Apache HttpClient - 关闭连接
如果您手动处理 HTTP 响应而不是使用响应处理器，则需要自行关闭所有 http 连接。本章说明如何手动关闭连接。
手动关闭 HTTP 连接时，请按照以下步骤操作：
步骤 1 - 创建 HttpClient 对象
HttpClients 类的 createDefault() 方法返回 CloseableHttpClient 类的对象，它是 HttpClient 接口的基本实现。
使用此方法，创建 HttpClient 对象，如下所示：
CloseableHttpClient httpClient = HttpClients.createDefault();
步骤 2 - 启动 try-finally 块
启动 try-finally 块，在 try 块中编写程序中的其余代码，并在 finally 块中关闭 CloseableHttpClient 对象。
CloseableHttpClient httpClient = HttpClients.createDefault();
try{
//Remaining code . . . . . . . . . . . . . . .
}finally{
httpClient.close();
}
步骤 3 - 创建 HttpGetobject
HttpGet 类表示 HTTP GET 请求，它使用 URI 检索给定服务器的信息。
通过实例化 HttpGet 类并传递表示 URI 的字符串来创建 HTTP GET 请求。
HttpGet httpGet = new HttpGet("https://tutorialspoint.com/");
步骤 4 - 执行 Get 请求
CloseableHttpClient 对象的 execute() 方法接受 HttpUriRequest（接口）对象（即 HttpGet、HttpPost、HttpPut、HttpHead 等）并返回响应对象。
使用给定方法执行请求：
HttpResponse httpResponse = httpclient.execute(httpGet);
步骤 5 - 启动另一个（嵌套）try-finally
启动另一个 try-finally 块（嵌套在之前的 try-finally 中），在程序的此 try 块中编写其余代码，并在 finally 块中关闭 HttpResponse 对象。
CloseableHttpClient httpclient = HttpClients.createDefault();
try{
. . . . . . .
. . . . . . .
CloseableHttpResponse httpresponse = httpclient.execute(httpget);
try{
. . . . . . .
. . . . . . .
}finally{
httpresponse.close();
}
}finally{
httpclient.close();
}
示例
每当您创建/获取请求、响应流等对象时，在下一行启动 try finally 块，在 try 中编写其余代码，并在 finally 块中关闭相应的对象，如下面的程序所示：
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.com/");
//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();
}
}
}
输出
执行上述程序后，将生成以下输出：
<!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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