Question

我是Maven的新手，为了解决这个问题，我尝试创建一个Dropwizard项目并尝试添加到mySQL数据库的连接。我已经在我的yml文件中完成了以下操作 -

a）yml -

# Database settings.
database:
    # the name of the JDBC driver, mysql in our case
    driverClass: com.mysql.jdbc.Driver
    # the username
    user: root
    # the password
    password: drivedge12
    # the JDBC URL; the database is called Hotel2
    url: jdbc:mysql://localhost:3306/hotelmanagement

以下在我的xml文件中 - b）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>
    <prerequisites>
        <maven>3.0.0</maven>
    </prerequisites>

    <artifactId>dropwizard-example</artifactId>
    <version>1.1.0-SNAPSHOT</version>
    <groupId>io.dropwizard</groupId>
    <name>Dropwizard Example Application</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>

        <!-- You'll probably want to remove this for your project. We're just using it here
             so that dropwizard-example doesn't get deployed as a library. -->
        <maven.deploy.skip>true</maven.deploy.skip>
        <!-- You'll probably want to remove this for your project. We'Re just using it here
             so that dropwizard-example site doesn't get staged and deployed. -->
        <maven.site.skip>true</maven.site.skip>
        <maven.site.deploy.skip>true</maven.site.deploy.skip>
    </properties>

    <repositories>
        <repository>
            <id>sonatype-nexus-snapshots</id>
            <name>Sonatype Nexus Snapshots</name>
            <url>http://oss.sonatype.org/content/repositories/snapshots</url>
        </repository>
    </repositories>

    <dependencyManagement>
        <dependencies>
        <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>5.1.37</version>
       </dependency>
            <dependency>
                <groupId>io.dropwizard</groupId>
                <artifactId>dropwizard-bom</artifactId>
                <version>${project.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-core</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-auth</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-assets</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-http2</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-hibernate</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-migrations</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-views-freemarker</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-views-mustache</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-metrics-graphite</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>
        <dependency>
            <groupId>io.dropwizard</groupId>
            <artifactId>dropwizard-testing</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-core</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.test-framework.providers</groupId>
            <artifactId>jersey-test-framework-provider-inmemory</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>javax.servlet-api</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.test-framework.providers</groupId>
            <artifactId>jersey-test-framework-provider-grizzly2</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>javax.servlet-api</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>2.6.1</version>
                </plugin>
                <plugin>
  <groupId>org.eclipse.jetty</groupId>
  <artifactId>jetty-maven-plugin</artifactId>
  <version>9.4.2-SNAPSHOT</version>
</plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>2.7</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-enforcer-plugin</artifactId>
                    <version>1.4.1</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.6.0</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-source-plugin</artifactId>
                    <version>2.4</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-jar-plugin</artifactId>
                    <version>2.6</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-shade-plugin</artifactId>
                    <version>2.4.3</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-site-plugin</artifactId>
                    <version>3.4</version>
                </plugin>
            </plugins>
        </pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-enforcer-plugin</artifactId>
                <executions>
                    <execution>
                        <id>enforce</id>
                        <configuration>
                            <rules>
                                <DependencyConvergence />
                            </rules>
                        </configuration>
                        <goals>
                            <goal>enforce</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId>
                <executions>
                    <execution>
                        <id>attach-sources</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <configuration>
                    <createDependencyReducedPom>true</createDependencyReducedPom>
                    <filters>
                        <filter>
                            <artifact>*:*</artifact>
                            <excludes>
                                <exclude>META-INF/*.SF</exclude>
                                <exclude>META-INF/*.DSA</exclude>
                                <exclude>META-INF/*.RSA</exclude>
                            </excludes>
                        </filter>
                    </filters>
                    <transformers>
                        <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
                        <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                            <mainClass>com.example.helloworld.HelloWorldApplication</mainClass>
                        </transformer>
                    </transformers>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <profiles>
        <profile>
            <id>dev</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-shade-plugin</artifactId>
                        <executions>
                            <execution>
                                <phase>none</phase>
                            </execution>
                        </executions>
                    </plugin>
                </plugins>
            </build>
        </profile>
    </profiles>
</project>

然而，在尝试作为Java应用程序运行时，我一直收到以下错误 -

WARN  [2017-02-16 04:44:52,491] org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator: HHH000342: Could not obtain connection to query metadata : Unable to load class: com.mysql.jdbc.Driver from ClassLoader:sun.misc.Launcher$AppClassLoader@73d16e93;ClassLoader:sun.misc.Launcher$AppClassLoader@73d16e93
Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

任何人都可以让我知道我要去哪里以及我需要做些什么来纠正它？

Answer 1

在pom.xml中，所有依赖项都位于xml标记dependencies下。因此，在pom.xml移动下面的mysql-connector依赖关系

                 <dependency>
                 <groupId>mysql</groupId>
                 <artifactId>mysql-connector-java</artifactId>
                 <version>5.1.37</version>
                 </dependency>

从dependencyManagement xml标记到其下方的dependencies标记。您还可以在mysql-connector 外部广告部分中查看是否已下载ide jar。

以下是IntelliJ Idea中的图像，其中将显示maven下载的所有jar。

如果您有任何疑问，请告诉我。

无法在Maven Dropwizard项目中加载类：com.mysql.jdbc.Driver错误

1 个答案: