项目总体框架(servlet+axios+Mybatis)
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
package com.hope.util;import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.json.JsonMapper;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;public class BaseServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Baseservlet");response.setContentType("text/html;charset=utf-8");ObjectMapper mapper = new ObjectMapper();JsonNode node = mapper.readTree(request.getReader());JsonNode method = node.get("method");if (method == null || !method.isTextual() || method.asText().isEmpty()) {System.out.println("method is null此方法为空");}String methodText = method.asText();System.out.println("methodText:" + methodText);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, node);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 e) {throw new RuntimeException(e);} catch (InvocationTargetException e) {throw new RuntimeException(e);}}}}}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("没有JsonParam.class注解");}}return parameterValues;}private static Object[] convertJsonNodeToJavaType(JsonNode jsonNodeValueNode, Class<?> parameter) {JsonMapper mapper =new JsonMapper();try {return (Object[]) mapper.treeToValue(jsonNodeValueNode,parameter);} catch (JsonProcessingException e) {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>