拦截器-登录检查与静态资源放行
1.编写一个拦截器实现HandlerInterceptor接口
2.拦截器注册到容器中（实现WebMvcConfigurer的addInterceptors()）
3.指定拦截规则（注意，如果是拦截所有，静态资源也会被拦截】
还是以上一节Springboot视图解析与模板引擎为例，访问除登录页面外的其它任何请求，都应该是登录之后才能访问的。我们可以使用拦截器对请求进行拦截，从而进行相应的处理。
public interface HandlerInterceptor {
default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
return true;
}
default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
}
default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
}
}
拦截器必须要实现HandlerInterceptor 接口
HandlerInterceptor 定义了3个方法，preHandle预先处理，即目标方法处理之前进行处理。目标方法处理完之后，但是还没有到达指定页面之前，我们需要给页面再放一些数据，可以用postHandle进行后置拦截。在请求处理完成之后要做的工作用afterCompletion来处理。
编写一个实现HandlerInterceptor接口的拦截器：
/*
登录检查
1.配置好拦截器要拦截哪些请求
2.把这些配置放在容器中(实现WebConfigurer的addUbtercepter）
3.指定拦截规则（如果是拦截所有，静态资源也会被拦截）
* */
public class LoginIntercepter implements HandlerInterceptor {
/*
* 目标方法执行之前
* */
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//登录检查逻辑
HttpSession session=request.getSession();
Object loginUser =session.getAttribute("loginUser");
if(loginUser!=null){
//放行
return true;
}
//拦截住,未登录，跳转到登录页
// session.setAttribute("msg","请先登录");
// response.sendRedirect("/");
request.setAttribute("msg","请先登录");
//如果是重定向取不出来错误消息
request.getRequestDispatcher("/").forward(request,response);
return false;
}
/*
* 目标方法执行完成之后
* */
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
/*
* 页面渲染以后
* */
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}
拦截器注册到容器中 && 指定拦截规则：
@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new LoginIntercepter())
// /**会拦截所有请求，包括静态资源
.addPathPatterns("/**") //拦截哪些
.excludePathPatterns("/","/login","/css/**","/js/**","/fonts/**","/images/**"); //放行哪些
}
}
注意：这里使用/的时候会拦截掉所有资源，包括静态资源，因此需要对静态资源进行放行，我们静态资源都是保存在static目录下， 而这里不能直接对/static/，因为访问静态资源的时候url不会写static。
拦截器-【源码分析】-拦截器的执行时机和原理
1.根据当前请求，找到HandlerExecutionChain（可以处理请求的handler以及handler的所有 拦截器）
2.先来顺序执行 所有拦截器的 preHandle()方法。
- 如果当前拦截器preHandle()返回为true。则执行下一个拦截器的preHandle()
- 如果当前拦截器返回为false。直接倒序执行所有已经执行了的拦截器的 afterCompletion();。
3.如果任何一个拦截器返回false，直接跳出不执行目标方法。
4.所有拦截器都返回true，才执行目标方法。
5.倒序执行所有拦截器的postHandle()方法。
6.前面的步骤有任何异常都会直接倒序触发 afterCompletion()。
7.页面成功渲染完成以后，也会倒序触发 afterCompletion()。
public class DispatcherServlet extends FrameworkServlet {
...
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
ModelAndView mv = null;
Exception dispatchException = null;
...
//该方法内调用HandlerInterceptor的preHandle()
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
...
//该方法内调用HandlerInterceptor的postHandle()
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Throwable err) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler,
new NestedServletException("Handler processing failed", err));
}
finally {
...
}
}
private void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, Exception ex) throws Exception {
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
mappedHandler.triggerAfterCompletion(request, response, ex);
}
throw ex;
}
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
...
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
// Exception (if any) is already handled..
mappedHandler.triggerAfterCompletion(request, response, null);
}
}
}
public class HandlerExecutionChain {
...
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
for (int i = 0; i < this.interceptorList.size(); i++) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor的preHandle方法
if (!interceptor.preHandle(request, response, this.handler)) {
triggerAfterCompletion(request, response, null);
return false;
}
this.interceptorIndex = i;
}
return true;
}
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv)
throws Exception {
for (int i = this.interceptorList.size() - 1; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor接口的postHandle方法
interceptor.postHandle(request, response, this.handler, mv);
}
}
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
try {
//HandlerInterceptor接口的afterCompletion方法
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}
文件上传-单文件上传与多文件上传
使用form_layouts.html文件来实现文件上传。
在common.html中修改form_layouts的请求发送，即当在main.html中点击Form Layouts能够响应form_layouts请求。
<li class="menu-list"><a href=""><i class="fa fa-tasks"></i> <span>Forms</span></a>
<ul class="sub-menu-list">
<li><a th:href="@{/form_layouts}"> Form Layouts</a></li>
<li><a href="form_advanced_components.html"> Advanced Components</a>
在FormTestController处理文件上传的请求
/*
* 文件上传测试
* */
@Slf4j
@Controller
public class FormTestController {
@GetMapping("/form_layouts")
public String form_layouts(){
return "form/form_layouts";
}
//因为使用post方式提交
//该函数的作用是可以自动封装上传过来的文件
@PostMapping("/upload")
/*
* @RequestParam代表从请求参数中取值
* 取出表单中的文件项用@RequestPart注解，文件用MultipartFile对象来存储
* */
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos) throws IOException {
log.info("上传的信息：email={}，username={}，headerImg={}，photos={}",
email,username,headerImg.getSize(),photos.length);
System.out.println(email+" "+username+" "+headerImg.getSize()+" "+photos.length);
if(!headerImg.isEmpty()){
//保存到文件服务器，OSS文件服务器
String originalFilename = headerImg.getOriginalFilename();
headerImg.transferTo(new File("D:\\bootimg\\"+originalFilename));
}
if(photos.length>0){
for(MultipartFile photo:photos){
if(!photo.isEmpty()){
String originalFilename = photo.getOriginalFilename();
photo.transferTo(new File("D:\\bootimg\\"+originalFilename));
}
}
}
return "main";
}
}
form_layouts.html文件中文件上传表单的信息
<form role="form" th:action="@{/upload}" method="post" enctype="multipart/form-data">
<div class="form-group">
<label for="exampleInputEmail1">邮箱</label>
<input type="email" name="email" class="form-control" id="exampleInputEmail1" placeholder="Enter email">
</div>
<div class="form-group">
<label for="exampleInputPassword1">名字</label>
<input type="text" name="username" class="form-control" id="exampleInputPassword1" placeholder="Password">
</div>
<div class="form-group">
<label for="exampleInputFile">头像</label>
<input type="file" name="headerImg" id="exampleInputFile">
<p class="help-block">Example block-level help text here.</p>
</div>
<div class="form-group">
<label for="exampleInputFile">生活照</label>
<!--multiple多文件上传-->
<input type="file" name="photos" multiple>
<p class="help-block">Example block-level help text here.</p>
</div>
<div class="checkbox">
<label>
<input type="checkbox"> Check me out
</label>
</div>
<button type="submit" class="btn btn-primary">提交</button>
</form>
可以在application.properties中设置文件上传的参数
# 单个文件的最大大小
spring.servlet.multipart.max-file-size=10MB
# 整个请求的最大文件大小
spring.servlet.multipart.max-request-size=100MB
文件上传相关的配置类：
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.MultipartProperties
文件上传源码流程
文件上传自动配置类MultipartAutoConfiguration-MultipartProperties
自动配置好了StandardServletMultipartResolver [文件.上传解析器]
原理步骤
1.请求进来使用文件上传解析器判断(isMultipart) 并封装(resolveMultipart, 返回MultipartHttpServletRequest)文件.上传请求
2.参数解析器来解析请求中的文件内容封装成MultipartFile
3.将request中文件信息封装为-个Map; MultiValueMap< String, MultipartFile>
FileCopyUtils。实现文件流的拷贝
@PostMapping("/upload")
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos)
文件上传相关的自动配置类MultipartAutoConfiguration有创建文件上传参数解析器StandardServletMultipartResolver。
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
private final MultipartProperties multipartProperties;
public MultipartAutoConfiguration(MultipartProperties multipartProperties) {
this.multipartProperties = multipartProperties;
}
@Bean
@ConditionalOnMissingBean({ MultipartConfigElement.class, CommonsMultipartResolver.class })
public MultipartConfigElement multipartConfigElement() {
return this.multipartProperties.createMultipartConfig();
}
@Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
@ConditionalOnMissingBean(MultipartResolver.class)
public StandardServletMultipartResolver multipartResolver() {
//配置好文件上传解析器
StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily());
return multipartResolver;
}
}
//文件上传解析器
public class StandardServletMultipartResolver implements MultipartResolver {
private boolean resolveLazily = false;
public void setResolveLazily(boolean resolveLazily) {
this.resolveLazily = resolveLazily;
}
@Override
public boolean isMultipart(HttpServletRequest request) {
return StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/");
}
@Override
public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
}
@Override
public void cleanupMultipart(MultipartHttpServletRequest request) {
if (!(request instanceof AbstractMultipartHttpServletRequest) ||
((AbstractMultipartHttpServletRequest) request).isResolved()) {
// To be on the safe side: explicitly delete the parts,
// but only actual file parts (for Resin compatibility)
try {
for (Part part : request.getParts()) {
if (request.getFile(part.getName()) != null) {
part.delete();
}
}
}
catch (Throwable ex) {
LogFactory.getLog(getClass()).warn("Failed to perform cleanup of multipart items", ex);
}
}
}
}
public class DispatcherServlet extends FrameworkServlet {
@Nullable
private MultipartResolver multipartResolver;
private void initMultipartResolver(ApplicationContext context) {
...
//这个就是配置类配置的StandardServletMultipartResolver文件上传解析器
this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
...
}
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;//最后finally的回收flag
...
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
//做预处理,如果有上传文件 就new StandardMultipartHttpServletRequest包装类
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
...
// Determine handler adapter for the current request.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
...
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
}
....
finally {
...
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
...
return this.multipartResolver.resolveMultipart(request);
...
}
}
protected void cleanupMultipart(HttpServletRequest request) {
if (this.multipartResolver != null) {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
if (multipartRequest != null) {
this.multipartResolver.cleanupMultipart(multipartRequest);
}
}
}
}
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());跳到以下的类
public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
implements BeanFactoryAware, InitializingBean {
@Override
protected ModelAndView handleInternal(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ModelAndView mav;
...
mav = invokeHandlerMethod(request, response, handlerMethod);
...
return mav;
}
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
if (this.argumentResolvers != null) {//关注点
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
...
invocableMethod.invokeAndHandle(webRequest, mavContainer);
...
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}
}
this.argumentResolvers其中主角类RequestPartMethodArgumentResolver用来生成
public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
...
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
...
}
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
...
return doInvoke(args);//反射调用
}
@Nullable
protected Object doInvoke(Object... args) throws Exception {
Method method = getBridgedMethod();
ReflectionUtils.makeAccessible(method);
return method.invoke(getBean(), args);
...
}
//处理得出multipart参数，准备稍后的反射调用（@PostMapping标记的上传方法）
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
MethodParameter[] parameters = getMethodParameters();
...
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
//关注点1
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
//关注点2
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
...
}
}
return args;
}
}
public class RequestPartMethodArgumentResolver extends AbstractMessageConverterMethodArgumentResolver {
//对应上面代码关注点1
@Override
public boolean supportsParameter(MethodParameter parameter) {
//标注@RequestPart的参数
if (parameter.hasParameterAnnotation(RequestPart.class)) {
return true;
}
else {
if (parameter.hasParameterAnnotation(RequestParam.class)) {
return false;
}
return MultipartResolutionDelegate.isMultipartArgument(parameter.nestedIfOptional());
}
}
//对应上面代码关注点2
@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {
HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
Assert.state(servletRequest != null, "No HttpServletRequest");
RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());
String name = getPartName(parameter, requestPart);
parameter = parameter.nestedIfOptional();
Object arg = null;
//封装成MultipartFile类型的对象作参数
Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
arg = mpArg;
}
...
return adaptArgumentIfNecessary(arg, parameter);
}
}
public final class MultipartResolutionDelegate {
...
@Nullable
public static Object resolveMultipartArgument(String name, MethodParameter parameter, HttpServletRequest request)
throws Exception {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
boolean isMultipart = (multipartRequest != null || isMultipartContent(request));
if (MultipartFile.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
return multipartRequest.getFile(name);
}
else if (isMultipartFileCollection(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files : null);
}
else if (isMultipartFileArray(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files.toArray(new MultipartFile[0]) : null);
}
else if (Part.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
return request.getPart(name);
}
else if (isPartCollection(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts : null);
}
else if (isPartArray(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts.toArray(new Part[0]) : null);
}
else {
return UNRESOLVABLE;
}
}
...
}