/*
* 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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*
*
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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);
}
}
}