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，最后讓我費了好大力氣才算把它解決掉，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(為了考慮到程序以后的移植,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：
<!--原始的del.jsp源文件-->
<%@ 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.*"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>刪除成功頁面</title>
</head>
<body>
File f=new File("/image/",test.gif);
boolean a=f.delete();
out.print("a="+a);
</body>
</html>
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編譯后，得到包pathtest,里面有path_test.class類，
把整個包放到虛擬目錄的classes下，然后再把del.jsp文件改成如下程序，一切都OK了！
<!--改后的del.jsp的源文件-->
<%@ 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.*"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>刪除成功頁面</title>
</head>
<body>
<jsp:useBean id="pathtest" scope="page" class="pathtest.path_test" />
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);
</body">
</html>
此時a=true;表示刪除成功！
到此為止，問題全部搞定。
posted on 2005-06-07 16:19
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