0

Java 9 和 11 通常需要使用自定义类加载器。所以我创建了一个BootstrapClassloader预加载我的类路径，并使用Thread.currentThread().setContextClassLoader(classloader)它来使其成为默认值。

我很快发现 Spring 在使用new ClassPathXmlApplicationContext().

我想没问题，并写了一个我调用的变体BootstrapClassLoader来尝试强制 Spring 使用我的类加载器。但是 Spring 仍然忽略了我的类加载器。

例如，我验证了 aopalliance-1.0.jar 在类加载器的类路径中，并且可以手动加载MethodInterceptor. 但是，如果我有一个标准 DBCP2 数据源 bean 的上下文（取决于 aopalliance），它会抛出一个ClassNotFoundExceptionfor org.aopalliance.intercept.MethodInterceptor.

任何人都可以在下面的代码中看到一个缺陷，或者是否有一些特殊的方法来注册类加载器，以便 Spring 始终在应用程序中使用它？

数据源片段：

  <bean id="msSqlDataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">
    <property name="driverClassName"            value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/>
    <property name="validationQuery"            value="select 1" />
  </bean>
  <bean id="dbEmailDataSource" parent="msSqlDataSource"  class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close" lazy-init="true">
    <property name="url"                        value="" />
    <property name="username"                   value="" />
    <property name="password"                   value="" />
  </bean>

测试应用代码：

  public static void main(String[] args) {
    try {
      Bootstrap.init();
      for(String urlName : Bootstrap.getClasspathUrlNames()) {
        if(StringUtils.containsIgnoreCase(urlName, "aopalliance")) {
          System.out.println(urlName);
        }
      }
      ConfigurableApplicationContext ctx = new BootstrappedApplicationContext("DbEmailContext.xml");
      
      ctx.close();
    }catch(Throwable t) {
      t.printStackTrace();
    }
    try {
      Class clazz = Bootstrap.getClassLoader().loadClass("org.aopalliance.intercept.MethodInterceptor");
      System.out.println("manually loaded:  "+clazz.getName());
    }catch(Throwable t) {
      t.printStackTrace();
    }
  }

BootstrappedApplicationContext（类似于 ClassPathXmlApplicationContext）：

public class BootstrappedApplicationContext extends AbstractXmlApplicationContext {
  
  private URLClassLoader classloader;
  private Resource[] configResources;
  
  public BootstrappedApplicationContext() {
    super();
    this.classloader = Bootstrap.getClassLoader();
    super.setClassLoader(this.classloader);
  }
  
  public BootstrappedApplicationContext(ApplicationContext parent) {
    this();
    setParent(parent);
  }
  
  public BootstrappedApplicationContext(String configLocation) 
  throws BeansException {
    this(new String[] {configLocation}, true, null);
  }
  
  public BootstrappedApplicationContext(String... configLocations) 
  throws BeansException {
    this(configLocations, true, null);
  }

  public BootstrappedApplicationContext(String[] configLocations, ApplicationContext parent) 
  throws BeansException {
    this(configLocations, true, parent);
  }

  public BootstrappedApplicationContext(String[] configLocations, boolean refresh) 
  throws BeansException {
    this(configLocations, refresh, null);
  }

  public BootstrappedApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)
  throws BeansException {
    this(parent);
    setConfigLocations(configLocations);
    if(refresh) {
      refresh();
    }
  }
  
  public BootstrappedApplicationContext(String path, Class<?>clazz)
  throws BeansException {
    this(new String[] {path}, clazz);
  }
  
  public BootstrappedApplicationContext(String[] paths, Class<?> clazz) throws BeansException {
    this(paths, clazz, null);
  }

  public BootstrappedApplicationContext(String[] paths, Class<?> clazz, ApplicationContext parent)
      throws BeansException {
    this(parent);
    Assert.notNull(paths, "Path array must not be null");
    Assert.notNull(clazz, "Class argument must not be null");
    this.configResources = new Resource[paths.length];
    for (int i = 0; i < paths.length; i++) {
      this.configResources[i] = new ClassPathResource(paths[i], clazz);
    }
    refresh();
  }
  
  @Override
  public ClassLoader getClassLoader() {
    if(classloader == null) {
      classloader = Bootstrap.getClassLoader();
    }
    super.setClassLoader(classloader);
    return classloader;
  }
  
  public void setClassLoader(URLClassLoader classloader) {
    this.classloader = classloader;
    super.setClassLoader(classloader);
  }
  
  @Override
  protected Resource[] getConfigResources() {
    return this.configResources;
  }
}
4

0 回答 0