Java http 服务器上的访客计数器

Question

晚上好，我发现这个非常基本的 http 服务器是用 Java.

编写的

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

public class Test {

public static void main(String[] args) throws Exception {
    HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
    server.createContext("/test", new MyHandler());
    server.setExecutor(null); // creates a default executor
    server.start();
}

static class MyHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange t) throws IOException {
        String response = "This is the response";
        t.sendResponseHeaders(200, response.length());
        OutputStream os = t.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }
}

}

现在我正在尝试在网站上添加一个简单的计数器来计算每次访问。我刚刚找到需要 Java EE 库的代码。像这里这样：

import java.io.*;
import java.sql.Date;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class PageHitCounter extends HttpServlet{

private int hitCount; 

public void init() 
{ 
 // Reset hit counter.
 hitCount = 0;
 } 

public void doGet(HttpServletRequest request,
                HttpServletResponse response)
        throws ServletException, IOException
 {
  // Set response content type
  response.setContentType("text/html");
  // This method executes whenever the servlet is hit 
  // increment hitCount 
  hitCount++; 
  PrintWriter out = response.getWriter();
  String title = "Total Number of Hits";
  String docType =
  "<!doctype html public \"-//w3c//dtd html 4.0 " +
  "transitional//en\">\n";
  out.println(docType +
    "<html>\n" +
    "<head><title>" + title + "</title></head>\n" +
    "<body bgcolor=\"#f0f0f0\">\n" +
    "<h1 align=\"center\">" + title + "</h1>\n" +
    "<h2 align=\"center\">" + hitCount + "</h2>\n" +
    "</body></html>");

  }
   public void destroy() 
  { 
  // This is optional step but if you like you
  // can write hitCount value in your database.
  } 
  }

是否可以使用 Java SE 开发工具包编写此代码？又如何？

Answer 1

如果我理解你的问题，那么是的。最简单的方法可能是在 Handler 中添加一个 counter。将 counter 添加到您的 response，然后增加它。像，

static class MyHandler implements HttpHandler {
    static int counter = 0;
    @Override
    public void handle(HttpExchange t) throws IOException {
        String response = String.format("This is response %d%n", counter++);
        t.sendResponseHeaders(200, response.length());
        OutputStream os = t.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }
}

Answer 2

我的建议是不要使用 int，因为它不是线程安全的，而应该使用 AtomicInteger

AtomicInteger atomicInteger = new AtomicInteger(123); // initialize it with a value or empty
int theValue = atomicInteger.get(); // this is how you get it
atomicInteger.addAndGet(1); // to add a value to it, you can also getAndAdd(x)

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