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【微服务开发一】Spring Boot详解_springboot微服务demo项目详解

作者：思考机器3 | 2024-02-03 18:50:59

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springboot微服务demo项目详解

一、SpringBoot详解

1、初始SpringBoot

SpringBoot它是一个javaweb的开发框架

SpringBoot以约定大于配置的核心思想，默认帮助我们进行可很多设置，多数SpringBoot应用只需要很少的Spring配置。它集成了大量的第三方库配置

2、第一个SpringBoot程序

可以在https://start.spring.io/官网去创建项目
在idea中直接创建项目（推荐）
- 新建工程Spring Initializr.
- Spring Boot 2.7.7（Spring Boot 3.0 使用 Java 17作为最低版本）
- SDK版本1.8
- java版本8
项目主程序XXXApplication.java的同级目录创建controller

更改项目端口号:

application.properties配置文件中更改server.port=8081

更改banner：

在resources目录下，创建banner.txt，内容为需要显示的banner

3、自动装配原理

3.1 pom.xml

spring-boot-dependencies核心依赖在父工程中
我们在引入springboot依赖时，不需要指定版本，因为父工程的pom中配置了相应版本号

3.2 启动器

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
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启动器就是springboot的启动场景
比如spring-boot-starter-web，帮我们自动导入web环境所有依赖
springboot会将所有的功能场景，都变成一个个启动器
启动器https://docs.spring.io/spring-boot/docs/2.7.7/reference/html/using.html#using

3.3 主程序

//该注解为必须的
@SpringBootApplication
public class SpringBoot01Application {
    
    public static void main(String[] args) {
        //使用该语句启动springboot项目
        SpringApplication.run(SpringBoot01Application.class, args);
    }

}
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注解：

@SpringBootApplication
	@SpringBootConfiguration//springboot的配置
		@Configuration//spring配置类
			@Component//说明是一个组件
	@EnableAutoConfiguration//自动配置
		@AutoConfigurationPackage//自动配置包
			@Import({Registrar.class})//导入，自动配置包这个类的内部类Registrar
		@Import({AutoConfigurationImportSelector.class})//导入，自动配置导入选择器类

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自动配置的核心配置文件：

spring-boot-autoconfigure-2.7.7的jar包下META-INF/spring.factories文件（2.7版本中弃用）

SpringApplication做了四个事情：

推断应用的类型是普通项目还是web项目
查找并加载所有可用初始化器，设置到initializers属性中
找出所有的应用程序监听器，设置到listeners属性中
推断并设置main方法的定义类，找到运行主类

4、Yaml讲解

springboot的全局配置文件

application.properties
- key=value
application.yaml
- key:空格value

server:
  port: 8080
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#普通的key-value
name: lisa
#对象
student:
  name: lisa
  age: 3
#对象行内写法
student1: {name: lisa,age: 3}
#数组
pets:
  - cat
  - dog
  - pig
#数组行内写法
pets1: [cat,dog,pig]
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yaml可以给实体类赋值

Dog.java

@Component
public class Dog {
    private String name;
    private int age;
}
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Person.java

@Component
@ConfigurationProperties(prefix = "person")
public class Person {
    private String name;
    private Integer age;
    private Boolean happy;
    private Date birth;
    private Map<String,Object> maps;
    private List<Object> lists;
    private Dog dog;
}
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application.yaml

person:
  name: lisa${random.uuid}
  age: 32
  happy: false
  birth: 2013/2/3
  maps: {k1: v1,k2: v2}
  lists:
    - code
    - music
    - read
  dog:
    name: 阿旺
    age: 3
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测试类

@SpringBootTest
class Springboot02ConfigApplicationTests {
    @Autowired
    private Person person;
    @Test
    void contextLoads() {
        System.out.println(person);
    }

}
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5、配置文件位置

配置文件参考配置地址：https://docs.spring.io/spring-boot/docs/2.7.7/reference/html/application-properties.html#appendix.application-properties

配置文件放置的位置（按优先级排列）：

file:./config/（项目根目录下的config文件夹下）
file:./（项目根目录下）
classpath:/config/（resources目录下的config文件夹下）
classpath:/（resources目录下）

主要要关注XXXAutoConfiguration和XXXProperties，两种文件，来参考去在配置文件中配置

6、SpringBoot Web开发

6.1 静态资源导入

源码：

public void addResourceHandlers(ResourceHandlerRegistry registry) {
    //如果有自定义配置，默认路径则失效
    if (!this.resourceProperties.isAddMappings()) {
        logger.debug("Default resource handling disabled");
    } else {
        this.addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
        this.addResourceHandler(registry, this.mvcProperties.getStaticPathPattern(), (registration) -> {
            registration.addResourceLocations(this.resourceProperties.getStaticLocations());
            if (this.servletContext != null) {
                ServletContextResource resource = new ServletContextResource(this.servletContext, "/");
                registration.addResourceLocations(new Resource[]{resource});
            }

        });
    }
}
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导入方式一（不推荐）：

使用webjars

classpath:/META-INF/resources/

什么是webjars：意思就是以maven的方式引入web的jar包，访问时地址/webjars/映射为/META-INF/resources/webjars/

导入方式二：（以下目录放置静态文件1.js，直接在http://localhost:8080/1.js可访问）

classpath为项目根目录下的resources

classpath:/resources/
classpath:/static/
classpath:/public/

6.2 首页和图标定制

在静态资源目录下的index.html会被当做首页

在templates下的页面，只能通过controller访问

使用templates下的文件时，需要使用thymeleaf依赖，不然报错

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
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图标放在static文件夹下

需要图标的网页引入<link rel="icon" href="favicon.ico">

6.3 thymeleaf模板引擎

文档：https://www.thymeleaf.org/documentation.html

使用前需要导包

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
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其次在html中需要导入命名空间xmlns:th="http://www.thymeleaf.org"

thymeleaf语法

简单表达式:
- Variable Expressions: ${...}
- Selection Variable Expressions: *{...}
- Message Expressions: #{...}
- Link URL Expressions: @{...}
- Fragment Expressions: ~{...}
Literals
- Text literals: 'one text', 'Another one!',…
- Number literals: 0, 34, 3.0, 12.3,…
- Boolean literals: true, false
- Null literal: null
- Literal tokens: one, sometext, main,…
Text operations:
- String concatenation: +
- Literal substitutions: |The name is ${name}|
Arithmetic operations:
- Binary operators: +, -, *, /, %
- Minus sign (unary operator): -
Boolean operations:
- Binary operators: and, or
- Boolean negation (unary operator): !, not
Comparisons and equality:
- Comparators: >, <, >=, <= (gt, lt, ge, le)
- Equality operators: ==, != (eq, ne)
Conditional operators:
- If-then: (if) ? (then)
- If-then-else: (if) ? (then) : (else)
- Default: (value) ?: (defaultvalue)

<p>[[${msg}]]</p>
<p th:text="${msg}"></p>
<p th:utext="${msg}"></p>
<h1 th:each="item:${list}" th:text="${item}"></h1>

代码复用
<div th:fragment="sidebar">一堆代码</div>定义侧边栏，该代码所在文件1.html
<div th:insert="~{1.html::sidebar}"></div>插入侧边栏,该代码所在文件2.html
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6.4 扩展MVC配置

编写一个@Configuration注解的类
该类实现WebMvcConfigurer接口
并且不能标注@EnableWebMvc注解
一般配置类写在config包下

package com.daban.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    //视图跳转，通过kk请求，跳转到test页面
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/kk").setViewName("test");
    }
}
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7、员工管理系统

7.1 创建页面，模拟数据库数据

pojo.Department.java

package com.daban.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Department {
    private Integer id;
    private String departmentName;
}
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pojo.Employee.java

package com.daban.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.Date;

@Data
@NoArgsConstructor
public class Employee {
    private Integer id;
    private String lastName;
    private String email;
    private Integer gender;
    private Department department;
    private Date birth;

    public Employee(Integer id, String lastName, String email, Integer gender, Department department) {
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.gender = gender;
        this.department = department;
        this.birth = new Date();
    }
}
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dao.DepartmentDao.java

package com.daban.dao;

import com.daban.pojo.Department;
import org.springframework.stereotype.Repository;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

@Repository
public class DepartmentDao {
    private static Map<Integer, Department> department = null;
    static {
        department = new HashMap<Integer, Department>();
        department.put(101,new Department(101,"教学部"));
        department.put(102,new Department(102,"市场部"));
        department.put(103,new Department(103,"教研部"));
        department.put(104,new Department(104,"运营部"));
        department.put(105,new Department(105,"后勤部"));
    }
    //获得所有部门信息
    public Collection<Department> getDepartment(){
        return department.values();
    }
    //通过id获取部门
    public Department getDepartmentById(Integer id){
        return department.get(id);
    }
}
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dao.EmployeeDao.java

package com.daban.dao;

import com.daban.pojo.Department;
import com.daban.pojo.Employee;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

@Repository
public class EmployeeDao {
    private static Map<Integer, Employee> employees = null;
    @Autowired
    private DepartmentDao departmentDao;
    static {
        employees = new HashMap<Integer, Employee>();
        employees.put(101,new Employee(1001,"AA","12345@qq.com",1,new Department(101,"教学部")));
        employees.put(102,new Employee(1002,"BB","12345@qq.com",0,new Department(102,"市场部")));
        employees.put(103,new Employee(1003,"CC","12345@qq.com",0,new Department(103,"教研部")));
        employees.put(104,new Employee(1004,"DD","12345@qq.com",1,new Department(104,"运营部")));
        employees.put(105,new Employee(1005,"EE","12345@qq.com",0,new Department(105,"后勤部")));
    }

    //主键自增
    private static Integer initId = 1006;
    //增加一个员工
    public void addEmployee(Employee employee){
        if(employee.getId()==null){
            employee.setId(initId++);
        }
    employee.setDepartment(departmentDao.getDepartmentById(employee.getDepartment().getId()));
        employees.put(employee.getId(),employee);
    }

    //查询全部员工
    public Collection<Employee> getAll(){
        return employees.values();
    }
    //通过id查询员工
    public Employee getEmployeeById(Integer id){
        return employees.get(id);
    }
    //删除员工
    public void delete(Integer id){
        employees.remove(id);
    }
}
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页面文件
- https://github.com/twbs/bootstrap/releases/download/v5.3.0-alpha1/bootstrap-5.3.0-alpha1-examples.zip
- 下载后解压文件中的dashboard和sign-in

7.2 首页

首页使用配置类来做

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    //视图跳转
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/index").setViewName("index");
    }
}
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7.3 页面国际化（多语言）

创建各语言文件

resources文件夹下创建i18n文件夹，里面创建三个文件

#全局配置文件application.properties中配置国际化参数
spring.messages.basename=i18n.login
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#创建如下三个文件，可以在idea的Resource Bundle中可以同步编辑三个文件
#login.properties
login.signin=登陆
login.password=密码
login.remember=记住我
login.tip=请登陆
login.username=用户名
#login_zh_CN.properties
login.signin=sign in
login.password=password
login.remember=Remember me
login.tip=please sign in
login.username=username
#login_en_US.properties
login.signin=登陆
login.password=密码
login.remember=记住我
login.tip=请登陆
login.username=用户名
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html文件绑定

html文件中使用#{}来绑定相应字段

<h1 class="h3 mb-3 fw-normal" th:text="#{login.tip}">Please sign in</h1>
<label for="floatingInput" th:text="#{login.username}">Username</label>
<label for="floatingPassword" th:text="#{login.password}">Password</label>
<button class="w-100 btn btn-lg btn-primary" type="submit" th:text="#{login.signin}">Sign in</button>
<span th:text="#{login.remember}">Remember me</span>
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设置中英文切换按钮

<a class="btn btn-sm" th:href="@{/index(l='zh_CN')}">中文</a>
<a class="btn btn-sm" th:href="@{/index(l='en_US')}">English</a>
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创建一个类MyLocaleResolver

package com.daban.config;

import org.springframework.web.servlet.LocaleResolver;
import org.thymeleaf.util.StringUtils;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;

public class MyLocaleResolver implements LocaleResolver {
    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        String language = request.getParameter("l");
        Locale locale = Locale.getDefault();
        if(!StringUtils.isEmpty(language)){
            String[] s = language.split("_");
            locale = new Locale(s[0], s[1]);
        }
        return locale;
    }

    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {

    }
}
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在MyMvcConfig类中注册

MyMvcConfig类参见《6.4扩展MVC配置》

@Bean
public LocaleResolver localeResolver(){
    return new MyLocaleResolver();
}
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7.4 登陆功能

登陆controller

package com.daban.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.thymeleaf.util.StringUtils;

@Controller
public class LoginController {
    @RequestMapping("/login")
    public String login(String username, String password, Model model){
        System.out.println(username+password);
        if(StringUtils.isEmpty(username) || StringUtils.isEmpty(password)){
            model.addAttribute("msg","用户名或密码不能为空");
            return "index";
        }
        else if (username.equals("admin") && password.equals("123")){
            session.setAttribute("loginUser",username);
            return "redirect:main.html";
        }else {
            model.addAttribute("msg","输入的用户名或密码有误");
            return "index";
        }

    }
}
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地址映射

package com.daban.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    //视图跳转
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/index").setViewName("index");
        registry.addViewController("/main.html").setViewName("dashboard");
    }
    //自定义的国际化就生效
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }
}
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7.5 登陆拦截器

写一个拦截器类

package com.daban.config;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object loginUser = request.getSession().getAttribute("loginUser");
        if(loginUser==null){
            request.setAttribute("msg","您还没有登陆");
            request.getRequestDispatcher("/index").forward(request,response);
            return false;
        }else {
            return true;
        }
    }
}
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MyMvcConfig类里增加

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new LoginInterceptor())
            .addPathPatterns("/**")
        	//过滤使不经过拦截器
            .excludePathPatterns("/index","/","/login","/css/**","/js/**","/img/**");
}
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7.6 展示员工列表

1、提取公共页面

代码复用
<div th:fragment="sidebar">一堆代码</div>定义侧边栏，该代码所在文件1.html
<div th:insert="~{1.html::sidebar}"></div>插入侧边栏,该代码所在文件2.html
或<div th:replace="~{1.html::sidebar}"></div>插入侧边栏,该代码所在文件2.html
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2、如果要传递参数

使用（）即可<div th:replace="~{1.html::sidebar(active="list.html")}"></div>

3、使用传递的参数

<a th:class="${active=='list.html'?'nav-link active': 'nav-link'}"/>

意思就是如果active==list.html，class属性为nav-link active，否则为nav-link

4、列表循环展示

<tr th:each="item:${emps}">
  <td th:text="${item.getId()}"></td>
  <td th:text="${item.getLastName()}"></td>
  <td th:text="${item.getEmail()}"></td>
  <td th:text="${item.getGender()==0?'女':'男'}"></td>
  <td th:text="${item.getDepartment().getDepartmentName()}"></td>
  <td th:text="${#dates.format(item.getBirth(),'yyyy-MM-dd')}"></td>
  <td>
    <a class="btn btn-sm btn-primary" th:href="">编辑</a>
    <a class="btn btn-sm btn-danger" th:href="">删除</a>
  </td>
</tr>
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7.7 增加员工

要点：

在全局配置文件中spring.mvc.format.date=yyyy/MM/dd，设置时间格式

表单字段是一个对象，只需要把id传递

<div class="form-group">
  <label>部门</label>
  <select name="department.id" class="form-control">
    <option th:each="item:${departments}"
            th:text="${item.getDepartmentName()}"
            th:value="${item.getId()}">
    </option>
  </select>
</div>
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7.8 修改员工信息

要点：

链接传递参数

<a class="btn btn-sm btn-primary" th:href="@{/toUpdate(id=${item.getId()})}">编辑</a>
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单选框的数据回显

<input type="radio" th:checked="${emps.getGender()==0}" class="form-check-input" name="gender" value="0">
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下拉框数据回显

<select name="department.id" class="form-control">
  <option th:selected="${item.getId() ==emps.getDepartment().getId()}"
          th:each="item:${departments}"
          th:text="${item.getDepartmentName()}"
          th:value="${item.getId()}">
  </option>
</select>
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表单隐藏域的提交

<input type="hidden" th:value="${emps.getId()}" name="id" class="form-control">
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7.9 删除员工及404

删除：

@RequestMapping("/delete")
public String delete(Integer id){
    //Employee employee = employeeDao.getEmployeeById(id);
    employeeDao.delete(id);
    return "redirect:/emps";
}
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404：

404功能就是在templates目录下创建一个error文件夹，里面放置404.html就可以，其他500了类似

注销：

@RequestMapping("/logout")
public String logout(HttpSession session){
    session.invalidate();
    return "redirect:index";
}
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