Vaadin 推送：推送不可用答案

【问题标题】：Vaadin push: Push is not availableVaadin 推送：推送不可用
【发布时间】：2018-02-20 17:40:58
【问题描述】：

我有一个 Maven 项目，我在 pom.xml 中添加了 vaadin-push 作为依赖项。

第一个问题是在 MainUI 类中，当我添加注释 @Push(PushMode.MANUAL) 时，它无法识别 PushMode，所以我被 @Push 卡住了。当我添加它时，我在访问 UI 时收到错误消息：

{"timestamp":1519112562626,"status":500,"error":"Internal Server Error","exception":"com.vaadin.server.ServiceException","message":"java.lang.IllegalStateException: Push is not available. See previous log messages for more information.","path":"/bp/list"}

我尝试按照vaadin website on push 上的说明进行操作，所以我添加了一个 web.xml（我以前没有）。我不确定它是否被使用。我宁愿只通过注释来配置它。

<?xml version="1.0" encoding="UTF-8"?>
<web-app
  id="WebApp_ID" version="3.0"
  xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
  <servlet>
    <servlet-name>Business Process UI</servlet-name>
    <servlet-class>com.vaadin.server.VaadinServlet</servlet-class>

    <init-param>
        <param-name>UI</param-name>
        <param-value>com.oursys.bpspkpibpcheck.view.MainUI</param-value>
    </init-param>

    <!-- Enable server push -->
    <init-param>
      <param-name>pushmode</param-name>
      <param-value>automatic</param-value>
    </init-param>
    <async-supported>true</async-supported>
  </servlet>
</web-app>

我真正想要实现的是在 Rest 请求上更新 UI，我认为除了 Push 之外，Rest 部分已经可以工作了：

public class UILister {

    private static HashMap<UUID,MainUI> uiByUuid = new HashMap<UUID,MainUI>();

    public static void closeUIConnectorFrame(UUID uuid) {
        MainUI ui = uiByUuid.get(uuid);
        if(ui != null) {
            ui.access(new Runnable() {
                @Override
                public void run() {
                    ui.closeConnectorFrame();
                    ui.push();
                }}
            );
        }
    }

    public static void addUI(UUID uuid, MainUI mainUI) {
        uiByUuid.put(uuid, mainUI);
    }
}

pom.xml。我删除了 vaadin-push，因为它告诉我我正在覆盖自动配置的那个。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.leosoftsys</groupId>
    <artifactId>bpsp-kpi-bp-check</artifactId>
    <version>0.0.1</version>
    <packaging>jar</packaging>

    <name>bpsp-kpi-bp-check</name>
    <description>Business Check For BPS+</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Dalston.SR4</spring-cloud.version>
        <vaadin.version>8.1.1</vaadin.version>
    </properties>

    <repositories>
        <repository>
        <id>vaadin-addons</id>
        <url>http://maven.vaadin.com/vaadin-addons</url>
        </repository>
    </repositories>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-actuator-docs</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-oauth2</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.security.oauth</groupId>
            <artifactId>spring-security-oauth2</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-spring-boot-starter</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-net/commons-net -->
        <dependency>
            <groupId>commons-net</groupId>
            <artifactId>commons-net</artifactId>
            <version>3.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.jcraft/jsch -->
        <dependency>
            <groupId>com.jcraft</groupId>
            <artifactId>jsch</artifactId>
            <version>0.1.54</version>
        </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa -->
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.11.6.RELEASE</version>
    </dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate.javax.persistence/hibernate-jpa-2.0-api -->
<!-- <dependency>
    <groupId>org.hibernate.javax.persistence</groupId>
    <artifactId>hibernate-jpa-2.0-api</artifactId>
    <version>1.0.1.Final</version>
</dependency>
-->
        <dependency>
            <groupId>org.vaadin.addon</groupId>
            <artifactId>confirmdialog</artifactId>
            <version>3.2.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-parameter-names</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jdk8</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jsr310</artifactId>
        </dependency>

        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-themes</artifactId>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-sass-compiler</artifactId>
            <version>0.9.13</version>
        </dependency>
        <dependency>
            <groupId>net.jodah</groupId>
            <artifactId>failsafe</artifactId>
            <version>1.0.4</version>
        </dependency>
        <dependency>
            <groupId>org.zalando</groupId>
            <artifactId>failsafe-actuator</artifactId>
            <version>0.4.1</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.json/json -->
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20171018</version>
        </dependency>
        <!--
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-push</artifactId>
            <version>${vaadin.version}</version>
        </dependency>
        -->
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-bom</artifactId>
                <version>${vaadin.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <resources>
          <resource>
                <directory>src/main/webapp</directory>
           </resource>
           <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>
        <testResources>
        </testResources>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>com.vaadin</groupId>
                <artifactId>vaadin-maven-plugin</artifactId>
                <version>${vaadin.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>clean</goal>
                            <goal>resources</goal>
                            <goal>update-theme</goal>
                            <goal>update-widgetset</goal>
                            <goal>compile-theme</goal>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>


</project>

【问题讨论】：

请给你看 pom.xml，因为问题似乎不在你的代码中。
将 pom.xml 添加到问题中
vaadin-push在您的 pom.xml 中被注释掉
感谢您指出 pom.xml，当我在 vaadin-push 中发表评论时，错误消息消失了。现在我只需要检查 UI.push 是否有效。
我仍然无法设置 PushMode，它说找不到变量。在@Push(PushMode.MANUAL)。而且我现在遇到了各种错误，如果没有推送，我不会得到这些错误

标签： push vaadin

【解决方案1】：

在你的 pom 中，添加

    <dependency>
        <groupId>com.vaadin</groupId>
        <artifactId>vaadin-push</artifactId>
    </dependency>

您无需在此处指定<version>，因为该版本由vaadin-bom（材料清单）管理，它为每个工件声明了正确的版本（因此它是更容易避免对同一框架的不同版本的依赖冲突），但导入 BOM 并不会自行添加依赖。

       <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-bom</artifactId>
            <version>${vaadin.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>

我删除了 vaadin-push，因为它告诉我我正在覆盖自动配置的那个。

自动配置的指的是由BOM管理的版本。例如，当使用 <version> 标签向 vaadin-push 添加依赖项时，Eclipse 会给出以下警告：

为 vaadin-push 覆盖托管版本 8.1.1

【讨论】：