javax.servlet.ServletException : java. lang.ClassCastException : XXX cannot be cast to spark. servlet.SparkApplication

Question

我是java新手。我正在 tomcat 上开发一个网络服务。当我在 webapps 文件夹中部署 WAR 文件时，

严重 [localhost-startStop-1] org.apache.catalina.core.StandardContext.filterStart 异常启动过滤器 [SparkFilter] javax.servlet.ServletException:java.lang.ClassCastException:HelloWorld 无法转换为spark.servlet.SparkApplication

这个错误可以在tomcat的日志中看到。我正在使用 Sparkjava 创建服务。

这是我的代码

import spark.servlet.SparkApplication;

//import static spark.Spark.get;

import static spark.Spark.*;

import java.awt.Toolkit;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Clipboard;

public class HelloWorld{

    public static void main(String[] args){

        get("/clipboard/:text", (req, res) -> {
            StringSelection selection = new StringSelection(req.params(":text"));
            Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
            clipboard.setContents(selection, selection);
            return req.params(":text");
        });


    }
}

还有我的 pom.xml

<?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>sparkjava-hello-world</groupId>
    <artifactId>sparkjava-hello-world</artifactId>
    <version>1.0</version>
    <packaging>war</packaging>

    <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>


    <dependencies>
        <dependency>
            <groupId>com.sparkjava</groupId>
            <artifactId>spark-core</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.7.25</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <optimize>true</optimize>
                    <debug>true</debug>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-enforcer-plugin</artifactId>
                <version>1.3.1</version>
                <executions>
                    <execution>
                        <id>enforce-java</id>
                        <goals>
                            <goal>enforce</goal>
                        </goals>
                        <configuration>
                            <rules>
                                <requireJavaVersion>
                                    <version>[1.8,)</version>
                                </requireJavaVersion>
                            </rules>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

我的代码是否存在问题，或者我的项目文件中缺少导出为 WAR 文件时的依赖项、插件或过程？

感谢您的建议。

更新我已经弄清楚我必须调用@Override中的函数 public void init(){}，但是当我部署在服务器上时，我无法通过服务器将内容复制到剪贴板。和服务器有关系吗？仅安装了 OpenJDK。

Answer 1

您需要在依赖项中排除 Jetty:

<dependencies>
    <dependency>
        <groupId>com.sparkjava</groupId>
        <artifactId>spark-core</artifactId>
        <version>2.7.2</version>
        <exclusions>
            <exclusion>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-server</artifactId>
            </exclusion>
            <exclusion>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-webapp</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>