目前JAVA实现HTTP请求的方法最常用的有两种：
-
通过HttpURLConnection去实现，HttpURLConnection是JAVA的标准类，是JAVA比较原生的一种实现方式。
-
通过HTTPClient这种第三方的开源框架去实现。HTTPClient对HTTP的封装性比较不错，通过它基本上能够满足我们大部分的需求。
近期工作中刚好有使用到，在这里整理分享给大家，也方便自己以后查阅，代码如下。
第一种方式：java原生HttpURLConnection
package net;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
/**
* java原生HttpURLConnection
**/
public class HttpConnect {
public static String doGet(String urlStr){
// 返回结果字符串
String result = null;
HttpURLConnection connection = null;
InputStream is = null;
BufferedReader br = null;
try{
//1.创建远程url链接对象
URL url = new URL(urlStr);
// 2.通过远程url连接对象打开一个连接，并把对象强转成httpURLConnection类
connection = (HttpURLConnection) url.openConnection();
// 设置连接方式：get
connection.setRequestMethod("GET");
// 设置连接主机服务器的超时时间：5000毫秒
connection.setConnectTimeout(5000);
// 设置读取远程返回的数据时间：6000毫秒
connection.setReadTimeout(6000);
// 设置通用的请求属性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
//对与需要鉴权的某些地址，就需要设置cookie
String cookie = "hm_guid=b618be5f-7721-47e8-a394-4875b37b893e";
connection.setRequestProperty("Cookie",cookie);
// 发送请求
connection.connect();
// 通过connection连接，获取输入流
if (connection.getResponseCode() == 200) {
is = connection.getInputStream();
// 封装输入流is，并指定字符集
br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
// 存放数据
StringBuffer sbf = new StringBuffer();
String temp = null;
while ((temp = br.readLine()) != null) {
sbf.append(temp);
sbf.append("\r\n");
}
result = sbf.toString();
}else {
System.out.println(connection.getResponseCode());
}
}catch (Exception e){
e.printStackTrace();
}finally {
// 关闭资源
if (null != br) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != is) {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
// 关闭远程连接
connection.disconnect();
}
return result;
}
}
第二种方式：apache HttpClient
package net;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
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.HttpGet;
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.io.UnsupportedEncodingException;
import java.util.*;
/**
* HttpClient 生成http请求
**/
public class HttpClient {
/**
* get类型请求
**/
public static String doGet(String urlStr){
CloseableHttpClient client = null;
CloseableHttpResponse response = null;
String result = "";
try {
// 通过址默认配置创建一个httpClient实例
client = HttpClients.createDefault();
// 创建httpGet远程连接实例
HttpGet httpGet = new HttpGet(urlStr);
// 设置配置请求参数
RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 连接主机服务超时时间
.setConnectionRequestTimeout(35000)// 请求超时时间
.setSocketTimeout(60000)// 数据读取超时时间
.setRedirectsEnabled(false) // 不自动重定向
.build();
httpGet.setConfig(requestConfig);
//需求鉴权的域名还需要，设置cookie
httpGet.setHeader("Cookie","hm_guid=b618be5");
// 为httpGet实例设置配置
httpGet.setConfig(requestConfig);
// 执行get请求得到返回对象
response = client.execute(httpGet);
System.out.println(response.getStatusLine().getStatusCode());
// 通过返回对象获取返回数据
HttpEntity entity = response.getEntity();
// 通过EntityUtils中的toString方法将结果转换为字符串
result = EntityUtils.toString(entity);
}catch (Exception e){
e.printStackTrace();
}finally {
// 关闭资源
if (null != response) {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != client) {
try {
client.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
/**
* post类型请求
**/
public static String doPost(String url, Map<String, Object> paramMap) {
CloseableHttpClient httpClient = null;
CloseableHttpResponse httpResponse = null;
String result = "";
// 创建httpClient实例
httpClient = HttpClients.createDefault();
// 创建httpPost远程连接实例
HttpPost httpPost = new HttpPost(url);
// 配置请求参数实例
RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 设置连接主机服务超时时间
.setConnectionRequestTimeout(35000)// 设置连接请求超时时间
.setSocketTimeout(60000)// 设置读取数据连接超时时间
.build();
// 为httpPost实例设置配置
httpPost.setConfig(requestConfig);
// 设置请求头
httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded");
httpPost.addHeader("Cookie","hm_guid=b618be5f-7721-47e8-a394-487");
// 封装post请求参数
if (null != paramMap && paramMap.size() > 0) {
List<NameValuePair> nvps = new ArrayList<>();
// 通过map集成entrySet方法获取entity
Set<Map.Entry<String, Object>> entrySet = paramMap.entrySet();
// 循环遍历，获取迭代器
Iterator<Map.Entry<String, Object>> iterator = entrySet.iterator();
while (iterator.hasNext()) {
Map.Entry<String, Object> mapEntry = iterator.next();
nvps.add(new BasicNameValuePair(mapEntry.getKey(), mapEntry.getValue().toString()));
}
// 为httpPost设置封装好的请求参数
try {
httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));
//可以设置post的请求参数类型
//httpPost.addHeader("Content-Type", "application/json");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
try {
// httpClient对象执行post请求,并返回响应参数对象
httpResponse = httpClient.execute(httpPost);
// 从响应对象中获取响应内容
HttpEntity entity = httpResponse.getEntity();
result = EntityUtils.toString(entity);
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
// 关闭资源
if (null != httpResponse) {
try {
httpResponse.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != httpClient) {
try {
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
}
此种方法需要导包，我用的是4.4.1版本的
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.4.1</version>
</dependency>