使用httpClient远程调用

第一部添加httpclient的依赖 ，添加gson的原因是httpclient远程调用返回时一个json数据，为了方便操作需要将json转换成对象

        <!--远程调用-->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </dependency>
        <!--json转换-->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.2</version>
        </dependency>

第二部编写远程调用的工具类HttpClientUtil 

package com.shiwen.yitihui.achievement.util;

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.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.client.LaxRedirectStrategy;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import java.io.IOException;
import java.net.URI;
import java.util.List;

/**
 * @author : wangjie
 * company : 石文软件有限公司
 * @date : 2020/6/9  14:27
 * httpClient远程调用的工具类
 */
public class HttpClientUtil {


    /**
     * 不带参数的get请求方式
     */
    public static String doGet(String url) {
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // 创建http GET请求
        HttpGet httpGet = new HttpGet(url);
        CloseableHttpResponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpGet);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 带参数的get请求
     */
    public static String doGetParam(String url, String param, String value) {
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        try {
            // 定义请求的参数
            URI uri = new URIBuilder(url).setParameter(param, value).build();
            // 创建http GET请求
            HttpGet httpGet = new HttpGet(uri);
            // 执行请求
            response = httpclient.execute(httpGet);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 不带参数的post请求
     * @param url
     */
    public static String doPost(String url){
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
        // 创建http POST请求
        HttpPost httpPost = new HttpPost(url);
        CloseableHttpResponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpPost);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     *
     * @throws Exception
     */
    public static String doPostParam(String url,List<BasicNameValuePair> parameters) throws Exception{
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();
        // 创建http POST请求
        HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
        // 设置2个post参数，一个是scope、一个是q
       /* List<BasicNameValuePair> parameters = new ArrayList<>();
        parameters.add(new BasicNameValuePair("scope", "project"));
        parameters.add(new BasicNameValuePair("q", "java"));*/
        // 构造一个form表单式的实体
        UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
        // 将请求实体设置到httpPost对象中
        httpPost.setEntity(formEntity);
        CloseableHttpResponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpPost);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } finally {
            if (response != null) {
                response.close();
            }
            httpclient.close();
        }
        return null;
    }

}

　　传入的url为了灵活一些可以直接在yml文件中配置

第三步远程调用接口

@RestController
@RequestMapping("/auth")
public class TemplateAuthController {

   //调用server层用户的地址
    @Value("${httpclient.address}")
    private String url;

   private Gson gson = new Gson();


   @RequestMapping("/http-client")
    public User getServerUser() {
       //远程调用获取server服务的接口数据
        String userJson = HttpClientUtil.doGetParam(url, "userName", UserUtil.getCurrUsername());
        if (userJson != null) {
            //json转换成user对象
            User user = gson.fromJson(userJson, User.class);
            return user;
        }
        return null;
    }

}