|
|
The JInfo.java Java example source code
/*
* Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.tools.jinfo;
import java.lang.reflect.Method;
import java.io.IOException;
import java.io.InputStream;
import com.sun.tools.attach.VirtualMachine;
import sun.tools.attach.HotSpotVirtualMachine;
/*
* This class is the main class for the JInfo utility. It parses its arguments
* and decides if the command should be satisfied using the VM attach mechanism
* or an SA tool. At this time the only option that uses the VM attach
* mechanism is the -flag option to set or print a command line option of a
* running application. All other options are mapped to SA tools.
*/
public class JInfo {
public static void main(String[] args) throws Exception {
if (args.length == 0) {
usage(1); // no arguments
}
boolean useSA = true;
String arg1 = args[0];
if (arg1.startsWith("-")) {
if (arg1.equals("-flags") ||
arg1.equals("-sysprops")) {
// SA JInfo needs <pid> or or
// (<executable> and ). So, total
// argument count including option has to 2 or 3.
if (args.length != 2 && args.length != 3) {
usage(1);
}
} else if (arg1.equals("-flag")) {
// do not use SA, use attach-on-demand
useSA = false;
} else {
// unknown option or -h or -help, print help
int exit;
if (arg1.equals("-help") || arg1.equals("-h")) {
exit = 0;
} else {
exit = 1;
}
usage(exit);
}
}
if (useSA) {
runTool(args);
} else {
if (args.length == 3) {
String pid = args[2];
String option = args[1];
flag(pid, option);
} else {
int exit;
if (arg1.equals("-help") || arg1.equals("-h")) {
exit = 0;
} else {
exit = 1;
}
usage(exit);
}
}
}
// Invoke SA tool with the given arguments
private static void runTool(String args[]) throws Exception {
String tool = "sun.jvm.hotspot.tools.JInfo";
// Tool not available on this platform.
Class<?> c = loadClass(tool);
if (c == null) {
usage(1);
}
// invoke the main method with the arguments
Class[] argTypes = { String[].class } ;
Method m = c.getDeclaredMethod("main", argTypes);
Object[] invokeArgs = { args };
m.invoke(null, invokeArgs);
}
// loads the given class using the system class loader
private static Class<?> loadClass(String name) {
//
// We specify the system clas loader so as to cater for development
// environments where this class is on the boot class path but sa-jdi.jar
// is on the system class path. Once the JDK is deployed then both
// tools.jar and sa-jdi.jar are on the system class path.
//
try {
return Class.forName(name, true,
ClassLoader.getSystemClassLoader());
} catch (Exception x) { }
return null;
}
private static void flag(String pid, String option) throws IOException {
VirtualMachine vm = attach(pid);
String flag;
InputStream in;
int index = option.indexOf('=');
if (index != -1) {
flag = option.substring(0, index);
String value = option.substring(index + 1);
in = ((HotSpotVirtualMachine)vm).setFlag(flag, value);
} else {
char c = option.charAt(0);
switch (c) {
case '+':
flag = option.substring(1);
in = ((HotSpotVirtualMachine)vm).setFlag(flag, "1");
break;
case '-':
flag = option.substring(1);
in = ((HotSpotVirtualMachine)vm).setFlag(flag, "0");
break;
default:
flag = option;
in = ((HotSpotVirtualMachine)vm).printFlag(flag);
break;
}
}
drain(vm, in);
}
// Attach to <pid>, exiting if we fail to attach
private static VirtualMachine attach(String pid) {
try {
return VirtualMachine.attach(pid);
} catch (Exception x) {
String msg = x.getMessage();
if (msg != null) {
System.err.println(pid + ": " + msg);
} else {
x.printStackTrace();
}
System.exit(1);
return null; // keep compiler happy
}
}
// Read the stream from the target VM until EOF, then detach
private static void drain(VirtualMachine vm, InputStream in) throws IOException {
// read to EOF and just print output
byte b[] = new byte[256];
int n;
do {
n = in.read(b);
if (n > 0) {
String s = new String(b, 0, n, "UTF-8");
System.out.print(s);
}
} while (n > 0);
in.close();
vm.detach();
}
// print usage message
private static void usage(int exit) {
Class<?> c = loadClass("sun.jvm.hotspot.tools.JInfo");
boolean usageSA = (c != null);
System.err.println("Usage:");
if (usageSA) {
System.err.println(" jinfo [option] <pid>");
System.err.println(" (to connect to running process)");
System.err.println(" jinfo [option] <executable to set the named VM flag to the given value");
System.err.println(" -flags to print VM flags");
System.err.println(" -sysprops to print Java system properties");
System.err.println(" <no option> to print both of the above");
System.err.println(" -h | -help to print this help message");
} else {
System.err.println(" jinfo <option> ");
System.err.println(" (to connect to a running process)");
System.err.println("");
System.err.println("where <option> is one of:");
System.err.println(" -flag <name> to print the value of the named VM flag");
System.err.println(" -flag [+|-]<name> to enable or disable the named VM flag");
System.err.println(" -flag <name>= to set the named VM flag to the given value");
System.err.println(" -h | -help to print this help message");
}
System.exit(exit);
}
}
Other Java examples (source code examples)
Here is a short list of links related to this Java JInfo.java source code file:
|
The search page
Other Java source code examples at this package level
Click here to learn more about this project
