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Как отправить HTTP-запрос GET/POST на Java

– Как отправить HTTP-запрос GET/POST на Java

В этой статье мы покажем вам несколько примеров выполнения HTTP-запросов GET/POST с помощью следующих API

  • HttpClient для Apache 4.5.10
  • ОХТТП 4.2.2
  • Java 11 HttpClient
  • Java 1.1 HttpURLConnection (Не рекомендуется)

1. HttpClient для Apache

В старые времена этот Apache HttpClient был стандартом де-факто для отправки HTTP-запроса GET/POST на Java.

	
		org.apache.httpcomponents
		httpclient
		4.5.10
	

package com.mkyong.http;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHeaders;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class HttpClientExample {

    // one instance, reuse
    private final CloseableHttpClient httpClient = HttpClients.createDefault();

    public static void main(String[] args) throws Exception {

        HttpClientExample obj = new HttpClientExample();

        try {
            System.out.println("Testing 1 - Send Http GET request");
            obj.sendGet();

            System.out.println("Testing 2 - Send Http POST request");
            obj.sendPost();
        } finally {
            obj.close();
        }
    }

    private void close() throws IOException {
        httpClient.close();
    }

    private void sendGet() throws Exception {

        HttpGet request = new HttpGet("https://www.google.com/search?q=mkyong");

        // add request headers
        request.addHeader("custom-key", "mkyong");
        request.addHeader(HttpHeaders.USER_AGENT, "Googlebot");

        try (CloseableHttpResponse response = httpClient.execute(request)) {

            // Get HttpResponse Status
            System.out.println(response.getStatusLine().toString());

            HttpEntity entity = response.getEntity();
            Header headers = entity.getContentType();
            System.out.println(headers);

            if (entity != null) {
                // return it as a String
                String result = EntityUtils.toString(entity);
                System.out.println(result);
            }

        }

    }

    private void sendPost() throws Exception {

        HttpPost post = new HttpPost("https://httpbin.org/post");

        // add request parameter, form parameters
        List urlParameters = new ArrayList<>();
        urlParameters.add(new BasicNameValuePair("username", "abc"));
        urlParameters.add(new BasicNameValuePair("password", "123"));
        urlParameters.add(new BasicNameValuePair("custom", "secret"));

        post.setEntity(new UrlEncodedFormEntity(urlParameters));

        try (CloseableHttpClient httpClient = HttpClients.createDefault();
             CloseableHttpResponse response = httpClient.execute(post)) {

            System.out.println(EntityUtils.toString(response.getEntity()));
        }

    }

}

2. ОХТТП

Этот OkHttp очень популярен на Android и широко используется во многих веб-проектах восходящей звезды.

	
		com.squareup.okhttp3
		okhttp
		4.2.2
	

package com.mkyong.http;

import okhttp3.*;

import java.io.IOException;

public class OkHttpExample {

    // one instance, reuse
    private final OkHttpClient httpClient = new OkHttpClient();

    public static void main(String[] args) throws Exception {

        OkHttpExample obj = new OkHttpExample();

        System.out.println("Testing 1 - Send Http GET request");
        obj.sendGet();

        System.out.println("Testing 2 - Send Http POST request");
        obj.sendPost();

    }

    private void sendGet() throws Exception {

        Request request = new Request.Builder()
                .url("https://www.google.com/search?q=mkyong")
                .addHeader("custom-key", "mkyong")  // add request headers
                .addHeader("User-Agent", "OkHttp Bot")
                .build();

        try (Response response = httpClient.newCall(request).execute()) {

            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

            // Get response body
            System.out.println(response.body().string());
        }

    }

    private void sendPost() throws Exception {

        // form parameters
        RequestBody formBody = new FormBody.Builder()
                .add("username", "abc")
                .add("password", "123")
                .add("custom", "secret")
                .build();

        Request request = new Request.Builder()
                .url("https://httpbin.org/post")
                .addHeader("User-Agent", "OkHttp Bot")
                .post(formBody)
                .build();

        try (Response response = httpClient.newCall(request).execute()) {

            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

            // Get response body
            System.out.println(response.body().string());
        }

    }

}

3. Java 11 HttpКлиент

В Java 11 новый HttpClient представлен в пакете java.net.http. *

SendAsync() вернет CompletableFuture , это делает параллельные запросы намного проще и гибче, больше никаких внешних библиотек для отправки HTTP-запроса!

package com.mkyong.http;

import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

public class Java11HttpClientExample {

    // one instance, reuse
    private final HttpClient httpClient = HttpClient.newBuilder()
            .version(HttpClient.Version.HTTP_2)
            .build();

    public static void main(String[] args) throws Exception {

        Java11HttpClientExample obj = new Java11HttpClientExample();

        System.out.println("Testing 1 - Send Http GET request");
        obj.sendGet();

        System.out.println("Testing 2 - Send Http POST request");
        obj.sendPost();

    }

    private void sendGet() throws Exception {

        HttpRequest request = HttpRequest.newBuilder()
                .GET()
                .uri(URI.create("https://httpbin.org/get"))
                .setHeader("User-Agent", "Java 11 HttpClient Bot")
                .build();

        HttpResponse response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

        // print status code
        System.out.println(response.statusCode());

        // print response body
        System.out.println(response.body());

    }

    private void sendPost() throws Exception {

        // form parameters
        Map data = new HashMap<>();
        data.put("username", "abc");
        data.put("password", "123");
        data.put("custom", "secret");
        data.put("ts", System.currentTimeMillis());

        HttpRequest request = HttpRequest.newBuilder()
                .POST(buildFormDataFromMap(data))
                .uri(URI.create("https://httpbin.org/post"))
                .setHeader("User-Agent", "Java 11 HttpClient Bot") // add request header
                .header("Content-Type", "application/x-www-form-urlencoded")
                .build();

        HttpResponse response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

        // print status code
        System.out.println(response.statusCode());

        // print response body
        System.out.println(response.body());

    }

    private static HttpRequest.BodyPublisher buildFormDataFromMap(Map data) {
        var builder = new StringBuilder();
        for (Map.Entry entry : data.entrySet()) {
            if (builder.length() > 0) {
                builder.append("&");
            }
            builder.append(URLEncoder.encode(entry.getKey().toString(), StandardCharsets.UTF_8));
            builder.append("=");
            builder.append(URLEncoder.encode(entry.getValue().toString(), StandardCharsets.UTF_8));
        }
        System.out.println(builder.toString());
        return HttpRequest.BodyPublishers.ofString(builder.toString());
    }

}

4. Соединение HttpURLConnection

Это HttpURLConnection класс доступен с Java 1.1, использует это, если вы осмелитесь 🙂 Как правило, не рекомендуется использовать этот класс, потому что кодовая база очень старая и устаревшая, она может не поддерживать новый стандарт HTTP/2, на самом деле, очень сложно настроить и использовать этот класс.

Приведенный ниже пример приведен только для справки, НЕ рекомендую использовать этот класс!

package com.mkyong.http;

import javax.net.ssl.HttpsURLConnection;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpURLConnectionExample {

    public static void main(String[] args) throws Exception {

        HttpURLConnectionExample obj = new HttpURLConnectionExample();

        System.out.println("Testing 1 - Send Http GET request");
        obj.sendGet();

        System.out.println("Testing 2 - Send Http POST request");
        obj.sendPost();

    }

    private void sendGet() throws Exception {

        String url = "https://www.google.com/search?q=mkyong";

        HttpURLConnection httpClient =
                (HttpURLConnection) new URL(url).openConnection();

        // optional default is GET
        httpClient.setRequestMethod("GET");

        //add request header
        httpClient.setRequestProperty("User-Agent", "Mozilla/5.0");

        int responseCode = httpClient.getResponseCode();
        System.out.println("\nSending 'GET' request to URL : " + url);
        System.out.println("Response Code : " + responseCode);

        try (BufferedReader in = new BufferedReader(
                new InputStreamReader(httpClient.getInputStream()))) {

            StringBuilder response = new StringBuilder();
            String line;

            while ((line = in.readLine()) != null) {
                response.append(line);
            }

            //print result
            System.out.println(response.toString());

        }

    }

    private void sendPost() throws Exception {

		// url is missing?
        //String url = "https://selfsolve.apple.com/wcResults.do";
        String url = "https://httpbin.org/post";

        HttpsURLConnection httpClient = (HttpsURLConnection) new URL(url).openConnection();

        //add reuqest header
        httpClient.setRequestMethod("POST");
        httpClient.setRequestProperty("User-Agent", "Mozilla/5.0");
        httpClient.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

        String urlParameters = "sn=C02G8416DRJM&cn=&locale=&caller=&num=12345";

        // Send post request
        httpClient.setDoOutput(true);
        try (DataOutputStream wr = new DataOutputStream(httpClient.getOutputStream())) {
            wr.writeBytes(urlParameters);
            wr.flush();
        }

        int responseCode = httpClient.getResponseCode();
        System.out.println("\nSending 'POST' request to URL : " + url);
        System.out.println("Post parameters : " + urlParameters);
        System.out.println("Response Code : " + responseCode);

        try (BufferedReader in = new BufferedReader(
                new InputStreamReader(httpClient.getInputStream()))) {

            String line;
            StringBuilder response = new StringBuilder();

            while ((line = in.readLine()) != null) {
                response.append(line);
            }

            //print result
            System.out.println(response.toString());

        }

    }

}

Рекомендации

Оригинал: “https://mkyong.com/java/how-to-send-http-request-getpost-in-java/”

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