前一段做个程序，遇到了这样一个问题，想利用相对路径删掉一个文件(实际存在的),老是删不掉. 真是急人呀，最后让我费了好大力气才算把它解决掉，问题不防跟大家说说，万一遇到这样的问题，就不用再费劲了！
情况是这样的：我的tomcat装在了c盘，而我的虚拟目录设在了e:/work下， 我在e:/work/test/image下有个图片，test.gif 我想通过程序删掉它，但他的绝对路径不确定(为了考虑到程序以后的移植,绝对路径是不确定的)。
假设del.jsp文件在e:/work/test 下，用下面的程序好像可以删掉：
<!--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>删除成功页面</title>
</head>
<body>
file f=new file("/image/",test.gif);
boolean a=f.delete();
out.print("a="+a);
</body>
</html>
但事实上不行，你会发现a=false;
这就需要获取其绝对路径， 我们用java程序来做一个专门来获取绝对路径的javabean(path_test.java)就可以了。
path_test.java的代码如下：
package pathtest;
import java.io.*;
import javax.servlet.*;
import javax.servlet.jsp.pagecontext;//导入pagecontext类，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) //判断是否是虚拟路径
{
if(m_application.getrealpath(pathname) != null)
{
java.io.file virtualfile = new java.io.file(m_application.getrealpath(pathname));
return virtualfile.exists();
}
else
{
return false;
}
}
}
对path_test.java编译后，得到包pathtest,里面有path_test.class类，
把整个包放到虚拟目录的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>删除成功页面</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);//传参数
out.print(dir1);//输出的是绝对路径
file file=new file(dir1,"test.gif");//生成文件对象
boolean a=file.delete();
out.print("a="+a);
</body">
</html>
此时a=true;表示删除成功！
到此为止，问题全部搞定。
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