Java 如何實現一個http伺服器
阿新 • • 發佈：2020-11-22
在Java中可以使用HttpServer類來實現Http伺服器，該類位於com.sun.net包下(rt.jar)。實現程式碼如下：
主程式類
package bg.httpserver;
import com.sun.net.httpserver.HttpServer;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
public class HttpServerStarter {
public static void main(String[] args) throws IOException {
//建立一個HttpServer例項，並繫結到指定的IP地址和埠號
HttpServer httpServer = HttpServer.create(new InetSocketAddress(8080),0);
//建立一個HttpContext，將路徑為/myserver請求對映到MyHttpHandler處理器
httpServer.createContext("/myserver",new MyHttpHandler());
//設定伺服器的執行緒池物件
httpServer.setExecutor(Executors.newFixedThreadPool(10));
//啟動伺服器
httpServer.start();
}
}HttpServer：HttpServer主要是通過帶參的create方法來建立，第一個引數InetSocketAddress表示繫結的ip地址和埠號。第二個引數為int型別，表示允許排隊的最大TCP連線數，如果該值小於或等於零，則使用系統預設值。
createContext：可以呼叫多次，表示將指定的url路徑繫結到指定的HttpHandler處理器物件上，伺服器接收到的所有路徑請求都將通過呼叫給定的處理程式物件來處理。
setExecutor：設定伺服器的執行緒池物件，不設定或者設為null則表示使用start方法建立的執行緒。
HttpHandler實現
package bg.httpserver;
import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
/**
* 處理/myserver路徑請求的處理器類
*/
public class MyHttpHandler implements HttpHandler {
@Override
public void handle(HttpExchange httpExchange) {
try {
StringBuilder responseText = new StringBuilder();
responseText.append("請求方法：").append(httpExchange.getRequestMethod()).append("<br/>");
responseText.append("請求引數：").append(getRequestParam(httpExchange)).append("<br/>");
responseText.append("請求頭：<br/>").append(getRequestHeader(httpExchange));
handleResponse(httpExchange,responseText.toString());
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* 獲取請求頭
* @param httpExchange
* @return
*/
private String getRequestHeader(HttpExchange httpExchange) {
Headers headers = httpExchange.getRequestHeaders();
return headers.entrySet().stream()
.map((Map.Entry<String,List<String>> entry) -> entry.getKey() + ":" + entry.getValue().toString())
.collect(Collectors.joining("<br/>"));
}
/**
* 獲取請求引數
* @param httpExchange
* @return
* @throws Exception
*/
private String getRequestParam(HttpExchange httpExchange) throws Exception {
String paramStr = "";
if (httpExchange.getRequestMethod().equals("GET")) {
//GET請求讀queryString
paramStr = httpExchange.getRequestURI().getQuery();
} else {
//非GET請求讀請求體
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(httpExchange.getRequestBody(),"utf-8"));
StringBuilder requestBodyContent = new StringBuilder();
String line = null;
while ((line = bufferedReader.readLine()) != null) {
requestBodyContent.append(line);
}
paramStr = requestBodyContent.toString();
}
return paramStr;
}
/**
* 處理響應
* @param httpExchange
* @param responsetext
* @throws Exception
*/
private void handleResponse(HttpExchange httpExchange,String responsetext) throws Exception {
//生成html
StringBuilder responseContent = new StringBuilder();
responseContent.append("<html>")
.append("<body>")
.append(responsetext)
.append("</body>")
.append("</html>");
String responseContentStr = responseContent.toString();
byte[] responseContentByte = responseContentStr.getBytes("utf-8");
//設定響應頭，必須在sendResponseHeaders方法之前設定！
httpExchange.getResponseHeaders().add("Content-Type:","text/html;charset=utf-8");
//設定響應碼和響應體長度，必須在getResponseBody方法之前呼叫！
httpExchange.sendResponseHeaders(200,responseContentByte.length);
OutputStream out = httpExchange.getResponseBody();
out.write(responseContentByte);
out.flush();
out.close();
}
}
執行HttpServerStarter，在瀏覽器中訪問如下：
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