可以获取到从页面传过来的参数，为什么报空指针呢？

Question

我通过打桩，可以从页面获取到参数，但是在调用方法往方法里面传参的时候，报空指针异常。

if (id != null && id.length > 0) {
            ApplicationContext context = new ClassPathXmlApplicationContext(
                "applicationContext.xml");

            IPurchase purchase = (IPurchase) context.getBean("purchaseProxy");
            purchase.setSId(session.getAttribute("userId").toString());
            //这里是可以获取到参数的
            System.out.println(id);
            purchase.insertById(id);

public boolean insertById(String[] id) {
        boolean result=false;
        ApplicationContext context = new ClassPathXmlApplicationContext(
                "applicationContext.xml");
        IDataConfig myData = (IDataConfig) context.getBean("dataConfigProxy");
        myData.init();
        try {
            myData.openConnection();
            myData.beginTransaction();
            for(int i=0;i<id.length;i++){

                myData.addBatch("delete from  purchase where id ="+id[i]);

            }

            if(myData.commit()){
                result=true;
            }else{
                result=false;
            }

            myData.endTransaction();

        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            myData.closeConnection();
        }
        return result;

    java.lang.NullPointerException
    at com.sun.proxy.$Proxy5.insertById(Unknown Source)
    at com.genius.sales_Manage.purchase.action.InsertHCAction.handleRequest(InsertHCAction.java:63)
    at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.genius.util.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:56)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

purchase.insertById(id); 你这里的null指针问题不一定是id影响的，也有可能purchase这个就是一个null，你在检查一下