SpringMVC的檔案上傳
檔案上傳
單檔案上傳
導入相應坐标
pom.xml
<!--檔案上傳-->
<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>
配置檔案上傳解析器
spring-mvc.xml
<!--配置檔案上傳解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="UYF-8"/>
<property name="maxUploadSize" value="500000"/>
</bean>
檔案上傳代碼
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="${pageContext.request.contextPath}/user/quick22" method="post" enctype="multipart/form-data">
名稱<input type="text" name="username"><br/>
檔案1<input type="file" name="uploadFile"><br/>
<input type="submit" value="送出">
</form>
</body>
</html>
name=“uploadFile” 要與 MultipartFile uploadFile 一緻
@RequestMapping(value="/quick22")
@ResponseBody
public void save22(String username, MultipartFile uploadFile) throws IOException {
System.out.println(username);
System.out.println(uploadFile);
//獲得上傳檔案的名稱
String originalFilename = uploadFile.getOriginalFilename();
uploadFile.transferTo(new File("C:\\Users\\auas\\Desktop\\建立檔案夾"+originalFilename));
}
桌面顯示有此檔案
多檔案上傳
檔案上傳代碼
@RequestMapping(value="/quick23")
@ResponseBody
public void save23(String username, MultipartFile[] uploadFile) throws IOException {
System.out.println(username);
for (MultipartFile multipartFile : uploadFile) {
String originalFilename = multipartFile.getOriginalFilename();
multipartFile.transferTo(new File("C:\\upload\\"+originalFilename));
}
}
upload.jsp
<%--
Created by IntelliJ IDEA.
User: auas
Date: 2021/1/7
Time: 18:37
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/user/quick23" method="post" enctype="multipart/form-data">
名稱<input type="text" name="username"><br/>
檔案1<input type="file" name="uploadFile"><br/>
檔案2<input type="file" name="uploadFile"><br/>
檔案3<input type="file" name="uploadFile"><br/>
<input type="submit" value="送出">
</form>
</body>
</html>
SpringMVC的攔截器
攔截器
Spring MVC 的攔截器類似于 Servlet 開發中的過濾器 Filter,用于對處理器進行預處理和後處理。
将攔截器按一定的順序聯結成一條鍊,這條鍊稱為攔截器鍊(InterceptorChain)。在通路被攔截的方法或字段時,攔截器鍊中的攔截器就會按其之前定義的順序被調用。攔截器也是AOP思想的具體實作。
- SpringMVC攔截器-interceptor和filter差別
- 攔截器方法
實作代碼
編寫攔截器:
public class MyInterceptor1 implements HandlerInterceptor {
//在目标方法執行之前 執行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
System.out.println("preHandle.....");
//return flase; 設定flase,後面所有都不執行
return true //放行
}
//在目标方法執行之後 視圖對象傳回之前執行
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
System.out.println("postHandle...");
}
//在流程都執行完畢後 執行
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
System.out.println("afterCompletion....");
}
}
配置:在SpringMVC的配置檔案中配置
Spring-mvc.xml
<!--配置攔截器-->
<mvc:interceptors>
<mvc:interceptor>
<!--對哪些資源執行攔截操作-->
<mvc:mapping path="/**"/>
<bean class="com.itheima.interceptor.MyInterceptor1"/>
</mvc:interceptor>
</mvc:interceptors>
編寫測試程式測試:
編寫Controller,發請求到controller,跳轉頁面
@Controller
public class TargetController {
@RequestMapping("/target")
public ModelAndView show(){
System.out.println("目标資源執行......");
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("name","itcast");
modelAndView.setViewName("index");
return modelAndView;
}
}
index.jsp頁面
<html>
<body>
<h2>Hello World! ${name}</h2>
</body>
</html>
http://localhost:8080/itheima_spring_mvc_war_exploded/target
preHandle…
目标資源執行…
postHandle…
afterCompletion…
應用場景
preHandle 應用場景
postHandle使用
多個攔截器執行
攔截器在預處理後什麼情況下會執行目标資源,什麼情況下不執行目标資源,以及在有多個攔截器的情況下攔截器的執行順序是什麼?
再編寫一個攔截器2,
public class MyInterceptor2 implements HandlerInterceptor {
//在目标方法執行之前 執行
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
System.out.println("preHandle22222.....");
return true;
}
//在目标方法執行之後 視圖對象傳回之前執行
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
System.out.println("postHandle2222...");
}
//在流程都執行完畢後 執行
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
System.out.println("afterCompletion2222....");
}
}
配置攔截器2
<!--配置攔截器-->
<mvc:interceptors>
<mvc:interceptor>
<!--對哪些資源執行攔截操作-->
<mvc:mapping path="/**"/>
<bean class="com.itheima.interceptor.MyInterceptor2"/>
</mvc:interceptor>
<mvc:interceptor>
<!--對哪些資源執行攔截操作-->
<mvc:mapping path="/**"/>
<bean class="com.itheima.interceptor.MyInterceptor1"/>
</mvc:interceptor>
</mvc:interceptors>
結論:
當攔截器的preHandle方法傳回true則會執行目标資源,如果傳回false則不執行目标資源
多個攔截器情況下,配置在前的先執行,配置在後的後執行
攔截器中的方法執行順序是:preHandler-------目标資源----postHandle---- afterCompletion
SpringMVC異常處理機制
系統中異常包括兩類:預期異常和運作時異常RuntimeException,前者通過捕獲異常進而擷取異常資訊,後者主要通過規範代碼開發、測試等手段減少運作時異常的發生。
系統的Dao、Service、Controller出現都通過throws Exception向上抛出,最後由SpringMVC前端控制器交由異常處理器進行異常處理,如下圖:
異常處理兩種方式
① 使用Spring MVC提供的簡單異常處理器SimpleMappingExceptionResolver
② 實作Spring的異常處理接口HandlerExceptionResolver 自定義自己的異常處理器
簡單異常處理器SimpleMappingExceptionResolver
代碼
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("抛出類型轉換異常....");
Object str = "zhangsan";
Integer num = (Integer)str;
}
public void show2() {
System.out.println("抛出除零異常....");
int i = 1/0;
}
public void show3() throws FileNotFoundException {
System.out.println("檔案找不到異常....");
InputStream in = new FileInputStream("C:/xxx/xxx/xxx.txt");
}
public void show4() {
System.out.println("空指針異常.....");
String str = null;
str.length();
}
public void show5() throws MyException {
System.out.println("自定義異常....");
throw new MyException();
}
}
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>通用的錯誤提示頁面</h1>
<h1>${info}</h1>
</body>
</html>
相應異常與視圖的映射配置
spring-mvc.xml
<!--配置簡單映射異常處理器-->
<bean class=“org.springframework.web.servlet.handler.SimpleMappingExceptionResolver”>
<!--統一使用異常-->
<property name=“defaultErrorView” value=“error”/> 預設錯誤視圖
<!-- 或 根據 不同情況顯示不同異常
<property name=“exceptionMappings”>
<map> 異常類型 錯誤視圖
<entry key="com.itheima.exception.MyException" value="error"/> 自定義異常
<entry key="java.lang.ClassCastException" value="error"/> 類型轉換異常
</map>
</property>
-->
</bean>
測試類
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";
}
}
自定義異常處理步驟
實作Spring的異常處理接口HandlerExceptionResolver 自定義自己的異常處理器
- 自定義異常
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 {
/*
參數Exception:異常對象
傳回值ModelAndView:跳轉到錯誤視圖資訊
*/
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
ModelAndView modelAndView = new ModelAndView();
if(e instanceof MyException){
modelAndView.addObject("info","自定義異常");
}else if(e instanceof ClassCastException){
modelAndView.addObject("info","類轉換異常");
}
modelAndView.setViewName("error");
return modelAndView;
}
}
- spring-mvc.xml