java發送http請求的兩種方式：HTTPClient和CloseableHttpClient

下面分別介紹使用HTTPClient和CloseableHTTPClient進行Get和Post請求的方式。

HttpClient

使用commons-httpclient.jar，maven依賴以下：

<dependency>
      <groupId>commons-httpclient</groupId>
      <artifactId>commons-httpclient</artifactId>
      <version>3.1</version>
    </dependency>
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java示例代碼以下：

package com.example.study.demo.http;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;

import java.io.IOException;

/** * HttpClient使用示例 * jar包：commons-httpclient.jar */
public class HttpClientTest {
  private static void doGet() {
    HttpClient client = new HttpClient();
    GetMethod getMethod = new GetMethod("https://www.thepaper.cn/");
    int code = 0;
    try {
      code = client.executeMethod(getMethod);
      if (code == 200) {
        String res = getMethod.getResponseBodyAsString();
        System.out.println(res);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  private static void doPost() {
    String praiseUrl = "https://www.thepaper.cn/www/commentPraise.msp"; // 澎湃新聞評論點贊url
    HttpClient client = new HttpClient();
    PostMethod postMethod = new PostMethod(praiseUrl);
    // 必須設置下面這個Header
    postMethod.addRequestHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
    postMethod.addParameter("commentId", "18718372"); // 評論的id，抓包得到
    try {
      int code = client.executeMethod(postMethod);
      if (code == 200) {
        String res = postMethod.getResponseBodyAsString();
        System.out.println(res);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public static void main(String[] args) {
    doGet();
    System.out.println("-----------分割線------------");
    System.out.println("-----------分割線------------");
    System.out.println("-----------分割線------------");
    doPost();
  }
}

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CloseableHttpClient

使用httpclient.jar，maven依賴以下：

<dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.2</version>
    </dependency>
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java示例代碼以下：

package com.example.study.demo.http;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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.HttpClientBuilder;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

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

/** * CloseableHttpClient使用示例 * jar包：httpclient.jar */
public class CloseableHttpClientTest {

  public static void doGet() {
    CloseableHttpClient client = HttpClientBuilder.create().build();
    HttpGet get = new HttpGet("http://www.thepaper.cn");
    try {
      // 很奇怪，使用CloseableHttpClient來請求澎湃新聞的首頁，GTE請求也必須加上下面這個Header，可是使用HTTPClient則不須要
      get.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
      HttpResponse response = client.execute(get);
      String res = EntityUtils.toString(response.getEntity());
      System.out.println(res);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public static void doPost() {
    CloseableHttpClient client = HttpClientBuilder.create().build();
    HttpPost post = new HttpPost("https://www.thepaper.cn/www/commentPraise.msp");
    try {
      post.addHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
      List<NameValuePair> params = new ArrayList<>();
      params.add(new BasicNameValuePair("commentId", "18718372"));
      post.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
      HttpResponse response = client.execute(post);
      String res = EntityUtils.toString(response.getEntity());
      System.out.println(res);
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }


  public static void main(String[] args) {
    doGet();
    System.out.println("-----------分割線------------");
    System.out.println("-----------分割線------------");
    System.out.println("-----------分割線------------");
    doPost();

  }
}

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