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root/i-scream/experimental/misc/JVMManager/JVMManager.java
Revision: 1.1
Committed: Fri Nov 3 22:05:33 2000 UTC (24 years ago) by ajm
Branch: MAIN
CVS Tags: PROJECT_COMPLETION, HEAD
Log Message:
Checked in the JVMManager, a look at running multiple classes in a single VM

File Contents

# User Rev Content
1 ajm 1.1 // Some imports
2     import java.util.*;
3     import java.lang.reflect.*;
4    
5     // This class is a wrapper for running applications
6     // a basic thread extension
7     class ApplicationThread extends Thread {
8    
9     // The constructor takes the name of the method we're gonna run
10     // and the arguments we're gonna pass into it
11     ApplicationThread(Method mainMethod, Object[] args) {
12     _mainMethod = mainMethod;
13     _args = args;
14     }
15    
16     // The main bit of the thread just starts the functionality of the given
17     // method running
18     public void run() {
19     try {
20     System.out.println(" Starting: "+ _mainMethod.getDeclaringClass().toString());
21     _mainMethod.invoke(null, _args);
22     System.out.println(" Finished: "+ _mainMethod.getDeclaringClass().toString());
23     } catch (Exception e){
24     System.err.println("ERROR: " + e);
25     e.printStackTrace(System.out);
26     }
27     }
28    
29     Method _mainMethod = null;
30     Object[] _args = null;
31     }
32    
33     // The JVMManager takes a list of classes and instantiates them within the
34     // single VM that it is running in
35     //
36     // Future enhancements include:
37     // Passing of arguements to each class
38     // Seperation of in/out/err for each app
39     // GUI mode
40     // VM Thread control (ie, Kill, HUP etc...)
41     // Implementation of Java Security, specifically ProtectionDomain for each app
42     //
43     // Version 1.0
44     //
45     // (c) Copyright 2000 Alex Moore
46     //
47     class JVMManager {
48     public static void main(String args[]) {
49     // no exceptions are yet caught - not good
50     try {
51    
52     // get hook on the runtime
53     Runtime myRuntime = Runtime.getRuntime();
54     // get hook on the system Class loader
55     ClassLoader myClassLoader = ClassLoader.getSystemClassLoader();
56     System.out.println("JVM Manager Started.");
57     System.out.println(" Total memory: " + myRuntime.totalMemory());
58     System.out.println(" Free memory: " + myRuntime.freeMemory());
59     System.out.println();
60    
61     // for the time being we are just accepting a list of classes
62     // so just get the command line and assume that is just a simple list of classes to run
63     String[] appList = args;
64    
65     // step through each app, and start it rolling
66     for (int i=0; i < appList.length; i++) {
67    
68     // Load the class
69     Class myClass = myClassLoader.loadClass(appList[i]);
70     // and we don't support passing of individual args, but we will ;-) so its just null
71     String[] passedArgs = {};
72    
73     System.out.println("*** Class Loaded: " + myClass.toString());
74    
75     System.out.println(" Listing declared methods:");
76    
77     // Just because we can, we're going to list the declared methods...no reason
78     Method[] theMethods = myClass.getDeclaredMethods();
79     for (int x=0; x < theMethods.length; x++) {
80     System.out.println(" "+ theMethods[x].toString());
81     }
82    
83     // create an array of classes that are listed in the main method header
84     // so we can get a hook to the main method
85     Class[] passedArgsClass = {passedArgs.getClass()};
86     // get a hook on the main method
87     Method myMethod = myClass.getMethod("main",passedArgsClass);
88    
89     System.out.println(" Got a hook to the main method.");
90     System.out.println(" Creating and passing start up arguments to thread.");
91    
92     // Now we know where it is, we need to create a thread for it, passing in
93     // a list of objects that represent its args.
94     Object[] passedArgsObject = {passedArgs};
95     ApplicationThread anApp = new ApplicationThread(myMethod, passedArgsObject);
96    
97     // Finally we start it going
98     System.out.println(" Starting Thread.");
99     anApp.start();
100    
101     // Now we go and start the rest of the Apps listed
102    
103     }
104    
105     // At this point we are finished, though in the future the VM Manager
106     // won't just die away, but will remain to carry out JVM administration and
107     // thread management.
108     System.out.println();
109     System.out.println("JVM Manager Finished.");
110     System.out.println(" Free memory: " + myRuntime.freeMemory());
111     System.out.println();
112    
113     } catch (Exception e) {
114     System.err.println("ERROR: " + e);
115     e.printStackTrace(System.out);
116     }
117     }
118     }
119