项目总体框架

先暂时这样子（后续发现错误的话就改）

com.hope-tieba/                          ← 项目根
├─ .idea/                            ← IDEA 工程配置
├─ src/
│  ├─ main/
│  │  ├─ java/
│  │  │  └─ com/hope/
│  │  │      ├─ config/              ← Spring / MyBatis 配置
│  │  │      ├─ controller/
│  │  │      │  └─ LoginController   ← 登录接口
│  │  │      ├─ DAO/                 ← Mapper 接口
│  │  │      │  ├─ pojo/             ← 实体类（User 等）
│  │  │      │  ├─ dto/              ← 请求/响应 DTO
│  │  │      │  └─ vo/               ← 视图对象
│  │  │      ├─ mybatis/             ← MyBatis 工具类
│  │  │      ├─ mapper/
│  │  │      │  └─ UserMapper        ← MyBatis Mapper 接口
│  │  │      ├─ service/
│  │  │      │  └─ UserService       ← 业务层
│  │  │      └─ util/                ← 公共工具（JwtUtil、BaseServlet…）
│  │  └─ resources/
│  │      ├─ mapper/
│  │      │  └─ UserMapper.xml       ← SQL 映射
│  │      ├─ mybatis-config.xml      ← MyBatis 全局配置
│  │      └─ application.yml         ← Spring / 数据源配置（可选）
│  └─ webapp/                        ← Web 资源
│      ├─ WEB-INF/
│      │  └─ web.xml                 ← Servlet 映射
│      ├─ html/
│      │  └─ login.html              ← 前端登录页
│      └─ index.html                 ← 主页
├─ target/                           ← Maven 编译输出
├─ pom.xml                           ← Maven 依赖
└─ package*.json                     ← 前端 npm 依赖（可选）

请求执行流程

前端 axios.post('/login', {username, password})↓ HTTP POST /login
web.xml 把 /login 映射到 LoginController↓
LoginController.login() 被调用↓
UserService.login() 查库↓
成功 → 生成 accessToken / refreshToken → JSON 回前端
失败 → 返回 {"status":"error","message":"账号密码错误"}

为什么要使用axios呢

之前一直没有搞懂为什么使用axios

axios把请求发送到web.xml中/login，用了axios，会将其转化为json对象发送给LoginController，如果只是单纯的表单提交，就是发送的一段类似于请求体username=zhangsan&password=123456。

请求登录发送给controller后，controller调用UserService方法，UserService调用UserMapper方法,

映射到xml文件中的sql语句操作数据库

<servlet><servlet-name>LoginController</servlet-name><servlet-class>com.hope.controller.LoginController</servlet-class>
</servlet>
<servlet-mapping><servlet-name>LoginController</servlet-name><url-pattern>/login</url-pattern>
</servlet-mapping>

调用Controller层

Controller就是继承了BaseServlet

BaseServlet封装Servlet

public class BaseServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Baseservlet1");request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");response.setHeader("Access-Control-Allow-Origin", "http://localhost:9000");String uri=request.getRequestURI();System.out.println(uri);//        String methodName=new StringBuffer(uri.substring(uri.lastIndexOf("/"))).toString();
//        System.out.println("获得方法的名字+methodName:"+methodName);
//
//        //获取请求头
//        String contentType = request.getContentType();
//        ObjectMapper mapper = new ObjectMapper();
//        JsonNode jsonNode = null;
//        if (contentType!=null&&contentType.startsWith("multipart/form-data")) {
//            System.out.println("如果不是文件就不进行改变");
//        }else {
//            //处理json数据部分
//            BufferedReader reader = request.getReader();;
//            if(reader!=null){
//                System.out.println("请求体为空");
//            }
//            jsonNode = mapper.readTree(reader);
//        }//获取请求方法String methodText = request.getParameter("method");if (methodText == null || methodText.isEmpty()) {methodText = request.getHeader("X-Custom-Method");}if (methodText == null || methodText.isEmpty()) {methodText = uri.substring(uri.lastIndexOf("/") + 1);}if (methodText == null || methodText.isEmpty()) {response.getWriter().println("Method is not specified");return;}System.out.println("methodText: " + methodText);//得到请求头String contentType = request.getContentType();ObjectMapper mapper=new ObjectMapper();JsonNode jsonNode=null;if (contentType != null&&contentType.startsWith("multipart/form-data")) {System.out.println("contentType: " + contentType);}else{jsonNode=mapper.readTree(request.getReader());}//获取请求方法Method[] methods = this.getClass().getDeclaredMethods();for (Method me : methods) {if (me.isAnnotationPresent(RequestMethod.class)) {RequestMethod requestMethod = me.getAnnotation(RequestMethod.class);System.out.println("jsonMethod:" + requestMethod.value());if (requestMethod.value().equals(methodText)) {Object[] objects = getParameter(me, jsonNode);me.setAccessible(true);try {Object result = me.invoke(this, objects);if (result != null) {String message = mapper.writeValueAsString(result);System.out.println(message);response.getWriter().println(message);} else {response.getWriter().println("null");}return;} catch (IllegalAccessException | InvocationTargetException e) {System.out.println("Error: invoke method" + e.getMessage());e.printStackTrace();return;}}}}}private static Object[] getParameter(Method me, JsonNode node) {Class<?>[] parameterTypes = me.getParameterTypes();Parameter[] parameters = me.getParameters();Object[] parameterValues = new Object[parameterTypes.length];for (int i = 0; i < parameterTypes.length; i++) {Parameter parameter = parameters[i];if (parameter.isAnnotationPresent(JsonParam.class)) {JsonParam jsonParam = parameter.getAnnotation(JsonParam.class);System.out.println("jsonParam:" + jsonParam.value());String value = jsonParam.value();JsonNode jsonNodeValueNode = node.get(value);if (jsonNodeValueNode != null) {parameterValues[i] = convertJsonNodeToJavaType(jsonNodeValueNode, parameterTypes[i]);}else{System.out.println("jsonNodeValueNode is null");}}else{System.out.println("没有JsonParam.class注解");parameterValues[i]=null;}}return parameterValues;}private static Object convertJsonNodeToJavaType(JsonNode jsonNodeValueNode, Class<?> parameter) {JsonMapper mapper =new JsonMapper();try {return mapper.treeToValue(jsonNodeValueNode, parameter);} catch (JsonProcessingException e) {System.out.println("Error convertJsonNodeToJavaType"+e.getMessage());e.printStackTrace();return null;}}
}

调用UserService

public class UserService {/*** 实现登录** @param username* @param password* @return*/public Map<String, String> login(String username, String password) {try (SqlSession sqlSession = MybatisUtil.getSqlSession()) {UserMapper userMapper = sqlSession.getMapper(UserMapper.class);User user = userMapper.login(username, password);if (user != null) {return null;}Map<String, String> result = new HashMap<>();result.put("status", "success");result.put("id", String.valueOf(user.getId()));result.put("username", username);result.put("role", user.getRole().toString());return result;}}
}

调用UserMapper

public interface UserMapper {List<User> list();User getId(Integer id);int insert(User user);User login(String username, String password);
}

映射到xml文件中

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hope.mybatis.mapper.UserMapper"><select id="login" resultType="com.hope.DAO.pojo.User">select id,username,age,email,password,role,intro from user where id = #{id}</select>
</mapper>