问题描述
在您的问题中
<bean name="ProductServlet" class="com.epam.productshop.controller.ProductServlet" scope="singleton">
<property name="requestHelper" ref="requestHelper"/>
</bean>
您不能使用spring容器实例化servlet,它们是由servlet容器实例化的。您只是在声明ProductServlet的另一个实例。
SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, getServletContext());`
要注入requestHelper @Autowired
,请在Servlet中声明带注释的字段或属性:
private RequestHelper requestHelper;
@Autowired
public void setRequestHelper(RequestHelper requestHelper){
this.requestHelper = requestHelper;
}
来自 processInjectionBasedOnServletContext javadoc:
处理 注射给定目标对象,根据与存储在ServletContext当前根web应用上下文。
解决方法
我是Spring的新手,想将spring ioc连接到我的小型(测试)网络应用程序中。
我有这样的Servlet ProductServlet
:
public class ProductServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
private RequestHelper requestHelper;
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
processRequest(request);
}
private void processRequest(HttpServletRequest request){
requestHelper.process(request);
}
public RequestHelper getRequestHelper() {
return requestHelper;
}
public void setRequestHelper(RequestHelper requestHelper) {
this.requestHelper = requestHelper;
}
}
和我的web.xml:
<servlet>
<servlet-name>ProductServlet</servlet-name>
<servlet-class>com.epam.productshop.controller.ProductShop</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ProductServlet</servlet-name>
<url-pattern>/ProductServlet</url-pattern>
</servlet-mapping>
<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener
</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/spring-config.xml
</param-value>
</context-param>
而且我也有这样的Spring配置XML:
<bean id="factory" class="com.epam.productshop.readerfactory.ReaderFactory">
<property name="file" value="/xml/products.xml" />
</bean>
<bean id="requestHelper" class="com.epam.productshop.requesthelper.RequestHelper" scope="singleton">
<property name="factory" ref="factory" />
</bean>
<bean name="ProductServlet" class="com.epam.productshop.controller.ProductServlet" scope="singleton">
<property name="requestHelper" ref="requestHelper"/>
</bean>
我有这样的问题:
我希望在servlet init()期间将requestHelper对象设置为我的servlet。但除了这个,它还给了我nullpointer。
我正在尝试从实现servlet
HttpRequestHandler
,将其写入SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this,getServletContext());
init()方法以及我在互联网上看到的其他东西,但所有这些都不能解决我的问题。
请帮我