从不含package名的class名 取得 含package名的class名

比如1）
有个类叫
a.b.c.MyClass

输入1个字符串"MyClass" 返回字符串"a.b.c.MyClass"

比如2）
有重名的情况，全部返回
有两个类
a.b.c.MyClass
x.y.z.MyClass


输入1个字符串"MyClass" 
返回字符串
"a.b.c.MyClass"
和
"x.y.z.MyClass"


调用方法

ArrayList<String> fullNames = FullClassNameGetter.getInstance().getFullClassName(不含包的类名);

完整代码

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
//import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;


public class FullClassNameGetter {

	private static final String JAVA_CLASS_PATH = "java.class.path";

	private static final String CLASSPATH_SEPARATOR = System.getProperty("path.separator");

	private static final String PACKAGE_SEPARATOR = ".";

	private static final String JAR_DIR_SEPARATOR = "/";

	private static final String CLASS_SUFFIX = ".class";

	private HashMap<String, ArrayList<String>> nameingMap;

	private String[] jdkJars = {"lib/rt.jar",
			"lib/jsse.jar",
			"lib/jce.jar",
			"lib/charsets.jar",
			"lib/ext/dnsns.jar",
			"lib/ext/localedata.jar",
			"lib/ext/sunjce_provider.jar",
			"lib/ext/sunmscapi.jar",
			"lib/ext/sunpkcs11.jar"};

	private static class FullClassNameGetterSingletonHolder {
		private static FullClassNameGetter instance = new FullClassNameGetter();
	}

	private FullClassNameGetter() {
		final String initialClasspath = System.getProperty(JAVA_CLASS_PATH);
		//Date now = new Date();
		setClassPath(initialClasspath);
		//System.out.println("initialize FullClassNameGetter done.  " + (new Date().getTime() - now.getTime()));
	}

	public static FullClassNameGetter getInstance() {
		return FullClassNameGetterSingletonHolder.instance;
	}

	public ArrayList<String> getFullClassName(String className) {
		ArrayList<String> ret = null;
		if (className.indexOf(PACKAGE_SEPARATOR) != -1) {
			ret = new ArrayList<String>();
			ret.add(className);
			return ret;
		}


		ret = nameingMap.get(className);
		return ret;
	}

	public void setClassPath(String classPath) {
		nameingMap = new HashMap<String, ArrayList<String>>();
		String[] classPathArray = classPath.split(CLASSPATH_SEPARATOR);

		File file;
		for (String onePath : classPathArray) {
			file = new File(onePath);
			if (file.exists()) {
				if (file.isDirectory()) {
					// dir
					setDirClasses(file, "");
				} else {
					// jar file
					setJarClasses(file);
				}
			}
		}
		String jreDir = System.getProperty("java.home");
		for (String jreJar : jdkJars) {
			file = new File(jreDir + JAR_DIR_SEPARATOR + jreJar);
			if (file.exists()) {
				// jar file
				setJarClasses(file);
			}
		}

	}

	private void setDirClasses(File classDir, String path) {
        File[] files = classDir.listFiles();
        String className;
        for (File file : files) {
            if (file.isDirectory()) {
            	setDirClasses(file, path + file.getName() + PACKAGE_SEPARATOR);
            } else {
            	if (file.getName().endsWith(CLASS_SUFFIX)) {
            		className  = file.getName().substring(0, file.getName().length() - CLASS_SUFFIX.length());
            		if (!"".equals(path)) {
            			setNamingMap(className, path + className);
            		} else {
            			//no package
            			setNamingMap(className, className);
            		}
            	}
            }
        }
	}

	private void setJarClasses(File jarFile) {
		JarFile jf = null;
        try {
            jf = new JarFile(jarFile);

            Enumeration<JarEntry> es = jf.entries();
            JarEntry entry;
            String simpleName;
            while (es.hasMoreElements()) {
            	entry = es.nextElement();
            	if (!entry.isDirectory()) {
            		String fullName = entry.getName();
            		if (fullName.endsWith(CLASS_SUFFIX)) {
            			fullName = fullName.substring(0, fullName.length() - CLASS_SUFFIX.length());
                        int index = fullName.lastIndexOf(JAR_DIR_SEPARATOR);
                        if (index != -1) {
                        	simpleName = fullName.substring(index + 1, fullName.length());
                        	fullName = fullName.replace(JAR_DIR_SEPARATOR, PACKAGE_SEPARATOR);
                        	setNamingMap(simpleName, fullName);
                        } else {
                        	//no package
                        	simpleName = fullName;
                        	setNamingMap(simpleName, fullName);
                        }
            		}
            	}
            }
        } catch (IOException e) {
        	//do nothing
        } finally {
            if (jf != null) {
                try {
                    jf.close();
                } catch (IOException e) {
                	//do nothing
                }
            }
        }
	}

	private void setNamingMap(String simpleName, String fullName) {
		ArrayList<String> value = nameingMap.get(simpleName);
		if (value == null) {
			value = new ArrayList<String>();
			nameingMap.put(simpleName, value);
		}
		if (!value.contains(fullName)) {
			value.add(fullName);
		}
	}


}

评论

2 楼 Goro 2012-02-26  

enet_java 写道

不错，不过不明白lZ为什么要通过这种方式来获取实例呢？给解释一下呗。多谢了

引用

    private static class FullClassNameGetterSingletonHolder
    {
        private static FullClassNameGetter instance = new FullClassNameGetter();
    }
    public static FullClassNameGetter getInstance()
    {
        return FullClassNameGetterSingletonHolder.instance;
    }

参考下面的文章
Initialization on demand holder
http://book.51cto.com/art/201202/318464.htm

如果只简单用static的成员变量来实现单例模式，不能实现延迟加载。
当然这是个小问题。 除非构造这个对象需要很大开销。

1 楼 enet_java 2010-12-22  

不错，不过不明白lZ为什么要通过这种方式来获取实例呢？给解释一下呗。多谢了

引用

    private static class FullClassNameGetterSingletonHolder
    {
        private static FullClassNameGetter instance = new FullClassNameGetter();
    }
    public static FullClassNameGetter getInstance()
    {
        return FullClassNameGetterSingletonHolder.instance;
    }