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Spring Boot 入门(2):Web 篇

Spring Boot winrains 来源:月光中的污点 1年前 (2019-09-02) 86次浏览

一、前言

上一篇《Spring Boot 入门之基础篇(一)》介绍了 Spring Boot 的环境搭建以及项目启动打包等基础内容,本篇继续深入介绍 Spring Boot 与 Web 开发相关的知识。

二、整合模板引擎

由于 jsp 不被 SpringBoot 推荐使用,所以模板引擎主要介绍 Freemarker 和 Thymeleaf。

2.1 整合 Freemarker

2.1.1 添加 Freemarker 依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

2.1.2 添加 Freemarker 模板配置

application.properties 中添加如下内容:

spring.freemarker.allow-request-override=false
spring.freemarker.cache=true
spring.freemarker.check-template-location=true
spring.freemarker.charset=UTF-8
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=false
spring.freemarker.expose-session-attributes=false
spring.freemarker.expose-spring-macro-helpers=false
spring.freemarker.prefix=
spring.freemarker.suffix=.ftl

上述配置都是默认值。

2.1.3 Freemarker 案例演示

controller 包中创建 FreemarkerController

@Controller
@RequestMapping("freemarker")
public class FreemarkerController {
    @RequestMapping("hello")
    public String hello(Map<String, Object> map) {
        map.put("msg", "Hello Freemarker");
        return "hello";
    }
}

templates 目录中创建名为 hello.ftl 文件,内容如下:

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <link href="/css/index.css" rel="stylesheet"/>
</head>
<body>
    <div class="container">
        <h2>${msg}</h2>
    </div>
</body>
</html>

结果如下:

2.2 整合 Thymeleaf

2.2.1 添加 Thymeleaf 依赖

pom.xml 文件中添加:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

2.2.2 添加 Thymeleaf 模板配置

application.properties 中添加如下内容:

spring.thymeleaf.cache=true
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html
spring.thymeleaf.mode=HTML5
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html

上述配置都是默认值。

2.2.3 Thymeleaf 案例演示

controller 包中创建 ThymeleafController:

@Controller
@RequestMapping("thymeleaf")
public class ThymeleafController {
    @RequestMapping("hello")
    public String hello(Map<String,Object> map) {
        map.put("msg", "Hello Thymeleaf");
        return "hello";
    }
}

template 目录下创建名为 hello.html 的文件,内容如下:

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <link href="/css/index.css" rel="stylesheet"/>
</head>
<body>
    <div class="container">
        <h2 th:text="${msg}"></h2>
    </div>
</body>
</html>

结果如下:

三、整合 Fastjson

3.1 添加依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.35</version>
</dependency>

3.2 整合 Fastjson

创建一个配置管理类 WebConfig ,如下:

@Configuration
public class WebConfig {
    @Bean
    public HttpMessageConverters fastJsonHttpMessageConverters() {
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        HttpMessageConverter<?> converter = fastJsonHttpMessageConverter;
        return new HttpMessageConverters(converter);
    }
}

3.3 演示案例:

创建一个实体类 User

public class User {
    private Integer id;
    private String username;
    private String password;
    private Date birthday;
}

getter 和 setter 此处省略。
创建控制器类 FastjsonController :

@Controller
@RequestMapping("fastjson")
public class FastJsonController {
    @RequestMapping("/test")
    @ResponseBody
    public User test() {
        User user = new User();
        user.setId(1);
        user.setUsername("jack");
        user.setPassword("jack123");
        user.setBirthday(new Date());
        return user;
    }
}

打开浏览器,访问 http://localhost:8080/fastjson/test,结果如下图:

此时,还不能看出 Fastjson 是否正常工作,我们在 User 类中使用 Fastjson 的注解,如下内容:

@JSONField(format="yyyy-MM-dd")
private Date birthday;

再次访问 http://localhost:8080/fastjson/test,结果如下图:
http://image.winrains.cn/2019/09/d335c-springboot-06-1.jpg
日期格式与我们修改的内容格式一致,说明 Fastjson 整合成功。

四、自定义 Servlet

4.1 编写 Servlet

public class ServletTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        resp.getWriter().write("自定义 Servlet");
    }
}

4.2 注册 Servlet

Servelt 注册成 Bean。在上文创建的 WebConfig 类中添加如下代码:

@Bean
public ServletRegistrationBean servletRegistrationBean() {
    return new ServletRegistrationBean(new ServletTest(),"/servletTest");
}

结果如下:

五、自定义过滤器/第三方过滤器

5.1 编写过滤器

public class TimeFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("=======初始化过滤器=========");
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
            throws IOException, ServletException {
        long start = System.currentTimeMillis();
        filterChain.doFilter(request, response);
        System.out.println("filter 耗时:" + (System.currentTimeMillis() - start));
    }
    @Override
    public void destroy() {
        System.out.println("=======销毁过滤器=========");
    }
}

5.2 注册过滤器

要是该过滤器生效,有两种方式:

  1. 使用 @Component 注解

  2. 添加到过滤器链中,此方式适用于使用第三方的过滤器。将过滤器写到 WebConfig 类中,如下:

    @Bean
    public FilterRegistrationBean timeFilter() {
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        TimeFilter timeFilter = new TimeFilter();
        registrationBean.setFilter(timeFilter);
        List<String> urls = new ArrayList<>();
        urls.add("/*");
        registrationBean.setUrlPatterns(urls);
        return registrationBean;
    }
    

结果如下:

六、自定义监听器

6.1 编写监听器

public class ListenerTest implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("监听器初始化...");
    }
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
    }
}

6.2 注册监听器

注册监听器为 Bean,在 WebConfig 配置类中添加如下代码:

@Bean
public ServletListenerRegistrationBean<ListenerTest> servletListenerRegistrationBean() {
    return new ServletListenerRegistrationBean<ListenerTest>(new ListenerTest());
}

当启动容器时,结果如下:

针对自定义 ServletFilterListener 的配置,还有另一种方式:

@SpringBootApplication
public class SpringbootWebApplication implements ServletContextInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        // 配置 Servlet
        servletContext.addServlet("servletTest",new ServletTest())
                      .addMapping("/servletTest");
        // 配置过滤器
        servletContext.addFilter("timeFilter",new TimeFilter())
                      .addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST),true,"/*");
        // 配置监听器
        servletContext.addListener(new ListenerTest());
    }
    public static void main(String[] args) {
        SpringApplication.run(SpringbootWebApplication.class, args);
    }
}

七、自定义拦截器

7.1 编写拦截器

使用 @Component 让 Spring 管理其生命周期:

@Component
public class TimeInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("========preHandle=========");
        System.out.println(((HandlerMethod)handler).getBean().getClass().getName());
        System.out.println(((HandlerMethod)handler).getMethod().getName());
        request.setAttribute("startTime", System.currentTimeMillis());
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
            throws Exception {
        System.out.println("========postHandle=========");
        Long start = (Long) request.getAttribute("startTime");
        System.out.println("耗时:"+(System.currentTimeMillis() - start));
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception)
            throws Exception {
        System.out.println("========afterCompletion=========");
        Long start = (Long) request.getAttribute("startTime");
        System.out.println("耗时:"+(System.currentTimeMillis() - start));
        System.out.println(exception);
    }
}

7.2 注册拦截器

编写拦截器后,我们还需要将其注册到拦截器链中,如下配置:

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{
    @Autowired
    private TimeInterceptor timeInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(timeInterceptor);
    }
}

请求一个 controller ,结果如下:

八、配置 AOP 切面

8.1 添加依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

8.2 编写切面类

使用 @Component@Aspect 标记到切面类上:

@Aspect
@Component
public class TimeAspect {
    @Around("execution(* com.light.springboot.controller.FastJsonController..*(..))")
    public Object method(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("=====Aspect处理=======");
        Object[] args = pjp.getArgs();
        for (Object arg : args) {
            System.out.println("参数为:" + arg);
        }
        long start = System.currentTimeMillis();
        Object object = pjp.proceed();
        System.out.println("Aspect 耗时:" + (System.currentTimeMillis() - start));
        return object;
    }
}

请求 FastJsonController 控制器的方法,结果如下:

九、错误处理

9.1 友好页面

先演示非友好页面,修改 FastJsonController 类中的 test 方法:

@RestController
@RequestMapping("fastjson")
public class FastJsonController {
    @RequestMapping("/test")
    public User test() {
        User user = new User();
        user.setId(1);
        user.setUsername("jack");
        user.setPassword("jack123");
        user.setBirthday(new Date());
        // 模拟异常
        int i = 1/0;
        return user;
    }
}

浏览器请求:http://localhost:8080/fastjson/test,结果如下:

当系统报错时,返回到页面的内容通常是一些杂乱的代码段,这种显示对用户来说不友好,因此我们需要自定义一个友好的提示系统异常的页面。
src/main/resources 下创建 /public/error,在该目录下再创建一个名为 5xx.html 文件,该页面的内容就是当系统报错时返回给用户浏览的内容:

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>系统错误</title>
    <link href="/css/index.css" rel="stylesheet"/>
</head>
<body>
    <div class="container">
        <h2>系统内部错误</h2>
    </div>
</body>
</html>

路径时固定的,Spring Boot 会在系统报错时将返回视图指向该目录下的文件。
如下图:

上边处理的 5xx 状态码的问题,接下来解决 404 状态码的问题。
当出现 404 的情况时,用户浏览的页面也不够友好,因此我们也需要自定义一个友好的页面给用户展示。
/public/error 目录下再创建一个名为 404.html 的文件:

<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>访问异常</title>
    <link href="/css/index.css" rel="stylesheet"/>
</head>
<body>
    <div class="container">
        <h2>找不到页面</h2>
    </div>
</body>
</html>

我们请求一个不存在的资源,如:http://localhost:8080/fastjson/test2,结果如下图:

9.2 全局异常捕获

如果项目前后端是通过 JSON 进行数据通信,则当出现异常时可以常用如下方式处理异常信息。
编写一个类充当全局异常的处理类,需要使用 @ControllerAdvice@ExceptionHandler 注解:

@ControllerAdvice
public class GlobalDefaultExceptionHandler {
    /**
     * 处理 Exception 类型的异常
     * @param e
     * @return
     */
    @ExceptionHandler(Exception.class)
    @ResponseBody
    public Map<String,Object> defaultExceptionHandler(Exception e) {
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("code", 500);
        map.put("msg", e.getMessage());
        return map;
    }
}

其中,方法名为任意名,入参一般使用 Exception 异常类,方法返回值可自定义。
启动项目,访问 http://localhost:8080/fastjson/test,结果如下图:

我们还可以自定义异常,在全局异常的处理类中捕获和判断,从而对不同的异常做出不同的处理。

十、文件上传和下载

10.1 添加依赖

<!-- 工具 -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>

10.2 实现

编写一个实体类,用于封装返回信息:

public class FileInfo {
    private String path;
    public FileInfo(String path) {
        this.path = path;
    }
    public String getPath() {
        return path;
    }
    public void setPath(String path) {
        this.path = path;
    }
}

编写 Controller,用于处理文件上传下载:

@RestController
@RequestMapping("/file")
public class FileController {
    private String path = "d:\\";
    @PostMapping
    public FileInfo upload(MultipartFile file) throws Exception {
        System.out.println(file.getName());
        System.out.println(file.getOriginalFilename());
        System.out.println(file.getSize());
        File localFile = new File(path, file.getOriginalFilename());
        file.transferTo(localFile);
        return new FileInfo(localFile.getAbsolutePath());
    }
    @GetMapping("/{id}")
    public void download(@PathVariable String id, HttpServletRequest request, HttpServletResponse response) {
        try (InputStream inputStream = new FileInputStream(new File(path, id + ".jpg"));
                OutputStream outputStream = response.getOutputStream();) {
            response.setContentType("application/x-download");
            response.addHeader("Content-Disposition", "attachment;filename=" + id + ".jpg");
            IOUtils.copy(inputStream, outputStream);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

基本上都是在学习 javaweb 时用到的 API。
文件上传测试结果如下图:

十一、CORS 支持

前端页面:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>跨域测试</title>
</head>
<body>
    <button id="test">测试</button>
    <script type="text/javascript" src="jquery-1.12.3.min.js"></script>
    <script type="text/javascript">
    $(function() {
        $("#test").on("click", function() {
            $.ajax({
                "url": "http://localhost:8080/fastjson/test",
                "type": "get",
                "dataType": "json",
                "success": function(data) {
                    console.log(data);
                }
            })
        });
    });
    </script>
</body>
</html>

通过 http 容器启动前端页面代码,笔者使用 Sublime Text 的插件启动的,测试结果如下:

从图中可知,前端服务器启动端口为 8088 与后端服务器 8080 不同源,因此出现跨域的问题。
现在开始解决跨域问题,可以两种维度控制客户端请求。
粗粒度控制
方式一

@Configuration
public class WebConfig {
    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurerAdapter() {
          @Override
          public void addCorsMappings(CorsRegistry registry) {
              registry.addMapping("/fastjson/**")
                      .allowedOrigins("http://localhost:8088");// 允许 8088 端口访问
          }
        };
    }
}

方式二

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/fastjson/**")
              .allowedOrigins("http://localhost:8088");// 允许 8088 端口访问
    }
}

配置后,重新发送请求,结果如下:

细粒度控制
在 FastJsonController 类中的方法上添加 @CrossOrigin(origins=”xx”) 注解:

@RequestMapping("/test")
@CrossOrigin(origins="http://localhost:8088")
public User test() {
    User user = new User();
    user.setId(1);
    user.setUsername("jack");
    user.setPassword("jack123");
    user.setBirthday(new Date());
    return user;
}

在使用该注解时,需要注意 @RequestMapping 使用的请求方式类型,即 GET 或 POST。

十二、整合 WebSocket

12.1 添加依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

12.2 实现方式

方式一:
该方式只适用于通过 jar 包直接运行项目的情况。
WebSocket 配置类:

@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

WebSocket 处理类:

@ServerEndpoint(value = "/webSocketServer/{userName}")
@Component
public class WebSocketServer {
    private static final Set<WebSocketServer> connections = new CopyOnWriteArraySet<>();
    private String nickname;
    private Session session;
    private static String getDatetime(Date date) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return format.format(date);
    }
    @OnOpen
    public void start(@PathParam("userName") String userName, Session session) {
        this.nickname = userName;
        this.session = session;
        connections.add(this);
        String message = String.format("* %s %s", nickname, "加入聊天!");
        broadcast(message);
    }
    @OnClose
    public void end() {
        connections.remove(this);
        String message = String.format("* %s %s", nickname, "退出聊天!");
        broadcast(message);
    }
    @OnMessage
    public void pushMsg(String message) {
        broadcast("【" + this.nickname + "】" + getDatetime(new Date()) + " : " + message);
    }
    @OnError
    public void onError(Throwable t) throws Throwable {
    }
    private static void broadcast(String msg) {
        // 广播形式发送消息
        for (WebSocketServer client : connections) {
            try {
                synchronized (client) {
                    client.session.getBasicRemote().sendText(msg);
                }
            } catch (IOException e) {
                connections.remove(client);
                try {
                    client.session.close();
                } catch (IOException e1) {
                    e.printStackTrace();
                }
                String message = String.format("* %s %s", client.nickname, "断开连接");
                broadcast(message);
            }
        }
    }
}

前端页面:

<!DOCTYPE html>
<html>
<head lang="zh">
    <meta charset="UTF-8">
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <link rel="stylesheet" href="css/bootstrap-theme.min.css">
    <script src="js/jquery-1.12.3.min.js"></script>
    <script src="js/bootstrap.js"></script>
    <style type="text/css">
    #msg {
        height: 400px;
        overflow-y: auto;
    }
    #userName {
        width: 200px;
    }
    #logout {
        display: none;
    }
    </style>
    <title>webSocket测试</title>
</head>
<body>
    <div class="container">
        <div class="page-header" id="tou">webSocket及时聊天Demo程序</div>
        <p class="text-right" id="logout">
            <button class="btn btn-danger" id="logout-btn">退出</button>
        </p>
        <div class="well" id="msg"></div>
        <div class="col-lg">
            <div class="input-group">
                <input type="text" class="form-control" placeholder="发送信息..." id="message"> <span class="input-group-btn">
                    <button class="btn btn-default" type="button" id="send"
                        disabled="disabled">发送</button>
                </span>
            </div>
            <div class="input-group">
                <input id="userName" type="text" class="form-control" name="userName" placeholder="输入您的用户名" />
                <button class="btn btn-default" type="button" id="connection-btn">建立连接</button>
            </div>
            <!-- /input-group -->
        </div>
        <!-- /.col-lg-6 -->
    </div>
    <!-- /.row -->
    </div>
    <script type="text/javascript">
    $(function() {
        var websocket;
        $("#connection-btn").bind("click", function() {
            var userName = $("#userName").val();
            if (userName == null || userName == "") {
                alert("请输入您的用户名");
                return;
            }
            connection(userName);
        });
        function connection(userName) {
            var host = window.location.host;
            if ('WebSocket' in window) {
                websocket = new WebSocket("ws://" + host +
                    "/webSocketServer/" + userName);
            } else if ('MozWebSocket' in window) {
                websocket = new MozWebSocket("ws://" + host +
                    "/webSocketServer/" + userName);
            }
            websocket.onopen = function(evnt) {
                $("#tou").html("链接服务器成功!")
                $("#send").prop("disabled", "");
                $("#connection-btn").prop("disabled", "disabled");
                $("#logout").show();
            };
            websocket.onmessage = function(evnt) {
                $("#msg").html($("#msg").html() + "<br/>" + evnt.data);
            };
            websocket.onerror = function(evnt) {
                $("#tou").html("报错!")
            };
            websocket.onclose = function(evnt) {
                $("#tou").html("与服务器断开了链接!");
                $("#send").prop("disabled", "disabled");
                $("#connection-btn").prop("disabled", "");
                $("#logout").hide();
            }
        }
        function send() {
            if (websocket != null) {
                var $message = $("#message");
                var data = $message.val();
                if (data == null || data == "") {
                    return;
                }
                websocket.send(data);
                $message.val("");
            } else {
                alert('未与服务器链接.');
            }
        }
        $('#send').bind('click', function() {
            send();
        });
        $(document).on("keypress", function(event) {
            if (event.keyCode == "13") {
                send();
            }
        });
        $("#logout-btn").on("click", function() {
            websocket.close(); //关闭TCP连接
        });
    });
    </script>
</body>
</html>

演示图如下:

如果使用该方式实现 WebSocket 功能并打包成 war 运行会报错:

javax.websocket.DeploymentException: Multiple Endpoints may not be deployed to the same path

方式二:
该方式适用于 jar 包方式运行和 war 方式运行。
WebSocket 配置类:

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(webSocketServer(), "/webSocketServer/*");
    }
    @Bean
    public WebSocketHandler webSocketServer() {
        return new WebSocketServer();
    }
}

WebSocket 处理类:

public class WebSocketServer extends TextWebSocketHandler {
    private static final Map<WebSocketSession, String> connections = new ConcurrentHashMap<>();
    private static String getDatetime(Date date) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return format.format(date);
    }
    /**
     * 建立连接
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        String uri = session.getUri().toString();
        String userName = uri.substring(uri.lastIndexOf("/") + 1);
        String nickname = URLDecoder.decode(userName, "utf-8");
        connections.put(session, nickname);
        String message = String.format("* %s %s", nickname, "加入聊天!");
        broadcast(new TextMessage(message));
    }
    /**
     * 断开连接
     */
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        String nickname = connections.remove(session);
        String message = String.format("* %s %s", nickname, "退出聊天!");
        broadcast(new TextMessage(message));
    }
    /**
     * 处理消息
     */
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        String msg = "【" + connections.get(session) + "】" + getDatetime(new Date()) + " : " + message.getPayload();
        broadcast(new TextMessage(msg));
    }
    private static void broadcast(TextMessage msg) {
        // 广播形式发送消息
        for (WebSocketSession session : connections.keySet()) {
            try {
                synchronized (session) {
                    session.sendMessage(msg);
                }
            } catch (Exception e) {
                connections.remove(session);
                try {
                    session.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
                String message = String.format("* %s %s", connections.get(session), "断开连接");
                broadcast(new TextMessage(message));
            }
        }
    }
}

运行结果与上图一致。

十三、整合 JavaMail

本次测试演示带模板的邮件,使用 Freemark 实现邮件的模板。

13.1 添加依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mail</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>

13.2 添加配置

application.properties 中添加

# javamail 配置
spring.mail.host=smtp.163.com
spring.mail.username=13738137546@163.com
spring.mail.password=
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.smtp.starttls.required=true

13.3 编码

@Component
@EnableConfigurationProperties(MailProperties.class)
public class JavaMailComponent {
    private static final String template = "mail.ftl";
    @Autowired
    private FreeMarkerConfigurer freeMarkerConfigurer;
    @Autowired
    private JavaMailSender javaMailSender;
    @Autowired
    private MailProperties mailProperties;
    public void sendMail(String email) {
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("email", email);
        try {
            // 获取内容
            String text = this.getTextByTemplate(template, map);
            // 发送
            this.send(email, text);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    private String getTextByTemplate(String template, Map<String, Object> model) throws Exception {
        return FreeMarkerTemplateUtils
                .processTemplateIntoString(this.freeMarkerConfigurer.getConfiguration().getTemplate(template), model);
    }
    private String send(String email, String text) throws MessagingException, UnsupportedEncodingException {
        MimeMessage message = this.javaMailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
        InternetAddress from = new InternetAddress();
        from.setAddress(this.mailProperties.getUsername());
        from.setPersonal("月光中的污点", "UTF-8");
        helper.setFrom(from);
        helper.setTo(email);
        helper.setSubject("SpringBoot 发送的第一封邮件");
        helper.setText(text, true);
        this.javaMailSender.send(message);
        return text;
    }
}

src/main/resources 下的 template 目录下创建名为 mail.ftl 的文件,其内容如下:

<!DOCTYPE html>
<html lang="zh">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
    <div style="width: 600px; text-align: left; margin: 0 auto;">
        <h1 style="color: #005da7;">月光中的污点</h1>
        <div style="border-bottom: 5px solid #005da7; height: 2px; width: 100%;"></div>
        <div style="border: 1px solid #005da7; font-size: 16px; line-height: 50px; padding: 20px;">
            <div>${email},您好!</div>
            <div>
                这是个测试
            </div>
            <div>
                想了解更多信息,请访问 <a href="https://www.extlight.com">https://www.extlight.com</a>
            </div>
        </div>
    </div>
</body>
</html>

13.4 测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class MailTest {
    @Autowired
    private JavaMailComponent javaMailComponent;
    @Test
    public void test() {
        this.javaMailComponent.sendMail("445847261@qq.com");
    }
}

运行结果如下图:

十四、整合定时任务

定时器的实现有 2 种方式:
1) Scheduled:spring 3.0 后自带的定时器
2)Quartz:第三放定时器框架

14.1 Scheduled 方式

14.1.1 任务类

@Component
public class Schedule {
    @Scheduled(fixedRate = 2000)
    public void task() {
        System.out.println("启动定时任务:" + new Date());
    }
}

使用 @Scheduled 定义任务执行时间,代码中表示每隔 2 秒执行一次任务。

14.1.2 开启定时计划

只需在 Spring Boot 的启动类上添加 @EnableScheduling 后,启动项目即可。
测试结果如下图:

14.1.3 并行执行

默认情况下,Spring Task 使用一条线程串行的执行所有的定时任务。为了提高执行效率,我们需要手动编写一个线程池实现定时任务的并行执行。

@Configuration
@EnableScheduling
public class AsyncTaskConfig implements SchedulingConfigurer, AsyncConfigurer {
    //线程池线程数量
    private int corePoolSize = 5;
    @Bean
    public ThreadPoolTaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
        scheduler.initialize();//初始化线程池
        scheduler.setPoolSize(corePoolSize);//线程池容量
        return scheduler;
    }
    @Override
    public Executor getAsyncExecutor() {
        Executor executor = this.taskScheduler();
        return executor;
    }
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
    @Override
    public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) {
        scheduledTaskRegistrar.setTaskScheduler(taskScheduler());
    }
}

只需编写上边的类即可实现并行的效果。

14.2 Quartz 方式

14.2.1 任务类

public class MyJob implements Job {
    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
        System.out.println("========quartz 测试==========");
    }
}

14.2.2 配置类

@Configuration
public class QuartzConfiguration {
    /**
     *  Job 工厂
     * @return
     */
    @Bean
    public JobDetailFactoryBean jobDetailFactoryBean() {
        JobDetailFactoryBean factory = new JobDetailFactoryBean();
        factory.setJobClass(MyJob.class);
        return factory;
    }
    /**
     *  Trigger 工厂
     * @return
     */
    @Bean
    public SimpleTriggerFactoryBean simpleTriggerFactoryBean(JobDetailFactoryBean jobDetailFactory) {
        SimpleTriggerFactoryBean factory = new SimpleTriggerFactoryBean();
        factory.setJobDetail(jobDetailFactory.getObject());
        // 执行间隔时间
        factory.setRepeatInterval(5000);
        // 重复执行次数
        factory.setRepeatCount(3);
        return factory;
    }
    /**
     *  Trigger 工厂
     * @return
     */
    @Bean
    public CronTriggerFactoryBean cronTriggerFactoryBean(JobDetailFactoryBean jobDetailFactory) {
        CronTriggerFactoryBean factory = new CronTriggerFactoryBean();
        factory.setJobDetail(jobDetailFactory.getObject());
        factory.setCronExpression("0/5 * * * * ?");
        return factory;
    }
   /* @Bean
    public SchedulerFactoryBean schedulerFactoryBean(SimpleTriggerFactoryBean simpleTriggerFactory){
        SchedulerFactoryBean factory = new SchedulerFactoryBean();
        factory.setTriggers(simpleTriggerFactory.getObject());
        return factory;
    }*/
    @Bean
    public SchedulerFactoryBean schedulerFactoryBean(CronTriggerFactoryBean cronTriggerFactory){
        SchedulerFactoryBean factory = new SchedulerFactoryBean();
        factory.setTriggers(cronTriggerFactory.getObject());
        return factory;
    }
}

同样地,需要在 Spring Boot 的启动类上添加 @EnableScheduling 后,启动项目即可。

14.2.3 依赖注入问题

实际开发中,任务类需要注入业务组件来执行定时任务,如下:

public class MyJob implements Job {
    @Autowired
    private UserService userService;
    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {
        this.userService.save();
    }
}

但是,MyJob 生命周期并没有被 Spring 容器管理,因此无法注入 UserService,当定时器执行任务时会报空指针异常。
解决方案:
自定义任务工厂,重写创建任务实例的方法:

@Component("customAdaptableJobFactory")
public class CustomAdaptableJobFactory extends AdaptableJobFactory {
    @Autowired
    private AutowireCapableBeanFactory autowireCapableBeanFactory;
    @Override
    protected Object createJobInstance(TriggerFiredBundle bundle) throws Exception {
        Object object = super.createJobInstance(bundle);
        // 将任务实例纳入 Spring 容器中
        this.autowireCapableBeanFactory.autowireBean(object);
        return object;
    }
}

修改 Scheduler 实现:

@Bean
public SchedulerFactoryBean schedulerFactoryBean(CronTriggerFactoryBean cronTriggerFactory,CustomAdaptableJobFactory customAdaptableJobFactory){
    SchedulerFactoryBean factory = new SchedulerFactoryBean();
    factory.setTriggers(cronTriggerFactory.getObject());
    factory.setJobFactory(customAdaptableJobFactory);
    return factory;
}

十五、整合 Swagger2

15.1 添加依赖

<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.7.0</version>
</dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>2.7.0</version>
</dependency>

15.2 配置

重新创建一个配置类,如下:

@Configuration
@EnableSwagger2
public class Swagger2Configuration {
    @Bean
    public Docket accessToken() {
        return new Docket(DocumentationType.SWAGGER_2)
                .groupName("api")// 定义组
                .select() // 选择那些路径和 api 会生成 document
                .apis(RequestHandlerSelectors.basePackage("com.light.springboot.controller")) // 拦截的包路径
                .paths(PathSelectors.regex("/*/.*"))// 拦截的接口路径
                .build() // 创建
                .apiInfo(apiInfo()); // 配置说明
    }
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()//
                .title("Spring Boot 之 Web 篇")// 标题
                .description("spring boot Web 相关内容")// 描述
                .termsOfServiceUrl("http://www.extlight.com")//
                .contact(new Contact("moonlightL", "http://www.extlight.com", "445847261@qq.com"))// 联系
                .version("1.0")// 版本
                .build();
    }
}

为了能更好的说明接口信息,我们还可以在 Controller 类上使用 Swagger2 相关注解说明信息。
我们以 FastJsonController 为例:

@Api(value = "FastJson测试", tags = { "测试接口" })
@RestController
@RequestMapping("fastjson")
public class FastJsonController {
    @ApiOperation("获取用户信息")
    @ApiImplicitParam(name = "name", value = "用户名", dataType = "string", paramType = "query")
    @GetMapping("/test/{name}")
    public User test(@PathVariable("name") String name) {
        User user = new User();
        user.setId(1);
        user.setUsername(name);
        user.setPassword("jack123");
        user.setBirthday(new Date());
        return user;
    }
}

注意,上边的方法是用 @GetMapping 注解,如果只是使用 @RequestMapping 注解,不配置 method 属性,那么 API 文档会生成 7 种请求方式。
启动项目,打开浏览器访问 http://localhost:8080/swagger-ui.html。结果如下图:

十六、参考资料

作者:月光中的污点
来源:https://www.extlight.com/2017/11/24/Spring-Boot-%E5%85%A5%E9%97%A8%E4%B9%8B-Web-%E7%AF%87%EF%BC%88%E4%BA%8C%EF%BC%89/

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