java发送http请求的几种方式

参考：
https://www.jb51.net/article/206762.htm JAVA发送HTTP请求的四种方式总结（主要是原生+依赖）
https://zhuanlan.zhihu.com/p/364017444 httpclient
https://blog.csdn.net/itguangit/article/details/78825505 resttemplate
http://forest.dtflyx.com/ forest官网
https://okhttps.ejlchina.com/ okhttp
https://blog.csdn.net/qq_25310669/article/details/120654788

1、java原生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¶ms=" + 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、独立jar包半原生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>

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>

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、独立jar包半原生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>

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、spring体系自带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。

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));
}

6.1 RestTemplate 用法详解

https://blog.csdn.net/weixin_38987366/article/details/109701339

6.2 RestTemplate调用IP或域名

https://blog.csdn.net/u011974797/article/details/90019533
在SpringCloud的项目中，我们使用了自动配置的OAuth2RestTemplate,RestTemplate,但是在使用这些restTemplate的时候,url必须是服务的名称,如果要调用真实的域名或者ip的url,会有错误，如下：

java.lang.IllegalStateException: No instances available for localhost

@Configuration
public class MyConfig {
 @Bean(name="loadBalanced")
 @LoadBalanced
 RestTemplate loadBalanced() {
  return new RestTemplate();
 }
 
 @Bean(name="restTemplate")
 RestTemplate restTemplate() {
  return new RestTemplate();
 }
}

调用

@RestController
public class WebController {
 @Autowired
 @Qualifier("loadBalanced")
 private RestTemplate loadBalanced;
 
 @Autowired
 @Qualifier("restTemplate")
 private RestTemplate restTemplate;
 
 @RequestMapping("/api/loadBalanced")
 public String loadBalanced() {
  loadBalanced.getForObject("http://service-hi/test", String.class);
  return "success";
 }
 
 @RequestMapping("/api/restTemplate")
 public String restTemplate() {
  restTemplate.getForObject("http://127.0.0.1:8082/test", String.class);
  return "success";
 }
}

7、HttpUtil hutu工具包封装的此模块基于JDK的HttpUrlConnection封装完成

7.1 get请求

// 最简单的HTTP请求，可以自动通过header等信息判断编码，不区分HTTP和HTTPS
String result1= HttpUtil.get("https://www.baidu.com");

// 当无法识别页面编码的时候，可以自定义请求页面的编码
String result2= HttpUtil.get("https://www.baidu.com", CharsetUtil.CHARSET_UTF_8);

//可以单独传入http参数，这样参数会自动做URL编码，拼接在URL中
HashMap<String, Object> paramMap = new HashMap<>();
paramMap.put("city", "北京");

String result3= HttpUtil.get("https://www.baidu.com", paramMap);

post请求

HashMap<String, Object> paramMap = new HashMap<>();
paramMap.put("city", "北京");

String result= HttpUtil.post("https://www.baidu.com", paramMap);

文件上传

HashMap<String, Object> paramMap = new HashMap<>();
//文件上传只需将参数中的键指定（默认file），值设为文件对象即可，对于使用者来说，文件上传与普通表单提交并无区别
paramMap.put("file", FileUtil.file("D:\\face.jpg"));

String result= HttpUtil.post("https://www.baidu.com", paramMap);

下载文件

因为Hutool-http机制问题，请求页面返回结果是一次性解析为byte[]的，如果请求URL返回结果太大（比如文件下载），那内存会爆掉，因此针对文件下载HttpUtil单独做了封装。文件下载在面对大文件时采用流的方式读写，内存中只是保留一定量的缓存，然后分块写入硬盘，因此大文件情况下不会对内存有压力。

String fileUrl = "http://mirrors.sohu.com/centos/8.4.2105/isos/x86_64/CentOS-8.4.2105-x86_64-dvd1.iso";

//将文件下载后保存在E盘，返回结果为下载文件大小
long size = HttpUtil.downloadFile(fileUrl, FileUtil.file("e:/"));
System.out.println("Download size: " + size);

当然，如果我们想感知下载进度，还可以使用另一个重载方法回调感知下载进度：

//带进度显示的文件下载
HttpUtil.downloadFile(fileUrl, FileUtil.file("e:/"), new StreamProgress(){
    
    @Override
    public void start() {
        Console.log("开始下载。。。。");
    }
    
    @Override
    public void progress(long progressSize) {
        Console.log("已下载：{}", FileUtil.readableFileSize(progressSize));
    }
    
    @Override
    public void finish() {
        Console.log("下载完成！");
    }
});

8、独立jar包高度封装forest

这里指的是forest，官网地址，只需要声明接口，就可以使用。具体的使用方式看官网，案例十分详细。

public interface MyClient {

    @Request(url = "http://localhost:8080/hello")
    String helloForest();

}