HttpClient 远程接口调用方式

远程接口调用方式HttpClient

问题：现在我们已经开发好了接口了，那该如何调用这个接口呢？

答：使用Httpclient客户端。

Httpclient简介

什么是httpclient

HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。实现了所有 HTTP 的方法（GET,POST,PUT,HEAD 等）

下载地址：http://hc.apache.org/

httpclient作用

在java代码中，发送Http请求。通常用来实现远程接口调用。

HttpClient测试

在工程中添加httpclient的pom依赖。

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

执行GET请求

 1 public static void doGet(){
 2  // 创建Httpclient对象
 3         CloseableHttpClient httpclient = HttpClients.createDefault();
 4  
 5         // 创建http GET请求
 6         HttpGet httpGet = new HttpGet("http://www.oschina.net/");
 7  
 8         CloseableHttpResponse response = null;
 9         try {
10             // 执行请求
11             response = httpclient.execute(httpGet);
12             System.out.println(response.getStatusLine());
13             // 判断返回状态是否为200
14             if (response.getStatusLine().getStatusCode() == 200) {
15                 String content = EntityUtils.toString(response.getEntity(), "UTF-8");
16                 System.out.println("内容长度：" + content.length());
17             }
18         }catch(Exception e){
19          e.printStackTrace();
20         
21         } finally {
22             if (response != null) {
23                 try {
24 　　response.close();
25 } catch (IOException e) {
26　　 e.printStackTrace();
27 }
28             }
29             try {
30 　　httpclient.close();
31 } catch (IOException e) {
32　　 e.printStackTrace();
33 }
34 }

执行GET带参数

 1 public static void doGetParam(){
 2  // 创建Httpclient对象
 3 CloseableHttpClient httpclient = HttpClients.createDefault();
 4 CloseableHttpResponse response = null;
 5 try {
 6  
 7         // 定义请求的参数
 8         URI uri = new URIBuilder("http://www.baidu.com/s").setParameter("wd", "数据库").build();
 9  
10         System.out.println(uri);
11  
12         // 创建http GET请求
13         HttpGet httpGet = new HttpGet(uri);
14  
15             // 执行请求
16             response = httpclient.execute(httpGet);
17             // 判断返回状态是否为200
18             if (response.getStatusLine().getStatusCode() == 200) {
19                 String content = EntityUtils.toString(response.getEntity(), "UTF-8");
20                 System.out.println(content);
21             }
22         }catch(Exception e){
23          e.printStackTrace();
24         
25         }finally {
26             if (response != null) {
27                 try {
28 response.close();
29 } catch (IOException e) {
30 // TODO Auto-generated catch block
31 e.printStackTrace();
32 }
33             }
34             try {
35 httpclient.close();
36 } catch (IOException e) {
37 // TODO Auto-generated catch block
38 e.printStackTrace();
39 }
40         }
41 }

执行post请求

 1 public static void doPost(){
 2  // 创建Httpclient对象
 3         CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
 4  
 5         // 创建http POST请求
 6         HttpPost httpPost = new HttpPost("http://www.oschina.net/");
 7  
 8         CloseableHttpResponse response = null;
 9         try {
10             // 执行请求
11             response = httpclient.execute(httpPost);
12             System.out.println(response.getStatusLine());
13             // 判断返回状态是否为200
14             if (response.getStatusLine().getStatusCode() == 200) {
15                 String content = EntityUtils.toString(response.getEntity(), "UTF-8");
16                 System.out.println(content);
17             }
18         }catch(Exception e){
19          e.printStackTrace();
20         
21         }finally {
22             if (response != null) {
23                 try {
24 response.close();
25 } catch (IOException e) {
26 // TODO Auto-generated catch block
27 e.printStackTrace();
28 }
29             }
30             try {
31 httpclient.close();
32 } catch (IOException e) {
33 // TODO Auto-generated catch block
34 e.printStackTrace();
35 }
36         }
37     }

执行post带参数

 1 public static void doPostParam() throws Exception{
 2  // 创建Httpclient对象
 3         CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
 4  
 5         // 创建http POST请求
 6         HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
 7        
 8         // 设置2个post参数，一个是scope、一个是q
 9         List<NameValuePair> parameters = new ArrayList<NameValuePair>();
10         parameters.add(new BasicNameValuePair("scope", "project"));
11         parameters.add(new BasicNameValuePair("q", "java"));
12         // 构造一个form表单式的实体
13         UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
14         // 将请求实体设置到httpPost对象中
15         httpPost.setEntity(formEntity);
16  
17         CloseableHttpResponse response = null;
18         try {
19             // 执行请求
20             response = httpclient.execute(httpPost);
21             System.out.println(response.getStatusLine());
22             // 判断返回状态是否为200
23             if (response.getStatusLine().getStatusCode() == 200) {
24                 String content = EntityUtils.toString(response.getEntity(), "UTF-8");
25                 System.out.println(content);
26             }
27         } finally {
28             if (response != null) {
29                 response.close();
30             }
31             httpclient.close();
32         }
33 }

httpclient常见问题及解决方案

请求参数乱码

设置请求的编码格式：

1 obj.addHeader("Content-Type","application/x-www-form-urlencoded; charset=UTF-8");

响应HTTP/1.1 403 Forbidden

原因：网站设置了反爬虫机制，禁止非法访问。

解决方案：伪装浏览器。

1 obj.addHeader("User-Agent"," Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537. 36 (KHTML, like Gecko) Chrome/31.0.1650.63")

封装通用工具类HttpClientUtils

  1 　package org.chu.ego.base.utils;
  2 
  3 import java.io.IOException;
  4 import java.util.ArrayList;
  5 import java.util.List;
  6 import java.util.Map;
  7 
  8 import org.apache.http.HttpEntity;
  9 import org.apache.http.NameValuePair;
 10 import org.apache.http.client.entity.UrlEncodedFormEntity;
 11 import org.apache.http.client.methods.CloseableHttpResponse;
 12 import org.apache.http.client.methods.HttpGet;
 13 import org.apache.http.client.methods.HttpPost;
 14 import org.apache.http.client.utils.URIBuilder;
 15 import org.apache.http.impl.client.CloseableHttpClient;
 16 import org.apache.http.impl.client.HttpClientBuilder;
 17 import org.apache.http.impl.client.HttpClients;
 18 import org.apache.http.impl.client.LaxRedirectStrategy;
 19 import org.apache.http.message.BasicNameValuePair;
 20 import org.apache.http.util.EntityUtils;
 21 /**
 22  * --发送get请求的api
 23  * CloseableHttpClient类 ，client实现类
 24  * HttpClients类 ，client工具类，用于创建客户端对象。
 25  * CloseableHttpResponse接口，请求的响应对象
 26  * URIBuilder类 ：url构建类，用于设置get请求的路径变量
 27  * HttpGet类 ：get请求的发送对象
 28  * EntityUtils类 实体处理类
 29  * 
 30  * --发送post 请求使用的api
 31  * CloseableHttpClient类
 32  * HttpClientBuilder client构建对象，用于创建客户端对象。
 33  * LaxRedirectStrategy类，post请求重定向的策略
 34  * CloseableHttpResponse 请求的响应对象
 35  * HttpPost post请求的发送对象
 36  * NameValuePair 类，用于设置参数值
 37  * UrlEncodedFormEntity：用于设置表单参数给发送对象HttpPost
 38  * 
 39  * @author ranger
 40  *
 41  */
 42 public class HttpClientUtils {
 43 
 44 public static String doGet(String url,Map<String, String> params){
 45         
 46         //获取httpclient客户端
 47         CloseableHttpClient httpclient = HttpClients.createDefault();
 48         
 49         String resultString = "";
 50         
 51         CloseableHttpResponse response = null;
 52         
 53         try {
 54             URIBuilder builder = new URIBuilder(url);
 55             
 56             if(null!=params){
 57                 for (String key:params.keySet()) {
 58                     builder.setParameter(key, params.get(key));
 59                 }
 60             }
 61             
 62             HttpGet get = new HttpGet(builder.build());
 63             
 64             
 65             response = httpclient.execute(get);
 66             
 67             System.out.println(response.getStatusLine());
 68             
 69             if(200==response.getStatusLine().getStatusCode()){
 70                 HttpEntity entity = response.getEntity();
 71                 resultString = EntityUtils.toString(entity, "utf-8");
 72             }
 73             
 74         } catch (Exception e) {
 75             
 76             e.printStackTrace();
 77         } finally {
 78             if(null!=response){
 79                 try {
 80                     response.close();
 81                 } catch (IOException e) {
 82                     // TODO Auto-generated catch block
 83                     e.printStackTrace();
 84                 }
 85             }
 86             if(null!=httpclient){
 87                 try {
 88                     httpclient.close();
 89                 } catch (IOException e) {
 90                     // TODO Auto-generated catch block
 91                     e.printStackTrace();
 92                 }
 93             }
 94         }
 95         
 96         return resultString;
 97     }
 98     
 99     public static String doGet(String url){
100         return doGet(url, null);
101     }
102     
103     public static String doPost(String url,Map<String,String> params){
104         /**
105          * 在4.0及以上httpclient版本中，post需要指定重定向的策略，如果不指定则按默认的重定向策略。
106          * 
107          * 获取httpclient客户端
108          */
109         CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy( new LaxRedirectStrategy()).build();
110         
111         String resultString = "";
112         
113         CloseableHttpResponse response = null;
114         
115         try {
116             
117             
118             HttpPost post = new HttpPost(url);
119             
120             List<NameValuePair> paramaters = new ArrayList<>();
121             
122             if(null!=params){
123                 for (String key : params.keySet()) {
124                     paramaters.add(new BasicNameValuePair(key,params.get(key)));
125                 }
126                 
127                 UrlEncodedFormEntity  formEntity = new UrlEncodedFormEntity (paramaters);
128                 
129                 post.setEntity(formEntity);
130             }
131             
132             
133             /**
134              * HTTP/1.1 403 Forbidden
135              *   原因：
136              *      有些网站，设置了反爬虫机制
137              *   解决的办法：
138              *      设置请求头，伪装浏览器
139              */
140             post.addHeader("user-agent", "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
141             
142             response = httpclient.execute(post);
143             
144             System.out.println(response.getStatusLine());
145             
146             if(200==response.getStatusLine().getStatusCode()){
147                 HttpEntity entity = response.getEntity();
148                 resultString = EntityUtils.toString(entity, "utf-8");
149             }
150             
151         } catch (Exception e) {
152             
153             e.printStackTrace();
154         } finally {
155             if(null!=response){
156                 try {
157                     response.close();
158                 } catch (IOException e) {
159                     // TODO Auto-generated catch block
160                     e.printStackTrace();
161                 }
162             }
163             if(null!=httpclient){
164                 try {
165                     httpclient.close();
166                 } catch (IOException e) {
167                     // TODO Auto-generated catch block
168                     e.printStackTrace();
169                 }
170             }
171         }
172         
173         return resultString;
174     }
175     
176     public static String doPost(String url){
177         return doPost(url, null);
178     }
179  
180 }

posted @ 2021-03-14 20:35 豆泡不是干粮阅读(234) 评论(0) 编辑收藏举报

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HttpClient 远程接口调用方式

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