详解Java读取Jar中资源文件及示例代码

import java.io.IOException; import java.io.InputStream; import java.net.JarURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.jar.JarEntry; import java.util.jar.JarFile;  import org.apache.commons.io.IOUtils;  public class ResourceLoadFromJarUtil {   /**   * @param args   * @throws IOException   */  public static void main(String[] args) throws IOException {    /* 资源文件路径,不能以'/'字符字符开头 */   String resourcePath = "struts-plugin.xml";    /* 获取ClassPath下的所有jar路径 */   String[] cps = System.getProperty("java.class.path").split(";");    /* 读取本地Jar文件 */   for (String cp : cps) {    if (!cp.endsWith(".jar")) {     continue;    }    InputStream in = loadResourceFromJarFile(cp, resourcePath);    if (in != null) {     System.err.println(IOUtils.toString(in));     in.close();    }   }    /* 读取本地Jar文件 */   for (String cp : cps) {    if (!cp.endsWith(".jar")) {     continue;    }    InputStream in = loadResourceFromJarURL(cp, resourcePath);    if (in != null) {     System.err.println(IOUtils.toString(in));     in.close();    }   }    /* 读取网络Jar文件 */   InputStream in = loadResourceFromJarURL(     "http://localhost:8080/SpringStruts2Integration/struts2-spring-plugin-2.3.4.1.jar", resourcePath);   if (in != null) {    System.err.println(IOUtils.toString(in));    in.close();   }  }   /**   * 读取Jar文件中的资源   *   * @param jarPath   *   本地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 loadResourceFromJarFile(String jarPath, String resPath) {   if (!jarPath.endsWith(".jar")) {    return null;   }   try {    JarFile jarFile = new JarFile(jarPath);    JarEntry jarEntry = jarFile.getJarEntry(resPath);    if (jarEntry == null) {     return null;    }    return jarFile.getInputStream(jarEntry);   } catch (IOException e) {    e.printStackTrace();    return null;   }  }   /**   * 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();    JarEntry jarEntry = jarFile.getJarEntry(resPath);    if (jarEntry == null) {     return null;    }    return jarFile.getInputStream(jarEntry);   } catch (IOException e) {    e.printStackTrace();    return null;   }  } }