/*
* Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
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*
*
*
*
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*
*/
package javax.tools;
import java.io.
File;
import java.lang.ref.
Reference;
import java.lang.ref.
WeakReference;
import java.net.
URL;
import java.net.
URLClassLoader;
import java.net.
MalformedURLException;
import java.util.
HashMap;
import java.util.
Locale;
import java.util.
Map;
import java.util.logging.
Logger;
import java.util.logging.
Level;
import static java.util.logging.
Level.*;
/**
* Provides methods for locating tool providers, for example,
* providers of compilers. This class complements the
* functionality of {@link java.util.ServiceLoader}.
*
* @author Peter von der Ahé
* @since 1.6
*/
public class
ToolProvider {
private static final
String propertyName = "sun.tools.ToolProvider";
private static final
String loggerName = "javax.tools";
/*
* Define the system property "sun.tools.ToolProvider" to enable
* debugging:
*
* java ... -Dsun.tools.ToolProvider ...
*/
static <T> T
trace(
Level level,
Object reason) {
// NOTE: do not make this method private as it affects stack traces
try {
if (
System.
getProperty(
propertyName) != null) {
StackTraceElement[]
st =
Thread.
currentThread().
getStackTrace();
String method = "???";
String cls =
ToolProvider.class.
getName();
if (
st.length > 2) {
StackTraceElement frame =
st[2];
method =
String.
format((
Locale)null, "%s(%s:%s)",
frame.
getMethodName(),
frame.
getFileName(),
frame.
getLineNumber());
cls =
frame.
getClassName();
}
Logger logger =
Logger.
getLogger(
loggerName);
if (
reason instanceof
Throwable) {
logger.
logp(
level,
cls,
method,
reason.
getClass().
getName(), (
Throwable)
reason);
} else {
logger.
logp(
level,
cls,
method,
String.
valueOf(
reason));
}
}
} catch (
SecurityException ex) {
System.
err.
format((
Locale)null, "%s: %s; %s%n",
ToolProvider.class.
getName(),
reason,
ex.
getLocalizedMessage());
}
return null;
}
private static final
String defaultJavaCompilerName
= "com.sun.tools.javac.api.JavacTool";
/**
* Gets the Java™ programming language compiler provided
* with this platform.
* @return the compiler provided with this platform or
* {@code null} if no compiler is provided
*/
public static
JavaCompiler getSystemJavaCompiler() {
return
instance().
getSystemTool(
JavaCompiler.class,
defaultJavaCompilerName);
}
private static final
String defaultDocumentationToolName
= "com.sun.tools.javadoc.api.JavadocTool";
/**
* Gets the Java™ programming language documentation tool provided
* with this platform.
* @return the documentation tool provided with this platform or
* {@code null} if no documentation tool is provided
*/
public static
DocumentationTool getSystemDocumentationTool() {
return
instance().
getSystemTool(
DocumentationTool.class,
defaultDocumentationToolName);
}
/**
* Returns the class loader for tools provided with this platform.
* This does not include user-installed tools. Use the
* {@linkplain java.util.ServiceLoader service provider mechanism}
* for locating user installed tools.
*
* @return the class loader for tools provided with this platform
* or {@code null} if no tools are provided
*/
public static
ClassLoader getSystemToolClassLoader() {
try {
Class<? extends
JavaCompiler>
c =
instance().
getSystemToolClass(
JavaCompiler.class,
defaultJavaCompilerName);
return
c.
getClassLoader();
} catch (
Throwable e) {
return
trace(
WARNING,
e);
}
}
private static
ToolProvider instance;
private static synchronized
ToolProvider instance() {
if (
instance == null)
instance = new
ToolProvider();
return
instance;
}
// Cache for tool classes.
// Use weak references to avoid keeping classes around unnecessarily
private
Map<
String,
Reference<
Class<?>>>
toolClasses = new
HashMap<
String,
Reference<
Class<?>>>();
// Cache for tool classloader.
// Use a weak reference to avoid keeping it around unnecessarily
private
Reference<
ClassLoader>
refToolClassLoader = null;
private
ToolProvider() { }
private <T> T
getSystemTool(
Class<T>
clazz,
String name) {
Class<? extends T>
c =
getSystemToolClass(
clazz,
name);
try {
return
c.
asSubclass(
clazz).
newInstance();
} catch (
Throwable e) {
trace(
WARNING,
e);
return null;
}
}
private <T>
Class<? extends T>
getSystemToolClass(
Class<T>
clazz,
String name) {
Reference<
Class<?>>
refClass =
toolClasses.
get(
name);
Class<?>
c = (
refClass == null ? null :
refClass.
get());
if (
c == null) {
try {
c =
findSystemToolClass(
name);
} catch (
Throwable e) {
return
trace(
WARNING,
e);
}
toolClasses.
put(
name, new
WeakReference<
Class<?>>(
c));
}
return
c.
asSubclass(
clazz);
}
private static final
String[]
defaultToolsLocation = { "lib", "tools.jar" };
private
Class<?>
findSystemToolClass(
String toolClassName)
throws
MalformedURLException,
ClassNotFoundException
{
// try loading class directly, in case tool is on the bootclasspath
try {
return
Class.
forName(
toolClassName, false, null);
} catch (
ClassNotFoundException e) {
trace(
FINE,
e);
// if tool not on bootclasspath, look in default tools location (tools.jar)
ClassLoader cl = (
refToolClassLoader == null ? null :
refToolClassLoader.
get());
if (
cl == null) {
File file = new
File(
System.
getProperty("java.home"));
if (
file.
getName().
equalsIgnoreCase("jre"))
file =
file.
getParentFile();
for (
String name :
defaultToolsLocation)
file = new
File(
file,
name);
// if tools not found, no point in trying a URLClassLoader
// so rethrow the original exception.
if (!
file.
exists())
throw
e;
URL[]
urls = {
file.
toURI().
toURL() };
trace(
FINE,
urls[0].
toString());
cl =
URLClassLoader.
newInstance(
urls);
refToolClassLoader = new
WeakReference<
ClassLoader>(
cl);
}
return
Class.
forName(
toolClassName, false,
cl);
}
}
}