动态加载class，卸载class
从指定位置的jar中加载class，和卸载class
第一种
代码语言：javascript复制 URL url = new File("/文件路径/entityMaker.jar").toURI().toURL();
ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader();
URLClassLoader classLoader = new URLClassLoader(
new URL[]{url},
systemClassLoader
);
//加载class
//不能使用Class.forName("com.hebaibai.entitymaker.util.SqlUtils")加载Class
Class sqlUtils = classLoader.loadClass("com.hebaibai.entitymaker.util.SqlUtils");
final Object instance = sqlUtils.newInstance();
System.out.println(instance.getClass());
//卸载类
Method close = URLClassLoader.class.getDeclaredMethod("close");
close.invoke(classLoader);
//已经加载过得没法卸载
sqlUtils = classLoader.loadClass("com.hebaibai.entitymaker.util.FileUtils");
instance = sqlUtils.newInstance();
System.out.println(instance.getClass());第二种
代码语言：javascript复制 URL url = new File("/home/hjx/Desktop/entityMaker/entityMaker.jar").toURI().toURL();
URLClassLoader classLoader = (URLClassLoader)ClassLoader.getSystemClassLoader();
Method addURL = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
if (!addURL.isAccessible()) {
addURL.setAccessible(true);
}
addURL.invoke(classLoader, url);
addURL.setAccessible(addURL.isAccessible());
//可以使用Class.forName("com.hebaibai.entitymaker.util.SqlUtils")加载Class
Class<?> aClass = Class.forName("com.hebaibai.entitymaker.util.SqlUtils");
Object instance = aClass.newInstance();
System.out.println(instance.getClass());
