1、rest使用与原理
- @xxxMapping;
- Rest风格支持(使用HTTP请求方式动词来表示对资源的操作)
- 以前:/getUser 获取用户 /deleteUser 删除用户 /editUser 修改用户 /saveUser 保存用户
- 现在: /user GET-获取用户 DELETE-删除用户 PUT-修改用户 POST-保存用户
- 核心Filter;HiddenHttpMethodFilter
- 用法: 表单method=post,隐藏域 _method=put
- SpringBoot中手动开启
- 扩展:如何把_method 这个名字换成我们自己喜欢的。
@RequestMapping(value = "/user",method = RequestMethod.GET)
public String getUser(){
return "GET-张三";
}
@RequestMapping(value = "/user",method = RequestMethod.POST)
public String saveUser(){
return "POST-张三";
}
@RequestMapping(value = "/user",method = RequestMethod.PUT)
public String putUser(){
return "PUT-张三";
}
@RequestMapping(value = "/user",method = RequestMethod.DELETE)
public String deleteUser(){
return "DELETE-张三";
}
@Bean
@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
@ConditionalOnProperty(prefix = "spring.mvc.hiddenmethod.filter", name = "enabled", matchIfMissing = false)
public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
return new OrderedHiddenHttpMethodFilter();
}
//自定义filter
@Bean
public HiddenHttpMethodFilter hiddenHttpMethodFilter(){
HiddenHttpMethodFilter methodFilter = new HiddenHttpMethodFilter();
methodFilter.setMethodParam("_m");
return methodFilter;
}
Rest原理(表单提交要使用REST的时候)
- 表单提交会带上**_method=PUT**
- 请求过来被HiddenHttpMethodFilter拦截
- 请求是否正常,并且是POST
- 获取到**_method**的值。
- 兼容以下请求;PUT.DELETE.PATCH
- 原生request(post),包装模式requesWrapper重写了getMethod方法,返回的是传入的值。
- 过滤器链放行的时候用wrapper。以后的方法调用getMethod是调用requesWrapper的。
- 请求是否正常,并且是POST
Rest使用客户端工具,
- 如PostMan直接发送Put、delete等方式请求,无需Filter。
spring:
mvc:
hiddenmethod:
filter:
enabled: true #开启页面表单的Rest功能
2、请求映射原理
SpringMVC功能分析都从 org.springframework.web.servlet.DispatcherServlet-》doDispatch()
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;
try {
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// 找到当前请求使用哪个Handler(Controller的方法)处理
mappedHandler = getHandler(processedRequest);
//HandlerMapping:处理器映射。/xxx->>xxxx
RequestMappingHandlerMapping:保存了所有@RequestMapping 和handler的映射规则。 所有的请求映射都在HandlerMapping中。
- SpringBoot自动配置欢迎页的 WelcomePageHandlerMapping 。访问 /能访问到index.html;
- SpringBoot自动配置了默认 的 RequestMappingHandlerMapping
- 请求进来,挨个尝试所有的HandlerMapping看是否有请求信息。
- 如果有就找到这个请求对应的handler
- 如果没有就是下一个 HandlerMapping
- 我们需要一些自定义的映射处理,我们也可以自己给容器中放HandlerMapping。自定义 HandlerMapping
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
if (this.handlerMappings != null) {
for (HandlerMapping mapping : this.handlerMappings) {
HandlerExecutionChain handler = mapping.getHandler(request);
if (handler != null) {
return handler;
}
}
}
return null;
}
1、普通参数与基本注解
路径变量: 矩阵变量: 就是在路径变量后面加分号的 键值关系 面试题:如果cookie被禁用了 如和获取到session的值 可以将sessionid值是用矩阵变量来进行传输
@RestController 表示一个Rest风格的Controller @Pathvariable注解的作用 获取路径变量 @RequestHeader获取请求头 @RequestParam获取请求参数 @CookieValue获取cookie的值 @ReqeustBody获取请求体
都可以使用map接收如下 @RequestAttribute获取request域属性值
@MatrixVariable获取矩阵变量 路径变量绑定了矩阵变量 这里获取的path就只是sell 手动开启矩阵变量
@RestController
public class ParameterTestController {
// car/2/owner/zhangsan
@GetMapping("/car/{id}/owner/{username}")
public Map<String,Object> getCar(@PathVariable("id") Integer id,
@PathVariable("username") String name,
@PathVariable Map<String,String> pv,
@RequestHeader("User-Agent") String userAgent,
@RequestHeader Map<String,String> header,
@RequestParam("age") Integer age,
@RequestParam("inters") List<String> inters,
@RequestParam Map<String,String> params,
@CookieValue("_ga") String _ga,
@CookieValue("_ga") Cookie cookie){
Map<String,Object> map = new HashMap<>();
// map.put("id",id);
// map.put("name",name);
// map.put("pv",pv);
// map.put("userAgent",userAgent);
// map.put("headers",header);
map.put("age",age);
map.put("inters",inters);
map.put("params",params);
map.put("_ga",_ga);
System.out.println(cookie.getName()+"===>"+cookie.getValue());
return map;
}
@PostMapping("/save")
public Map postMethod(@RequestBody String content){
Map<String,Object> map = new HashMap<>();
map.put("content",content);
return map;
}
//1、语法: 请求路径:/cars/sell;low=34;brand=byd,audi,yd
//2、SpringBoot默认是禁用了矩阵变量的功能
// 手动开启:原理。对于路径的处理。UrlPathHelper进行解析。
// removeSemicolonContent(移除分号内容)支持矩阵变量的
//3、矩阵变量必须有url路径变量才能被解析
@GetMapping("/cars/{path}")
public Map carsSell(@MatrixVariable("low") Integer low,
@MatrixVariable("brand") List<String> brand,
@PathVariable("path") String path){
Map<String,Object> map = new HashMap<>();
map.put("low",low);
map.put("brand",brand);
map.put("path",path);
return map;
}
// /boss/1;age=20/2;age=10
@GetMapping("/boss/{bossId}/{empId}")
public Map boss(@MatrixVariable(value = "age",pathVar = "bossId") Integer bossAge,
@MatrixVariable(value = "age",pathVar = "empId") Integer empAge){
Map<String,Object> map = new HashMap<>();
map.put("bossAge",bossAge);
map.put("empAge",empAge);
return map;
}
}
请求参数绑定原理
复杂参数绑定
Map和Model为何会放在request域当中 Map、**Model(map、model里面的数据会被放在request的请求域 request.setAttribute)、**Errors/BindingResult、RedirectAttributes( 重定向携带数据)、ServletResponse(response)、SessionStatus、UriComponentsBuilder、ServletUriComponentsBuilder
Map<String,Object> map, Model model, HttpServletRequest request 都是可以给request域中放数据,
request.getAttribute();
Map、Model类型的参数,会返回 mavContainer.getModel();---> BindingAwareModelMap 是Model 也是Map mavContainer.getModel(); 获取到值的
在目标方法执行完成之后
将所有的数据都放在 ModelAndViewContainer;包含要去的页面地址View。还包含Model数据
如果此方法返回了,就会处理派发结果 中央处理器就会暴露model和map作为请求域的属性 processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
renderMergedOutputModel(mergedModel, getRequestToExpose(request), response);
InternalResourceView:
@Override
protected void renderMergedOutputModel(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
// Expose the model object as request attributes.
exposeModelAsRequestAttributes(model, request);
// Expose helpers as request attributes, if any.
exposeHelpers(request);
// Determine the path for the request dispatcher.
String dispatcherPath = prepareForRendering(request, response);
// Obtain a RequestDispatcher for the target resource (typically a JSP).
RequestDispatcher rd = getRequestDispatcher(request, dispatcherPath);
if (rd == null) {
throw new ServletException("Could not get RequestDispatcher for [" + getUrl() +
"]: Check that the corresponding file exists within your web application archive!");
}
// If already included or response already committed, perform include, else forward.
if (useInclude(request, response)) {
response.setContentType(getContentType());
if (logger.isDebugEnabled()) {
logger.debug("Including [" + getUrl() + "]");
}
rd.include(request, response);
}
else {
// Note: The forwarded resource is supposed to determine the content type itself.
if (logger.isDebugEnabled()) {
logger.debug("Forwarding to [" + getUrl() + "]");
}
rd.forward(request, response);
}
}
暴露模型作为请求域属性
// Expose the model object as request attributes.
exposeModelAsRequestAttributes(model, request);
protected void exposeModelAsRequestAttributes(Map<String, Object> model,
HttpServletRequest request) throws Exception {
//model中的所有数据遍历挨个放在请求域中
model.forEach((name, value) -> {
if (value != null) {
request.setAttribute(name, value);
}
else {
request.removeAttribute(name);
}
});
}
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