spring-mvc-执行流程
不要问我阅读spring源码有什么用,问就是没有用,只是让我本身使用spring的过程当中自信点!java
相关文章
spring-相关文章web
相关连接
- spring-mvc-handlerMapping 是怎么存放咱们的请求路径的-源码
- springmvc-执行流程
- spring-mvc 时如何选择 messageConverter
- springMVC-Interceptor-源码分析
说明如下几点:
- 本文针对的是普通的请求(处理@Controller).
- spring-mvc 的执行流程很简单,主要就是经过java反射执行方法
- 执行目标为handlerMethod(假如不懂请看juejin.im/post/5ddf84…)
- 虽然执行流程很简单,可是也很难,难在对请求参数的处理.
- 内容会不少
开始
直接上代码了spring
org.springframework.web.servlet.DispatcherServlet.doDispatch()json
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);
// Determine handler for the current request.
//获取执行链
mappedHandler = getHandler(processedRequest);
if (mappedHandler == null) {
noHandlerFound(processedRequest, response);
return;
}
// Determine handler adapter for the current request.
//获取适配器
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
// Process last-modified header, if supported by the handler.
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
//执行 拦截器
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// Actually invoke the handler.
// 今天的重点,处理请求 进入这个方法
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
applyDefaultViewName(processedRequest, mv);
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
......................................
}
@Override
protected ModelAndView handleInternal(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ModelAndView mav;
// 检查请求参数
checkRequest(request);
// Execute invokeHandlerMethod in synchronized block if required.
if (this.synchronizeOnSession) {
//这里应该是处理异步的,不清楚
HttpSession session = request.getSession(false);
if (session != null) {
Object mutex = WebUtils.getSessionMutex(session);
synchronized (mutex) {
mav = invokeHandlerMethod(request, response, handlerMethod);
}
}
else {
// No HttpSession available -> no mutex necessary
mav = invokeHandlerMethod(request, response, handlerMethod);
}
}
else {
// No synchronization on session demanded at all...
//这里 主线 进入方法
mav = invokeHandlerMethod(request, response, handlerMethod);
}
if (!response.containsHeader(HEADER_CACHE_CONTROL)) {
if (getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) {
applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers);
}
else {
prepareResponse(response);
}
}
return mav;
}
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
.......................................
// 这里 进入主线
invocableMethod.invokeAndHandle(webRequest, mavContainer);
if (asyncManager.isConcurrentHandlingStarted()) {
return null;
}
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
// 这里 是主线 返回了 响应结果 进入方法
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
setResponseStatus(webRequest);
if (returnValue == null) {
if (isRequestNotModified(webRequest) || getResponseStatus() != null || mavContainer.isRequestHandled()) {
mavContainer.setRequestHandled(true);
return;
}
}
else if (StringUtils.hasText(getResponseStatusReason())) {
mavContainer.setRequestHandled(true);
return;
}
mavContainer.setRequestHandled(false);
Assert.state(this.returnValueHandlers != null, "No return value handlers");
try {
//处理响应结果 例如返回的是json 仍是 xml,今天不说,下篇文章会说,也很重要
this.returnValueHandlers.handleReturnValue(
returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
}
catch (Exception ex) {
if (logger.isTraceEnabled()) {
logger.trace(formatErrorForReturnValue(returnValue), ex);
}
throw ex;
}
}
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
// 这篇文 最重要的地方,没有之一 获取请求参数
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
if (logger.isTraceEnabled()) {
logger.trace("Arguments: " + Arrays.toString(args));
}
//继续执行流程 从名字大概也能够猜到
return doInvoke(args);
}
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
if (ObjectUtils.isEmpty(getMethodParameters())) {
return EMPTY_ARGS;
}
//MethodParameter 描述的 是 方法参数 : 包含 Method classType 参数下标
//下面的代码都是围绕这 MethodParameter进行的 因此咱们稍微的去看看 MethodParameter 在哪里注册的.
//是在 注册 handlerMethod 的时候 被赋值的 因此咱们应该是从 requestMappingHandlerMapping 的afterPropertiesSet //开始看,可是咱们上篇已经讲过了一部分的 requestMappingHandlerMapping 因此不细说了.
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;
}
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
// Leave stack trace for later, exception may actually be resolved and handled..
if (logger.isDebugEnabled()) {
String error = ex.getMessage();
if (error != null && !error.contains(parameter.getExecutable().toGenericString())) {
logger.debug(formatArgumentError(parameter, error));
}
}
throw ex;
}
}
return args;
}
复制代码
parameters 是如何被加载的
//从这行代码能够看到 值就是 methodhandler 的 parameters属性
public MethodParameter[] getMethodParameters() {
return this.parameters;
}
//直接到 建立methodHandler 的地方
protected HandlerMethod createHandlerMethod(Object handler, Method method) {
HandlerMethod handlerMethod;
if (handler instanceof String) {
String beanName = (String) handler;
//new 了 一个 methodHandler
handlerMethod = new HandlerMethod(beanName,
obtainApplicationContext().getAutowireCapableBeanFactory(), method);
}
else {
handlerMethod = new HandlerMethod(handler, method);
}
return handlerMethod;
}
//HandlerMethod 的构造方法
public HandlerMethod(String beanName, BeanFactory beanFactory, Method method) {
//这一些赋值不说了,一目了然
Assert.hasText(beanName, "Bean name is required");
Assert.notNull(beanFactory, "BeanFactory is required");
Assert.notNull(method, "Method is required");
this.bean = beanName;
this.beanFactory = beanFactory;
Class<?> beanType = beanFactory.getType(beanName);
if (beanType == null) {
throw new IllegalStateException("Cannot resolve bean type for bean with name '" + beanName + "'");
}
this.beanType = ClassUtils.getUserClass(beanType);
this.method = method;
//这个地方其实就是把 Method 赋值给 bridgedMethod
this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
//在这个地方 给 parameters 赋值
this.parameters = initMethodParameters();
evaluateResponseStatus();
}
//建立MethodParameter
private MethodParameter [] initMethodParameters() {
//上面说过了 bridgedMethod 就是 method,说明方法存在几个参数,parameters 的长度就是多少
int count = this.bridgedMethod.getParameterCount();
MethodParameter[] result = new MethodParameter[count];
for (int i = 0; i < count; i++) {
//调用 HandlerMethodParameter的构造方法,i 这个参数是下标,别干别的事,里面不看了
HandlerMethodParameter parameter = new HandlerMethodParameter(i);
//修改 建立的HandlerMethodParameter 里面也就是对parmeter 一系列的赋值
GenericTypeResolver.resolveParameterType(parameter, this.beanType);
result[i] = parameter;
}
//结束
//可是,注意,这个HandlerMethodParameter 里面 存在 描述 参数名 的属性,可是如今并无值.
return result;
}
复制代码
上面看了 parameters是如何被赋值的,如今接着看
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
if (ObjectUtils.isEmpty(getMethodParameters())) {
return EMPTY_ARGS;
}
//刚刚看到了这里,如今接着看
MethodParameter[] parameters = getMethodParameters();
//建立一个空的 定长的数组,用来存放请求参数
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
//获取 MethodParameter
MethodParameter parameter = parameters[i];
//赋值操做,是个处理器
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
//这里挺重要的,这里的做用是判断是否存在能处理当前参数的解析器,假如存在就放入缓存(map)
//key 为 parameter value 为 resolvers 里面调用了 getArgumentResolver 下面代码还会再次调用
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
//这里 进入代码
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
// Leave stack trace for later, exception may actually be resolved and handled..
if (logger.isDebugEnabled()) {
String error = ex.getMessage();
if (error != null && !error.contains(parameter.getExecutable().toGenericString())) {
logger.debug(formatArgumentError(parameter, error));
}
}
throw ex;
}
}
return args;
}
//获取解析器,并执行
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
//上面说过这个方法还会再次调用,获取解析器
/** *这个方法比较重要,不一样的参数不一样的解析器,比较多,可是不进去看了,咱们只说,两种状况,1参数为实体类的状况,2参数为基本类型和String *1 的 处理器 为: ServletModelAttributeMethodProcessor(获取的) *ModelAttributeMethodProcessor(实际执行的,父子关系) *2 的 处理器 为:RequestParamMethodArgumentResolver(获取的) AbstractNamedValueMethodArgumentResolver(实际执行的,父子关系) */
HandlerMethodArgumentResolver resolver = getArgumentResolver(parameter);
if (resolver == null) {
throw new IllegalArgumentException(
"Unsupported parameter type [" + parameter.getParameterType().getName() + "]." +
" supportsParameter should be called first.");
}
//执行
return resolver.resolveArgument(parameter, mavContainer, webRequest, binderFactory);
}
复制代码
AbstractNamedValueMethodArgumentResolver
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
//这个方法重点看下 主要就是建立 NamedValueInfo
NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
MethodParameter nestedParameter = parameter.nestedIfOptional();
Object resolvedName = resolveStringValue(namedValueInfo.name);
if (resolvedName == null) {
throw new IllegalArgumentException(
"Specified name must not resolve to null: [" + namedValueInfo.name + "]");
}
Object arg = resolveName(resolvedName.toString(), nestedParameter, webRequest);
if (arg == null) {
if (namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
else if (namedValueInfo.required && !nestedParameter.isOptional()) {
handleMissingValue(namedValueInfo.name, nestedParameter, webRequest);
}
arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
}
else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
if (binderFactory != null) {
WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
try {
arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
}
catch (ConversionNotSupportedException ex) {
throw new MethodArgumentConversionNotSupportedException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
catch (TypeMismatchException ex) {
throw new MethodArgumentTypeMismatchException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
}
handleResolvedValue(arg, namedValueInfo.name, parameter, mavContainer, webRequest);
return arg;
}
//建立 NamedValueInfo
private NamedValueInfo getNamedValueInfo(MethodParameter parameter) {
NamedValueInfo namedValueInfo = this.namedValueInfoCache.get(parameter);
if (namedValueInfo == null) {
// 里面 代码是 new RequestParamNamedValueInfo();
//建立出来的 属性 name value 都是空的
namedValueInfo = createNamedValueInfo(parameter);
// 给 namedValueInfo name 赋值 就是根据 parameter 的下标属性 java反射 获取参数名称 ,东西太多了 不看了
namedValueInfo = updateNamedValueInfo(parameter, namedValueInfo);
this.namedValueInfoCache.put(parameter, namedValueInfo);
}
return namedValueInfo;
}
<font color=#0034fff>//接着看主线代码 </font>
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
//获取了 namedValueInfo 三个属性,name,defaultValue,required ,参数名,参数值,是否必须
//如今 尚未参数值
NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
MethodParameter nestedParameter = parameter.nestedIfOptional();
Object resolvedName = resolveStringValue(namedValueInfo.name);
if (resolvedName == null) {
throw new IllegalArgumentException(
"Specified name must not resolve to null: [" + namedValueInfo.name + "]");
}
//重点之一,获取值,可是获取的是个Object 类型的值 点进去看看 是如何获取值的
Object arg = resolveName(resolvedName.toString(), nestedParameter, webRequest);
....................................
handleResolvedValue(arg, namedValueInfo.name, parameter, mavContainer, webRequest);
return arg;
}
//获取值,可是object类型的值
protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
if (servletRequest != null) {
Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
return mpArg;
}
}
Object arg = null;
MultipartRequest multipartRequest = request.getNativeRequest(MultipartRequest.class);
if (multipartRequest != null) {
List<MultipartFile> files = multipartRequest.getFiles(name);
if (!files.isEmpty()) {
arg = (files.size() == 1 ? files.get(0) : files);
}
}
if (arg == null) {
<font color=#0034fff>// 看到了吧 是根绝getParameterValues获取值,这个方法相信你们都很熟悉</font>
String[] paramValues = request.getParameterValues(name);
if (paramValues != null) {
arg = (paramValues.length == 1 ? paramValues[0] : paramValues);
}
}
return arg;
}
<font color=#0034fff>//接着看主线代码 </font>
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
MethodParameter nestedParameter = parameter.nestedIfOptional();
Object resolvedName = resolveStringValue(namedValueInfo.name);
if (resolvedName == null) {
throw new IllegalArgumentException(
"Specified name must not resolve to null: [" + namedValueInfo.name + "]");
}
//获取值,上面说了这个值是 Object 类型的,全部说确定会有类型转化的过程
Object arg = resolveName(resolvedName.toString(), nestedParameter, webRequest);
if (arg == null) {
if (namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
else if (namedValueInfo.required && !nestedParameter.isOptional()) {
handleMissingValue(namedValueInfo.name, nestedParameter, webRequest);
}
arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
}
else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
arg = resolveStringValue(namedValueInfo.defaultValue);
}
if (binderFactory != null) {
WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
try {
//这里作了类型转化 点进去看下
arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
}
catch (ConversionNotSupportedException ex) {
throw new MethodArgumentConversionNotSupportedException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
catch (TypeMismatchException ex) {
throw new MethodArgumentTypeMismatchException(arg, ex.getRequiredType(),
namedValueInfo.name, parameter, ex.getCause());
}
}
handleResolvedValue(arg, namedValueInfo.name, parameter, mavContainer, webRequest);
return arg;
}
//最后来到了org.springframework.core.convert.support.ConversionUtils.invokeConverter(GenericConverter, Object, TypeDescriptor, TypeDescriptor)
@Override
@Nullable
public static Object invokeConverter(GenericConverter converter, @Nullable Object source,
TypeDescriptor sourceType, TypeDescriptor targetType) {
try {
//这里 执行的 三个参数 值,元类型,目标类型
return converter.convert(source, sourceType, targetType);
}
catch (ConversionFailedException ex) {
throw ex;
}
catch (Throwable ex) {
throw new ConversionFailedException(sourceType, targetType, source, ex);
}
}
复制代码
//spring 写了好多类型之间的转化器 数组
//随便找一个点进去,你会发现用的也是jdk spring-mvc
ModelAttributeMethodProcessor(处理实体类参数)
//处理实体类参数
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");
Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");
//获取实体类的名称
String name = ModelFactory.getNameForParameter(parameter);
ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
if (ann != null) {
mavContainer.setBinding(name, ann.binding());
}
Object attribute = null;
BindingResult bindingResult = null;
if (mavContainer.containsAttribute(name)) {
attribute = mavContainer.getModel().get(name);
}
else {
// Create attribute instance
try {
<font color=#0034fff>//这里要关注下,功能是建立你请求的实体类,假如你接收参数的实体类存在无参构造器则使用无参构造器
//假如没有无参构造器,则使用有参构造器,并赋值.
//通常状况都是无参构造器
//进入代码看下
</font>
attribute = createAttribute(name, parameter, binderFactory, webRequest);
}
...............................................................
}
//建立请求实体参数,假如是有参构造器则同时赋值 (但也不必定所有属性都赋值)
protected Object createAttribute(String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
MethodParameter nestedParameter = parameter.nestedIfOptional();
Class<?> clazz = nestedParameter.getNestedParameterType();
//获取默认构造器(无参构造器)
Constructor<?> ctor = BeanUtils.findPrimaryConstructor(clazz);
if (ctor == null) {
//假如没有默认构造器,则获取全部构造器
Constructor<?>[] ctors = clazz.getConstructors();
if (ctors.length == 1) {
//选择第一个构造器
ctor = ctors[0];
}
else {
try {
ctor = clazz.getDeclaredConstructor();
}
catch (NoSuchMethodException ex) {
throw new IllegalStateException("No primary or default constructor found for " + clazz, ex);
}
}
}
//建立并赋值
Object attribute = constructAttribute(ctor, attributeName, parameter, binderFactory, webRequest);
if (parameter != nestedParameter) {
attribute = Optional.of(attribute);
}
return attribute;
}
protected Object constructAttribute(Constructor<?> ctor, String attributeName, MethodParameter parameter,
WebDataBinderFactory binderFactory, NativeWebRequest webRequest) throws Exception {
..................................................
ConstructorProperties cp = ctor.getAnnotation(ConstructorProperties.class);
//获取构造器 参数名称
String[] paramNames = (cp != null ? cp.value() : parameterNameDiscoverer.getParameterNames(ctor));
Assert.state(paramNames != null, () -> "Cannot resolve parameter names for constructor " + ctor);
Class<?>[] paramTypes = ctor.getParameterTypes();
Assert.state(paramNames.length == paramTypes.length,
() -> "Invalid number of parameter names: " + paramNames.length + " for constructor " + ctor);
Object[] args = new Object[paramTypes.length];
WebDataBinder binder = binderFactory.createBinder(webRequest, null, attributeName);
String fieldDefaultPrefix = binder.getFieldDefaultPrefix();
String fieldMarkerPrefix = binder.getFieldMarkerPrefix();
boolean bindingFailure = false;
Set<String> failedParams = new HashSet<>(4);
//循环操做
for (int i = 0; i < paramNames.length; i++) {
String paramName = paramNames[i];
Class<?> paramType = paramTypes[i];
//仍是用的这个方法
Object value = webRequest.getParameterValues(paramName);
if (value == null) {
if (fieldDefaultPrefix != null) {
value = webRequest.getParameter(fieldDefaultPrefix + paramName);
}
if (value == null && fieldMarkerPrefix != null) {
if (webRequest.getParameter(fieldMarkerPrefix + paramName) != null) {
value = binder.getEmptyValue(paramType);
}
}
}
try {
MethodParameter methodParam = new FieldAwareConstructorParameter(ctor, i, paramName);
if (value == null && methodParam.isOptional()) {
args[i] = (methodParam.getParameterType() == Optional.class ? Optional.empty() : null);
}
else {
//去绑定,就是去作类型转化,里面的参数就个 上面讲的同样了,就不说了.
args[i] = binder.convertIfNecessary(value, paramType, methodParam);
}
}
..........................................................................
<font color=#0034fff>//回到主线</font>
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
...................................................
if (mavContainer.containsAttribute(name)) {
attribute = mavContainer.getModel().get(name);
}
else {
// Create attribute instance
try {
//获取 请求类型 实例
attribute = createAttribute(name, parameter, binderFactory, webRequest);
}
catch (BindException ex) {
if (isBindExceptionRequired(parameter)) {
// No BindingResult parameter -> fail with BindException
throw ex;
}
// Otherwise, expose null/empty value and associated BindingResult
if (parameter.getParameterType() == Optional.class) {
attribute = Optional.empty();
}
bindingResult = ex.getBindingResult();
}
}
if (bindingResult == null) {
// Bean property binding and validation;
// skipped in case of binding failure on construction.
WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
if (binder.getTarget() != null) {
if (!mavContainer.isBindingDisabled(name)) {
//这个方法 重要 赋值 在里面完成的
bindRequestParameters(binder, webRequest);
}
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
throw new BindException(binder.getBindingResult());
}
}
// Value type adaptation, also covering java.util.Optional
if (!parameter.getParameterType().isInstance(attribute)) {
attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
}
bindingResult = binder.getBindingResult();
}
// Add resolved attribute and BindingResult at the end of the model
Map<String, Object> bindingResultModel = bindingResult.getModel();
mavContainer.removeAttributes(bindingResultModel);
mavContainer.addAllAttributes(bindingResultModel);
return attribute;
}
//赋值 和类型转换
public void bind(ServletRequest request) {
//这个里面完成的获取值 可是还没赋值
MutablePropertyValues mpvs = new ServletRequestParameterPropertyValues(request);
MultipartRequest multipartRequest = WebUtils.getNativeRequest(request, MultipartRequest.class);
if (multipartRequest != null) {
bindMultipart(multipartRequest.getMultiFileMap(), mpvs);
}
addBindValues(mpvs, request);
//完成的绑定 就不看了 这篇说的太多了,不想继续写了.
doBind(mpvs);
}
public ServletRequestParameterPropertyValues(
ServletRequest request, @Nullable String prefix, @Nullable String prefixSeparator) {
super(WebUtils.getParametersStartingWith(
request, (prefix != null ? prefix + prefixSeparator : null)));
}
//获取值的方法 到这里也就没有了.
public static Map<String, Object> getParametersStartingWith(ServletRequest request, @Nullable String prefix) {
Assert.notNull(request, "Request must not be null");
//获取全部参数
Enumeration<String> paramNames = request.getParameterNames();
Map<String, Object> params = new TreeMap<>();
if (prefix == null) {
prefix = "";
}
while (paramNames != null && paramNames.hasMoreElements()) {
String paramName = paramNames.nextElement();
if ("".equals(prefix) || paramName.startsWith(prefix)) {
String unprefixed = paramName.substring(prefix.length());
//获取值 都是用的getParameterValues
String[] values = request.getParameterValues(paramName);
if (values == null || values.length == 0) {
// Do nothing, no values found at all.
}
else if (values.length > 1) {
params.put(unprefixed, values);
}
else {
params.put(unprefixed, values[0]);
}
}
}
return params;
}
复制代码
执行流程继续 主线
其实剩下的东西没啥要说的了,就是贴下代码吧缓存
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
//上面 这么多 都是说这行代码 就是获取到了请求参数,而且保证了顺序
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
if (logger.isTraceEnabled()) {
logger.trace("Arguments: " + Arrays.toString(args));
}
//执行
return doInvoke(args);
}
@Nullable
protected Object doInvoke(Object... args) throws Exception {
ReflectionUtils.makeAccessible(getBridgedMethod());
try {
//这里 结束了 调用了方法 使用的是 java 的 反射
return getBridgedMethod().invoke(getBean(), args);
}
catch (IllegalArgumentException ex) {
assertTargetBean(getBridgedMethod(), getBean(), args);
String text = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
throw new IllegalStateException(formatInvokeError(text, args), ex);
}
catch (InvocationTargetException ex) {
// Unwrap for HandlerExceptionResolvers ...
Throwable targetException = ex.getTargetException();
if (targetException instanceof RuntimeException) {
throw (RuntimeException) targetException;
}
else if (targetException instanceof Error) {
throw (Error) targetException;
}
else if (targetException instanceof Exception) {
throw (Exception) targetException;
}
else {
throw new IllegalStateException(formatInvokeError("Invocation failure", args), targetException);
}
}
}
复制代码
总结
- 正常的请求(controller)的原理是java的反射
- spring保存了请求方法和对应路径
- 请求的时候获取参数的过程很难,类型也不少
- 获取参数都是使用 HttpServletRequest 的相关获取参数的方法
- 会作一个类型转换,例如你接收一个Integer,可是刚到spring的时候类型是string,spring本身作的作换,因此说假如不符合java类型转化的规则会报错. 例如 接收参数 Integer age 你传值 sb 会报错,这个错实际上是java报的.
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