servlet api 3.0 jar中缺少异步方法

Question

我正在开发一个servlet 3.0应用程序，它必须异步处理请求。

使用

编译失败

cannot find symbol
symbol  : method startAsync(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
location: interface javax.servlet.http.HttpServletRequest

消息。

在我的pom.xml中有以下依赖项:

<dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-web-api</artifactId>
    <version>6.0</version>
</dependency>

有趣的是，导入javax.servlet。AsyncContext 成功。但是当我列出javax.servlet的方法时。ServletRequest，没有3.0 API处理异步请求。

public abstract java.lang.String javax.servlet.ServletRequest.getScheme()
public abstract java.lang.String javax.servlet.ServletRequest.getProtocol()
public abstract javax.servlet.ServletInputStream javax.servlet.ServletRequest.getInputStream() throws java.io.IOException
public abstract int javax.servlet.ServletRequest.getContentLength()
public abstract java.lang.Object javax.servlet.ServletRequest.getAttribute(java.lang.String)
public abstract java.lang.String javax.servlet.ServletRequest.getContentType()
public abstract java.util.Locale javax.servlet.ServletRequest.getLocale()
public abstract java.util.Enumeration javax.servlet.ServletRequest.getAttributeNames()
public abstract java.lang.String javax.servlet.ServletRequest.getCharacterEncoding()
public abstract void javax.servlet.ServletRequest.setCharacterEncoding(java.lang.String) throws java.io.UnsupportedEncodingException
public abstract java.lang.String javax.servlet.ServletRequest.getParameter(java.lang.String)
public abstract java.util.Enumeration javax.servlet.ServletRequest.getParameterNames()
public abstract java.lang.String[] javax.servlet.ServletRequest.getParameterValues(java.lang.String)
public abstract java.util.Map javax.servlet.ServletRequest.getParameterMap()
public abstract java.lang.String javax.servlet.ServletRequest.getServerName()
public abstract int javax.servlet.ServletRequest.getServerPort()
public abstract java.io.BufferedReader javax.servlet.ServletRequest.getReader() throws java.io.IOException
public abstract java.lang.String javax.servlet.ServletRequest.getRemoteAddr()
public abstract java.lang.String javax.servlet.ServletRequest.getRemoteHost()
public abstract void javax.servlet.ServletRequest.setAttribute(java.lang.String,java.lang.Object)
public abstract void javax.servlet.ServletRequest.removeAttribute(java.lang.String)
public abstract java.util.Enumeration javax.servlet.ServletRequest.getLocales()
public abstract boolean javax.servlet.ServletRequest.isSecure()
public abstract javax.servlet.RequestDispatcher javax.servlet.ServletRequest.getRequestDispatcher(java.lang.String)
public abstract java.lang.String javax.servlet.ServletRequest.getRealPath(java.lang.String)
public abstract int javax.servlet.ServletRequest.getRemotePort()
public abstract java.lang.String javax.servlet.ServletRequest.getLocalName()
public abstract java.lang.String javax.servlet.ServletRequest.getLocalAddr()
public abstract int javax.servlet.ServletRequest.getLocalPort()

我错过了什么?

Answer 1

我假设您已经以某种方式"设法"引用了位于javaee-web-api之前的类路径中的较旧的servlet-api库(可能是传递的)。这意味着现有的类是从旧的servlet-api中获取的，而旧规范中不存在的类是从javaee-web-api中加载的。

您可以运行mvn dependency:tree查看引用过时库的位置，然后将其排除