在学习了《Spring实战》的一些章节后，我打算写一个项目来锻炼一下。在创建项目前，我希望用全注解的方式来开发。后来就知道，debug掉的头发，都是前期拍脑袋进的水——网上关于注解的资料也太少了吧！！！
经过千辛万苦后，我终于顺利完成了项目的搭建：）
项目的源代码地址：https://github.com/FuGaZn/SpringBlog
欢迎给个star哦 (￣∇￣)

概述

首先介绍一下这个SpringBlog项目：
本项目基于Spring+SpringMVC+Mybatis的技术框架，实现个人博客的登入登出、管理文章、在线编写和发布文章、浏览博客等基本功能。
在一步步搭建项目的过程中，你将学习到：

• DispatcherServlet的配置
• Web界面访问的配置
• 用Interceptor实现拦截功能
• 自动装配（Auto wire）
• Controller和Service的编写
• 基于Mybatis实现的Mapper接口

以上所有功能将使用注解的形式配置！
（除了使用web.xml配置对静态资源的访问）

博客界面示例

登陆界面：
后台管理界面：

撰写文章界面：
博客主页：

查看博客界面：

搭建项目

新建一个Java web项目，引入Maven框架，将pom.xml的内容配置好就完成了基本的搭建。

项目结构：
本项目采用Maven来管理，pom.xml文件内容如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><packaging>war</packaging><groupId>com.fjx.blog.spring</groupId><artifactId>SpringBlog</artifactId><version>1.0-SNAPSHOT</version><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencies><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.0.16</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>1.1.9</version></dependency><dependency><groupId>javax</groupId><artifactId>javaee-api</artifactId><version>7.0</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency><dependency><groupId>org.json</groupId><artifactId>json</artifactId><version>20170516</version></dependency><!--spring依赖--><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.7.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>5.2.7.RELEASE</version></dependency><!--springMVC依赖--><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>5.2.7.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>5.2.7.RELEASE</version></dependency><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version></dependency><dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency><!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa --><dependency><groupId>org.springframework.data</groupId><artifactId>spring-data-jpa</artifactId><version>2.3.1.RELEASE</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.3.1</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.4.6</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>1.1.2</version></dependency><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>1.7.21</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.7.21</version><scope>compile</scope></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.30</version></dependency><!--springMVC依赖结束--></dependencies>
</project>

编写Java web Config文件

java web cofig配置类是xml配置文件的替代，在Java类上添加@Configuration注解后，该类会被Spring识别为配置类。

配置DispatherServlet

DispatcherServlet用于将请求发送给SpringMVC控制器（controller）DispatcherServlet 会查询一个或多个处理器映射（ handler mapping ） 来确定请求的下一站在哪里。处理器映射会根据请求所携带的 URL 信息来进行决策。

MyWebInitializer.java：

package com.fjx.blog.spring.config;import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;public class MyWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {//根配置 和我们目前的项目无关，所有不用去关心protected Class<?>[] getRootConfigClasses() {return new Class<?>[] {RootConfig.class};}//指定配置类protected Class<?>[] getServletConfigClasses() {return new Class<?>[] {WebConfig.class};}//将DispatcherServlet映射到“/”，即该DispatcherServlet会处理所有的请求protected String[] getServletMappings() {return new String[]{"/"};}
}

《Spring实战》对AbstractAnnotationConfigDispatcherServletInitializer的讲解：

配置WebConfig

package com.fjx.blog.spring.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;@Configuration
@ComponentScan("com.fjx.blog.spring")
public class WebConfig implements WebMvcConfigurer {@Beanpublic ViewResolver viewResolver() {InternalResourceViewResolver resolver = new InternalResourceViewResolver();resolver.setPrefix("/WEB-INF/views/");resolver.setSuffix(".jsp");resolver.setViewClass(JstlView.class);resolver.setExposeContextBeansAsAttributes(true);return resolver;}@Bean(name = "multipartResolver") // bean必须写name属性且必须为multipartResolver//用于传输MultipartFileprotected CommonsMultipartResolver multipartResolver() {CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();commonsMultipartResolver.setMaxUploadSize(5 * 1024 * 1024);commonsMultipartResolver.setMaxInMemorySize(0);commonsMultipartResolver.setDefaultEncoding("UTF-8");return commonsMultipartResolver;}@Override//用于处理静态资源public void addResourceHandlers(ResourceHandlerRegistry registry) {registry.addResourceHandler("/resource/**").addResourceLocations("/resource/asset/");}@Overridepublic void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {configurer.enable();}
}

InternalResourceViewResolver用于查找JSP文件，对于传入的视图名称（Controller里@RequestMapping注解的方法返回的String是视图名称），为其添加前缀和后缀，在web/webapp文件夹下查找对应的JSP文件。
例如，对以下方法：

    @RequestMapping({"/index","/"})public String index(Model model){return "home/index";}

InternalResourceViewResolver接收到“/home/index”字符串后，拼接前缀后缀得“/WEB-INF/views/home/index.jsp”。
注意：setPrefix方法里的/WEB-INF/views/不能写成WEB-INF/views/，前者通过相对路径访问资源，后者使用绝对路径，因此后者会出错。

addResourceHandlers方法用于处理对静态资源的访问。如果不设置，访问静态资源会被拦截。
如果addResourceHandlers不起作用的话，可以在web.xml中配置如下内容：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee" xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"><display-name>SpringBlog</display-name><servlet-mapping><servlet-name>default</servlet-name><url-pattern>*.js</url-pattern><url-pattern>*.css</url-pattern><url-pattern>*.woff</url-pattern><url-pattern>*.svg</url-pattern><url-pattern>*.ttf</url-pattern><url-pattern>*.woff2</url-pattern><url-pattern>*.eot</url-pattern><url-pattern>*.otf</url-pattern><url-pattern>*.ico</url-pattern><url-pattern>*.gif</url-pattern><url-pattern>*.jpg</url-pattern><url-pattern>*.png</url-pattern></servlet-mapping>
</web-app>

RootConfig.java：

package com.fjx.blog.spring.config;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;@Configuration
@ComponentScan(basePackages = {"com.fjx.blog.spring"},excludeFilters = @ComponentScan.Filter(type = FilterType.ANNOTATION, value = EnableWebMvc.class))
public class RootConfig {
}

配置SecurityConfig.java以实现对登陆状态的判断

package com.fjx.blog.spring.config;import com.fjx.blog.spring.interceptor.SecurityInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;@Configuration
public class SecurityConfig extends WebMvcConfigurationSupport {@Beanpublic SecurityInterceptor securityInterceptor() {return new SecurityInterceptor();}@Overridepublic void addInterceptors(InterceptorRegistry registry) {InterceptorRegistration registration = registry.addInterceptor(securityInterceptor());registration.excludePathPatterns("/home/*"); //排除对该路径的拦截registration.excludePathPatterns("/");registration.excludePathPatterns("/login");registration.addPathPatterns("/admin/*"); //添加对该路径的拦截registration.addPathPatterns("/admin");}
}

SecurityInterceptor.java的内容：

package com.fjx.blog.spring.interceptor;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@Component
public class SecurityInterceptor extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws IOException {//这里根据session的用户来判断角色的权限，根据权限来转发不同的页面if(request.getSession().getAttribute("user") == null) {response.sendRedirect("/login");return false;}return true;}
}

在第一次访问被SecurityConfig拦截的界面时，因为session里的user属性不存在，所以会重定向到login界面。登陆后，添加user属性，再次访问这些界面时，就不会被重定向了。

配置Mybatis：

在resources文件夹下建立properties文件，添加如下内容：

server.port=8080
# 数据库连接
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/springblog
# 用户名
spring.datasource.username=root
# 密码
spring.datasource.password=123456
# 数据库驱动
spring.datasource.driver=com.mysql.jdbc.Driver#mybatis设置相关
mybatis.type.alias.package=com.bdqn.lyrk.ssm.study.entity
logging.leve.com.fjx.blog.spring.mapper=debug 
mybatis.configuration.mapUnderscoreToCamelCase=true

添加PropertiesConfig.java：

package com.fjx.blog.spring.config;import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;@Configuration
@PropertySource("classpath:application.properties")
public class PropertiesConfig {@Value("${spring.datasource.url}")private String url;@Value("${spring.datasource.driver}")private String driver;@Value("${spring.datasource.username}")private String username;@Value("${spring.datasource.password}")private String password;@Value("${mybatis.type.alias.package}")private String mybatisTypeAliasPackage;public String getUrl() {return url;}public String getDriver() {return driver;}public String getUsername() {return username;}public String getPassword() {return password;}@Beanpublic static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer(){return new PropertySourcesPlaceholderConfigurer();}
}

添加MyBatisConfig.java：

package com.fjx.blog.spring.config;import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;import javax.sql.DataSource;@Configuration
@MapperScan("com.fjx.blog.spring.mapper")
public class MyBatisConfig {@AutowiredPropertiesConfig propertiesConfig;@Bean//如果项目运行后报“Error querying database.  Cause: java.lang.NullPointerExceptio”这样的错误，你或许要检查一下这里的配置，看看是不是url或者driverClassName为空public DataSource dataSource(PropertiesConfig propertiesConfig) {DruidDataSource dataSource = new DruidDataSource();dataSource.setUsername(propertiesConfig.getUsername());dataSource.setPassword(propertiesConfig.getPassword());dataSource.setUrl(propertiesConfig.getUrl());dataSource.setDriverClassName(propertiesConfig.getDriver());return dataSource;}@Beanpublic SqlSessionFactory sqlSessionFactory() throws Exception  {SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();//不能用new PropertiesConfig()的方式引入参数，否则得不到变量sessionFactory.setDataSource(dataSource(propertiesConfig));return sessionFactory.getObject();}@Beanpublic PlatformTransactionManager transactionManager(DataSource dataSource) {DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager(dataSource);return dataSourceTransactionManager;}@Beanpublic static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer = new PropertySourcesPlaceholderConfigurer();return propertySourcesPlaceholderConfigurer;}}

在以上所有文件都配置完毕后，我们就可以开发具体页面啦！是不是很激动呢，如果你是第一次开发SpringMVC项目，可能会觉得上面的配置很繁琐，但是如果你接触过用XML文件进行配置的话，那肯定会觉得上面的配置太简单了。
而且接下来，当我们配置Controller、Service、Mapper时，只需要在类上添加注解就可以完成了，不用在辛辛苦苦写完java文件后，还要在xml文件里进行添加或修改。

接下来让我们以登陆操作为例，从数据库到jsp页面，自底向上一条龙讲述其中的全部操作。

登陆：Mapper->Service->Controller->JSP

Mapper

我们先在数据库中建立一张表，名字为users（在IDEA里可以图形化操作）

-- auto-generated definition
CREATE TABLE users
(id              INT AUTO_INCREMENTPRIMARY KEY,ukey            VARCHAR(255) NULL,name            VARCHAR(255) NULL,password        VARCHAR(255) NULL,CONSTRAINT user_uid_uindexUNIQUE (id)
)ENGINE = InnoDB;

然后创建对应的User.java：

package com.fjx.blog.spring.entity;public class User {private int id;private String name; //昵称private String ukey; //用户身份识别key，登陆使用private String password;//还有一系列getter和setter方法，别忘了哦。在IDEA里，同时摁住Alt和Insert键，可以一键添加全部getter和setter方法哦
}

配置UserMapper.java：

package com.fjx.blog.spring.mapper;import com.fjx.blog.spring.entity.User;
import org.apache.ibatis.annotations.*;
import org.springframework.stereotype.Component;import java.util.List;@Mapper
@Component(value = "userMapper")
public interface UserMapper {@Select("select * from users")List<User> selectAll();@Select("select * from users where ukey = #{ukey}")List<User> selectUserByKey(String ukey);@Insert("insert into users values(#{user.id},#{user.ukey},#{user.name},#{user.password},#{user.userLastLoginIp})")@Options(useGeneratedKeys = true)int save(@Param("user") User user);
}

@Mapper注解表明该类是一个Mybatis Mapper
@Select/@Insert注解等用来操作sql语句。在传入对象参数时，在参数前使用@Param注解，否则会报 xxx not found错误。
Mybatis的注解详细用法可以参照：MyBatis常用11种注解

创建UserService和UserServiceImpl文件：

package com.fjx.blog.spring.service;import com.fjx.blog.spring.entity.User;public interface UserService {User getUserByKey(String key);void save(User user);
}

package com.fjx.blog.spring.service.impl;import com.fjx.blog.spring.entity.User;
import com.fjx.blog.spring.mapper.UserMapper;
import com.fjx.blog.spring.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class UserServiceImpl implements UserService {@Autowiredprivate UserMapper userMapper;@Overridepublic User getUserByKey(String key) {List<User> users = userMapper.selectUserByKey(key);if (users == null || users.size() == 0){return null;}elsereturn users.get(0);}public void save(User user) {int i = userMapper.save(user);}
}

可以看到UserServiceImpl实现自UserServcie接口，@Service注解要放在UserServiceImpl上
使用@AutoWired注解来为UserMapper自动装配

创建LoginController.java：

package com.fjx.blog.spring.controller.admin;import com.fjx.blog.spring.entity.User;
import com.fjx.blog.spring.service.UserService;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;/*** @author fujiaxing* 登陆登出功能*/
@Controller
public class LoginController {@AutowiredUserService userService;@RequestMapping({"/login","/"})public String login(){return "/admin/login";}@RequestMapping(value = "/loginVerify",method = RequestMethod.POST)@ResponseBodypublic String loginVerify(HttpServletRequest request, HttpServletResponse response) {Map<String, Object> map = new HashMap();String userkey = request.getParameter("ukey");String password = request.getParameter("password");String rememberme = request.getParameter("rememberme");User user = userService.getUserByKey(userkey);if (user == null) {map.put("code", 0);map.put("msg", "用户名无效！");} else if (!user.getPassword().equals(password)) {map.put("code", 0);map.put("msg", "密码错误！");} else {System.out.println("登陆成功");//登录成功map.put("code", 1);map.put("msg", "");//添加sessionrequest.getSession().setAttribute("user", user);if (rememberme != null) {//创建两个Cookie对象Cookie keyCookie = new Cookie("ukey", userkey);//设置Cookie的有效期为3天keyCookie.setMaxAge(60 * 60 * 24 * 3);Cookie pwdCookie = new Cookie("password", password);pwdCookie.setMaxAge(60 * 60 * 24 * 3);response.addCookie(keyCookie);response.addCookie(pwdCookie);}//  user.setUserLastLoginTime(new Date());user.setUserLastLoginIp(getIpAddr(request));userService.save(user);}String result = new JSONObject(map).toString();return result;}@RequestMapping(value = "/logOut",method = RequestMethod.GET)@ResponseBodypublic String loginOut(HttpServletRequest request, HttpServletResponse response){request.getSession().removeAttribute("user");Map<String, Object> map = new HashMap();map.put("code", 1);map.put("msg", "");String result = new JSONObject(map).toString();return result;}
}

可以看到，在LoginController里，自动装配的对象是UserService， 而不是UserServiceImpl
login()方法上注解配置了映射“/login”，对应的jsp文件则是/WEB-INF/views/admin/login.jsp
上文提到，我们使用session里的user属性判断用户是否需要登陆，在执行登陆操作后，我们调用request.getSession().addAttribute()方法添加user属性。在登出系统后，我们调用request.getSession().removeAttribute()方法删除user属性

后端的所有类和方法都写好啦，接下来我们就可以编写前端界面和js代码了。
新建一个/admin/login.jsp文件，添加如下代码：

<body><%String username = "", password = "";Cookie[] cookies = request.getCookies();if (cookies!=null){for (int i = 0; i < cookies.length; i++) {//对cookies中的数据进行遍历，找到用户名、密码的数据if ("ukey".equals(cookies[i].getName())) {username = cookies[i].getValue();} else if ("password".equals(cookies[i].getName())) {password = cookies[i].getValue();}}}%><form name="loginForm" id="loginForm" method="post"><input type="text" placeholder="用户名" name="username" id="user_login" class="input" value="<%=username%>" size="20" required/><input type="password" placeholder="密码" name="password" id="user_pass" class="input" value="<%=password%>" size="20" required/><p class="forgetmenot"><label for="rememberme"><input name="rememberme" type="checkbox" id="rememberme" value="1" checked /> 记住密码</label></p><a class="submit">登陆<input type="button" name="wp-submit" id="submit-btn" value="登录" /></a><p id="backtoblog" style="margin-left: 160px;color: black"><a href="/index">&larr; 返回到博客</a></p></form>
</body>
<script src="/resource/assets/js/jquery.min.js"></script>
<script type="text/javascript">$("#submit-btn").click(function () {var user = $("#user_login").val();var password = $("#user_pass").val();console.log(user+' '+password)if(user=="") {alert("用户名不可为空!");} else if(password==""){alert("密码不可为空!");} else {$.ajax({async: false,//同步，待请求完毕后再执行后面的代码type: "POST",url: '/loginVerify',contentType: "application/x-www-form-urlencoded; charset=utf-8",data: $("#loginForm").serialize(),dataType: "json",success: function (data) {if(data.code==0) {alert(data.msg);} else {window.location.href="/admin";}},error: function () {alert("数据获取失败")}})}})

只摘取了关键代码，要看全部代码可以点击Github: SpringBlog/Login.sjp

全部完成后，运行tomcat，就可以在localhost:8080上看到我们写的界面啦，并且可以正常使用哦！

总结

好的，本篇文章到这里就结束了。似乎写了不少内容（好吧，大部分都是代码）
注解有着比xm更简单的配置和更好的可读性，使用得当的话会大大减轻springmvc开发的复杂度和代码量。
本文也未涉及深层次的spring知识，主要还是以一个简单的登陆流程为例，讲一下如何以全注解的方式来开发一个springmvc项目。
如果对这个简单的个人博客框架有兴趣的话，可以关注https://github.com/FuGaZn/SpringBlog
SpringMVC相对于SpringBoot来说，开发起来还是太复杂了。所以这个博客项目仅用于熟悉springmvc注解配置的用法，不会搭建为成熟的博客系统。

博客的在线编辑功能使用了Editormd，如果想了解Editormd的用法，可以看下一篇博客。