在流程都执行完毕后 执行
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
System.out.println("afterCompletion....");
}
}
- 配置拦截器
<!--配置拦截器-->
<mvc:interceptors>
<mvc:interceptor>
<!--对哪些资源执行拦截操作-->
<mvc:mapping path="/**"/>
<bean class="com.study.interceptor.myInterceptor"/>
</mvc:interceptor>
</mvc:interceptors>
- 编写测试控制器
@RequestMapping(value = "/login")
@ResponseBody
public ModelAndView testInterceptor() {
System.out.println("目标资源执行......");
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("username","jack");
modelAndView.setViewName("success");
return modelAndView;
}
- 测试
spring mvc异常处理机制
过程图解
如下图所示，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
演示范例
非自定义异常处理器配置范例
步骤
- 业务层编写错误代码
package com.study.service.impl;
import com.study.exception.MyException;
import com.study.service.UserService;
import com.study.dao.UserDao;
/**
* Created by Zsy on 2020/8/5.
*/
public class UserServiceImpl implements UserService {
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
public void save() {
userDao.save();
}
public void ex1() {
System.out.println("抛出类型转换异常....");
Object str = "zhangsan";
Integer num = (Integer)str;
}
public void ex2() throws MyException {
System.out.println("自定义异常....");
throw new MyException();
}
}
- 控制层调用这些作死的代码
@RequestMapping(value = "/ex1")
@ResponseBody
public void testException(){
service.ex1();
}
- spring-mvc.xml配置异常处理器
<!--配置异常处理器-->
<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<!--<property name="defaultErrorView" value="error"/>-->
<property name="exceptionMappings">
<map>
<entry key="java.lang.ClassCastException" value="error"/>
<entry key="com.itheima.exception.MyException" value="error"/>
</map>
</property>
</bean>
- 编写错误网页
<%--
Created by IntelliJ IDEA.
User: Zsy
Date: 2020/8/9
Time: 14:54
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
error
</body>
</html>
- 测试
自定义异常处理器配置范例
步骤
- 编写自定义异常处理器
package com.study.resolver;
public class MyExceptionResolver implements HandlerExceptionResolver {
/*
参数Exception：异常对象
返回值ModelAndView：跳转到错误视图信息
*/
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, @Nullable Object o, Exception e) {
ModelAndView modelAndView=new ModelAndView();
System.out.println("error catch");
if (e instanceof MyException)
modelAndView.addObject("type","myException");
else
modelAndView.addObject("type","otherException");
modelAndView.setViewName("error");
return modelAndView;
}
}
- 编写错误测试jsp
<%--
Created by IntelliJ IDEA.
User: Zsy
Date: 2020/8/9
Time: 14:54
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false"%>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1> error type ${type}</h1>
error
</body>
</html>
- 配置自定义拦截器，注意将之前配置好的spring异常处理器去掉
- 测试结果
