两个步骤搞定
1：工具类
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.http.HttpServlet;
public class Counter extends HttpServlet {
// 写入文件的方法
public static void write2File(String filename, long count) {
try {
PrintWriter out = new PrintWriter(new FileWriter(filename));
out.println(count);
out.close();
} catch (IOException e) {
// TODO: handle exception
e.printStackTrace();
}
}
// 读文件的方法
public static long readFromFile(String filename) {
File file = new File(filename);
long count = 0;
if (!file.exists()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
write2File(filename, 0);
}
try {
BufferedReader in = new BufferedReader(new FileReader(file));
try {
count = Long.parseLong(in.readLine());
} catch (NumberFormatException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return count;
}
}
2：jsp页面
Counter CountFileHandler = new Counter();
long count = 0;
if(application.getAttribute("count") == null){
count = CountFileHandler.readFromFile(session.getServletContext().getRealPath("count.txt"));
application.setAttribute("count", new Long(count));
}
count = (Long)application.getAttribute("count");
if(session.isNew()){
count++;
application.setAttribute("count", count);
//更新文件目录
CountFileHandler.write2File(session.getServletContext().getRealPath("count.txt"),count);
}
%>
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