【发布时间】：2021-11-15 08:56:21
【问题描述】：
我正在尝试将名为 (DataActions) 的类中的方法调用到仪表板视图，以便网格能够接收方法执行后给出的对象，但仍然无法解决此错误 (java.lang.IllegalArgumentException : 对象不是声明类的实例）。
-Class (DataSession) 是负责打开数据库会话的类。 -Class（DataActions）是负责使用由（DataSession对象）创建的会话从数据库中提取信息的方法的类 - 方法 updateGrid 使用创建的对象调用 (DataActions) 中的方法。
这个项目是用vaadin hello world示例项目创建的，所以它使用springboot（2.4.5版）和vaadin flow（14.7.0版）。
--仪表板视图--
package com.example.application.views.dashboard;
import com.example.application.Controller.DataActions;
import com.vaadin.flow.component.grid.Grid;
import com.vaadin.flow.component.orderedlayout.VerticalLayout;
import com.example.application.Model.PatientsTblEntity;
import com.vaadin.flow.router.Route;
import com.vaadin.flow.router.PageTitle;
import com.example.application.views.MainLayout;
import com.vaadin.flow.router.RouteAlias;
@PageTitle("Dashboard")
@Route(value = "dashboard", layout = MainLayout.class)
@RouteAlias(value = "", layout = MainLayout.class)
public class DashboardView extends VerticalLayout {
Grid<PatientsTblEntity> patients_grid = new Grid<>(PatientsTblEntity.class);
DataActions actions = new DataActions();
public DashboardView(){
addClassName("list-view");
configureGrid();
add(patients_grid);
updateGrid();
}
/*
-Configuring grid properties, so it can handle data coming from another function
*/
public void configureGrid(){
patients_grid.addClassName("contact-grid");
patients_grid.setSizeFull();
// patients_grid.setColumns("txtCode", "txtName", "dblAge", "datDateOfBirth", "datOfLasttVisit");
patients_grid.getColumns().forEach(patientsTblEntityColumn -> {
patientsTblEntityColumn.setAutoWidth(true);
});
}
/*
-Update grid with information coming from the database using actions from class DataActions
*/
public void updateGrid(){
patients_grid.setItems(actions.getAllPatientsList());
}
}
--DataActions 类--
package com.example.application.Controller;
import com.example.application.Model.PatientsTblEntity;
import org.hibernate.Session;
import java.util.List;
public class DataActions {
public DataActions(){}
DataSessions dataSessions = new DataSessions();
/*
-Variable where session is created
-Created as a variable, so it can be opened and closed at ease in every function
*/
private Session session = dataSessions.getSession();
public List<PatientsTblEntity> getAllPatientsList(){
session.beginTransaction();
List<PatientsTblEntity> list = session.getSession().createQuery("FROM PatientsTblEntity P").getResultList();
session.close();
return list;
}
--Pom.xml 文件--
<?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>
<!-- Vaadin project from https://start.vaadin.com/project/a13f6a96-e47e-432d-bf78-e4e60571348e -->
<groupId>com.example.application</groupId>
<artifactId>asd-8</artifactId>
<name>Project base for Spring Boot and Vaadin Flow</name>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<properties>
<java.version>8</java.version>
<vaadin.version>14.7.0</vaadin.version>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.5</version>
</parent>
<repositories>
<!-- The order of definitions matters. Explicitly defining central here to make sure it has the highest priority. -->
<!-- Main Maven repository -->
<repository>
<id>central</id>
<url>https://repo.maven.apache.org/maven2</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<!-- Repository used by many Vaadin add-ons -->
<repository>
<id>Vaadin Directory</id>
<url>https://maven.vaadin.com/vaadin-addons</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<!-- Main Maven repository -->
<pluginRepository>
<id>central</id>
<url>https://repo.maven.apache.org/maven2</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-bom</artifactId>
<version>${vaadin.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>com.vaadin</groupId>
<!-- Replace artifactId with vaadin-core to use only free components -->
<artifactId>vaadin</artifactId>
<exclusions>
<!-- Webjars are only needed when running in Vaadin 13 compatibility mode -->
<exclusion>
<groupId>com.vaadin.webjar</groupId>
<artifactId>*</artifactId>
</exclusion>
<exclusion>
<groupId>org.webjars.bowergithub.insites</groupId>
<artifactId>*</artifactId>
</exclusion>
<exclusion>
<groupId>org.webjars.bowergithub.polymer</groupId>
<artifactId>*</artifactId>
</exclusion>
<exclusion>
<groupId>org.webjars.bowergithub.polymerelements</groupId>
<artifactId>*</artifactId>
</exclusion>
<exclusion>
<groupId>org.webjars.bowergithub.vaadin</groupId>
<artifactId>*</artifactId>
</exclusion>
<exclusion>
<groupId>org.webjars.bowergithub.webcomponents</groupId>
<artifactId>*</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-spring-boot-starter</artifactId>
<exclusions>
<!-- Excluding so that webjars are not included. -->
<exclusion>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-core</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.vaadin.artur</groupId>
<artifactId>a-vaadin-helper</artifactId>
<version>1.7.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-testbench</artifactId>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/com.microsoft.sqlserver/mssql-jdbc -->
<dependency>
<groupId>com.microsoft.sqlserver</groupId>
<artifactId>mssql-jdbc</artifactId>
<version>9.2.1.jre8</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.5.7.Final</version>
</dependency>
<!-- Include JUnit 4 support for TestBench and others -->
<dependency>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.hamcrest</groupId>
<artifactId>hamcrest-core</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.github.bonigarcia</groupId>
<artifactId>webdrivermanager</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<defaultGoal>spring-boot:run</defaultGoal>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<!-- Clean build and startup time for Vaadin apps sometimes may exceed
the default Spring Boot's 30sec timeout. -->
<configuration>
<wait>500</wait>
<maxAttempts>240</maxAttempts>
</configuration>
</plugin>
<!--
Take care of synchronizing java dependencies and imports in
package.json and main.js files.
It also creates webpack.config.js if not exists yet.
-->
<plugin>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-maven-plugin</artifactId>
<version>${vaadin.version}</version>
<executions>
<execution>
<goals>
<goal>prepare-frontend</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<!-- Production mode is activated using -Pproduction -->
<id>production</id>
<build>
<plugins>
<plugin>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-maven-plugin</artifactId>
<version>${vaadin.version}</version>
<executions>
<execution>
<goals>
<goal>build-frontend</goal>
</goals>
<phase>compile</phase>
</execution>
</executions>
<configuration>
<productionMode>true</productionMode>
</configuration>
</plugin>
</plugins>
</build>
</profile>
<profile>
<id>it</id>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<id>start-spring-boot</id>
<phase>pre-integration-test</phase>
<goals>
<goal>start</goal>
</goals>
</execution>
<execution>
<id>stop-spring-boot</id>
<phase>post-integration-test</phase>
<goals>
<goal>stop</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Runs the integration tests (*IT) after the server is started -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
</execution>
</executions>
<configuration>
<trimStackTrace>false</trimStackTrace>
<enableAssertions>true</enableAssertions>
</configuration>
</plugin>
</plugins>
</build>
</profile>
</profiles>
</project>
【问题讨论】：
-
请不要发图片。只需将代码复制为文本即可。
-
那么如何将列添加到网格中？
-
我发布了代码而不是图片，对于网格，我在网格括号之间声明了类名。
标签： java spring-boot maven vaadin pom.xml