Java绝对路径读取jar包

方法一：

package com.demo.action;

import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

public class Test {

public static void main(String[] args) {
// TODO Auto-generated method stub
try {
URL url = new URL("file:/D:/maven_web.jar");
@SuppressWarnings("resource")
URLClassLoader myClassLoader  =   new  URLClassLoader( new  URL[]   { url } );
Class<?> myClass  =  myClassLoader.loadClass("com.huahua.inter.impl.UserImpl");
Method[] methods = myClass.getDeclaredMethods();
for (Method method : methods) {
System.out.println(method.getName());
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}

}

方法二：

package com.demo.action;

import java.io.File;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

public class test1 {
 public static void main(String[] args) {
 String path = "D:\\maven_web.jar";//外部jar包的路径  
 Set<Class<?>> classes = new LinkedHashSet<Class<?>>();//所有的Class对象  
 Map<Class<?>, Annotation[]> classAnnotationMap = new HashMap<Class<?>, Annotation[]>();//每个Class对象上的注释对象  
 Map<Class<?>, Map<Method, Annotation[]>> classMethodAnnoMap = new HashMap<Class<?>, Map<Method,Annotation[]> >();//每个Class对象中每个方法上的注释对象  

 try {
 @SuppressWarnings("resource")
 JarFile jarFile = new JarFile(new File(path));  
 URL url = new URL("file:" + path);  
 @SuppressWarnings("resource")
 ClassLoader loader = new URLClassLoader(new URL[]{url});//自己定义的classLoader类，把外部路径也加到load路径里，使系统去该路经load对象  
 Enumeration<JarEntry> es = jarFile.entries();  
 while (es.hasMoreElements()) { 
 JarEntry jarEntry = (JarEntry) es.nextElement();  
 String name = jarEntry.getName(); 
 //System.out.println(name);
 if(name != null && name.endsWith(".class")){//只解析了.class文件，没有解析里面的jar包  
 //默认去系统已经定义的路径查找对象，针对外部jar包不能用  
 //Class<?> c = Thread.currentThread().getContextClassLoader().loadClass(name.replace("/", ".").substring(0,name.length() - 6));  
 Class<?> c = loader.loadClass(name.replace("/", ".").substring(0,name.length() - 6));//自己定义的loader路径可以找到

 if(c.isInterface()) continue; //排除接口类

 System.out.println(c);  
 classes.add(c);  
 Annotation[] classAnnos = c.getDeclaredAnnotations();  
 classAnnotationMap.put(c, classAnnos);  
 Method[] classMethods = c.getDeclaredMethods();  
 for (Method method : classMethods) {
System.out.println(method.getName());//打印所有自定义的方法
 }
 Map<Method, Annotation[]> methodAnnoMap = new HashMap<Method, Annotation[]>();  
 for(int i = 0;i<classMethods.length;i++){  
 Annotation[] a = classMethods[i].getDeclaredAnnotations();  
 methodAnnoMap.put(classMethods[i], a);  
 }  
 classMethodAnnoMap.put(c, methodAnnoMap);  
 }  
 }  
 System.out.println(classes.size());  
 } catch (Exception e) {  
 e.printStackTrace();  
 } 
}
}

方法二转自： http://blog.csdn.net/wan368500/article/details/8215668