springmvc3：ajax请求，文件上传下载，拦截器，异常处理，注解配置mvc

一.框架与代码

1.ajax

①ajax访问

②具体代码

• 发送ajax请求

<script type="text/javascript" th:src="@{/js/vue.js}">script>
<script type="text/javascript" th:src="@{/js/axios.min.js}">script>
<script type="text/javascript">
var vue = new Vue({
el:"#app",
methods:{
testRequestBody(){
axios.post(
"/SpringMVC/test/RequestBody/json",
{username:"admin",password:"123456"}
).then(response=>{
console.log(response.data);
});
}
}
});
script>

• 服务器利用RequestBody转换json字符串

//将json格式的数据转换为map集合
@RequestMapping("/test/RequestBody/json")
public void testRequestBody(@RequestBody Map<String, Object> map,
HttpServletResponse response) throws IOException {
System.out.println(map);
//{username=admin, password=123456}
response.getWriter().print("hello,axios");
}
//将json格式的数据转换为实体类对象
@RequestMapping("/test/RequestBody/json")
public void testRequestBody(@RequestBody User user, HttpServletResponse
response) throws IOException {
System.out.println(user);
//User{id=null, username='admin', password='123456', age=null,
gender='null'}
response.getWriter().print("hello,axios");
}

• 服务器利用responseBody返回响应的数据

//响应浏览器list集合
@RequestMapping("/test/ResponseBody/json")
@ResponseBody
public List<User> testResponseBody(){
User user1 = new User(1001,"admin1","123456",23,"男");
User user2 = new User(1002,"admin2","123456",23,"男");
User user3 = new User(1003,"admin3","123456",23,"男");
List<User> list = Arrays.asList(user1, user2, user3);
return list;
}
//响应浏览器map集合
@RequestMapping("/test/ResponseBody/json")
@ResponseBody
public Map<String, Object> testResponseBody(){
User user1 = new User(1001,"admin1","123456",23,"男");
User user2 = new User(1002,"admin2","123456",23,"男");
User user3 = new User(1003,"admin3","123456",23,"男");
Map<String, Object> map = new HashMap<>();
map.put("1001", user1);
map.put("1002", user2);
map.put("1003", user3);
return map;
}

• responsebody返回数据的转换格式
  • 实体类–>json对象
  • map–>json对象
  • list–>json数组

2.文件上传与下载

①框架

②使用

• 下载功能

@RequestMapping("/testDown")
public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws
IOException {
//获取ServletContext对象
ServletContext servletContext = session.getServletContext();
//获取服务器中文件的真实路径
String realPath = servletContext.getRealPath("/static/img/1.jpg");
//创建输入流
InputStream is = new FileInputStream(realPath);
//创建字节数组
byte[] bytes = new byte[is.available()];
//将流读到字节数组中
is.read(bytes);
//创建HttpHeaders对象设置响应头信息
MultiValueMap<String, String> headers = new HttpHeaders();
//设置要下载方式以及下载文件的名字
headers.add("Content-Disposition", "attachment;filename=1.jpg");
//设置响应状态码
HttpStatus statusCode = HttpStatus.OK;
//创建ResponseEntity对象
ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers,
statusCode);
//关闭输入流
is.close();
return responseEntity;
}

• 上传功能

<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
bean>

@RequestMapping("/testUp")
public String testUp(MultipartFile photo, HttpSession session) throws
IOException {
//获取上传的文件的文件名
String fileName = photo.getOriginalFilename();
//处理文件重名问题
String hzName = fileName.substring(fileName.lastIndexOf("."));
fileName = UUID.randomUUID().toString() + hzName;
//获取服务器中photo目录的路径
ServletContext servletContext = session.getServletContext();
String photoPath = servletContext.getRealPath("photo");
File file = new File(photoPath);
if(!file.exists()){
file.mkdir();
}
String finalPath = photoPath + File.separator + fileName;
//实现上传功能
photo.transferTo(new File(finalPath));
return "success";
}

3.拦截器

①框架

②代码

<bean class="com.atguigu.interceptor.FirstInterceptor">bean>
<ref bean="firstInterceptor">ref>

<mvc:interceptor>
	<mvc:mapping path="/**"/>
		<mvc:exclude-mapping path="/testRequestEntity"/>
	<ref bean="firstInterceptor">ref>
mvc:interceptor>

public class FirstInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

4.异常处理

①框架

②代码

<bean
class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<property name="exceptionMappings">
<props>

<prop key="java.lang.ArithmeticException">errorprop>
props>
property>

<property name="exceptionAttribute" value="ex">property>
bean>

//@ControllerAdvice将当前类标识为异常处理的组件
@ControllerAdvice
public class ExceptionController {
//@ExceptionHandler用于设置所标识方法处理的异常
@ExceptionHandler(ArithmeticException.class)
//ex表示当前请求处理中出现的异常对象
public String handleArithmeticException(Exception ex, Model model){
model.addAttribute("ex", ex);
return "error";
}
}

5.基于注解的Springmvc

①为什么可以配置基于注解的Springmvc

• servlet环境中，首先会有servlet容器
• serlvet容器会自动发现 继承了AbstractAnnotationConfigDispatcherServletInitializer的类来配置servlet的上下文

②配置代码（部分）

• 配置web.xml

public class WebInit extends
AbstractAnnotationConfigDispatcherServletInitializer {
/**
* 指定spring的配置类
* @return
*/
@Override
protected Class[] getRootConfigClasses() {
return new Class[]{SpringConfig.class};
}
/**
* 指定SpringMVC的配置类
* @return
*/
@Override
protected Class[] getServletConfigClasses() {
return new Class[]{WebConfig.class};
}
}

• 配置springmvc.xml

@Configuration
//扫描组件
@ComponentScan("com.atguigu.mvc.controller")
//开启MVC注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
//使用默认的servlet处理静态资源
@Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer
configurer) {
configurer.enable();
}