使用springboot进行web项目开发1（含数据库连接，国际化，登录控制，拦截器）

￡神魔★判官ぃ 2023-01-08 04:23 49阅读 0赞

#### springboot-web项目的开发过程 ####

> 该项目使用了thymeleaf模板引擎，整合了mybatis，实现了CRUD，权限控制（拦截器）

##### 1.准备工作 #####

1.  创建spring boot项目，在resources目录下的static目录下导入静态资源css，js，img
2.  在resources目录下的templates目录下导入静态资源xxx.html
    
     *  项目中使用了bootstrap的模板

##### 2.连接数据库 #####

1.  pom文件中引入相关依赖
    
        <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        
        <dependency>
           <groupId>mysql</groupId>
           <artifactId>mysql-connector-java</artifactId>
           <scope>runtime</scope>
        </dependency>
2.  在主配置文件application.properties文件中配置相关参数
    
        spring.datasource.username=root
        spring.datasource.password=123456
        spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
        spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
    
    注意：serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8，需要添加时间地区和编码方式
3.  启动idea的mysql连接，选择schemas（要使用到的数据库表），若连接失败，在advanced中配置serverTimezone=UTC

##### 3.国际化（i18n） #####

页面支持中英文切换

1.  pom.xml中引入thymeleaf引擎依赖
    
        <dependency>
           <groupId>org.thymeleaf</groupId>
           <artifactId>thymeleaf-spring5</artifactId>
        </dependency>
        
        <dependency>
           <groupId>org.thymeleaf.extras</groupId>
           <artifactId>thymeleaf-extras-java8time</artifactId>
        </dependency>
2.  在resources创建i18n目录，在该目录下创建login.properties
    
     *  创建login\_en\_US.properties
     *  创建login\_zh\_CN.properties
    
    点击login.properties文件，点击下方的 Resource Bundle，然后页面内容进行中英文匹配
    
    ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg5NDc3MQ_size_16_color_FFFFFF_t_70][]
3.  在主配置文件application.properties文件中配置i18n的配置
    
        spring.thymeleaf.cache=false
        spring.messages.basename=i18n.login
    
    关闭thymeleaf引擎的缓存，设置国际化信息的来源为i18n目录下的login
4.  依照thymeleaf语法修改index中的相关代码
    
        <!DOCTYPE html>
        <html lang="en_US" xmlns:th="http://www.thymeleaf.org">
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
            <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
            <meta name="description" content="">
            <meta name="author" content="">
            <title>Signin Template for Bootstrap</title>
            
            <link th:href="@{/css/bootstrap.min.css}" rel="stylesheet">
            
            <link th:href="@{/css/signin.css}" rel="stylesheet">
        </head>
        
        <body class="text-center">
        <form class="form-signin" th:action="@{/user/login}">
            <img class="mb-4" th:src="@{/img/bootstrap-solid.svg}" alt="" width="72" height="72">
            <h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}">Please sign in</h1>
            
            <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
            <label class="sr-only" th:text="#{login.username}">Username</label>
            <input type="text" name="username" class="form-control" th:placeholder="#{login.username}" required="" autofocus="">
            <label class="sr-only" th:text="#{login.password}">Password</label>
            <input type="password" name="password" class="form-control" th:placeholder="#{login.password}" required="">
            <div class="checkbox mb-3">
                <label>
                    <input type="checkbox" value="remember-me"> [[#{login.remember}]]
                </label>
            </div>
            <button class="btn btn-lg btn-primary btn-block" type="submit">[[#{login.btn}]]</button>
            <p class="mt-5 mb-3 text-muted">© 2017-2018</p>
            <a class="btn btn-sm" th:href="@{/index.html(l='zh_CN')}">中文</a>
            <a class="btn btn-sm" th:href="@{/index.html(l='en_US')}">English</a>
        </form>
        
        </body>
        
        </html>
    
    小结：
    
     *  引入thymeleaf的命名空间
     *  根据thymeleaf的语法规则对原有的html代码进行修改
        
         *  链接使用@
            
                <link th:href="@{/css/bootstrap.min.css}" rel="stylesheet">
                <img class="mb-4" th:src="@{/img/bootstrap-solid.svg}" alt="" width="72" height="72">
                <a class="btn btn-sm" th:href="@{/index.html(l='zh_CN')}">中文</a>
         *  文本信息使用\#
            
                <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
         *  if等使用$
            
                <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
5.  自定义mvcconfig
    
        package com.cai.config;
        
        
        import org.springframework.context.annotation.Bean;
        import org.springframework.context.annotation.Configuration;
        import org.springframework.stereotype.Component;
        import org.springframework.web.servlet.LocaleResolver;
        import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
        import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
        import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
        import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
        import org.yaml.snakeyaml.events.Event;
        
        import java.util.Locale;
        
        
        @Configuration
        public class MyMvcConfig implements WebMvcConfigurer { 
        
            @Override
            public void addViewControllers(ViewControllerRegistry registry) { 
                registry.addViewController("/").setViewName("index");
                registry.addViewController("/index.html").setViewName("index");
                registry.addViewController("/main.html").setViewName("dashboard");
            }
        
        
        
            @Bean
            public LocaleResolver localeResolver(){ 
                return new LocaleConfig();
            }
        
        }
6.  自定义localeconfig
    
        package com.cai.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 LocaleConfig implements LocaleResolver{ 
        
        
                @Override
                public Locale resolveLocale(HttpServletRequest httpServletRequest) { 
                    String l= httpServletRequest.getParameter("l");
                    //System.out.println("debug====================>"+l);
                    Locale locale =Locale.getDefault();
                    if(!StringUtils.isEmpty(l)){ 
                        String [] split= l.split("_");
                        locale=new Locale(split[0],split[1]);
                    }
                    return locale;
                }
        
                @Override
                public void setLocale(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Locale locale) { 
        
        
            }
        }
7.  国际化总结：
    
    国际化其实就是对原有页面中的内容进行中英文替换。在点击中文，英文切换时，携带参数传递给自定义的localeconfig，判断显示中文还是英文页面，然后将localeconfig注入到mvcconfig当中。当页面接收到显示中文或英文时，会通过th:text="\#\{login.tip\}"进行显示。

##### 4.登录控制 #####

1.  输入用户名密码访问
    
    1.  编写logincontroller，接收index.html页面传来的账号和密码，进行判断
        
            package com.cai.controller;
            
            import org.springframework.stereotype.Controller;
            import org.springframework.ui.Model;
            import org.springframework.web.bind.annotation.RequestMapping;
            import org.springframework.web.bind.annotation.RequestParam;
            import org.springframework.web.bind.annotation.ResponseBody;
            import org.thymeleaf.util.StringUtils;
            
            import javax.lang.model.element.NestingKind;
            import javax.servlet.http.HttpSession;
            
            
            @Controller
            public class LoginController { 
                @RequestMapping("/user/login")
                //@Responsebody这个注解的作用是返回一个json格式
                //@ResponseBody
                //为了防止出现不必要的错误，需要加requestparam来保证参数的准确
                public String login(@RequestParam("username") String username, @RequestParam("password") String password, Model model, HttpSession session) { 
                    //具体的业务
                    if (!StringUtils.isEmpty(username) && "123456".equals(password)) { 
                        session.setAttribute("loginUser",username);
                        //登录成功的话重定向到main.html，隐藏用户名和密码
                        return "redirect:/main.html";
                    } else { 
                        //登录失败的话，告诉用户登录失败，返回index页面
                        model.addAttribute("msg", "用户名或者密码错误");
                        return "index";
                    }
                }
                //注销
                @RequestMapping("/user/logout")
                public String logout(HttpSession session){ 
                    session.invalidate();
                    return "redirect:/index.html";
                }
            }
    2.  将判断结果返回给html页面进行显示，成功则进入，不成功则显示提示信息(index.html部分代码，完整代码同上)
        
            <form class="form-signin" th:action="@{/user/login}">
            
            <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
2.  通过页面路径访问需要拦截
    
    1.  自定义一个拦截器LoginHandlerinterceptor
        
            package com.cai.config;
            
            import org.springframework.web.servlet.HandlerInterceptor;
            import org.springframework.web.servlet.ModelAndView;
            
            import javax.servlet.http.HttpServletRequest;
            import javax.servlet.http.HttpServletResponse;
            
            /** * @BelongsProject:IntelliJ IDEA * @Package:com.cai.config * @Author:superman * @CreateTime:2021--01--14 10:58 * @Description:登录拦截器 */
            public class LoginHandlerinterceptor implements HandlerInterceptor { 
                @Override
                public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
            
                    //登录成功之后，应该有用户的session；
                    Object loginUser = request.getSession().getAttribute("loginUser");
            
                    if (loginUser==null){ 
                        request.setAttribute("msg","没有权限，请先登录");
                        request.getRequestDispatcher("/index.html").forward(request,response);
                        return false;
                    }else { 
                        return true;
                    }
            
                }
            }
    2.  在自定义的mvcconfig配置拦截器，放行静态资源和首页
        
            //配置拦截器
                @Override
                public void addInterceptors(InterceptorRegistry registry) { 
                    registry.addInterceptor(new LoginHandlerinterceptor()).addPathPatterns("/**").excludePathPatterns("/index.html","/","/user/login","/css/**","/js/**","/img/**");
                }

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