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¶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. HttpClient
需要用到commons-httpclient-3.1.jar，maven依赖如下：
commons-httpclient commons-httpclient 3.1
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：
org.apache.httpcomponents httpclient 4.5.6
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 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();
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：
com.squareup.okhttp3 okhttp 3.10.0
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 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));
}
总结
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