JAVA发送HTTP请求的四种方式总结

源代码：http://github.com/lovewenyo/HttpDemo

1. HttpURLConnection

使用JDK原生提供的net，无需其他jar包；

HttpURLConnection是URLConnection的子类，提供更多的方法，使用更方便。

package httpURLConnection;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

import java.net.HttpURLConnection;
import java.net.URL;

public class HttpURLConnectionHelper {

public static String sendRequest(String urlParam,String requestType) {

HttpURLConnection con = null;

BufferedReader buffer = null;
 StringBuffer resultBuffer = null;

try {
  URL url = new URL(urlParam);
  //得到连接对象
  con = (HttpURLConnection) url.openConnection();
  //设置请求类型
  con.setRequestMethod(requestType);
  //设置请求需要返回的数据类型和字符集类型
  con.setRequestProperty("Content-Type", "application/json;charset=GBK");
  //允许写出
  con.setDoOutput(true);
  //允许读入
  con.setDoInput(true);
  //不使用缓存
  con.setUseCaches(false);
  //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);
   }
   return resultBuffer.toString();
  }

}catch(Exception e) {
  e.printStackTrace();
 }
 return "";
}
public static void main(String[] args) {

String url ="http://int.dpool.sina.com.cn/iplookup/iplookup.php?ip=120.79.75.96";
 System.out.println(sendRequest(url,"POST"));
}
}

2. URLConnection

使用JDK原生提供的net，无需其他jar包；

建议使用HttpURLConnection

package uRLConnection;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class URLConnectionHelper {

public static String sendRequest(String urlParam) {

URLConnection con = null;

BufferedReader buffer = null;
 StringBuffer resultBuffer = null;

try {
   URL url = new URL(urlParam);
   con = url.openConnection();

//设置请求需要返回的数据类型和字符集类型
  con.setRequestProperty("Content-Type", "application/json;charset=GBK");
  //允许写出
  con.setDoOutput(true);
  //允许读入
  con.setDoInput(true);
  //不使用缓存
  con.setUseCaches(false);
  //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);
  }
  return resultBuffer.toString();

}catch(Exception e) {
  e.printStackTrace();
 }

return "";
}
public static void main(String[] args) {
 String url ="http://int.dpool.sina.com.cn/iplookup/iplookup.php?ip=120.79.75.96";
 System.out.println(sendRequest(url));
}
}

3. HttpClient

使用方便，我个人偏爱这种方式，但依赖于第三方jar包，相关maven依赖如下：

<!-- https://mvnrepository.com/artifact/commons-httpclient/commons-httpclient -->
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>3.1</version>
</dependency

package httpClient;

import java.io.IOException;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClientHelper {
public static String sendPost(String urlParam) throws HttpException, IOException {
 // 创建httpClient实例对象
 HttpClient httpClient = new HttpClient();
 // 设置httpClient连接主机服务器超时时间：15000毫秒
 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
 // 创建post请求方法实例对象
 PostMethod postMethod = new PostMethod(urlParam);
 // 设置post请求超时时间
 postMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);
 postMethod.addRequestHeader("Content-Type", "application/json");

httpClient.executeMethod(postMethod);

String result = postMethod.getResponseBodyAsString();
 postMethod.releaseConnection();
 return result;
}
public static String sendGet(String urlParam) throws HttpException, IOException {
 // 创建httpClient实例对象
 HttpClient httpClient = new HttpClient();
 // 设置httpClient连接主机服务器超时时间：15000毫秒
 httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
 // 创建GET请求方法实例对象
 GetMethod getMethod = new GetMethod(urlParam);
 // 设置post请求超时时间
 getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);
 getMethod.addRequestHeader("Content-Type", "application/json");

httpClient.executeMethod(getMethod);

String result = getMethod.getResponseBodyAsString();
 getMethod.releaseConnection();
 return result;
}
public static void main(String[] args) throws HttpException, IOException {
 String url ="http://int.dpool.sina.com.cn/iplookup/iplookup.php?ip=120.79.75.96";
 System.out.println(sendPost(url));
 System.out.println(sendGet(url));
}
}

4. Socket

使用JDK原生提供的net，无需其他jar包；

使用起来有点麻烦。

package socket;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.URLEncoder;

import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;

public class SocketForHttpTest {

private int port;
private String host;
private Socket socket;
private BufferedReader bufferedReader;
private BufferedWriter bufferedWriter;

public SocketForHttpTest(String host,int port) throws Exception{

this.host = host;
 this.port = port;

/**
  * http协议
  */
 // socket = new Socket(this.host, this.port);

/**
  * https协议
  */
 socket = (SSLSocket)((SSLSocketFactory)SSLSocketFactory.getDefault()).createSocket(this.host, this.port);

}

public void sendGet() throws IOException{
 //String requestUrlPath = "/z69183787/article/details/17580325";
 String requestUrlPath = "/";  

OutputStreamWriter streamWriter = new OutputStreamWriter(socket.getOutputStream());
 bufferedWriter = new BufferedWriter(streamWriter);    
 bufferedWriter.write("GET " + requestUrlPath + " HTTP/1.1\r\n");
 bufferedWriter.write("Host: " + this.host + "\r\n");
 bufferedWriter.write("\r\n");
 bufferedWriter.flush();

BufferedInputStream streamReader = new BufferedInputStream(socket.getInputStream());
 bufferedReader = new BufferedReader(new InputStreamReader(streamReader, "utf-8"));
 String line = null;
 while((line = bufferedReader.readLine())!= null){
  System.out.println(line);
 }
 bufferedReader.close();
 bufferedWriter.close();
 socket.close();

}

public void sendPost() throws IOException{
  String path = "/";
  String data = URLEncoder.encode("name", "utf-8") + "=" + URLEncoder.encode("张三", "utf-8") + "&" +
     URLEncoder.encode("age", "utf-8") + "=" + URLEncoder.encode("32", "utf-8");
  // String data = "name=zhigang_jia";
  System.out.println(">>>>>>>>>>>>>>>>>>>>>"+data);    
  OutputStreamWriter streamWriter = new OutputStreamWriter(socket.getOutputStream(), "utf-8");
  bufferedWriter = new BufferedWriter(streamWriter);    
  bufferedWriter.write("POST " + path + " HTTP/1.1\r\n");
  bufferedWriter.write("Host: " + this.host + "\r\n");
  bufferedWriter.write("Content-Length: " + data.length() + "\r\n");
  bufferedWriter.write("Content-Type: application/x-www-form-urlencoded\r\n");
  bufferedWriter.write("\r\n");
  bufferedWriter.write(data);

bufferedWriter.write("\r\n");
  bufferedWriter.flush();

BufferedInputStream streamReader = new BufferedInputStream(socket.getInputStream());
  bufferedReader = new BufferedReader(new InputStreamReader(streamReader, "utf-8"));
  String line = null;
  while((line = bufferedReader.readLine())!= null)
  {
   System.out.println(line);
  }
  bufferedReader.close();
  bufferedWriter.close();
  socket.close();
}

public static void main(String[] args) throws Exception {
 /**
  * http协议测试
  */
 //SocketForHttpTest forHttpTest = new SocketForHttpTest("www.baidu.com", 80);
 /**
  * https协议测试
  */
 SocketForHttpTest forHttpTest = new SocketForHttpTest("www.baidu.com", 443);
 try {
  forHttpTest.sendGet();
 // forHttpTest.sendPost();
 } catch (IOException e) {

e.printStackTrace();
 }
}

}

总结

来源：https://blog.csdn.net/longshehe9319/article/details/80509829