1.使用HttpClient发送get请求(不带参数)

import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;import org.apache.http.client.methods.HttpGet;import org.apache.http.HttpResponse;import org.apache.http.HttpEntity;// 创建一个HttpClient实例CloseableHttpClient httpClient = null;try{    httpClient = HttpClients.createDefault();    // 创建一个HttpGet实例    HttpGet httpGet = new HttpGet("http://127.0.0.1:8080/test/demo");    // 发送GET请求    HttpResponse execute = httpClient.execute(httpGet);    //获取状态码    int statusCode = execute.getStatusLine().getStatusCode();    System.out.println(statusCode);    HttpEntity entity = execute.getEntity();    String resutlt = EntityUtils.toString(entity, "utf-8");    System.out.println(resutlt);}catch (Exception e) {	e.printStackTrace();}finally{   if (httpClient != null) {	try {		httpClient.close();	} catch (IOException e) {		e.printStackTrace();	}   }}

2.使用HttpClient发送get请求(带参数)

import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.message.BasicNameValuePair;import org.apache.http.NameValuePair;import org.apache.http.util.EntityUtils;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.Consts;import org.apache.http.client.methods.HttpGet;import org.apache.http.HttpResponse;import org.apache.http.HttpEntity;import java.util.ArrayList;import java.util.List;// 创建一个HttpClient实例CloseableHttpClient httpClient = null;try{    httpClient  = HttpClients.createDefault();    // 装填参数    List
    
      params = new ArrayList
     
      ();    params.add(new BasicNameValuePair("id", "1"));  //字符串参数    // 转换为键值对    String str = EntityUtils.toString(new UrlEncodedFormEntity(nvps, Consts.UTF_8));    // 创建一个HttpGet实例    HttpGet httpGet = new HttpGet("http://127.0.0.1:8080/test/demo?"+str);    // 发送GET请求    HttpResponse execute = httpClient.execute(httpGet);    //获取状态码    int statusCode = execute.getStatusLine().getStatusCode();    System.out.println(statusCode);    HttpEntity entity = execute.getEntity();    String resutlt = EntityUtils.toString(entity, "utf-8");    System.out.println(resutlt);}catch (Exception e) {	e.printStackTrace();} finally {	if (httpClient != null) {		try {			httpClient.close();		} catch (IOException e) {			e.printStackTrace();		}	}}
     
    

3.使用HttpClient发送post请求

import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.message.BasicNameValuePair;import org.apache.http.NameValuePair;import org.apache.http.util.EntityUtils;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.Consts;import org.apache.http.client.methods.HttpPost;import org.apache.http.HttpResponse;import org.apache.http.HttpEntity;import java.util.ArrayList;import java.util.List;// 创建HttpClient实例CloseableHttpClient httpClient = null;// 创建HttpPost实例HttpPost httpPost = new HttpPost("http://127.0.0.1/test/demo");// 装填参数List
    
      params = new ArrayList
     
      ();params.add(new BasicNameValuePair("id", "1")); //字符串参数 可以循环添加多个try {		httpClient = HttpClients.createDefault();                // 设置请求参数		httpPost.setEntity(new UrlEncodedFormEntity(params, "utf-8"));		// 设置header信息		httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");		httpPost.setHeader("User-Agent","Mozilla/5.0 (Windows NT 6.1; WOW64; rv:56.0) Gecko/20100101 Firefox/56.0");		// 执行请求		HttpResponse httpResponse = httpClient.execute(httpPost);		HttpEntity resEntity = httpResponse.getEntity();		// 按指定编码转换结果实体为String类型		String result = EntityUtils.toString(resEntity, "utf-8");		System.out.println(result);} catch (Exception e) {		e.printStackTrace();} finally {		if (httpClient != null) {			try {				httpClient.close();			} catch (IOException e) {				e.printStackTrace();			}		}}
     
    

参考：http://blog.csdn.net/xiaoxian8023/article/details/49863967

maven 下载包

<dependency>

            <groupId>org.apache.httpcomponents</groupId>             <artifactId>httpclient</artifactId>             <version>4.5.2</version>  </dependency>

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