java加载第三方jar并实例化类

/**
*
* @param declareClass:类声明,eg:com.HelloWordImpl
* @param jarPath:jar包路径,目前只支持file协议,其他需要自己改造
* @param <T>:实例对象,eg：HelloWord的实现类HelloWordImpl
* @return
*/
public static <T> T loadJarAndNewIns(String declareClass, String jarPath) {
logger.info("==============================>loadJarAndNewIns declareClass[" + declareClass
+ "],jarPath[" + jarPath + "]");
ClassLoader cl = null;
try {
// 从Jar文件得到一个Class加载器
cl = new URLClassLoader(new URL[] { new URL(jarPath) },
Thread.currentThread().getContextClassLoader());
// 从加载器中加载Class
Class<?> c = cl.loadClass(declareClass);
// 从Class中实例出一个对象

return (T) c.newInstance();

} catch (Exception e) {
logger.error("===============================>loadJarAndNewIns fail");
logger.error(e.getMessage());
}

return null;
}