SpringMVC跨域解析
【摘要】 《读尽源码 第十二篇》
CrossOrigin注解
- 通过注解设置跨域 demo 如下
package com.huifer.source.controller;
import org.springframework.web.bind.annotation.*;
import java.util.HashMap;
@CrossOrigin(maxAge = 3600)
@RequestMapping("/")
@RestController
public class JSONController {
@ResponseBody
@GetMapping(value = "/json")
public Object ob() {
HashMap<String, String> hashMap = new HashMap<>();
hashMap.put("1", "a");
return hashMap;
}
}
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切入点:
-
org.springframework.web.servlet.handler.AbstractHandlerMethodMapping#registerHandlerMethod
- org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.MappingRegistry#register方法
/** * 注册方法 将controller 相关信息存储 * * @param mapping 请求地址 * @param handler 处理类 * @param method 函数 */ public void register(T mapping, Object handler, Method method) { // 上锁 this.readWriteLock.writeLock().lock(); try { // 创建 HandlerMethod , 通过 handler 创建处理的对象(controller) HandlerMethod handlerMethod = createHandlerMethod(handler, method); assertUniqueMethodMapping(handlerMethod, mapping); // 设置值 this.mappingLookup.put(mapping, handlerMethod); // 获取url List<String> directUrls = getDirectUrls(mapping); for (String url : directUrls) { // 设置 this.urlLookup.add(url, mapping); } String name = null; if (getNamingStrategy() != null) { name = getNamingStrategy().getName(handlerMethod, mapping); addMappingName(name, handlerMethod); } /** * 跨域设置 * {@link org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#initCorsConfiguration(Object, Method, RequestMappingInfo)} **/ CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping); if (corsConfig != null) { this.corsLookup.put(handlerMethod, corsConfig); } this.registry.put(mapping, new MappingRegistration<>(mapping, handlerMethod, directUrls, name)); } finally { // 开锁 this.readWriteLock.writeLock().unlock(); } } Copy to clipboardErrorCopied
-
-
着重查看**CorsConfiguration**初始化方法
- org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#initCorsConfiguration
@Override
protected CorsConfiguration initCorsConfiguration(Object handler, Method method, RequestMappingInfo mappingInfo) {
// 重新创建,为什么不作为参数传递: 还有别的实现方法
HandlerMethod handlerMethod = createHandlerMethod(handler, method);
// 获取bean
Class<?> beanType = handlerMethod.getBeanType();
// 获取注解信息
CrossOrigin typeAnnotation = AnnotatedElementUtils.findMergedAnnotation(beanType, CrossOrigin.class);
CrossOrigin methodAnnotation = AnnotatedElementUtils.findMergedAnnotation(method, CrossOrigin.class);
if (typeAnnotation == null && methodAnnotation == null) {
return null;
}
CorsConfiguration config = new CorsConfiguration();
// 更新跨域信息
updateCorsConfig(config, typeAnnotation);
updateCorsConfig(config, methodAnnotation);
if (CollectionUtils.isEmpty(config.getAllowedMethods())) {
for (RequestMethod allowedMethod : mappingInfo.getMethodsCondition().getMethods()) {
config.addAllowedMethod(allowedMethod.name());
}
}
// 返回跨域配置默认值
return config.applyPermitDefaultValues();
}Copy to clipboardErrorCopied信息截图:
updateCorsConfig
- 该方法对原有的配置信息做补充
private void updateCorsConfig(CorsConfiguration config, @Nullable CrossOrigin annotation) {
if (annotation == null) {
return;
}
for (String origin : annotation.origins()) {
config.addAllowedOrigin(resolveCorsAnnotationValue(origin));
}
for (RequestMethod method : annotation.methods()) {
config.addAllowedMethod(method.name());
}
for (String header : annotation.allowedHeaders()) {
config.addAllowedHeader(resolveCorsAnnotationValue(header));
}
for (String header : annotation.exposedHeaders()) {
config.addExposedHeader(resolveCorsAnnotationValue(header));
}
String allowCredentials = resolveCorsAnnotationValue(annotation.allowCredentials());
if ("true".equalsIgnoreCase(allowCredentials)) {
config.setAllowCredentials(true);
}
else if ("false".equalsIgnoreCase(allowCredentials)) {
config.setAllowCredentials(false);
}
else if (!allowCredentials.isEmpty()) {
throw new IllegalStateException("@CrossOrigin's allowCredentials value must be \"true\", \"false\", " +
"or an empty string (\"\"): current value is [" + allowCredentials + "]");
}
if (annotation.maxAge() >= 0 && config.getMaxAge() == null) {
config.setMaxAge(annotation.maxAge());
}
}
Copy to clipboardErrorCopied最终解析结果
-
解析完成后放入 corsLookup对象中 类:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping
if (corsConfig != null) { this.corsLookup.put(handlerMethod, corsConfig); } Copy to clipboardErrorCopied
xml 配置方式
<mvc:cors>
<mvc:mapping path="/**"
allowed-origins="http://domain1.com, http://domain2.com"
allowed-methods="GET, PUT"
allowed-headers="header1, header2, header3"
exposed-headers="header1, header2" allow-credentials="false"
max-age="3600" />
<mvc:mapping path="/**"
allowed-origins="http://domain1.com" />
</mvc:cors>Copy to clipboardErrorCopied-
mvc标签解析类: org.springframework.web.servlet.config.MvcNamespaceHandler，这个类对 Spring 配置文件中的<mvc:xxx>标签做了解析设定，如这次我们的关注点**CORS**
public class MvcNamespaceHandler extends NamespaceHandlerSupport { /** * 初始化一些SpringMvc 的解析类 */ @Override public void init() { // 注解驱动 registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenBeanDefinitionParser()); // 默认的 servlet 处理器 registerBeanDefinitionParser("default-servlet-handler", new DefaultServletHandlerBeanDefinitionParser()); // 拦截器 registerBeanDefinitionParser("interceptors", new InterceptorsBeanDefinitionParser()); // 资源 registerBeanDefinitionParser("resources", new ResourcesBeanDefinitionParser()); // 视图控制器 registerBeanDefinitionParser("view-controller", new ViewControllerBeanDefinitionParser()); // 重定向视图控制器 registerBeanDefinitionParser("redirect-view-controller", new ViewControllerBeanDefinitionParser()); registerBeanDefinitionParser("status-controller", new ViewControllerBeanDefinitionParser()); // 视图解析器 registerBeanDefinitionParser("view-resolvers", new ViewResolversBeanDefinitionParser()); // tiles 处理器 registerBeanDefinitionParser("tiles-configurer", new TilesConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("freemarker-configurer", new FreeMarkerConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("groovy-configurer", new GroovyMarkupConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("script-template-configurer", new ScriptTemplateConfigurerBeanDefinitionParser()); // 跨域处理 registerBeanDefinitionParser("cors", new CorsBeanDefinitionParser()); } } Copy to clipboardErrorCopied
CorsBeanDefinitionParser
类图
解析
- 实现BeanDefinitionParser 接口的都有一个parse方法直接看方法.
- 通过查看我们可以知道最终目的获取 xml 标签中的属性,对 CorsConfiguration进行初始化，最后 Spring 中注册
public class CorsBeanDefinitionParser implements BeanDefinitionParser {
@Override
@Nullable
public BeanDefinition parse(Element element, ParserContext parserContext) {
Map<String, CorsConfiguration> corsConfigurations = new LinkedHashMap<>();
List<Element> mappings = DomUtils.getChildElementsByTagName(element, "mapping");
if (mappings.isEmpty()) {
// 最简配置
CorsConfiguration config = new CorsConfiguration().applyPermitDefaultValues();
corsConfigurations.put("/**", config);
}
else {
// 单个 mapping 处理
// mvc:mapping 标签
for (Element mapping : mappings) {
// 跨域配置
CorsConfiguration config = new CorsConfiguration();
// 处理每个属性值,并且赋值
if (mapping.hasAttribute("allowed-origins")) {
String[] allowedOrigins = StringUtils.tokenizeToStringArray(mapping.getAttribute("allowed-origins"), ",");
config.setAllowedOrigins(Arrays.asList(allowedOrigins));
}
if (mapping.hasAttribute("allowed-methods")) {
String[] allowedMethods = StringUtils.tokenizeToStringArray(mapping.getAttribute("allowed-methods"), ",");
config.setAllowedMethods(Arrays.asList(allowedMethods));
}
if (mapping.hasAttribute("allowed-headers")) {
String[] allowedHeaders = StringUtils.tokenizeToStringArray(mapping.getAttribute("allowed-headers"), ",");
config.setAllowedHeaders(Arrays.asList(allowedHeaders));
}
if (mapping.hasAttribute("exposed-headers")) {
String[] exposedHeaders = StringUtils.tokenizeToStringArray(mapping.getAttribute("exposed-headers"), ",");
config.setExposedHeaders(Arrays.asList(exposedHeaders));
}
if (mapping.hasAttribute("allow-credentials")) {
config.setAllowCredentials(Boolean.parseBoolean(mapping.getAttribute("allow-credentials")));
}
if (mapping.hasAttribute("max-age")) {
config.setMaxAge(Long.parseLong(mapping.getAttribute("max-age")));
}
corsConfigurations.put(mapping.getAttribute("path"), config.applyPermitDefaultValues());
}
}
// 注册到 Spring
MvcNamespaceUtils.registerCorsConfigurations(
corsConfigurations, parserContext, parserContext.extractSource(element));
return null;
}
}Copy to clipboardErrorCopied-
属性截图
- 可以看出这个是我们的第一个跨域配置的信息
-
注册方法
public static RuntimeBeanReference registerCorsConfigurations( @Nullable Map<String, CorsConfiguration> corsConfigurations, ParserContext context, @Nullable Object source) { // 判断是否包含跨域bean(beanName:mvcCorsConfigurations) if (!context.getRegistry().containsBeanDefinition(CORS_CONFIGURATION_BEAN_NAME)) { RootBeanDefinition corsDef = new RootBeanDefinition(LinkedHashMap.class); corsDef.setSource(source); corsDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE); if (corsConfigurations != null) { corsDef.getConstructorArgumentValues().addIndexedArgumentValue(0, corsConfigurations); } context.getReaderContext().getRegistry().registerBeanDefinition(CORS_CONFIGURATION_BEAN_NAME, corsDef); // 注册组件,并且通知监听器 context.registerComponent(new BeanComponentDefinition(corsDef, CORS_CONFIGURATION_BEAN_NAME)); } else if (corsConfigurations != null) { // 注册bean BeanDefinition corsDef = context.getRegistry().getBeanDefinition(CORS_CONFIGURATION_BEAN_NAME); corsDef.getConstructorArgumentValues().addIndexedArgumentValue(0, corsConfigurations); } return new RuntimeBeanReference(CORS_CONFIGURATION_BEAN_NAME); } Copy to clipboardErrorCopied -
CorsConfiguration
- 跨域信息
/**
* 允许请求源
*/
@Nullable
private List<String> allowedOrigins;
/**
* 允许的http方法
*/
@Nullable
private List<String> allowedMethods;
/**
*
*/
@Nullable
private List<HttpMethod> resolvedMethods = DEFAULT_METHODS;
/**
* 允许的请求头
*/
@Nullable
private List<String> allowedHeaders;
/**
* 返回的响应头
*/
@Nullable
private List<String> exposedHeaders;
/**
* 是否允许携带 cookies
*/
@Nullable
private Boolean allowCredentials;
/**
* 存货有效期
*/
@Nullable
private Long maxAge;Copy to clipboardErrorCopied处理请求
-
请求处理的一部分，前置后置都还有其他处理，这里只对跨域请求进行说明
@Override @Nullable public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { Object handler = getHandlerInternal(request); if (handler == null) { handler = getDefaultHandler(); } if (handler == null) { return null; } // Bean name or resolved handler? if (handler instanceof String) { String handlerName = (String) handler; handler = obtainApplicationContext().getBean(handlerName); } HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request); if (logger.isTraceEnabled()) { logger.trace("Mapped to " + handler); } else if (logger.isDebugEnabled() && !request.getDispatcherType().equals(DispatcherType.ASYNC)) { logger.debug("Mapped to " + executionChain.getHandler()); } // 判断是否为跨域请求 if (CorsUtils.isCorsRequest(request)) { CorsConfiguration globalConfig = this.corsConfigurationSource.getCorsConfiguration(request); // 当前请求的跨域配置 CorsConfiguration handlerConfig = getCorsConfiguration(handler, request); CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig); executionChain = getCorsHandlerExecutionChain(request, executionChain, config); } return executionChain; } Copy to clipboardErrorCopied
判断是否跨域
- org.springframework.web.cors.CorsUtils#isCorsRequest
public static boolean isCorsRequest(HttpServletRequest request) {
// 是否携带 请求头:Origin
return (request.getHeader(HttpHeaders.ORIGIN) != null);
}
Copy to clipboardErrorCopied获取跨域信息
// 判断是否为跨域请求
if (CorsUtils.isCorsRequest(request)) {
CorsConfiguration globalConfig = this.corsConfigurationSource.getCorsConfiguration(request);
// 当前请求的跨域配置
CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);
CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);
executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
}
Copy to clipboardErrorCopied跨域拦截器创建
protected HandlerExecutionChain getCorsHandlerExecutionChain(HttpServletRequest request,
HandlerExecutionChain chain, @Nullable CorsConfiguration config) {
if (CorsUtils.isPreFlightRequest(request)) {
HandlerInterceptor[] interceptors = chain.getInterceptors();
chain = new HandlerExecutionChain(new PreFlightHandler(config), interceptors);
}
else {
// 创建跨域拦截器
chain.addInterceptor(new CorsInterceptor(config));
}
return chain;
}
Copy to clipboardErrorCopied跨域拦截器
/**
* 跨域拦截器
*/
private class CorsInterceptor extends HandlerInterceptorAdapter implements CorsConfigurationSource {
@Nullable
private final CorsConfiguration config;
public CorsInterceptor(@Nullable CorsConfiguration config) {
this.config = config;
}
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
return corsProcessor.processRequest(this.config, request, response);
}
@Override
@Nullable
public CorsConfiguration getCorsConfiguration(HttpServletRequest request) {
return this.config;
}
}
Copy to clipboardErrorCopiedDefaultCorsProcessor
- 经过跨域拦截器 **CorsInterceptor**之后会调用
@Override
@SuppressWarnings("resource")
public boolean processRequest(@Nullable CorsConfiguration config, HttpServletRequest request,
HttpServletResponse response) throws IOException {
// 判断是否跨域请求
if (!CorsUtils.isCorsRequest(request)) {
return true;
}
ServletServerHttpResponse serverResponse = new ServletServerHttpResponse(response);
// 判断是否有 Access-Control-Allow-Origin
if (responseHasCors(serverResponse)) {
logger.trace("Skip: response already contains \"Access-Control-Allow-Origin\"");
return true;
}
ServletServerHttpRequest serverRequest = new ServletServerHttpRequest(request);
if (WebUtils.isSameOrigin(serverRequest)) {
logger.trace("Skip: request is from same origin");
return true;
}
boolean preFlightRequest = CorsUtils.isPreFlightRequest(request);
if (config == null) {
if (preFlightRequest) {
rejectRequest(serverResponse);
return false;
}
else {
return true;
}
}
return handleInternal(serverRequest, serverResponse, config, preFlightRequest);
}
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GET http://localhost:9999/json
Origin: localhostCopy to clipboardErrorCopied变量截图
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