使用HttpClient调用外部系统接口

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package xx;

import org.apache.http.HttpEntity;
import org.apache.http.ParseException;
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.ArrayList;
import java.util.List;

/**
 * 调用外部接口
 *
 * @author 
 * @date 2018/9/3 09:54
 */
public class HttpClient {
    /**
     * 发送 post请求访问本地应用并根据传递参数不同返回不同结果
     */
    public void post() {
        // 创建默认的httpClient实例.
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // 创建httppost
        HttpPost httppost = new HttpPost("http://localhost:8080/demo");
        // 创建参数队列
        List formparams = new ArrayList<>();
        formparams.add(new BasicNameValuePair("type", "house"));
        UrlEncodedFormEntity uefEntity;
        try {
            uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8");
            httppost.setEntity(uefEntity);
            System.out.println("executing request " + httppost.getURI());
            CloseableHttpResponse response = httpclient.execute(httppost);
            try {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    System.out.println("--------------------------------------");
                    System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8"));
                    System.out.println("--------------------------------------");
                }
            } finally {
                response.close();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接,释放资源
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 发送 get请求
     */
    public void get() {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            // 创建httpget.
            HttpGet httpget = new HttpGet("https://www.baidu.com");
            System.out.println("executing request " + httpget.getURI());
            // 执行get请求.
            CloseableHttpResponse response = httpclient.execute(httpget);
            try {
                // 获取响应实体
                HttpEntity entity = response.getEntity();
                System.out.println("--------------------------------------");
                // 打印响应状态
                System.out.println(response.getStatusLine());
                if (entity != null) {
                    // 打印响应内容长度
                    System.out.println("Response content length: " + entity.getContentLength());
                    // 打印响应内容
                    System.out.println("Response content: " + EntityUtils.toString(entity));
                }
                System.out.println("------------------------------------");
            } finally {
                response.close();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接,释放资源
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public String doHttpGet() {
        // 需要访问的接口路径
        String url = "https://www.baidu.com";
        // 配置请求信息（请求时间）
        RequestConfig rc = RequestConfig.custom().setSocketTimeout(5000)
                .setConnectTimeout(5000).build();
        // 获取使用DefaultHttpClient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // 返回结果
        String result = null;
        try {
            if (url != null) {
                // 创建HttpGet对象，将URL通过构造方法传入HttpGet对象
                HttpGet httpget = new HttpGet(url);
                // 将配置好请求信息附加到http请求中
                httpget.setConfig(rc);
                // 执行DefaultHttpClient对象的execute方法发送GET请求，通过CloseableHttpResponse接口的实例，可以获取服务器返回的信息
                CloseableHttpResponse response = httpclient.execute(httpget);
                try {
                    // 得到返回对象
                    HttpEntity entity = response.getEntity();
                    if (entity != null) {
                        // 获取返回结果
                        result = EntityUtils.toString(entity);
                    }
                } finally {
                    // 关闭到客户端的连接
                    response.close();
                }
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                // 关闭http请求
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    public static void main(String[] args) {
        HttpClient httpClient=new HttpClient();
        httpClient.get();

        String str=httpClient.doHttpGet();
        System.out.println(str);

    }
}

要引入jar包

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.5</version>
</dependency>