我试图在运行时添加外部jar然后使用该jar连接到数据库（而不是必须向pom添加许多驱动程序，目标是为用户提供加载任何驱动程序jar的能力运行）。我正在使用spring boot项目，我正在尝试使用spring boots DataSourceBuilder来创建数据源。
Loading JDBC Driver at Runtime和Loading jars at runtime中的答案和建议似乎不适用于以下代码：
@Component
public class DriverLoader {
private static final String URL = "jdbc:mysql://localhost:3306/sakila?useSSL=false";
private static final String USER = "root";
private static final String ADMIN = "admin";
private static final String DRIVER_JAR = "C:\\Users\\Sander\\Downloads\\mysql-connector-java-5.1.40.jar";
@PostConstruct
private void loadDriver() throws Exception {
File file = new File(DRIVER_JAR);
if (file != null) {
URLClassLoader URLClassLoader = new URLClassLoader(new URL[] {file.toURI().toURL()}, System.class.getClassLoader());
String driverName = DatabaseDriver.fromJdbcUrl(URL).getDriverClassName();
System.out.println(driverName);
// lets try to load the class
Class<?> driverClass = URLClassLoader.loadClass(driverName);
Driver actualDriver = (Driver) driverClass.newInstance();
URLClassLoader.close();
// Throws: Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.StringUtils
/*Properties properties = new Properties();
properties.put("user", USER);
properties.put("password", ADMIN);
Connection con = actualDriver.connect(URL, properties);*/
DataSource dataSource = createNewDataSource(URL, USER, ADMIN);
if (dataSource != null) {
// lets try to connect
// Throws: Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
dataSource.getConnection().isValid(1);
}
}
}
public DataSource createNewDataSource(String url, String username, String password) {
return DataSourceBuilder
.create()
.url(url)
.username(username)
.password(password)
.build();
}
}
我正在使用的pom片段：
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.1.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>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
如果在运行时添加了jar文件，我如何使用DataSourceBuilder成功建立与数据源的连接？
完整堆栈跟踪：
2017-02-04 20:13:22.201 ERROR 12528 --- [ main] o.a.tomcat.jdbc.pool.ConnectionPool : Unable to create initial connections of pool.
java.sql.SQLException: Unable to load class: com.mysql.jdbc.Driver from ClassLoader:sun.misc.Launcher$AppClassLoader@764c12b6;ClassLoader:sun.misc.Launcher$AppClassLoader@764c12b6
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:283) ~[tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:203) ~[tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:732) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:664) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:479) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:154) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107) [tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:131) [tomcat-jdbc-8.5.11.jar:na]
at nl.mierasmade.driver.DriverLoader.loadDriver(DriverLoader.java:54) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_112]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_112]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_112]
at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_112]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:366) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:311) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:134) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:409) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1620) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) [spring-beans-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) [spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) [spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at nl.mierasmade.JdbcRuntimeDriverApplication.main(JdbcRuntimeDriverApplication.java:10) [classes/:na]
Caused by: java.lang.ClassNotFoundException: Unable to load class: com.mysql.jdbc.Driver from ClassLoader:sun.misc.Launcher$AppClassLoader@764c12b6;ClassLoader:sun.misc.Launcher$AppClassLoader@764c12b6
at org.apache.tomcat.jdbc.pool.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:56) ~[tomcat-jdbc-8.5.11.jar:na]
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:271) ~[tomcat-jdbc-8.5.11.jar:na]
... 33 common frames omitted
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass(Unknown Source) ~[na:1.8.0_112]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_112]
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[na:1.8.0_112]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_112]
at java.lang.Class.forName0(Native Method) ~[na:1.8.0_112]
at java.lang.Class.forName(Unknown Source) ~[na:1.8.0_112]
at org.apache.tomcat.jdbc.pool.ClassLoaderUtil.loadClass(ClassLoaderUtil.java:38) ~[tomcat-jdbc-8.5.11.jar:na]
... 34 common frames omitted
答案 0 :(得分：2)
我能够像这样开始工作：
@Bean
public DataSource dynamicDataSource() {
ClassLoader classLoader = new URLClassLoader(new URL[]{new URL("file:///C:/Users/xxxx/Desktop/h2-1.4.193.jar")}, Thread.currentThread().getContextClassLoader());
Thread.currentThread().setContextClassLoader(classLoader);
DataSource dataSource = DataSourceBuilder.create().url('jdbc:h2:mem:test;DB_CLOSE_DELAY=-1').build();
dataSource.getConnection().isValid(10);
return dataSource;
}
答案 1 :(得分：0)
尝试this.getClass().getClassLoader()或Thread.getContextClassLoader()，而不是使用系统的类加载器。请参阅this部分 E.5.2系统类加载器