servlet-servletContext網站計數器
在web.xml檔案配置
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>NumServlet</servlet-name>
<servlet-class>servlet.NumServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
public class NumServlet extends HttpServlet {
//複寫init初始化方法,將資料讀取到ServletContext物件中
@Override
public void init() throws ServletException {
//獲取檔案路徑
String path=this.getServletContext().getRealPath("/nums/nums.txt");
//宣告流物件
FileReader fr=null;
BufferedReader br=null;
try{
fr=new FileReader(path);
br=new BufferedReader(fr);
String nums=br.readLine();
System.out.println(nums);
this.getServletContext().setAttribute("nums",nums);
}catch(Exception e){
e.printStackTrace();
}finally{
try {
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
fr.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
//複寫銷燬方法，儲存計數器到檔案中
@Override
public void destroy(){
//獲取網頁計數器
int nums=(int)this.getServletContext().getAttribute("nums");
//獲取檔案路徑
String path=this.getServletContext().getRealPath("/nums/nums.txt");
//宣告流物件
BufferedWriter bw=null;
FileWriter fw=null;
try{
fw=new FileWriter(path);
bw=new BufferedWriter(fw);
bw.write(nums+"");
bw.flush();
}catch(Exception e){
e.printStackTrace();
}finally{
try {
fw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
bw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}