JAVA发送HTTP请求的多种方式总结

        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));
}