SpringBoot中Service实现类添加@Service却任然无法注入的问题

最近一直在研究Spring Boot。从GitHub上下载了一个my-Blog源码，一边看，一边自己尝试去实现，结果掉在坑了，研究了近一周才爬出来，特地来这博客园记录下来，一是避免自己在放这样的错误，二是希望看到的朋友能有所帮助，毕竟我在网上查了很多资料，答案基本上千篇一律，并不能解决我的问题。

先说问题：我在Controller层中引用Service层的实现类，报错，错误代码如下：

-- ::45.094 ERROR  --- [nio--exec-] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.mydemo.service.AdminUserService.login] with root cause

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.mydemo.service.AdminUserService.login
    at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:) ~[mybatis-3.5..jar:3.5.]
    at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:) ~[mybatis-3.5..jar:3.5.]
    at org.apache.ibatis.binding.MapperProxy.lambda$cachedInvoker$(MapperProxy.java:) ~[mybatis-3.5..jar:3.5.]
    at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:) ~[na:1.8.0_151]
    at org.apache.ibatis.binding.MapperProxy.cachedInvoker(MapperProxy.java:) ~[mybatis-3.5..jar:3.5.]
    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:) ~[mybatis-3.5..jar:3.5.]
    at com.sun.proxy.$Proxy66.login(Unknown Source) ~[na:na]
    at com.example.mydemo.controller.admin.AdminController.login(AdminController.java:) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:) ~[na:1.8.0_151]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:) ~[na:1.8.0_151]
    at java.lang.reflect.Method.invoke(Method.java:) ~[na:1.8.0_151]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:) ~[spring-webmvc-5.1..RELEASE.jar:5.1..RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:) ~[tomcat-embed-websocket-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:) ~[spring-web-5.1..RELEASE.jar:5.1..RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:) ~[tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:) [na:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:) [na:1.8.0_151]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:) [tomcat-embed-core-9.0..jar:9.0.]
    at java.lang.Thread.run(Thread.java:) [na:1.8.0_151]

总的来说就是绑定语句无效，并未找到  com.example.mydemo.service.AdminUserService.login此方法。我从网上百度一下，看到大多数都是再讲Mapper.xml设置错误导致，需要排查：

1. 检查xml文件所在package名称是否和Mapper interface所在的包名一一对应；
2. 检查xml的namespace是否和xml文件的package名称一一对应；
3. 检查方法名称是否对应；

但我看了很多遍，我的程序都没有这些问题，并且我在Test中测试Mapper时可以用的。

@SpringBootTest
class MydemoApplicationTests {
    @Autowired
    AdminUserMapper adminUserMapper;
    @Resource
    TestService testService;
   @Test
   void TestInsert(){
       AdminUser adminUser =new AdminUser();
       adminUser.setAdminUserId(5);
       adminUser.setLocked(Byte.parseByte("1"));
       adminUser.setLoginPassword("123");
       adminUser.setLoginUserName("zzc");
       adminUser.setNickName("BigBang");
       adminUserMapper.insert(adminUser);
   }
   @Test
    void get(){
       AdminUser get= adminUserMapper.login("zzc","123");
       System.out.println(get);
    }

    @Test
    void TestMyService(){
       testService.Test();
    }
}

-- ::08.234  INFO  --- [           main] c.example.mydemo.MydemoApplicationTests  : Starting MydemoApplicationTests on LAPTOP-MFBL0MLV with PID  (started by zc in D:\Lab_Java\Demo)
-- ::08.236  INFO  --- [           main] c.example.mydemo.MydemoApplicationTests  : No active profile set, falling back to default profiles: default
-- ::10.117  INFO  --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
-- ::10.814  INFO  --- [           main] c.example.mydemo.MydemoApplicationTests  : Started MydemoApplicationTests in 2.776 seconds (JVM running for 4.072)
-- ::11.102  INFO  --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool- - Starting...
-- ::11.287  INFO  --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool- - Start completed.
AdminUser{adminUserId=, loginUserName='zzc', loginPassword='', nickName='BigBang', locked=}
-- ::11.356  INFO  --- [       Thread-] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
-- ::11.357  INFO  --- [       Thread-] com.zaxxer.hikari.HikariDataSource       : HikariPool- - Shutdown initiated...
-- ::11.359  INFO  --- [       Thread-] com.zaxxer.hikari.HikariDataSource       : HikariPool- - Shutdown completed.

Process finished with exit code 

可以看到get()方法是可以使用adminUserMapper的，也就是说Mapper的注入是没有问题的。此外还写了一个TestService，里面不涉及任何Mapper相关的东西，还是报这个错误。也就是说我的问题原因和Mapper并没有关系，至少不是上述这三点导致的。

问题还是出现再Service层里，我的Service层代码如下：

package com.example.mydemo.service;

import com.example.mydemo.entity.AdminUser;

public interface AdminUserService {

    AdminUser login(String userName, String password);

    /**
     * 获取用户信息
     *
     * @param loginUserId
     * @return
     */
    AdminUser getUserDetailById(Integer loginUserId);

    /**
     * 修改当前登录用户的密码
     *
     * @param loginUserId
     * @param originalPassword
     * @param newPassword
     * @return
     */
    Boolean updatePassword(Integer loginUserId, String originalPassword, String newPassword);

    /**
     * 修改当前登录用户的名称信息
     *
     * @param loginUserId
     * @param loginUserName
     * @param nickName
     * @return
     */
    Boolean updateName(Integer loginUserId, String loginUserName, String nickName);
}

package com.example.mydemo.service.impl;

import com.example.mydemo.dao.AdminUserMapper;
import com.example.mydemo.entity.AdminUser;
import com.example.mydemo.service.AdminUserService;
import com.example.mydemo.util.MD5Util;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

@Service
public class AdminUserServiceImpl implements AdminUserService {

    @Resource
    private AdminUserMapper adminUserMapper;

    @Override
    public AdminUser login(String userName, String password) {
        String passwordMd5 = MD5Util.MD5Encode(password, "UTF-8");
        System.out.println("Md5:"+passwordMd5);
        return adminUserMapper.login(userName, passwordMd5);
    }

    @Override
    public AdminUser getUserDetailById(Integer loginUserId) {
        return adminUserMapper.selectByPrimaryKey(loginUserId);
    }

    @Override
    public Boolean updatePassword(Integer loginUserId, String originalPassword, String newPassword) {
        AdminUser adminUser = adminUserMapper.selectByPrimaryKey(loginUserId);
        //当前用户非空才可以进行更改
        if (adminUser != null) {
            String originalPasswordMd5 = MD5Util.MD5Encode(originalPassword, "UTF-8");
            String newPasswordMd5 = MD5Util.MD5Encode(newPassword, "UTF-8");
            //比较原密码是否正确
            if (originalPasswordMd5.equals(adminUser.getLoginPassword())) {
                //设置新密码并修改
                adminUser.setLoginPassword(newPasswordMd5);
                if (adminUserMapper.updateByPrimaryKeySelective(adminUser) > 0) {
                    //修改成功则返回true
                    return true;
                }
            }
        }
        return false;
    }

    @Override
    public Boolean updateName(Integer loginUserId, String loginUserName, String nickName) {
        AdminUser adminUser = adminUserMapper.selectByPrimaryKey(loginUserId);
        //当前用户非空才可以进行更改
        if (adminUser != null) {
            //设置新密码并修改
            adminUser.setLoginUserName(loginUserName);
            adminUser.setNickName(nickName);
            if (adminUserMapper.updateByPrimaryKeySelective(adminUser) > 0) {
                //修改成功则返回true
                return true;
            }
        }
        return false;
    }

}

controller层中的调用如下：

package com.example.mydemo.controller.admin;

import com.example.mydemo.entity.AdminUser;
import com.example.mydemo.service.AdminUserService;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;
import javax.servlet.http.HttpSession;

@Controller
@RequestMapping("/admin")

public class AdminController {
    @Resource
    private AdminUserService adminUserService;

    @GetMapping({"/login"})
    public String login() {

        return "admin/login";
    }

    @PostMapping(value = "/login")
    public String login(@RequestParam("userName") String userName,
                        @RequestParam("password") String password,
                        @RequestParam("verifyCode") String verifyCode,
                        HttpSession session){
        if (StringUtils.isEmpty(verifyCode)) {
            session.setAttribute("errorMsg", "验证码不能为空");
            return "admin/login";
        }
        if (StringUtils.isEmpty(userName) || StringUtils.isEmpty(password)) {
            session.setAttribute("errorMsg", "用户名或密码不能为空");
            return "admin/login";
        }
        String kaptchaCode = session.getAttribute("verifyCode") + "";
        if (StringUtils.isEmpty(kaptchaCode) || !verifyCode.equals(kaptchaCode)) {
            session.setAttribute("errorMsg", "验证码错误");
            return "admin/login";
        }
        AdminUser adminUser = adminUserService.login(userName, password);
        if (adminUser != null) {
            session.setAttribute("loginUser", adminUser.getNickName());
            session.setAttribute("loginUserId", adminUser.getAdminUserId());
            //session过期时间设置为7200秒 即两小时
            //session.setMaxInactiveInterval(60 * 60 * 2);
            return "redirect:/admin/index";
        } else {
            session.setAttribute("errorMsg", "登陆失败");
            return "admin/login";
        }

    }

}

package com.example.mydemo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.example.mydemo")

public class MydemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(MydemoApplication.class, args);
    }
}

在网上查资料，发现有人说如果Application类包所在的位置也很关键，SpringBoot项目的Bean装配默认规则是根据Application类所在的包位置从上往下扫描！Application类是指SpringBoot项目入口类。也就是我的Service层所在的包必须在com.example.mydemo或其子包下，否则Service层中的Bean不会被扫描到，但我的程序也满足啊。

结果就在这里思索了一周都没有一点进展，直到一天我发现我的@MapperScan扫描的路径是"com.example.mydemo"。WTF!!!

我又赶快上网查了一下@MapperScan注解

作用：指定要变成实现类的接口所在的包，然后包下面的所有接口在编译之后都会生成相应的实现类
       添加位置：是在Springboot启动类上面添加。

看到没，包下面所有的接口在编译后之后都会生成相应的实现类，也就是说除了我的AdminUserServiceImp外Spring Boot还注入了一个mapper实现类，当我在Controller中使用@AutoWired或@Resource获取时，获取到时这个Mapper实现类的实例，但实际上并没有真正继承AdminUserService接口，只有你在运行的时候服务器才会报错，找不到对应的方法。

于是我把Mapper扫描具体到DAO路径下，即：

package com.example.mydemo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.example.mydemo.dao")

public class MydemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(MydemoApplication.class, args);
    }
}

修改后果然不再报错。

其实这个错误说起来还是挺简单，主要时自己对Spring Boot的注解，一些基本知识还是不够了解导致，看来以后还是要继续夯实基础啊。