用Java程序獲取絕對路徑

     前一段做個程序，遇到了這樣一個問題，想利用相對路徑刪掉一個文件(實際存在的),老是刪不掉. 真是急人呀，最後讓我費了好大力氣纔算把它解決掉，問題不防跟大家說說，萬一遇到這樣的問題，就不用再費勁了！

     情況是這樣的：我的Tomcat裝在了c盤，而我的虛擬目錄設在了E:/work下， 我在E:/work/test/image下有個圖片，test.gif 我想通過程序刪掉它，但他的絕對路徑不確定(爲了考慮到程序以後的移植,絕對路徑是不確定的)。

    假設del.jsp文件在e:/work/test 下，用下面的程序好像可以刪掉：

<%@ page contentType="text/html; charset=GBK" errorPage="" %> <%request.setCharacterEncoding("GBK");%> <%@ page language="java" import="java.sql.*" import="java.util.*" import ="java.text.*" import="java.io.*"%> File f=new File("/image/",test.gif); boolean a=f.delete(); out.print("a="+a);

 

    但事實上不行，你會發現a=false;

    這就需要獲取其絕對路徑， 我們用java程序來做一個專門來獲取絕對路徑的javaBean(path_test.java)就可以了。

path_test.java的代碼如下： package pathtest; import java.io.*; import javax.servlet.*; import javax.servlet.jsp.PageContext;//導入PageContext類，不要忘了 public class path_test { protected ServletContext m_application; private boolean m_denyPhysicalPath; public path_test() { } public final void initialize(PageContext pageContext) throws ServletException { m_application = pageContext.getServletContext(); } public String getPhysicalPath(String filePathName, int option) throws IOException { String path = new String(); String fileName = new String(); String fileSeparator = new String(); boolean isPhysical = false; fileSeparator=System.getProperty("file.separator"); if(filePathName == null) throw new IllegalArgumentException("There is no specified destination file (1140)."); if(filePathName.equals("")) throw new IllegalArgumentException("There is no specified destination file (1140)."); if(filePathName.lastIndexOf("//") >= 0) { path = filePathName.substring(0, filePathName.lastIndexOf("//")); fileName = filePathName.substring(filePathName.lastIndexOf("//") + 1); } if(filePathName.lastIndexOf("/") >= 0) { path = filePathName.substring(0, filePathName.lastIndexOf("/")); fileName = filePathName.substring(filePathName.lastIndexOf("/") + 1); } path = path.length() != 0 ? path : "/"; java.io.File physicalPath = new java.io.File(path); if(physicalPath.exists()) isPhysical = true; if(option == 0) { if(isVirtual(path)) { path = m_application.getRealPath(path); if(path.endsWith(fileSeparator)) path = path + fileName; else path = String.valueOf((new StringBuffer(String.valueOf(path))).append(fileSeparator).append(fileName)); return path; } if(isPhysical) { if(m_denyPhysicalPath) throw new IllegalArgumentException("Physical path is denied (1125)."); else return filePathName; } else { throw new IllegalArgumentException("This path does not exist (1135)."); } } if(option == 1) { if(isVirtual(path)) { path = m_application.getRealPath(path); if(path.endsWith(fileSeparator)) path = path + fileName; else path = String.valueOf((new StringBuffer(String.valueOf(path))).append(fileSeparator).append(fileName)); return path; } if(isPhysical) throw new IllegalArgumentException("The path is not a virtual path."); else throw new IllegalArgumentException("This path does not exist (1135)."); } if(option == 2) { if(isPhysical) if(m_denyPhysicalPath) throw new IllegalArgumentException("Physical path is denied (1125)."); else return filePathName; if(isVirtual(path)) throw new IllegalArgumentException("The path is not a physical path."); else throw new IllegalArgumentException("This path does not exist (1135)."); } else { return null; } } private boolean isVirtual(String pathName) //判斷是否是虛擬路徑 { if(m_application.getRealPath(pathName) != null) { java.io.File virtualFile = new java.io.File(m_application.getRealPath(pathName)); return virtualFile.exists(); } else { return false; } } } 對path_test.java編譯後，得到包pathtest,裏面有path_test.class類， 把整個包放到虛擬目錄的classes下，然後再把del.jsp文件改成如下程序，一切都OK了！ <%@ page contentType="text/html; charset=GBK" errorPage="" %> <%request.setCharacterEncoding("GBK");%> <%@ page language="java" import="java.sql.*" import="java.util.*" import ="java.text.*" import="java.io.*"%> pathtest.initialize(pageContext);//初始化 String dir1=pathtest.getPhysicalPath("/test/image/",0);//傳參數 out.print(dir1);//輸出的是絕對路徑 File file=new File(dir1,"test.gif");//生成文件對象 boolean a=file.delete(); out.print("a="+a);

 

    此時a=true;表示刪除成功！    

    到此爲止，問題全部搞定。