Spring REST服务：从请求检索JSON

廉学潞

2023-03-14

问题内容：

我正在Spring 3.1上构建REST服务。我为此使用@EnableWebMVC注释。由于我的服务将仅接受JSON请求，因此我也想将传入的请求转储到MongoDB集合中以进行日志记录（以及以后的数据转换）。我想访问原始JSON请求（我可以在使用“ @Content HttpServletRequest请求”作为方法参数的非spring实现中进行此操作）。

我是Spring新手。因此，请帮助我指导实现这一目标。谢谢！

更新：该问题尚未完全解决。只有我的GET测试有效。POST失败。因此，取消选中接受的答案

问题是，即使创建了HttpServletRequestWrapper，也无法在处理并包装请求后转发请求。这是发生了什么：

拦截器：

public class DBLogInterceptor extends HandlerInterceptorAdapter {
    MyRequestWrapper requestWrapper;

    private final static Logger logger = Logger.getLogger(DBLogInterceptor.class);

    @Override
    public boolean preHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler) throws Exception 
    {
        requestWrapper = new MyRequestWrapper(request);
        // Code removed, but it just dumps requestWrapper.getBody() into DB
        return super.preHandle(requestWrapper, response, handler);
    }
}

HTTP POST服务方法

@RequestMapping(method = RequestMethod.POST, consumes="application/json", produces="application/json", value = "employee")
@ResponseBody
public String updateEntity(@RequestBody Employee emp) {
    // Do some DB Stuff. Anyway, the control flow does not reach this place.
    return "Employee " + emp.getName() + " updated successfully!";
}

现在，无论何时发送POST都会得到一个异常：

12:04:53,821 DEBUG DBLogInterceptor:22 - {"name":"Van Damme","dept":"Applied Martial Arts"}
12:04:53,843 DEBUG RequestResponseBodyMethodProcessor:117 - Reading [com.test.webapp.login.domain.Employee] as "application/json" using [org.springframework.http.converter.json.MappingJacksonHttpMessageConverter@154174f9]
12:04:53,850 DEBUG ExceptionHandlerExceptionResolver:132 - Resolving exception from handler [public java.lang.String com.test.webapp.controller.EmployeeService.updateEntity(com.test.webapp.login.domain.Employee)]: java.io.IOException: Stream closed
12:04:53,854 DEBUG ResponseStatusExceptionResolver:132 - Resolving exception from handler [public java.lang.String com.test.webapp.controller.EmployeeService.updateEntity(com.test.webapp.login.domain.Employee)]: java.io.IOException: Streamclosed
12:04:53,854 DEBUG DefaultHandlerExceptionResolver:132 - Resolving exception from handler [public java.lang.String com.test.webapp.controller.EmployeeService.updateEntity(com.test.webapp.login.domain.Employee)]: java.io.IOException: Streamclosed
12:04:53,859 DEBUG DispatcherServlet:910 - Could not complete request
java.io.IOException: Stream closed
        at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:312)
        at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:200)
        at org.codehaus.jackson.impl.ByteSourceBootstrapper.ensureLoaded(ByteSourceBootstrapper.java:507)
        at org.codehaus.jackson.impl.ByteSourceBootstrapper.detectEncoding(ByteSourceBootstrapper.java:129)
        at org.codehaus.jackson.impl.ByteSourceBootstrapper.constructParser(ByteSourceBootstrapper.java:224)
        at org.codehaus.jackson.JsonFactory._createJsonParser(JsonFactory.java:785)
        at org.codehaus.jackson.JsonFactory.createJsonParser(JsonFactory.java:561)
        at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1914)
        at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.readInternal(MappingJacksonHttpMessageConverter.java:124)
        at org.springframework.http.converter.AbstractHttpMessageConverter.read(AbstractHttpMessageConverter.java:153)
        at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:120)
        at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:91)
        at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:71)
        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:75)
        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:156)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:117)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)

我希望HttpServletRequestWrapper能够照顾到缓存请求。但这不会以某种方式发生。

问题答案：

使用HttpServletRequest对象，你可以访问客户端用于发出请求的URL，使用的方法（GET，POST，PUT等），查询字符串和标头。

获取RequestBody可能会有些棘手，并且可能需要使用HttpServletRequestWrapper对象。由于请求正文只能被读取一次，因此你需要扩展包装器以访问它，以便你的目标控制器以后仍可以访问它，以将JSON反序列化为POJO对象。

public class MyRequestWrapper extends HttpServletRequestWrapper {
 private final String body;
 public MyRequestWrapper(HttpServletRequest request) throws IOException {
   super(request);
   StringBuilder stringBuilder = new StringBuilder();
   BufferedReader bufferedReader = null;
   try {
     InputStream inputStream = request.getInputStream();
     if (inputStream != null) {
       bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
       char[] charBuffer = new char[128];
       int bytesRead = -1;
       while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
         stringBuilder.append(charBuffer, 0, bytesRead);
       }
     } else {
       stringBuilder.append("");
     }
   } catch (IOException ex) {
       throw ex;
   } finally {
     if (bufferedReader != null) {
       try {
         bufferedReader.close();
       } catch (IOException ex) {
         throw ex;
       }
     }
   }
   body = stringBuilder.toString();
 }

 @Override
 public ServletInputStream getInputStream() throws IOException {
   final ByteArrayInputStream byteArrayInputStream = new     ByteArrayInputStream(body.getBytes());
   ServletInputStream servletInputStream = new ServletInputStream() {
     public int read() throws IOException {
       return byteArrayInputStream.read();
     }
   };
   return servletInputStream;
 }

 @Override
 public BufferedReader getReader() throws IOException {
   return new BufferedReader(new InputStreamReader(this.getInputStream()));
 }

 public String getBody() {
   return this.body;
 }
}

要在中央位置访问请求，可以使用过滤器或Spring拦截器。这两个请求都在将请求委派给控制器之前被调用，并且都可以访问servlet。

这是一个使用Spring Interceptor的实际记录示例：

package com.vaannila.interceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Logger;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler. HandlerInterceptorAdapter;

public class LoggerInterceptor extends HandlerInterceptorAdapter {
    static Logger logger = Logger.getLogger(LoggerInterceptor.class);

    static {
        BasicConfigurator.configure();
    }

    @Override

    public boolean preHandle(HttpServletRequest request,
        HttpServletResponse response, Object handler) throws Exception {

        logger.info("Before handling the request");
        return super.preHandle(request, response, handler);
    }

    @Override
    public void postHandle(HttpServletRequest request,
        HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {

        logger.info("After handling the request");
        super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request,
        HttpServletResponse response, Object handler, Exception ex)
            throws Exception {

        logger.info("After rendering the view");
        super.afterCompletion(request, response, handler, ex);
    }
}


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="viewResolver" class="org.springframework.web.servlet.view.    InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />

    <bean id="handlerMapping" class="org.springframework.web.servlet.handler. BeanNameUrlHandlerMapping" p:interceptors-ref="loggerInterceptor" />

    <bean id="loggerInterceptor" class="com.vaannila.interceptor.LoggerInterceptor" />

    <bean id="userService" class="com.vaannila.service.UserServiceImpl" />

    <bean name="/userRegistration.htm" class="com.vaannila.web.UserController" p:userService-ref="userService" p:formView="userForm" p:successView="userSuccess" />

</beans>

在LoggerInterceptor中，你可以使用以下代码访问请求：

MyRequestWrapper myRequestWrapper = new MyRequestWrapper((HttpServletRequest) request);

String body = myRequestWrapper.getBody();
String clientIP = myRequestWrapper.getRemoteHost();
int clientPort = request.getRemotePort();
String uri = myRequestWrapper.getRequestURI();

System.out.println(body);
System.out.println(clientIP);
System.out.println(clientPort);
System.out.println(uri);

Spring REST服务：从请求检索JSON

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