Admin: 1 версия

2010-06-01T06:02:01Z

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в 18:01, 31 мая 2010

2010-05-31T18:01:43Z

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== Demonstrates how to get declaration information on a Class ==



<source lang="java">

/*
* file: PackageInfoDemo.java
* package: oreilly.hcj.reflection
*
* This software is granted under the terms of the Common Public License,
* CPL, which may be found at the following URL:
* http://www-124.ibm.ru/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags.
* All Rights are Reserved by the various authors.
*
########## DO NOT EDIT ABOVE THIS LINE ########## */

import java.util.Collection;
/**
* Demonstrates how to get declaration information on a Class.
*
* @author
* @version $Revision: 1.3 $
*/
public class PackageInfoDemo {
/**
* Demonstration Method.
*
* @param args Command line arguments.
*/
public static void main(final String[] args) {
System.out.println(Object.class.getPackage());
System.out.println(Float.class.getPackage());
System.out.println(Collection.class.getPackage());
System.out.println(int.class.getPackage());
System.out.println(String.class.getPackage());
}
}
/* ########## End of File ########## */

</source>



== Detect if a package is available ==



<source lang="java">

public class Main{
public static void main(String args[]) {
System.out.println(isAvailable("javax.swing.JComponent"));
}
public static boolean isAvailable(String className) {
boolean isFound = false;
try {
Class.forName(className, false, null);
isFound = true;
}
catch (ClassNotFoundException e) {
isFound = false;
}
return isFound;
}
}

</source>



== Get all information about a package ==



<source lang="java">

class PackageInfo {
public static void main(String[] args) {
Package p = Package.getPackage("java.lang");
System.out.println("Name = " + p.getName());
System.out.println("Implementation title = " + p.getImplementationTitle());
System.out.println("Implementation vendor = " + p.getImplementationVendor());
System.out.println("Implementation version = " + p.getImplementationVersion());
System.out.println("Specification title = " + p.getSpecificationTitle());
System.out.println("Specification vendor = " + p.getSpecificationVendor());
System.out.println("Specification version = " + p.getSpecificationVersion());
}
}

</source>



== Get full package name ==



<source lang="java">

public class Main {
public static String getPackageName(Class c) {
String fullyQualifiedName = c.getName();
int lastDot = fullyQualifiedName.lastIndexOf(".");
if (lastDot == -1) {
return "";
}
return fullyQualifiedName.substring(0, lastDot);
}
public static void main(String[] args) {
System.out.println(getPackageName(java.awt.Frame.class));
}
}

</source>



== Get package by name ==



<source lang="java">

public class Main {
public static void main(String[] a) {
Package p = Package.getPackage("java.lang");
System.out.println("Name = " + p.getName());
System.out.println("Implementation title = " + p.getImplementationTitle());
System.out.println("Implementation vendor = " + p.getImplementationVendor());
System.out.println("Implementation version = " + p.getImplementationVersion());
}
}
/*Name = java.lang
Implementation title = Java Runtime Environment
Implementation vendor = Sun Microsystems, Inc.
Implementation version = 1.6.0_02
*/

</source>



== Get package name of a class ==



<source lang="java">

import java.util.Date;
public class Main {
public static void main(String[] args) {
Date date = new Date();
Package pack = date.getClass().getPackage();
String packageName = pack.getName();
System.out.println("Package Name = " + packageName);
}
}

</source>



== Get Package Names From Dir ==



<source lang="java">

/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.io.File;
import java.util.List;
public final class ReflectionUtil {
private static void getPackageNamesFromDir(File base, File dir, List<String> pkgs) {
boolean foundClass = false;
for (File file : dir.listFiles()) {
if (file.isDirectory()) {
getPackageNamesFromDir(base, file, pkgs);
} else if (!foundClass && file.getName().endsWith(".class")) {
foundClass = true;
String pkg = "";
file = dir;
while (!file.equals(base)) {
if (!"".equals(pkg)) {
pkg = "." + pkg;
}
pkg = file.getName() + pkg;
file = file.getParentFile();
}
if (!pkgs.contains(pkg)) {
pkgs.add(pkg);
}
}
}
}
private static String getPackageName(String clzName) {
if (clzName.indexOf("/") == -1) {
return null;
}
String packageName = clzName.substring(0, clzName.lastIndexOf("/"));
return packageName.replace("/", ".");
}
}

</source>



== getPackage() returns null for a class in the unnamed package ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
Class cls = MyClass.class;
Package pkg = cls.getPackage(); // null
}
}
class MyClass{}

</source>



== getPackage() returns null for a primitive type or array ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
Package pkg = int.class.getPackage(); // null
pkg = int[].class.getPackage(); // null
}
}

</source>



== Get the class name with or without the package ==



<source lang="java">

public class Main {
public static String getClassName(Class c) {
String className = c.getName();
int firstChar;
firstChar = className.lastIndexOf(".") + 1;
if (firstChar > 0) {
className = className.substring(firstChar);
}
return className;
}

public static void main(String[] args) {
System.out.println(getClassName(java.awt.Frame.class));
}
}

</source>



== Getting the Package of a Class ==



<source lang="java">

public class Main {
public static void main(String[] argv) throws Exception {
Class cls = java.lang.String.class;
Package pkg = cls.getPackage();
String name = pkg.getName(); // java.lang
}
}

</source>



== Package Utils ==



<source lang="java">

/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;

public final class PackageUtils {

private static final Set<String> KEYWORDS = new HashSet<String>(Arrays
.asList(new String[] {"abstract", "boolean", "break", "byte", "case", "catch", "char", "class",
"const", "continue", "default", "do", "double", "else", "extends", "final",
"finally", "float", "for", "goto", "if", "implements", "import", "instanceof",
"int", "interface", "long", "native", "new", "package", "private", "protected",
"public", "return", "short", "static", "strictfp", "super", "switch",
"synchronized", "this", "throw", "throws", "transient", "try", "void",
"volatile", "while", "true", "false", "null", "assert", "enum"}));

private PackageUtils() {

}

static String getPackageName(String className) {
int pos = className.lastIndexOf(".");
if (pos != -1) {
return className.substring(0, pos);
} else {
return "";
}
}

public static String getPackageName(Class<?> clazz) {
String className = clazz.getName();
if (className.startsWith("[L")) {
className = className.substring(2);
}
return getPackageName(className);
}

public static String parsePackageName(String namespace, String defaultPackageName) {
String packageName = (defaultPackageName != null && defaultPackageName.trim().length() > 0)
? defaultPackageName : null;
if (packageName == null) {
packageName = getPackageNameByNameSpaceURI(namespace);
}
return packageName;
}

public static String getPackageNameByNameSpaceURI(String nameSpaceURI) {
int idx = nameSpaceURI.indexOf(":");
String scheme = "";
if (idx >= 0) {
scheme = nameSpaceURI.substring(0, idx);
if ("http".equalsIgnoreCase(scheme) || "urn".equalsIgnoreCase(scheme)) {
nameSpaceURI = nameSpaceURI.substring(idx + 1);
}
}
List<String> tokens = tokenize(nameSpaceURI, "/: ");
if (tokens.size() == 0) {
return null;
}
if (tokens.size() > 1) {
String lastToken = tokens.get(tokens.size() - 1);
idx = lastToken.lastIndexOf(".");
if (idx > 0) {
lastToken = lastToken.substring(0, idx);
tokens.set(tokens.size() - 1, lastToken);
}
}
String domain = tokens.get(0);
idx = domain.indexOf(":");
if (idx >= 0) {
domain = domain.substring(0, idx);
}
List<String> r = reverse(tokenize(domain, "urn".equals(scheme) ? ".-" : "."));
if ("www".equalsIgnoreCase(r.get(r.size() - 1))) {
// remove leading www
r.remove(r.size() - 1);
}
// replace the domain name with tokenized items
tokens.addAll(1, r);
tokens.remove(0);
// iterate through the tokens and apply xml->java name algorithm
for (int i = 0; i < tokens.size(); i++) {
// get the token and remove illegal chars
String token = tokens.get(i);
token = removeIllegalIdentifierChars(token);
// this will check for reserved keywords
if (containsReservedKeywords(token)) {
token = "_" + token;
}
tokens.set(i, token.toLowerCase());
}
// concat all the pieces and return it
return combine(tokens, ".");
}
private static List<String> tokenize(String str, String sep) {
StringTokenizer tokens = new StringTokenizer(str, sep);
List<String> r = new ArrayList<String>();
while (tokens.hasMoreTokens()) {
r.add(tokens.nextToken());
}
return r;
}
private static <T> List<T> reverse(List<T> a) {
List<T> r = new ArrayList<T>();
for (int i = a.size() - 1; i >= 0; i--) {
r.add(a.get(i));
}
return r;
}
private static String removeIllegalIdentifierChars(String token) {
StringBuffer newToken = new StringBuffer();
for (int i = 0; i < token.length(); i++) {
char c = token.charAt(i);
if (i == 0 && !Character.isJavaIdentifierStart(c)) {
// prefix an "_" if the first char is illegal
newToken.append("_" + c);
} else if (!Character.isJavaIdentifierPart(c)) {
// replace the char with an "_" if it is illegal
newToken.append("_");
} else {
// add the legal char
newToken.append(c);
}
}
return newToken.toString();
}
private static String combine(List r, char sep) {
StringBuilder buf = new StringBuilder(r.get(0).toString());
for (int i = 1; i < r.size(); i++) {
buf.append(sep);
buf.append(r.get(i));
}
return buf.toString();
}
private static boolean containsReservedKeywords(String token) {
return KEYWORDS.contains(token);
}
public static String getNamespace(String packageName) {
if (packageName == null || packageName.length() == 0) {
return null;
}
StringTokenizer tokenizer = new StringTokenizer(packageName, ".");
String[] tokens;
if (tokenizer.countTokens() == 0) {
tokens = new String[0];
} else {
tokens = new String[tokenizer.countTokens()];
for (int i = tokenizer.countTokens() - 1; i >= 0; i--) {
tokens[i] = tokenizer.nextToken();
}
}
StringBuffer namespace = new StringBuffer("http://");
String dot = "";
for (int i = 0; i < tokens.length; i++) {
if (i == 1) {
dot = ".";
}
namespace.append(dot + tokens[i]);
}
namespace.append("/");
return namespace.toString();
}

}

</source>



== Show the Packages ==



<source lang="java">

/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
/**
* Show the Packages. Requires JDK1.2.
* @author Ian F. Darwin, http://www.darwinsys.ru/
* @version $Id: Packages.java,v 1.4 2004/02/09 03:33:51 ian Exp $
*/
public class Packages {
public static void main(String[] argv) {
//+
java.lang.Package[] all = java.lang.Package.getPackages();
for (int i=0; i<all.length; i++)
System.out.println(all[i]);
//-
}
}

</source>

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Admin: 1 версия

в 18:01, 31 мая 2010