#副標=Java於Web Tier上的應用
#大標=Java 動態編譯、載入與執行 Part1
#眉標=Java
#作者=文／歐宣修



-----------------------box 程式1-----------------------
/** Programmatic interface.
 * @param args   The command line parameters.
 */
public static int compile(String[] args) {
　com.sun.tools.javac.main.Main compiler =
	new com.sun.tools.javac.main.Main("javac");
　return compiler.compile(args);
}

---------------------------- end -----------------------------


-------------------------- box 程式2 -----------------------
/** Programmatic interface for main function.
 * @param args    The command line parameters.
 */
public int compile(String[] args, Context context) {
　boolean assertionsEnabled = false;
　assert assertionsEnabled = true;
　if (!assertionsEnabled) {
　　// Log.printLines(out, "fatal error: assertions must
　　 be enabled when running javac");
	// return EXIT_ABNORMAL;
　}
  以下略…
}
-------------------------------- end --------------------------------


---------------------- box 程式3 -----------------------------
Object objectParameters[] = {new String[]{}};
Class classParameters[] = {objectParameters[0].
getClass()};
Method theMethod = aClass.getDeclaredMethod(
"main", classParameters);
// Static method, no instance needed
theMethod.invoke(null, objectParameters);
-------------------------- end ----------------------------


------------------------------- box 桯式4 -----------------------------
Process.java

public interface Process {
 
  public String doProcess(String arg); //…(1)
      
}
------------------------------------- end ---------------------------------


-------------------------------- box 程式5-------------------------------
AProcess.java

public class AProcess implements Process {

  public String doProcess(String arg) { //…(1)        
    return "Hello!!! "+arg + " at "+Time.
getNowTime();
  }
}
------------------------------------------- end ---------------------------------------


------------------------------- box 程式 6 --------------------
     ProcessFactory.java
     
     public interface ProcessFactory {
     
       public void newClassLoader();  //…(1)   
         
       public Process getProcess(String name); 
       //…(2)
     }
------------------------------- end -----------------------------------


------------------------------------------- box 程式7 ----------------------------------
ProcessFactoryImpl.java

/**
 * Reset ClassLoader  //…(1)
 */
public void newClassLoader() {
  try {
    File file = new File(PROCESS_PATH); //…(2)
    loader = new URLClassLoader(new URL[] { 
file.toURL() });
  } catch (MalformedURLException e) {
    e.printStackTrace();
  }
        
  processes = new HashMap();//…(3)
  log.debug("reset ok");
}

/**
 * 依名稱取得Process  //…(4)
 */
public Process getProcess(String name) {

  idv.senshaw.dynamic.Process process = 
(idv.senshaw.dynamic.Process) processes.get(name); 

  String full_name = 
"idv.senshaw.dynamic.userprocess." + name;
  log.debug("full_name=" + full_name);

  if (process != null) { //…(5)
            
    log.debug("已有Process");
    return process;
  }

  log.debug("new Process");
  try {
    log.debug("目前ClassLoader=" + 
(this.getClass().getClassLoader() == null ? 
"bootstrap" : this.getClass().getClassLoader().
getClass().getName() ) );            
            
    // load class through new loader
    Class processClass = loader.loadClass(
full_name); //…(6)
    log.debug("class_name=" + processClass.
getName());
    log.debug("processClass classloader=" + 
(processClass.getClassLoader() == null ? "bootstrap" : processClass.getClassLoader().getClass().getName()));

    Object obj = processClass.newInstance();

    log.debug("obj class=" + obj.getClass().
getName());

    log.debug("new instance ok");
    Class[] interfaces = obj.getClass().getInterfaces();
    for (int i = 0; i < interfaces.length; i++) {
      log.debug("interface name=" + interfaces[i].
getName());
      log.debug("interface classloader=" + (
interfaces[i].getClassLoader() == null ? "bootstrap" : interfaces[i].getClassLoader().getClass().getName()));
    }
    if (obj instanceof idv.senshaw.dynamic.Process) {
      log.debug("yes!");
    } else {
      log.debug("no!");
    }

    process = (idv.senshaw.dynamic.Process) obj;
    processes.put(name, process);
  } catch (InstantiationException e1) {
    e1.printStackTrace();
  } catch (IllegalAccessException e1) {
    e1.printStackTrace();
  } catch (ClassNotFoundException e) {
    e.printStackTrace();
  }

  return process;
}
以下略…
-------------------------------------- end ------------------------------


--------------------------------- box 程式8 ---------------------
ShowServlet.java

/**
 * 展現內容 //…(1)
 * @param request
 * @param response
 */
private void show(HttpServletRequest request, 
HttpServletResponse response) {

  String process_name = request.getParameter(
"process"); //…(2)
  if (process_name == null) {
    process_name = "AProcess";
  }
  log.debug("process_name="+process_name);
        
  String arg = request.getParameter("arg"); //…(3)
  if (arg == null) {
    arg = "nana";
  }
  log.debug("arg="+arg);
         
  Process process = processFactory.getProcess(
process_name); //…(4)
  String result = process.doProcess(arg);
  以下略…
}
---------------------------------- end------------------------------------------


---------------------------------- box 程式9 ----------------------------
loader = new URLClassLoader(new URL[] { 
file.toURL() });
----------------------------------- end --------------------------



---------------------------------- box 程式10 ------------------------
loader = new URLClassLoader(new URL[] { 
file.toURL() }, this.getClass().getClassLoader());
--------------------------------------- end -----------------------------


------------------------- box 程式11 -------------------------
ResetServlet.java
//…(1)
private void reset(HttpServletRequest request, 
HttpServletResponse response) {
  processFactory.newClassLoader();//…(2)
  以下略..
        
}
-------------------------------------- end -----------------------


----------------------- box 程式12 ------------------------
public String doProcess(String arg) {
  return "Hello!!! "+arg + " at "+Time.getNowTime() 
+ "in Kaohsiung.";
}
--------------------------- end -----------------------------