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算是自己第一个正式的java项目，加油！

项目配置

修改中央仓库、镜像配置

阿里云maven镜像仓库

修改IDEA中 maven 设置

搜索、管理maven包

搜索
https://mvnrepository.com/

管理
https://start.spring.io/

Spring入门

Spring MVC 入门

获取参数的值

通过不同的注解，获取值，但是一般不加

 // GET请求

    // /students?current=1&limit=20
    @RequestMapping(path = "/students", method = RequestMethod.GET)
    @ResponseBody
    public String getStudents(
            @RequestParam(name = "current", required = false, defaultValue = "1") int current,
            @RequestParam(name = "limit", required = false, defaultValue = "10") int limit) {
        System.out.println(current);
        System.out.println(limit);
        return "some students";
    }

    // /student/123
    @RequestMapping(path = "/student/{id}", method = RequestMethod.GET)
    @ResponseBody
    public String getStudent(@PathVariable("id") int id) {
        System.out.println(id);
        return "a student";
    }

 // POST请求
    @RequestMapping(path = "/student", method = RequestMethod.POST)
    @ResponseBody
    public String saveStudent(String name, int age) {
        System.out.println(name);
        System.out.println(age);
        return "success";
    }

 // 响应HTML数据

    @RequestMapping(path = "/teacher", method = RequestMethod.GET)
    public ModelAndView getTeacher() {
        ModelAndView mav = new ModelAndView();
        mav.addObject("name", "张三");
        mav.addObject("age", 30);
        mav.setViewName("/demo/view");
        return mav;
    }

    @RequestMapping(path = "/school", method = RequestMethod.GET)
    public String getSchool(Model model) {
        model.addAttribute("name", "北京大学");
        model.addAttribute("age", 80);
        return "/demo/view";
    }

返回json需要加 @ResponseBody ，否则返回html

  // 响应JSON数据(异步请求)
    // Java对象 -> JSON字符串 -> JS对象

    @RequestMapping(path = "/emp", method = RequestMethod.GET)
    @ResponseBody
    public Map<String, Object> getEmp() {
        Map<String, Object> emp = new HashMap<>();
        emp.put("name", "张三");
        emp.put("age", 23);
        emp.put("salary", 8000.00);
        return emp;
    }

    @RequestMapping(path = "/emps", method = RequestMethod.GET)
    @ResponseBody
    public List<Map<String, Object>> getEmps() {
        List<Map<String, Object>> list = new ArrayList<>();

        Map<String, Object> emp = new HashMap<>();
        emp.put("name", "张三");
        emp.put("age", 23);
        emp.put("salary", 8000.00);
        list.add(emp);

        emp = new HashMap<>();
        emp.put("name", "李四");
        emp.put("age", 24);
        emp.put("salary", 9000.00);
        list.add(emp);

        emp = new HashMap<>();
        emp.put("name", "王五");
        emp.put("age", 25);
        emp.put("salary", 10000.00);
        list.add(emp);

        return list;
    }

Mybatis入门

配置信息

MyBatis 增删改查语句

在Dao层定义查询接口 实体类，表中有什么就建什么

利用方法名 制定对应关系

日志级别调整为Debug

community\src\main\resources\application-develop.properties

# logger
#logging.level.com.nowcoder.community=debug
#logging.file=d:/work/data/nowcoder/community.log

1.30 开发社区首页

server层调 dao层

server层管理dao层 数据库查询的方法， Controller的逻辑来管理server层

渲染html

加载html static文件

		
				<ul class="list-unstyled">
					<li class="media pb-3 pt-3 mb-3 border-bottom" th:each="map:${discussPosts}">
						<a href="site/profile.html">
							<img th:src="${map.user.headerUrl}" class="mr-4 rounded-circle" alt="用户头像" style="width:50px;height:50px;">
						a>
						<div class="media-body">
							<h6 class="mt-0 mb-3">
								<a href="#" th:utext="${map.post.title}">备战春招，面试刷题跟他复习，一个月全搞定！a>
								<span class="badge badge-secondary bg-primary" th:if="${map.post.type==1}">置顶span>
								<span class="badge badge-secondary bg-danger" th:if="${map.post.status==1}">精华span>
							h6>
							<div class="text-muted font-size-12">
								<u class="mr-3" th:utext="${map.user.username}">寒江雪u> 发布于 <b th:text="${#dates.format(map.post.createTime,'yyyy-MM-dd HH:mm:ss')}">2019-04-15 15:32:18b>
								<ul class="d-inline float-right">
									<li class="d-inline ml-2">赞 11li>
									<li class="d-inline ml-2">|li>
									<li class="d-inline ml-2">回帖 7li>
								ul>
							div>
						div>						
					li>
				ul>

分页

package com.nowcoder.community.entity;

/**
 * 封装分页相关的信息.
 */
public class Page {

    // 当前页码
    private int current = 1;
    // 显示上限
    private int limit = 10;
    // 数据总数(用于计算总页数)
    private int rows;
    // 查询路径(用于复用分页链接)
    private String path;

    public int getCurrent() {
        return current;
    }

    public void setCurrent(int current) {
        if (current >= 1) {
            this.current = current;
        }
    }

    public int getLimit() {
        return limit;
    }

    public void setLimit(int limit) {
        if (limit >= 1 && limit <= 100) {
            this.limit = limit;
        }
    }

    public int getRows() {
        return rows;
    }

    public void setRows(int rows) {
        if (rows >= 0) {
            this.rows = rows;
        }
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    /**
     * 获取当前页的起始行
     *
     * @return
     */
    public int getOffset() {
        // current * limit - limit
        return (current - 1) * limit;
    }

    /**
     * 获取总页数
     *
     * @return
     */
    public int getTotal() {
        // rows / limit [+1]
        if (rows % limit == 0) {
            return rows / limit;
        } else {
            return rows / limit + 1;
        }
    }

    /**
     * 获取起始页码
     *
     * @return
     */
    public int getFrom() {
        int from = current - 2;
        return from < 1 ? 1 : from;
    }

    /**
     * 获取结束页码
     *
     * @return
     */
    public int getTo() {
        int to = current + 2;
        int total = getTotal();
        return to > total ? total : to;
    }

}

| 静态资源 |
${动态资源}

@{${page.path}(current=1)}

= @{${page.path}？current=1)

				<nav class="mt-5" th:if="${page.rows>0}">
					<ul class="pagination justify-content-center">
						<li class="page-item">
							<a class="page-link" th:href="@{${page.path}(current=1)}">首页a>
						li>
						<li th:class="|page-item ${page.current==1?'disabled':''}|">
							<a class="page-link" th:href="@{${page.path}(current=${page.current-1})}">上一页a>li>
						<li th:class="|page-item ${i==page.current?'active':''}|" th:each="i:${#numbers.sequence(page.from,page.to)}">
							<a class="page-link" href="#" th:text="${i}">1a>
						li>
						<li th:class="|page-item ${page.current==page.total?'disabled':''}|">
							<a class="page-link" th:href="@{${page.path}(current=${page.current+1})}">下一页a>
						li>
						<li class="page-item">
							<a class="page-link" th:href="@{${page.path}(current=${page.total})}">末页a>
						li>
					ul>
				nav>

项目调试技巧

Debug调试 与
Logger日志记录配置：src/main/resources/logback-spring.xml