@SpringBootApplication
public class DemoServiceApplication {
public static void main(String[] args) {
SpringApplication.run(DemoServiceApplication.class, args);
}
}
java复制代码
@RestController
public class HelloController {
@PatchMapping("/hello")
// above statement is a shortcut for below statement
// @RequestMapping(value = "/hello", method = RequestMethod.PATCH)
public ResponseData hello() {
return ResponseData.success(null);
}
@PutMapping ("/hello")
// above statement is a shortcut for below statement
// @RequestMapping(value = "/hello", method = RequestMethod.PUT)
public ResponseData hello2() {
return ResponseData.success(null);
}
}
package jakarta.servlet.http;
public abstract class HttpServlet extends GenericServlet {
// ...
/**
* Dispatches client requests to the protected service method. There's no need to override this method.
* ...
*/
@Override
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
HttpServletRequest request;
HttpServletResponse response;
try {
request = (HttpServletRequest) req;
response = (HttpServletResponse) res;
} catch (ClassCastException e) {
throw new ServletException(lStrings.getString("http.non_http"));
}
service(request, response);
}
// ...
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String method = req.getMethod();
if (method.equals(METHOD_GET)) {
// ..
doGet(req, resp);
// ...
} else if (method.equals(METHOD_HEAD)) {
// ..
doHead(req, resp);
} else if (method.equals(METHOD_POST)) {
doPost(req, resp);
} else if (method.equals(METHOD_PUT)) {
doPut(req, resp);
} else if (method.equals(METHOD_DELETE)) {
doDelete(req, resp);
} else if (method.equals(METHOD_OPTIONS)) {
doOptions(req, resp);
} else if (method.equals(METHOD_TRACE)) {
doTrace(req, resp);
} else {
// Note that this means NO servlet supports whatever
// method was requested, anywhere on this server.
}
}
// ...
}
java复制代码
package org.springframework.web.servlet;
public abstract class HttpServletBean extends HttpServlet implements EnvironmentCapable, EnvironmentAware {
// ...
// no override service(), subclass `FrameworkServlet` will implement this method
// ...
}
java复制代码
package org.springframework.web.servlet;
public abstract class FrameworkServlet extends HttpServletBean implements ApplicationContextAware {
// ...
private static final Set<String> HTTP_SERVLET_METHODS =
Set.of("DELETE", "HEAD", "GET", "OPTIONS", "POST", "PUT", "TRACE");
// ...
/**
* Override the parent class implementation in order to intercept requests
* using PATCH or non-standard HTTP methods (WebDAV).
*/
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if (HTTP_SERVLET_METHODS.contains(request.getMethod())) {
super.service(request, response);
} // PATCH is missing, so process will go here
else {
processRequest(request, response);
}
}
// ...
@Override
protected final void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Delegate POST requests to {@link #processRequest}.
* @see #doService
*/
@Override
protected final void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Delegate PUT requests to {@link #processRequest}.
* @see #doService
*/
@Override
protected final void doPut(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Delegate DELETE requests to {@link #processRequest}.
* @see #doService
*/
@Override
protected final void doDelete(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Delegate OPTIONS requests to {@link #processRequest}, if desired.
* <p>Applies HttpServlet's standard OPTIONS processing otherwise,
* and also if there is still no 'Allow' header set after dispatching.
* @see #doService
*/
@Override
protected void doOptions(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if (this.dispatchOptionsRequest || CorsUtils.isPreFlightRequest(request)) {
processRequest(request, response);
if (response.containsHeader(HttpHeaders.ALLOW)) {
// Proper OPTIONS response coming from a handler - we're done.
return;
}
}
// Use response wrapper in order to always add PATCH to the allowed methods
super.doOptions(request, new HttpServletResponseWrapper(response) {
@Override
public void setHeader(String name, String value) {
if (HttpHeaders.ALLOW.equals(name)) {
value = (StringUtils.hasLength(value) ? value + ", " : "") + HttpMethod.PATCH.name();
}
super.setHeader(name, value);
}
});
}
/**
* Delegate TRACE requests to {@link #processRequest}, if desired.
* <p>Applies HttpServlet's standard TRACE processing otherwise.
* @see #doService
*/
@Override
protected void doTrace(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
if (this.dispatchTraceRequest) {
processRequest(request, response);
if ("message/http".equals(response.getContentType())) {
// Proper TRACE response coming from a handler - we're done.
return;
}
}
super.doTrace(request, response);
}
/**
* Process this request, publishing an event regardless of the outcome.
* <p>The actual event handling is performed by the abstract
* {@link #doService} template method.
*/
protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
long startTime = System.currentTimeMillis();
Throwable failureCause = null;
LocaleContext previousLocaleContext = LocaleContextHolder.getLocaleContext();
LocaleContext localeContext = buildLocaleContext(request);
RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();
ServletRequestAttributes requestAttributes = buildRequestAttributes(request, response, previousAttributes);
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new RequestBindingInterceptor());
initContextHolders(request, localeContext, requestAttributes);
try {
doService(request, response);
}
catch (ServletException | IOException ex) {
failureCause = ex;
throw ex;
}
catch (Throwable ex) {
failureCause = ex;
throw new ServletException("Request processing failed: " + ex, ex);
}
finally {
resetContextHolders(request, previousLocaleContext, previousAttributes);
if (requestAttributes != null) {
requestAttributes.requestCompleted();
}
logResult(request, response, failureCause, asyncManager);
publishRequestHandledEvent(request, response, startTime, failureCause);
}
}
// ...
protected abstract void doService(HttpServletRequest request, HttpServletResponse response) throws Exception;
// ...
}
java复制代码
package org.springframework.web.servlet;
public class DispatcherServlet extends FrameworkServlet {
// ...
@Override
protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
// ...
try {
doDispatch(request, response);
}
finally {
// ...
}
// ...
}
// ...
/**
* Process the actual dispatching to the handler.
* The handler will be obtained by applying the servlet's HandlerMappings in order.
* The HandlerAdapter will be obtained by querying the servlet's installed HandlerAdapters to find the first that supports the handler class.
* All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers themselves to decide which methods are acceptable.
*/
@SuppressWarnings("deprecation")
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
// ...
try {
// ...
try {
// ...
// Determine handler for the current request.
// important here
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());
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
applyDefaultViewName(processedRequest, mv);
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
// catch()
}
//catch()
}
// ...
/**
* Return the HandlerExecutionChain for this request.
* <p>Tries all handler mappings in order.
*/
@Nullable
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;
}
// ...
}
package org.springframework.web.method;
public class HandlerMethod {
// ...
public HandlerMethod createWithResolvedBean() {
Object handler = this.bean;
// default would go here
if (this.bean instanceof String beanName) {
Assert.state(this.beanFactory != null, "Cannot resolve bean name without BeanFactory");
handler = this.beanFactory.getBean(beanName);
}
return new HandlerMethod(this, handler);
}
// ...
}
