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FactoryFinder.javaAPI DocApache Axis 1.49371Sat Apr 22 18:57:28 BST 2006javax.xml.rpc

FactoryFinder

public class FactoryFinder extends Object
This code is designed to implement the pluggability feature and is designed to both compile and run on JDK version 1.1 and later. The code also runs both as part of an unbundled jar file and when bundled as part of the JDK. This class is duplicated for each subpackage so keep it in sync. It is package private and therefore is not exposed as part of the JAXRPC API.

Fields Summary
private static final boolean
debug
Set to true for debugging.
Constructors Summary
Methods Summary
private static voiddebugPrintln(java.lang.String msg)


         
        if (debug) {
            System.err.println("JAXRPC: " + msg);
        }
static java.lang.Objectfind(java.lang.String factoryId, java.lang.String fallbackClassName)
Finds the implementation Class object in the specified order. Main entry point.

return
Class object of factory, never null
param
factoryId Name of the factory to find, same as a property name
param
fallbackClassName Implementation class name, if nothing else is found. Use null to mean no fallback.
exception
FactoryFinder.ConfigurationError Package private so this code can be shared.

        debugPrintln("debug is on");

        ClassLoader classLoader = findClassLoader();

        // Use the system property first
        try {
            String systemProp =
                System.getProperty( factoryId );
            if( systemProp!=null) {
                debugPrintln("found system property " + systemProp);
                return newInstance(systemProp, classLoader);
            }
        } catch (SecurityException se) {
        }

        // try to read from $java.home/lib/xml.properties
        try {
            String javah=System.getProperty( "java.home" );
            String configFile = javah + File.separator +
                "lib" + File.separator + "jaxrpc.properties";
            File f=new File( configFile );
            if( f.exists()) {
                Properties props=new Properties();
                props.load( new FileInputStream(f));
                String factoryClassName = props.getProperty(factoryId);
                debugPrintln("found java.home property " + factoryClassName);
                return newInstance(factoryClassName, classLoader);
            }
        } catch(Exception ex ) {
            if( debug ) ex.printStackTrace();
        }

        String serviceId = "META-INF/services/" + factoryId;
        // try to find services in CLASSPATH
        try {
            InputStream is=null;
            if (classLoader == null) {
                is=ClassLoader.getSystemResourceAsStream( serviceId );
            } else {
                is=classLoader.getResourceAsStream( serviceId );
            }

            if( is!=null ) {
                debugPrintln("found " + serviceId);

                // Read the service provider name in UTF-8 as specified in
                // the jar spec.  Unfortunately this fails in Microsoft
                // VJ++, which does not implement the UTF-8
                // encoding. Theoretically, we should simply let it fail in
                // that case, since the JVM is obviously broken if it
                // doesn't support such a basic standard.  But since there
                // are still some users attempting to use VJ++ for
                // development, we have dropped in a fallback which makes a
                // second attempt using the platform's default encoding. In
                // VJ++ this is apparently ASCII, which is a subset of
                // UTF-8... and since the strings we'll be reading here are
                // also primarily limited to the 7-bit ASCII range (at
                // least, in English versions), this should work well
                // enough to keep us on the air until we're ready to
                // officially decommit from VJ++. [Edited comment from
                // jkesselm]
                BufferedReader rd;
                try {
                    rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
                } catch (java.io.UnsupportedEncodingException e) {
                    rd = new BufferedReader(new InputStreamReader(is));
                }

                String factoryClassName = rd.readLine();
                rd.close();

                if (factoryClassName != null &&
                    ! "".equals(factoryClassName)) {
                    debugPrintln("loaded from services: " + factoryClassName);
                    return newInstance(factoryClassName, classLoader);
                }
            }
        } catch( Exception ex ) {
            if( debug ) ex.printStackTrace();
        }

        if (fallbackClassName == null) {
            throw new ConfigurationError(
                "Provider for " + factoryId + " cannot be found", null);
        }

        debugPrintln("loaded from fallback value: " + fallbackClassName);
        return newInstance(fallbackClassName, classLoader);
private static java.lang.ClassLoaderfindClassLoader()
Figure out which ClassLoader to use. For JDK 1.2 and later use the context ClassLoader.

return
the ClassLoader
throws
ConfigurationError if this class is unable to work with the host JDK

        Method m = null;

        try {
            m = Thread.class.getMethod("getContextClassLoader", null);
        } catch (NoSuchMethodException e) {
            // Assume that we are running JDK 1.1, use the current ClassLoader
            debugPrintln("assuming JDK 1.1");
            return FactoryFinder.class.getClassLoader();
        }

        try {
            return (ClassLoader) m.invoke(Thread.currentThread(), null);
        } catch (IllegalAccessException e) {
            // assert(false)
            throw new ConfigurationError("Unexpected IllegalAccessException",
                                         e);
        } catch (InvocationTargetException e) {
            // assert(e.getTargetException() instanceof SecurityException)
            throw new ConfigurationError("Unexpected InvocationTargetException",
                                         e);
        }
private static java.lang.ObjectnewInstance(java.lang.String className, java.lang.ClassLoader classLoader)
Create an instance of a class using the specified ClassLoader, or if that fails from the ClassLoader that loaded this class.

param
className the name of the class to instantiate
param
classLoader a ClassLoader to load the class from
return
a new Object that is an instance of the class of the given name from the given class loader
throws
ConfigurationError if the class could not be found or instantiated

        try {
            if (classLoader != null) {
                try {
                    return classLoader.loadClass(className).newInstance ();
                } catch (ClassNotFoundException x) {
                      // try again
                }
            }
            return Class.forName(className).newInstance();
        } catch (ClassNotFoundException x) {
            throw new ConfigurationError(
                "Provider " + className + " not found", x);
        } catch (Exception x) {
            throw new ConfigurationError(
                "Provider " + className + " could not be instantiated: " + x,
                x);
        }