java 拦截、过滤器2
一、概述
在SpringMVC中，除了Filter和Interceptor拦截器外，还有对请求Controller的处理，即对请求和响应内容的处理和对请求参数的处理。
二、ControllerAdvice
@ControllerAdvice本质上同Component一样，因此也会被当成组件扫描。
其中@ExceptionHandler常用到。即抛出的异常会被统一拦截处理。在项目中对MethodArgumentNotValidException异常拦截处理
@ControllerAdvice
public class GlobalHandler {
@ExceptionHandler(MethodArgumentNotValidException.class)
public Result exceptionHandler(MethodArgumentNotValidException e) {
Result result = new Result(BizExceptionEnum.INVALID_REQ_PARAM.getErrorCode(),
BizExceptionEnum.INVALID_REQ_PARAM.getErrorMsg());
logger.error("req params error", e);
return result;
}
}
// 上述对MethodArgumentNotValidException异常统一拦截后并统一返回异常
实现原理：
public class DispatcherServlet extends FrameworkServlet {
// ......
protected void initStrategies(ApplicationContext context) {
initMultipartResolver(context);
initLocaleResolver(context);
initThemeResolver(context);
initHandlerMappings(context);
initHandlerAdapters(context);
// 处理所有异常
initHandlerExceptionResolvers(context);
initRequestToViewNameTranslator(context);
initViewResolvers(context);
initFlashMapManager(context);
}
// ......
}
DispatcherServlet的initHandlerExceptionResolvers(context)方法，方法会取得所有实现了HandlerExceptionResolver接口的bean并保存起来，其中就有一个类型为ExceptionHandlerExceptionResolver的bean，这个bean在应用启动过程中会获取所有被@ControllerAdvice注解标注的bean对象做进一步处理，关键代码在这里
public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExceptionResolver
implements ApplicationContextAware, InitializingBean {
// ......
private void initExceptionHandlerAdviceCache() {
// ......
List<ControllerAdviceBean> adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());
AnnotationAwareOrderComparator.sort(adviceBeans);
for (ControllerAdviceBean adviceBean : adviceBeans) {
ExceptionHandlerMethodResolver resolver = new ExceptionHandlerMethodResolver(adviceBean.getBeanType());
if (resolver.hasExceptionMappings()) {
// 找到所有ExceptionHandler标注的方法并保存成一个ExceptionHandlerMethodResolver类型的对象缓存起来
this.exceptionHandlerAdviceCache.put(adviceBean, resolver);
if (logger.isInfoEnabled()) {
logger.info("Detected @ExceptionHandler methods in " + adviceBean);
}
}
// ......
}
}
}
public ExceptionHandlerMethodResolver(Class<?> handlerType) {
// 查询当前类中@ExceptionHandler的方法
for (Method method : MethodIntrospector.selectMethods(handlerType, EXCEPTION_HANDLER_METHODS)) {
// 获取方法的异常类型
for (Class<? extends Throwable> exceptionType : detectExceptionMappings(method)) {
// 添加到缓存中
addExceptionMapping(exceptionType, method);
}
}
}
最后ExceptionHandler被执行过程
// 处理返回结果时，如果异常不为空，则进行异常处理
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
boolean errorView = false;
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
// ...
}
else {
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
// 调用异常Handler处理
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
// ...
}
三、RequestBodyAdvice和ResponseBodyAdvice
该类是对入参或者是返回值的处理
RequestBodyAdvice和ResponseBodyAdvice
在ControllerAdvice中，还包含了RequestBodyAdvice，ResponseBodyAdvice
- RequestBodyAdvice对请求Body的处理
- ResponseBodyAdvice对响应Body的处理
3.1 Spring如何管理
RequestBodyAdvice和ResponseBodyAdvice的实现方式是RequestResponseBodyAdviceChain，其中存储了xxBodyAdvice的方法，在spring处理请求参数和返回数据是被调用。
class RequestResponseBodyAdviceChain implements RequestBodyAdvice, ResponseBodyAdvice<Object> {
//它持有所有的，记住是所有的advice们
private final List<Object> requestBodyAdvice = new ArrayList<>(4);
private final List<Object> responseBodyAdvice = new ArrayList<>(4);
// 可以看到这是个通用的方法。内来进行区分存储的 getAdviceByType这个区分方法可以看一下
// 兼容到了ControllerAdviceBean以及beanType本身
public RequestResponseBodyAdviceChain(@Nullable List<Object> requestResponseBodyAdvice) {
this.requestBodyAdvice.addAll(getAdviceByType(requestResponseBodyAdvice, RequestBodyAdvice.class));
this.responseBodyAdvice.addAll(getAdviceByType(requestResponseBodyAdvice, ResponseBodyAdvice.class));
}
@Override
public boolean supports(MethodParameter param, Type type, Class<? extends HttpMessageConverter<?>> converterType) {
throw new UnsupportedOperationException("Not implemented");
}
@Override
public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
throw new UnsupportedOperationException("Not implemented");
}
// 可以看到最终都是委托给具体的Advice去执行的（supports方法）
// 特点：符合条件的所有的`Advice`都会顺序的、依次的执行
@Override
public HttpInputMessage beforeBodyRead(HttpInputMessage request, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) throws IOException {
for (RequestBodyAdvice advice : getMatchingAdvice(parameter, RequestBodyAdvice.class)) {
if (advice.supports(parameter, targetType, converterType)) {
request = advice.beforeBodyRead(request, parameter, targetType, converterType);
}
}
return request;
}
... // 其余方法略。处理逻辑同上顺序执行。
// 最重要的是如下这个getMatchingAdvice()匹配方法
private <A> List<A> getMatchingAdvice(MethodParameter parameter, Class<? extends A> adviceType) {
// 简单的说你想要的是Request的还是Response的List呢？
List<Object> availableAdvice = getAdvice(adviceType);
if (CollectionUtils.isEmpty(availableAdvice)) {
return Collections.emptyList();
}
List<A> result = new ArrayList<>(availableAdvice.size());
for (Object advice : availableAdvice) {
if (advice instanceof ControllerAdviceBean) {
ControllerAdviceBean adviceBean = (ControllerAdviceBean) advice;
// 这里面会调用beanTypePredicate.test(beanType)方法
// 也就是根据basePackages等等判断此advice是否是否要作用在本类上
if (!adviceBean.isApplicableToBeanType(parameter.getContainingClass())) {
continue;
}
advice = adviceBean.resolveBean();
}
// 当前的advice若是满足类型要求的，那就添加进去 最终执行切面操作
if (adviceType.isAssignableFrom(advice.getClass())) {
result.add((A) advice);
}
}
return result;
}
}
我们知道所有的xxxBodyAdvice最终都是通过暴露的RequestResponseBodyAdviceChain来使用的，它内部持有容器内所有的Advice的引用。由于RequestResponseBodyAdviceChain的访问权限是default，所以这套机制完全由Spring内部控制。
他唯一设值处是：AbstractMessageConverterMethodArgumentResolver。
AbstractMessageConverterMethodArgumentResolver（一般实际为RequestResponseBodyMethodProcessor）：
// 唯一构造函数，指定所有的advices
public AbstractMessageConverterMethodArgumentResolver(List<HttpMessageConverter<?>> converters, @Nullable List<Object> requestResponseBodyAdvice) {
Assert.notEmpty(converters, "'messageConverters' must not be empty");
this.messageConverters = converters;
this.allSupportedMediaTypes = getAllSupportedMediaTypes(converters);
this.advice = new RequestResponseBodyAdviceChain(requestResponseBodyAdvice);
}
此构造函数在new RequestResponseBodyMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice)时候调用，传进来的requestResponseBodyAdvice就刚好是在初始化RequestMappingHandlerAdapter的时候全局扫描进来的所有的增强器们
3.2 如何使用
请求日志的打印，用于POST请求的，这里实现了RequestBodyAdvice用来打印请求参数，也使用了ResponseBodyAdvice打印返回的信息
// 生成日志信息，并放到request中
@ControllerAdvice
public class RequestBodyAdviceHandler implements RequestBodyAdvice {
public RequestBodyAdviceHandler() {
}
public boolean supports(MethodParameter methodParameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
Method method = methodParameter.getMethod();
Class<?> declaringClass = method.getDeclaringClass();
RestController RestController = (RestController)declaringClass.getAnnotation(RestController.class);
return RestController != null;
}
public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) throws IOException {
return inputMessage;
}
public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
this.writeRequestLog(body, inputMessage, parameter, targetType, converterType);
return body;
}
public Object handleEmptyBody(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
this.writeRequestLog(body, inputMessage, parameter, targetType, converterType);
return body;
}
private String toJSONString(Object body, MethodParameter parameter) {
IgnoreLogBody ignore = (IgnoreLogBody)parameter.getMethodAnnotation(IgnoreLogBody.class);
if (ignore == null) {
return JSON.toJSONString(body);
} else {
String[] ignoreKey = ignore.ignoreKey();
return ignoreKey != null && ignoreKey.length != 0 ? JSON.toJSONString(body, new IgnoreLogPropertyFilter(ignore.ignoreKey(), ignore.key()), new SerializerFeature[0]) : JSON.toJSONString(body);
}
}
private void writeRequestLog(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
HttpServletRequest request = RequestHelper.getRequest();
request.setAttribute("_REQUEST_STARTTIME_", System.currentTimeMillis());
String requestId = request.getHeader("_REQUEST_ID_");
if (StringUtils.isEmptyStr(requestId)) {
requestId = TraceContext.traceId();
}
if (StringUtils.isEmptyStr(requestId) || "Ignored_Trace".equals(requestId)) {
requestId = UUID.randomUUID().toString().replaceAll("-", "");
}
request.setAttribute("_REQUEST_ID_", requestId);
StringBuilder info = new StringBuilder("==>\n");
info.append("[*=请求requestID=]>: ").append(requestId).append("\n");
info.append("[==请求地址=======]>: ").append(request.getRequestURL().toString()).append("\n");
info.append("[==请求方法=======]>: ").append(request.getMethod()).append("\n");
info.append("[==操作用户=======]>: ").append(UserInfoContext.getCurrentUserCode()).append("\n");
info.append("[==客户IP========]>: ").append(RequestHelper.getClientIP()).append("\n");
info.append("[==映射方法=======]>: ").append(parameter.getMethod()).append(".").append("\n");
if (body == null) {
info.append("[==请求参数=======]>: ").append("该接口未定义参数或参数为空");
} else if (converterType == FastJsonHttpMessageConverter.class) {
info.append("[==请求参数=======]>: ").append(this.toJSONString(body, parameter));
} else {
info.append("[==请求参数=======]>: ").append(converterType);
}
info.append("\n");
request.setAttribute("_REQUEST_LOG_INFO_", info);
}
}
@ControllerAdvice
public class ResponseBodyAdviceHandler implements ResponseBodyAdvice<Object> {
private static final IEventLogger logger = Logtube.getLogger(ResponseBodyAdviceHandler.class.getName());
public ResponseBodyAdviceHandler() {
}
public boolean supports(MethodParameter methodParamter, Class<? extends HttpMessageConverter<?>> converterType) {
return this.isRestController(methodParamter);
}
public Object beforeBodyWrite(Object body, MethodParameter methodParamter, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest req, ServerHttpResponse response) {
HttpServletRequest request = RequestHelper.getRequest();
if (request == null) {
return body;
} else {
StringBuilder info = (StringBuilder)request.getAttribute("_REQUEST_LOG_INFO_");
if (info == null) {
info = new StringBuilder();
}
String requestBodyData = null;
if (body == null) {
requestBodyData = null;
} else if (selectedContentType.includes(MediaType.APPLICATION_JSON)) {
requestBodyData = JSON.toJSONString(body);
} else {
requestBodyData = body.toString();
}
Long startTime = (Long)request.getAttribute("_REQUEST_STARTTIME_");
info.append("[==响应结果=======]>: ").append(requestBodyData == null ? "null" : requestBodyData);
info.append("\n");
if (startTime != null) {
info.append("[==执行耗时=======]>: ").append(System.currentTimeMillis() - startTime).append("ms").append("\n");
}
String requestId = (String)request.getAttribute("_REQUEST_ID_");
logger.info(info.toString());
return body;
}
}
private boolean isRestController(MethodParameter methodParamter) {
RestController annotation = (RestController)methodParamter.getDeclaringClass().getAnnotation(RestController.class);
return annotation != null;
}
}
最后打印的日志信息
四、HandlerMethodReturnValueHandler
4.1 HandlerMethodReturnValueHandler
对返回信息做特殊处理，且只会被调用一次，谨慎处理
默认情况下，spring会调用RequestResponseBodyMethodProcessor来处理返回执行。它实现了HandlerMethodReturnValueHandler的handleReturnValue的方法，
如何选择returnHandler是在HandlerMethodReturnValueHandlerComposite类做了选择
@Override
public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
// 选择返回的handler处理
HandlerMethodReturnValueHandler handler = selectHandler(returnValue, returnType);
if (handler == null) {
throw new IllegalArgumentException("Unknown return value type: " + returnType.getParameterType().getName());
}
// 执行handleReturnValue将数据写入到reponse流中
handler.handleReturnValue(returnValue, returnType, mavContainer, webRequest);
}
// 被@ResponseBody注解的方法，会被执行该类
@Override
public boolean supportsReturnType(MethodParameter returnType) {
return (AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ResponseBody.class) ||
returnType.hasMethodAnnotation(ResponseBody.class));
}
//将returnValue写入到流中
@Override
public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
throws IOException, HttpMediaTypeNotAcceptableException, HttpMessageNotWritableException {
mavContainer.setRequestHandled(true);
ServletServerHttpRequest inputMessage = createInputMessage(webRequest);
ServletServerHttpResponse outputMessage = createOutputMessage(webRequest);
// Try even with null return value. ResponseBodyAdvice could get involved.
writeWithMessageConverters(returnValue, returnType, inputMessage, outputMessage);
}
知道了HandlerMethodReturnValueHandler是用于返回数据的handler，那么自己实现这个类用户封装自己返回的方法。
4.2 如何使用
一般请求下，返回的数据如下：
{
"data": {
},
"errorCode": "0",
"errorMsg": "成功",
}
data是其真实数据。在Controller层，需要调用如下
@RestController
@RequestMapping("/stock/depotinventorybalance")
public class DepotInventoryBalanceController {
@RequestMapping(value = "findById", method = RequestMethod.POST)
public DepotInventoryBalanceDto findById(@RequestBody DepotInventoryBalanceDto depotInventoryBalance) {
DepotInventoryBalanceDto balance = this.depotInventoryBalanceService.findById(depotInventoryBalance);
return ResponseResultUtil.result(balance);
}
}
@Data
public class ResponseResult<T> {
private T data;
private String errorCode;
private String errorMsg;
}
public static class ResponseResultUtil<T> {
public static <T> ResponseResult<T> result(T data){
ResponseResult<T> result = new ResponseResult<>();
result.setErrorCode( ErrorCode.SUCCESS.getCode());
result.setErrorMsg(ErrorCode.SUCCESS.getMessage());
result.setData(data);
return result;
}
}
那么通过注解@AutoResult可以将ResponseResultUtil替换调用，就是在处理HandlerMethodReturnValueHandler时，处理自己handleReturnValue返回数据。但是这里有一个点，就是实现了自己的类，那么自己实现的ResponseBodyAdvice，将不会被调用，因为AutoResultReturnValueHandler拦截的请求，会直接返回，不会再调用后续的handler方法。
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface AutoResult {
boolean value() default true;
}
public class AutoResultReturnValueHandler implements HandlerMethodReturnValueHandler {
private static final IEventLogger logger = Logtube.getLogger(AutoResultReturnValueHandler.class.getName());
public AutoResultReturnValueHandler() {
}
public boolean supportsReturnType(MethodParameter returnType) {
return this.isRestController(returnType) && this.isAutoResult(returnType);
}
public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
HttpServletRequest request = (HttpServletRequest)webRequest.getNativeRequest(HttpServletRequest.class);
mavContainer.setRequestHandled(true);
HttpServletResponse response = (HttpServletResponse)webRequest.getNativeResponse(HttpServletResponse.class);
response.setCharacterEncoding("UTF-8");
response.setContentType("application/json; charset=utf-8");
StringBuilder info = (StringBuilder)request.getAttribute("_REQUEST_LOG_INFO_");
if (info == null) {
info = new StringBuilder();
}
String requestId = (String)request.getAttribute("_REQUEST_ID_");
ResponseResult result = new ResponseResult();
result.setData(returnValue);
result.setErrorCode( ErrorCode.SUCCESS.getCode());
result.setErrorMsg(ErrorCode.SUCCESS.getMessage());
result.setRequestId(requestId);
String jsonString = JSON.toJSONString(result, new SerializerFeature[]{SerializerFeature.WriteDateUseDateFormat});
Long startTime = (Long)request.getAttribute("_REQUEST_STARTTIME_");
info.append("[==响应结果=======]>: ").append(jsonString);
info.append("\n");
if (startTime != null) {
info.append("[==执行耗时=======]>: ").append(System.currentTimeMillis() - startTime).append("ms").append("\n");
}
logger.info(info.toString());
response.getWriter().append(jsonString);
}
private boolean isRestController(MethodParameter returnType) {
RestController annotation = (RestController)returnType.getDeclaringClass().getAnnotation(RestController.class);
return annotation != null;
}
private boolean isAutoResult(MethodParameter returnType) {
AutoResult methodAnnotation = (AutoResult)returnType.getMethodAnnotation(AutoResult.class);
if (methodAnnotation != null) {
return methodAnnotation.value();
} else {
AutoResult annotation = (AutoResult)returnType.getDeclaringClass().getAnnotation(AutoResult.class);
return annotation != null && annotation.value();
}
}
}
// 该类下的所有方法都会被拦截
@AutoResult
@RestController
@RequestMapping("/stock/depotinventorybalance")
public class DepotInventoryBalanceController {
@RequestMapping(value = "findById", method = RequestMethod.POST)
public DepotInventoryBalanceDto findById(@RequestBody DepotInventoryBalanceDto depotInventoryBalance) {
return this.depotInventoryBalanceService.findById(depotInventoryBalance);
}
// 导出的方法，最后是已文件流的方式返回，
// 不使用AutoResult返回的结果形式，即不使用自定义Handler类
@AutoResult(value = false)
public void export() {
depotInventoryBalanceService.export();
}
}