在工作中使用到spring的mvc框架,分为controller/service/dao三个层次。偶尔会用到servlet替换掉controller,这就遇到如何在servlet中使用注入到spring上下文中的service bean。
通过查询相关资料,可以在servlet的初始化方法中调用spring的方法进行注入
@Override public void init(ServletConfig config) throws ServletException { SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, config.getServletContext()); }
同时需要在当前的servlet中加上需要注入的类型实例对应的字段,如下所示
@Autowired private TestAppService testAppService;
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项目中示例:
public class WeixinServlet1 extends HttpServlet {
@Override
public void init(ServletConfig config) throws ServletException { SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, config.getServletContext()); } @Autowired private GoodService goodService; ......
不加init方法只是注入service是会报错:
严重: Servlet.service() for servlet [WeixinServlet] in context with path [/weixin] threw exception java.lang.NullPointerException at com.test.www.servlet.WeixinServlet1.doPost(WeixinServlet1.java:127) at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:124) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:748)
加上init方法就正常了。