Example analysis of how Java reads resource files in Jar

This article mainly introduces the detailed information about Java reading resource files and implementation codes in Jar. When developing Java projects, jar packages are often used. Here is how to read them. Friends who need them can For reference,

For details, Java reads resource files and implementation code

## counter to directly apply code. The annotation part of the article is clear.

##Tool class source code: ResourceLoadFromJarUtil.java

Implementation code:

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; 
  } 
 } 
}

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