JAVA获得绝对路径

转载自:http://hi.baidu.com/kylind/blog/item/457793a5ae30a9ff9052ee3f.html 工程下文件工程下文件获得绝对路径：FilePathUtil.getAbsolutePath("./11.txt");
WebRoot下文件获得绝对路径：FilePathUtil.getAbsolutePath("/11.txt");
ClassPath下文件获得绝对路径：FilePathUtil.getAbsolutePath("11.txt");

import java.io.File;
import java.net.URISyntaxException;
import java.net.URL;

/**
* 由相对路径获得 绝对路径、File、文件列表，此工具根据 ClassPath寻找路径 注意：本类不要加到jar包中，不然会失效
* 在Servlet中获得文件真实路径 string file_real_path=getServletContext().getRealPath("/1.swf");
*
* @author KyLinD 2009-4-28 http://hi.baidu.com/kylind
* @version 1.0
*/
public class FilePathUtil {
private FilePathUtil() {
}

/**
* 根据相对路径获得 File
*
* @param relativePath
* 工程下的以"./"开头，web下的以"/"开头，ClassPath下的直接相对路径
* @return File
*/
public static File getFileByRelativePath(String relativePath) {
return new File(getAbsolutePath(relativePath));
}

/**
* 根据相对路径获得绝对路径
*
* @param relativePath
* 工程下的以"./"开头，web下的以"/"开头，ClassPath下的直接相对路径
* @return 绝对路径字符串
*/
public static String getAbsolutePath(String relativePath) {
String result = null;
if (null != relativePath) {
if (relativePath.indexOf("./") == 0) {
String workspacePath = new File("").getAbsolutePath();
relativePath = relativePath.substring(2);
if (relativePath.length() > 0) {
relativePath = relativePath
.replace('/', File.separatorChar);
result = workspacePath + String.valueOf(File.separatorChar)
+ relativePath;
} else {
result = workspacePath;
}
} else if (relativePath.indexOf("/") == 0) {
String webRootPath = getAbsolutePathOfWebRoot();
if (relativePath.length() > 0) {
relativePath = relativePath
.replace('/', File.separatorChar);
result = webRootPath + relativePath;
} else {
result = webRootPath;
}
} else {
String classPath = getAbsolutePathOfClassPath();
if (relativePath.length() > 0) {
relativePath = relativePath
.replace('/', File.separatorChar);
result = classPath + File.separatorChar + relativePath;
} else {
result = classPath;
}
}
}
return result;
}

// 得到WebRoot目录的绝对地址
private static String getAbsolutePathOfWebRoot() {
String result = null;
result = getAbsolutePathOfClassPath();
result = result.replace(File.separatorChar + "WEB-INF"
+ File.separatorChar + "classes", "");
return result;
}

// 得到ClassPath的绝对路径
private static String getAbsolutePathOfClassPath() {
String result = null;
try {
File file = new File(getURLOfClassPath().toURI());
result = file.getAbsolutePath();
} catch (URISyntaxException e) {
e.printStackTrace();
}
return result;
}

// 得到ClassPath的URL
private static URL getURLOfClassPath() {
return getClassLoader().getResource("");
}

// 得到类加载器
private static ClassLoader getClassLoader() {
return FilePathUtil.class.getClassLoader();
}
}