JAVA发送HTTP请求的多种方式详细总结

程序员日常工作中，发送http请求特别常见。本文以Java为例，总结发送http请求的多种方式。

1. HttpURLConnection

使用JDK原生提供的net，无需其他jar包，代码如下：

import com.alibaba.fastjson.JSON;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

public class HttpTest1 {

public static void main(String[] args) {
       HttpURLConnection con = null;

BufferedReader buffer = null;
       StringBuffer resultBuffer = null;

try {
           URL url = new URL("http://10.30.10.151:8012/gateway.do");
           //得到连接对象
           con = (HttpURLConnection) url.openConnection();
           //设置请求类型
           con.setRequestMethod("POST");
           //设置Content-Type，此处根据实际情况确定
           con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
           //允许写出
           con.setDoOutput(true);
           //允许读入
           con.setDoInput(true);
           //不使用缓存
           con.setUseCaches(false);
           OutputStream os = con.getOutputStream();
           Map paraMap = new HashMap();
           paraMap.put("type", "wx");
           paraMap.put("mchid", "10101");
           //组装入参
           os.write(("consumerAppId=test&serviceName=queryMerchantService&params=" + JSON.toJSONString(paraMap)).getBytes());
           //得到响应码
           int responseCode = con.getResponseCode();
           if (responseCode == HttpURLConnection.HTTP_OK) {
               //得到响应流
               InputStream inputStream = con.getInputStream();
               //将响应流转换成字符串
               resultBuffer = new StringBuffer();
               String line;
               buffer = new BufferedReader(new InputStreamReader(inputStream, "GBK"));
               while ((line = buffer.readLine()) != null) {
                   resultBuffer.append(line);
               }
               System.out.println("result:" + resultBuffer.toString());
           }
       } catch (Exception e) {
           e.printStackTrace();
       }
   }
}

2. HttpClient

需要用到commons-httpclient-3.1.jar，maven依赖如下：

<dependency>
   <groupId>commons-httpclient</groupId>
   <artifactId>commons-httpclient</artifactId>
   <version>3.1</version>
</dependency>

代码如下：

import com.alibaba.fastjson.JSON;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.PostMethod;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class HttpTest2 {

public static void main(String[] args) {
       HttpClient httpClient = new HttpClient();
       PostMethod postMethod = new PostMethod("http://10.30.10.151:8012/gateway.do");

postMethod.addRequestHeader("accept", "*/*");
       //设置Content-Type，此处根据实际情况确定
       postMethod.addRequestHeader("Content-Type", "application/x-www-form-urlencoded");
       //必须设置下面这个Header
       //添加请求参数
       Map paraMap = new HashMap();
       paraMap.put("type", "wx");
       paraMap.put("mchid", "10101");
       postMethod.addParameter("consumerAppId", "test");
       postMethod.addParameter("serviceName", "queryMerchantService");
       postMethod.addParameter("params", JSON.toJSONString(paraMap));
       String result = "";
       try {
           int code = httpClient.executeMethod(postMethod);
           if (code == 200){
               result = postMethod.getResponseBodyAsString();
               System.out.println("result:" + result);
           }
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
}

3. CloseableHttpClient

需要用到httpclient-4.5.6.jar，maven依赖如下： 

<dependency>
   <groupId>org.apache.httpcomponents</groupId>
   <artifactId>httpclient</artifactId>
   <version>4.5.6</version>
</dependency>

代码如下：

import com.alibaba.fastjson.JSON;
import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
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.HashMap;
import java.util.List;
import java.util.Map;

public class HttpTest3 {

public static void main(String[] args) {
       int timeout = 120000;
       CloseableHttpClient httpClient = HttpClients.createDefault();
       RequestConfig defaultRequestConfig = RequestConfig.custom().setConnectTimeout(timeout)
               .setConnectionRequestTimeout(timeout).setSocketTimeout(timeout).build();
       HttpPost httpPost = null;
       List<NameValuePair> nvps = null;
       CloseableHttpResponse responses = null;// 命名冲突，换一个名字，response
       HttpEntity resEntity = null;
       String result;
       try {
           httpPost = new HttpPost("http://10.30.10.151:8012/gateway.do");
           httpPost.setConfig(defaultRequestConfig);

Map paraMap = new HashMap();
           paraMap.put("type", "wx");
           paraMap.put("mchid", "10101");
           nvps = new ArrayList<NameValuePair>();
           nvps.add(new BasicNameValuePair("consumerAppId", "test"));
           nvps.add(new BasicNameValuePair("serviceName", "queryMerchantService"));
           nvps.add(new BasicNameValuePair("params", JSON.toJSONString(paraMap)));
           httpPost.setEntity(new UrlEncodedFormEntity(nvps, Consts.UTF_8));

responses = httpClient.execute(httpPost);
           resEntity = responses.getEntity();
           result = EntityUtils.toString(resEntity, Consts.UTF_8);
           EntityUtils.consume(resEntity);
           System.out.println("result:" + result);
       } catch (Exception e) {
           e.printStackTrace();
       } finally {
           try {
               responses.close();
               httpClient.close();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   }
}

4. okhttp

需要用到okhttp-3.10.0.jar，maven依赖如下：

<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
<version>3.10.0</version>
</dependency>

代码如下：

import com.alibaba.fastjson.JSON;
import okhttp3.*;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class HttpTest4 {

public static void main(String[] args) throws IOException {
       String url = "http://10.30.10.151:8012/gateway.do";
       OkHttpClient client = new OkHttpClient();
       Map paraMap = new HashMap();
       paraMap.put("yybh", "1231231");

RequestBody requestBody = new MultipartBody.Builder()
               .addFormDataPart("consumerAppId", "tst")
               .addFormDataPart("serviceName", "queryCipher")
               .addFormDataPart("params", JSON.toJSONString(paraMap))
               .build();

Request request = new Request.Builder()
               .url(url)
               .post(requestBody)
               .addHeader("Content-Type", "application/x-www-form-urlencoded")
               .build();
       Response response = client
               .newCall(request)
               .execute();
       if (response.isSuccessful()) {
           System.out.println("result:" + response.body().string());
       } else {
           throw new IOException("Unexpected code " + response);
       }
   }
}

5. Socket

使用JDK原生提供的net，无需其他jar包

此处参考：https://www.cnblogs.com/hehongtao/p/5276425.html

代码如下：

import com.alibaba.fastjson.JSON;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.URLEncoder;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class HttpTest6 {

private static String encoding = "utf-8";

public static void main(String[] args) {
       try {
           Map paraMap = new HashMap();
           paraMap.put("yybh", "12312311");
           String data = URLEncoder.encode("consumerAppId", "utf-8") + "=" + URLEncoder.encode("test", "utf-8") + "&" +
                   URLEncoder.encode("serviceName", "utf-8") + "=" + URLEncoder.encode("queryCipher", "utf-8")
                   + "&" +
                   URLEncoder.encode("params", "utf-8") + "=" + URLEncoder.encode(JSON.toJSONString(paraMap), "utf-8");
           Socket s = new Socket("10.30.10.151", 8012);
           OutputStreamWriter osw = new OutputStreamWriter(s.getOutputStream());
           StringBuffer sb = new StringBuffer();
           sb.append("POST /gateway.do HTTP/1.1\r\n");
           sb.append("Host: 10.30.10.151:8012\r\n");
           sb.append("Content-Length: " + data.length() + "\r\n");
           sb.append("Content-Type: application/x-www-form-urlencoded\r\n");
           //注，这里很关键。这里一定要一个回车换行，表示消息头完，不然服务器会等待
           sb.append("\r\n");
           osw.write(sb.toString());
           osw.write(data);
           osw.write("\r\n");
           osw.flush();

//--输出服务器传回的消息的头信息
           InputStream is = s.getInputStream();
           String line = null;
           int contentLength = 0;//服务器发送回来的消息长度
           // 读取所有服务器发送过来的请求参数头部信息
           do {
               line = readLine(is, 0);
               //如果有Content-Length消息头时取出
               if (line.startsWith("Content-Length")) {
                   contentLength = Integer.parseInt(line.split(":")[1].trim());
               }
               //打印请求部信息
               System.out.print(line);
               //如果遇到了一个单独的回车换行，则表示请求头结束
           } while (!line.equals("\r\n"));

//--输消息的体
           System.out.print(readLine(is, contentLength));

//关闭流
           is.close();

} catch (UnknownHostException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }

/*
    * 这里我们自己模拟读取一行，因为如果使用API中的BufferedReader时，它是读取到一个回车换行后
    * 才返回，否则如果没有读取，则一直阻塞，直接服务器超时自动关闭为止，如果此时还使用BufferedReader
    * 来读时，因为读到最后一行时，最后一行后不会有回车换行符，所以就会等待。如果使用服务器发送回来的
    * 消息头里的Content-Length来截取消息体，这样就不会阻塞
    *
    * contentLe 参数 如果为0时，表示读头，读时我们还是一行一行的返回；如果不为0，表示读消息体，
    * 时我们根据消息体的长度来读完消息体后，客户端自动关闭流，这样不用先到服务器超时来关闭。
    */
   private static String readLine(InputStream is, int contentLe) throws IOException {
       ArrayList lineByteList = new ArrayList();
       byte readByte;
       int total = 0;
       if (contentLe != 0) {
           do {
               readByte = (byte) is.read();
               lineByteList.add(Byte.valueOf(readByte));
               total++;
           } while (total < contentLe);//消息体读还未读完
       } else {
           do {
               readByte = (byte) is.read();
               lineByteList.add(Byte.valueOf(readByte));
           } while (readByte != 10);
       }

byte[] tmpByteArr = new byte[lineByteList.size()];
       for (int i = 0; i < lineByteList.size(); i++) {
           tmpByteArr[i] = ((Byte) lineByteList.get(i)).byteValue();
       }
       lineByteList.clear();

return new String(tmpByteArr, encoding);
   }
}

6. RestTemplate

RestTemplate 是由Spring提供的一个HTTP请求工具。比传统的Apache和HttpCLient便捷许多，能够大大提高客户端的编写效率。代码如下：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

@Configuration
public class RestTemplateConfig {

@Bean
   public RestTemplate restTemplate(ClientHttpRequestFactory factory){
       return new RestTemplate(factory);
   }

@Bean
   public ClientHttpRequestFactory simpleClientHttpRequestFactory(){
       SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
       factory.setConnectTimeout(15000);
       factory.setReadTimeout(5000);
       return factory;
   }
}

@Autowired
RestTemplate restTemplate;

@Test
public void postTest() throws Exception {
   MultiValueMap<String, String> requestEntity = new LinkedMultiValueMap<>();
   Map paraMap = new HashMap();
   paraMap.put("type", "wx");
   paraMap.put("mchid", "10101");
   requestEntity.add("consumerAppId", "test");
   requestEntity.add("serviceName", "queryMerchant");
   requestEntity.add("params", JSON.toJSONString(paraMap));
   RestTemplate restTemplate = new RestTemplate();
   System.out.println(restTemplate.postForObject("http://10.30.10.151:8012/gateway.do",         requestEntity, String.class));
}

来源：https://blog.csdn.net/liuyunyihao/article/details/125262877