Apache HttpClient - 關閉連線
如果您手動處理 HTTP 響應而不是使用響應處理器，則需要自行關閉所有 http 連線。本章說明如何手動關閉連線。
手動關閉 HTTP 連線時，請按照以下步驟操作：
步驟 1 - 建立 HttpClient 物件
HttpClients 類的 createDefault() 方法返回 CloseableHttpClient 類的物件，它是 HttpClient 介面的基本實現。
使用此方法，建立 HttpClient 物件，如下所示：
CloseableHttpClient httpClient = HttpClients.createDefault();
步驟 2 - 啟動 try-finally 塊
啟動 try-finally 塊，在 try 塊中編寫程式中的其餘程式碼，並在 finally 塊中關閉 CloseableHttpClient 物件。
CloseableHttpClient httpClient = HttpClients.createDefault();
try{
//Remaining code . . . . . . . . . . . . . . .
}finally{
httpClient.close();
}
步驟 3 - 建立 HttpGetobject
HttpGet 類表示 HTTP GET 請求，它使用 URI 檢索給定伺服器的資訊。
透過例項化 HttpGet 類並傳遞表示 URI 的字串來建立 HTTP GET 請求。
HttpGet httpGet = new HttpGet("https://tutorialspoint.tw/");
步驟 4 - 執行 Get 請求
CloseableHttpClient 物件的 execute() 方法接受 HttpUriRequest（介面）物件（即 HttpGet、HttpPost、HttpPut、HttpHead 等）並返回響應物件。
使用給定方法執行請求：
HttpResponse httpResponse = httpclient.execute(httpGet);
步驟 5 - 啟動另一個（巢狀）try-finally
啟動另一個 try-finally 塊（巢狀在之前的 try-finally 中），在程式的此 try 塊中編寫其餘程式碼，並在 finally 塊中關閉 HttpResponse 物件。
CloseableHttpClient httpclient = HttpClients.createDefault();
try{
. . . . . . .
. . . . . . .
CloseableHttpResponse httpresponse = httpclient.execute(httpget);
try{
. . . . . . .
. . . . . . .
}finally{
httpresponse.close();
}
}finally{
httpclient.close();
}
示例
每當您建立/獲取請求、響應流等物件時，在下一行啟動 try finally 塊，在 try 中編寫其餘程式碼，並在 finally 塊中關閉相應的物件，如下面的程式所示：
import java.util.Scanner;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
public class CloseConnectionExample {
public static void main(String args[])throws Exception{
//Create an HttpClient object
CloseableHttpClient httpclient = HttpClients.createDefault();
try{
//Create an HttpGet object
HttpGet httpget = new HttpGet("https://tutorialspoint.tw/");
//Execute the Get request
CloseableHttpResponse httpresponse = httpclient.execute(httpget);
try{
Scanner sc = new Scanner(httpresponse.getEntity().getContent());
while(sc.hasNext()) {
System.out.println(sc.nextLine());
}
}finally{
httpresponse.close();
}
}finally{
httpclient.close();
}
}
}
輸出
執行上述程式後，將生成以下輸出：
<!DOCTYPE html>
<!--[if IE 8]><html class = "ie ie8"> <![endif]-->
<!--[if IE 9]><html class = "ie ie9"> <![endif]-->
<!--[if gt IE 9]><!-->
<html lang = "en-US"> <!--<![endif]-->
<head>
<!-- Basic -->
<meta charset = "utf-8">
<meta http-equiv = "X-UA-Compatible" content = "IE = edge">
<meta name = "viewport" content = "width = device-width,initial-scale = 1.0,userscalable = yes">
<link href = "https://cdn.muicss.com/mui-0.9.39/extra/mui-rem.min.css"
rel = "stylesheet" type = "text/css" />
<link rel = "stylesheet" href = "/questions/css/home.css?v = 3" />
<script src = "/questions/js/jquery.min.js"></script>
<script src = "/questions/js/fontawesome.js"></script>
<script src = "https://cdn.muicss.com/mui-0.9.39/js/mui.min.js"></script>
</head>
. . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
<script>
window.dataLayer = window.dataLayer || [];
function gtag() {dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'UA-232293-17');
</script>
</body>
</html>
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