SpringMVC的文件上传
文件上传
单文件上传
导入相应坐标
pom.xml
<!--文件上传-->
<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>2.6</version>
</dependency>
配置文件上传解析器
spring-mvc.xml
<!--配置文件上传解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="UYF-8"/>
<property name="maxUploadSize" value="500000"/>
</bean>
文件上传代码
upload.jsp
<%--
Created by IntelliJ IDEA.
User: auas
Date: 2021/1/7
Time: 18:37
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>
<form action="${pageContext.request.contextPath}/user/quick22" method="post" enctype="multipart/form-data">
名称<input type="text" name="username"><br/>
文件1<input type="file" name="uploadFile"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
name=“uploadFile” 要与 MultipartFile uploadFile 一致
@RequestMapping(value="/quick22")
@ResponseBody
public void save22(String username, MultipartFile uploadFile) throws IOException {
System.out.println(username);
System.out.println(uploadFile);
//获得上传文件的名称
String originalFilename = uploadFile.getOriginalFilename();
uploadFile.transferTo(new File("C:\\Users\\auas\\Desktop\\新建文件夹"+originalFilename));
}
桌面显示有此文件
多文件上传
文件上传代码
@RequestMapping(value="/quick23")
@ResponseBody
public void save23(String username, MultipartFile[] uploadFile) throws IOException {
System.out.println(username);
for (MultipartFile multipartFile : uploadFile) {
String originalFilename = multipartFile.getOriginalFilename();
multipartFile.transferTo(new File("C:\\upload\\"+originalFilename));
}
}
upload.jsp
<%--
Created by IntelliJ IDEA.
User: auas
Date: 2021/1/7
Time: 18:37
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/user/quick23" method="post" enctype="multipart/form-data">
名称<input type="text" name="username"><br/>
文件1<input type="file" name="uploadFile"><br/>
文件2<input type="file" name="uploadFile"><br/>
文件3<input type="file" name="uploadFile"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
SpringMVC的拦截器
拦截器
Spring MVC 的拦截器类似于 Servlet 开发中的过滤器 Filter,用于对处理器进行预处理和后处理。
将拦截器按一定的顺序联结成一条链,这条链称为拦截器链(InterceptorChain)。在访问被拦截的方法或字段时,拦截器链中的拦截器就会按其之前定义的顺序被调用。拦截器也是AOP思想的具体实现。
- SpringMVC拦截器-interceptor和filter区别
- 拦截器方法
实现代码
编写拦截器:
public class MyInterceptor1 implements HandlerInterceptor {
//在目标方法执行之前 执行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
System.out.println("preHandle.....");
//return flase; 设置flase,后面所有都不执行
return true //放行
}
//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, ModelAndView modelAndView) {
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:在SpringMVC的配置文件中配置
Spring-mvc.xml
<!--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.itheima.interceptor.MyInterceptor1"/>
</mvc:interceptor>
</mvc:interceptors>
编写测试程序测试:
编写Controller,发请求到controller,跳转页面
@Controller
public class TargetController {
@RequestMapping("/target")
public ModelAndView show(){
System.out.println("目标资源执行......");
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("name","itcast");
modelAndView.setViewName("index");
return modelAndView;
}
}
index.jsp页面
<html>
<body>
<h2>Hello World! ${name}</h2>
</body>
</html>
http://localhost:8080/itheima_spring_mvc_war_exploded/target
preHandle…
目标资源执行…
postHandle…
afterCompletion…
应用场景
preHandle 应用场景
postHandle使用
多个拦截器执行
拦截器在预处理后什么情况下会执行目标资源,什么情况下不执行目标资源,以及在有多个拦截器的情况下拦截器的执行顺序是什么?
再编写一个拦截器2,
public class MyInterceptor2 implements HandlerInterceptor {
//在目标方法执行之前 执行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
System.out.println("preHandle22222.....");
return true;
}
//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, ModelAndView modelAndView) {
System.out.println("postHandle2222...");
}
//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("afterCompletion2222....");
}
}
配置拦截器2
<!--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.itheima.interceptor.MyInterceptor2"/>
</mvc:interceptor>
<mvc:interceptor>
<!--对哪些资源执行拦截操作-->
<mvc:mapping path="/**"/>
<bean class="com.itheima.interceptor.MyInterceptor1"/>
</mvc:interceptor>
</mvc:interceptors>
结论:
当拦截器的preHandle方法返回true则会执行目标资源,如果返回false则不执行目标资源
多个拦截器情况下,配置在前的先执行,配置在后的后执行
拦截器中的方法执行顺序是:preHandler-------目标资源----postHandle---- afterCompletion
SpringMVC异常处理机制
系统中异常包括两类:预期异常和运行时异常RuntimeException,前者通过捕获异常从而获取异常信息,后者主要通过规范代码开发、测试等手段减少运行时异常的发生。
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,如下图:
异常处理两种方式
① 使用Spring MVC提供的简单异常处理器SimpleMappingExceptionResolver
② 实现Spring的异常处理接口HandlerExceptionResolver 自定义自己的异常处理器
简单异常处理器SimpleMappingExceptionResolver
代码
package com.itheima.service;
import com.itheima.exception.MyException;
import java.io.FileNotFoundException;
public interface DemoService {
void show1();
void show2();
void show3() throws FileNotFoundException;
void show4();
void show5() throws MyException;
}
package com.itheima.service;
import com.itheima.exception.MyException;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
public class DemoServiceImpl implements DemoService {
public void show1() {
System.out.println("抛出类型转换异常....");
Object str = "zhangsan";
Integer num = (Integer)str;
}
public void show2() {
System.out.println("抛出除零异常....");
int i = 1/0;
}
public void show3() throws FileNotFoundException {
System.out.println("文件找不到异常....");
InputStream in = new FileInputStream("C:/xxx/xxx/xxx.txt");
}
public void show4() {
System.out.println("空指针异常.....");
String str = null;
str.length();
}
public void show5() throws MyException {
System.out.println("自定义异常....");
throw new MyException();
}
}
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>通用的错误提示页面</h1>
<h1>${info}</h1>
</body>
</html>
相应异常与视图的映射配置
spring-mvc.xml
<!--配置简单映射异常处理器-->
<bean class=“org.springframework.web.servlet.handler.SimpleMappingExceptionResolver”>
<!--统一使用异常-->
<property name=“defaultErrorView” value=“error”/> 默认错误视图
<!-- 或 根据 不同情况显示不同异常
<property name=“exceptionMappings”>
<map> 异常类型 错误视图
<entry key="com.itheima.exception.MyException" value="error"/> 自定义异常
<entry key="java.lang.ClassCastException" value="error"/> 类型转换异常
</map>
</property>
-->
</bean>
测试类
package com.itheima.controller;
import com.itheima.exception.MyException;
import com.itheima.service.DemoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import java.io.FileNotFoundException;
@Controller
public class DemoController {
@Autowired
private DemoService demoService;
@RequestMapping(value = "/show")
public String show() throws FileNotFoundException, MyException {
System.out.println("show running......");
demoService.show1();
return "index";
}
}
自定义异常处理步骤
实现Spring的异常处理接口HandlerExceptionResolver 自定义自己的异常处理器
- 自定义异常
package com.itheima.resolver;
import com.itheima.exception.MyException;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
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, Object o, Exception e) {
ModelAndView modelAndView = new ModelAndView();
if(e instanceof MyException){
modelAndView.addObject("info","自定义异常");
}else if(e instanceof ClassCastException){
modelAndView.addObject("info","类转换异常");
}
modelAndView.setViewName("error");
return modelAndView;
}
}
- spring-mvc.xml