A.使用工具IDEA

B.MySQL数据库 

C.Maven JavaWeb项目

——————————————————————

问题：

　　map里面的值传不到 user1Mapper.xml 的 MySQL 语句里

发送的SQL语句为null

18:31:58,446 DEBUG loginFind:145 - ==>  Preparing: SELECT * FROM user WHERE loginname=? and password=? 
18:31:58,493 DEBUG loginFind:145 - ==> Parameters: null, null
18:31:58,514 DEBUG loginFind:145 - <==      Total: 0

————————

报错：内容

java.lang.NullPointerException
at com.dunef.service.User1ServiceImp.loginFind(User1ServiceImp.java:31)
at com.dunef.controller.User1Controller.findLogin(User1Controller.java:18)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:625)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1372)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

--------------------------------------------

1定义了一个entity类，已经有set，get，方法

public class User1 {
    private String loginname;
    private String password;

2，mapper层

public interface User1Mapper {
    User1 loginFind(Map<String,String>map);
}

3 ，mapper.xml代码

<mapper namespace="com.dunef.mapper.User1Mapper">
    <select id="loginFind" parameterType="java.util.Map" resultType="com.dunef.entity.User1">
        SELECT
　　　　　　　　 *
　　　　 FROM 
　　　　　　　　user
        WHERE
      　　  loginname=#{loginname} and password=#{password}
    </select>
</mapper>

4 ， service 接口层

public interface User1Service {
    User1 loginFind(String loginname,String password);
}

5， service 实现类

   @Service
　　public class User1ServiceImp implements User1Service{
　　@Resource
    private User1Mapper user1Mapper;
    private HashMap<String, String> map;
    private User1 user2;


    @Override
    public User1 loginFind(String loginname, String password) {
        map = new HashMap<>();
        map.put(loginname, loginname);
        map.put(password, password);
        user2 = user1Mapper.loginFind(map);／／31行，这句返回值为空，数据库，map值传不进去
　　　　　　System.out.println(user2);

       return user2;
    }
}

6，controller层，设置了数据库里的一条信息

@Controller
public class User1Controller {
    @Resource
    private User1Service user1Service;
    @RequestMapping("/find")
    public void findLogin(){
        user1Service.loginFind("c","c");
    }