java读取jar包的lib包列表jar包，模拟Springbootjar包加载方式

Z时代
2024-01-10
分类：综合

package com.dominos.cloud.mq;

import java.io.IOException;
import java.io.InputStream;
import java.net.JarURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

public class ResourceLoadFromJarUtil {

   /**
   * @param args
   * @throws IOException
   */
   public static void main(String[] args) throws IOException {
       loadResourceFromJarURL("C:\eclipse-workspace\dominos-user\target\x"x-user.jar", "");
   }

   /**
   * 读取Jar文件中的资源
   *
   * @param jarUrl 本地jar文件或网络上(ttp://host:port/subpath/jarfile.jar)jar文件路径
   * @param resPath 资源文件所在jar中的路径(不能以"/"字符开头)
   * @return 如果资源加载失败,返回null
   */
   public static InputStream loadResourceFromJarURL(String jarUrl, String resPath) {
       if (!jarUrl.endsWith(".jar")) {
           return null;
       }
       URL url = null;
       if (jarUrl.startsWith("http://")) {
           try {
               url = new URL("jar:" + jarUrl + "!/");
           } catch (MalformedURLException e) {
               e.printStackTrace();
               return null;
           }
       } else {
           try {
               url = new URL("jar:file:/" + jarUrl + "!/");
           } catch (MalformedURLException e) {
               e.printStackTrace();
               return null;
           }
       }
       try {
           JarURLConnection jarURLConnection;
           jarURLConnection = (JarURLConnection) url.openConnection();
           JarFile jarFile = jarURLConnection.getJarFile();
           for (Enumeration<JarEntry> e = jarFile.entries(); e.hasMoreElements();) { // 这个循环会读取jar包中所有文件，包括文件夹
               JarEntry jarEntry = e.nextElement();// jarEntry就是我们读取的jar包中每一个文件了，包括目录
               if(jarEntry.getName().endsWith(".jar")) {
                   System.out.println(jarEntry.getName());
                   // URLClassLoader myClassLoader = new URLClassLoader(new URL[]{jarEntry.}, Thread.currentThread().getContextClassLoader());
               }

           }