The Java thing.

Dynamically Loading class libraries

 PackageCP;Importjava.lang.reflect.InvocationTargetException;ImportJava.lang.reflect.Method;Importjava.net.MalformedURLException;ImportJava.net.URL;ImportJava.net.URLClassLoader; Public classAddjar2classpath {//Although this method changes the classpath, the load jar cannot be used for the current ClassLoader    Private voidUpdateclasspath () {Classpath Classpath=NewClasspath (System.getproperty ("Java.class.path")); System.out.println (System.getproperty ("Java.class.path")); Classpath.addclasspath (System.getproperty ("User.dir") + "/lib/activemq-all-5.10.0.jar"); System.setproperty ("Java.class.path", classpath.tostring ()); System.out.println (System.getproperty ("Java.class.path")); ClassLoader ClassLoader=Classpath.getclassloader ();       Thread.CurrentThread (). Setcontextclassloader (ClassLoader); }        //This method can be used after the load jar for the current ClassLoader    Private voidLoadjar () {URL URLs; Try{URLs=NewURL ("file:/" +system.getproperty ("User.dir") + "/lib/activemq-all-5.10.0.jar"); //Getpi.classURLClassLoader UrlLoader =(URLClassLoader) Classloader.getsystemclassloader (); Class<URLClassLoader> Sysclass = URLClassLoader.class; Method Method= Sysclass.getdeclaredmethod ("Addurl",NewClass[]{url.class}); Method.setaccessible (true);                         Method.invoke (UrlLoader, URLs); URLs=NewURL ("file:/" +system.getproperty ("User.dir") + "/lib/images.jar");                         Method.invoke (UrlLoader, URLs); URLs=NewURL ("file:/" +system.getproperty ("User.dir") + "/lib/poi-3.11-20141221.jar");         Method.invoke (UrlLoader, URLs); } Catch(malformedurlexception e) {e.printstacktrace (); } Catch(SecurityException e) {e.printstacktrace (); } Catch(nosuchmethodexception e) {e.printstacktrace (); } Catch(IllegalArgumentException e) {e.printstacktrace (); } Catch(illegalaccessexception e) {e.printstacktrace (); } Catch(InvocationTargetException e) {e.printstacktrace (); }      }}

two different methods

 PackageCP;ImportJava.io.File; Importjava.io.IOException; Importjava.net.MalformedURLException; ImportJava.net.URL; ImportJava.net.URLClassLoader; ImportJava.util.StringTokenizer; ImportJava.util.Vector; /*** Class to handle CLASSPATH construction*/   Public   classClasspath {Vector _elements=NewVector ();  PublicClasspath () {} PublicClasspath (String initial) {Addclasspath (initial); }           Public   Booleanaddcomponent (String component) {if((Component! =NULL) && (component.length () > 0))   {                          Try{File F=NewFile (component); if(F.exists ()) {File key=F.getcanonicalfile (); if(!_elements.contains (Key))                                                  {_elements.add (key); return   true; }                                  }                          }   Catch(IOException e) {}}return   false; }           Public   Booleanaddcomponent (File component) {if(Component! =NULL)   {                          Try   {                                  if(Component.exists ()) {File key=Component.getcanonicalfile (); if(!_elements.contains (Key))                                                  {_elements.add (key); return   true; }                                  }                          }   Catch(IOException e) {}}return   false; }           Public   BooleanAddclasspath (String s) {BooleanAdded =false; if(s! =NULL) {StringTokenizer T=NewStringTokenizer (S, file.pathseparator);  while(T.hasmoretokens ()) {Added|=addcomponent (T.nexttoken ()); }                  }                  returnadded; }           PublicString toString () {stringbuffer CP=NewStringBuffer (1024); intCNT =_elements.size (); if(CNT >= 1) {cp.append ((File) (_elements.elementat (0)) . GetPath ()); }                   for(inti = 1;   I < CNT; i++) {cp.append (File.pathseparatorchar);                  Cp.append ((File) (_elements.elementat (i))). GetPath ()); }                  returncp.tostring (); }           Publicurl[] Geturls () {intCNT =_elements.size (); Url[] URLs=Newurl[cnt];  for(inti = 0;   I < CNT; i++)   {                          Try{Urls[i]=( File) (_elements.elementat (i)). Tourl (); }   Catch(Malformedurlexception e) {}}returnURLs; }           PublicClassLoader getClassLoader () {url[] URLs=Geturls (); ClassLoader Parent=Thread.CurrentThread (). Getcontextclassloader (); if(Parent = =NULL) {Parent= Classpath.class. getClassLoader (); }                  if(Parent = =NULL) {Parent=Classloader.getsystemclassloader (); }                  return   NewURLClassLoader (URLs, parent); }  }   

class Classpath

Private voidLoadjar () {Try{urlclassloader UrlLoader=(URLClassLoader) Classloader.getsystemclassloader (); Class<URLClassLoader> Sysclass = URLClassLoader.class; Method Method= Sysclass.getdeclaredmethod ("Addurl",NewClass[]{url.class}); Method.setaccessible (true); //TODO If the jar is not added in Classpath//System.out.println (System.getproperty ("Java.class.path"));String classpath=system.getproperty ("Java.class.path"); String Libdir=system.getproperty ("User.dir") + "/lib"; File Libdirfile=NewFile (Libdir); if(Libdirfile.isdirectory ()) {file[] libs=libdirfile.listfiles (NewFileFilter () { Public BooleanAccept (file file) {if(File.getname (). EndsWith (". Jar")) {                            return true; }                        return false;                }                });                URL URLs; if(libs!=NULL&&classpath!=NULL)                     for(inti=0;i<libs.length;i++){                        if(!Classpath.contains (Libs[i].getname ())) {System.out.println ("Libarary is not found in classpath:" +libs[i].getname ()); URLs=NewURL ("file:/" +libdir+ "/" +libs[i].getname ());                         Method.invoke (UrlLoader, URLs); }                    }                ElseSystem.out.println ("Check and load the class package:" +libdir+ "directory is null or classpath is null! "); }            //URL urls = new URL ("file:/" +system.getproperty ("User.dir") + "/lib/activemq-all-5.10.0.jar");//Method.invoke (UrlLoader, URLs);//            //urls = new URL ("file:/" +system.getproperty ("User.dir") + "/lib/images.jar");//Method.invoke (UrlLoader, URLs);//            //urls = new URL ("file:/" +system.getproperty ("User.dir") + "/lib/poi-3.11-20141221.jar");//Method.invoke (UrlLoader, URLs);}Catch(malformedurlexception e) {e.printstacktrace (); } Catch(SecurityException e) {e.printstacktrace (); } Catch(nosuchmethodexception e) {e.printstacktrace (); } Catch(IllegalArgumentException e) {e.printstacktrace (); } Catch(illegalaccessexception e) {e.printstacktrace (); } Catch(InvocationTargetException e) {e.printstacktrace (); }      }

dynamically loading class libraries

The Java thing.