Java使用HttpClient发送请求

使用HttpClient发送请求、接收响应很简单，一般需要以下几步：

1.通过maven导入依赖的JAR包。
2.创建CloseableHttpClient对象。
3.如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。
4.调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。
5.调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。
6.释放连接。无论执行方法是否成功，都必须释放连接。

导入maven依赖：

<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpclient</artifactId>
	<version>4.5.13</version>
</dependency>
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpcore</artifactId>
	<version>4.4.14</version>
</dependency>

后台代码：

import java.io.IOException;
import java.nio.charset.Charset;

import org.apache.commons.codec.binary.Base64;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;

public class HttpClientUtils {

    /**
     * 发送post请求
     * @param url
     * @param soapRequestXml
     * @return
     * @throws Exception
     */
    public static String sendPostSoapXml(String url, String soapRequestXml) throws Exception {
        // 创建HttpClientBuilder
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        // HttpClient
        CloseableHttpClient closeableHttpClient = httpClientBuilder.build();
        HttpPost httpPost = new HttpPost(url);
        // 设置请求和传输超时时间
        RequestConfig requestConfig = RequestConfig.custom()
                .setSocketTimeout(60000)
                .setConnectionRequestTimeout(60000)
                .setConnectTimeout(60000)
                .build();
        httpPost.setConfig(requestConfig);

        CloseableHttpResponse response = null;

        try {
            //设置post请求方式为SOAP+XML
            httpPost.setHeader("Content-Type", "text/xml;charset=UTF-8");
            StringEntity data = new StringEntity(soapRequestXml, Charset.forName("UTF-8"));
            httpPost.setEntity(data);

            //发送post请求
            response = closeableHttpClient.execute(httpPost);
            if (response == null || response.getStatusLine() == null) {
                throw new RuntimeException("发送POST请求失败，返回结果为空！");
            }

            //返回状态是否200
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == HttpStatus.SC_OK) {
                //得到请求结果
                HttpEntity entityRes = response.getEntity();
                if (entityRes != null) {
                    String responsetData = EntityUtils.toString(entityRes, "UTF-8");
                    return responsetData;
                }
            } else {
                throw new Exception("发送POST-SOAP+XML请求出错：" + response);
            }
        } catch (Exception e) {
            throw new Exception("发送POST请求出现异常,"+e.getMessage());
        } finally {
            try {
                // 关闭连接释放资源
                if (response != null) {
                    response.close();
                }
                if (closeableHttpClient != null) {
                    closeableHttpClient.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return "";
    }


    /**
     * 发送post请求
     * @param url
     * @param requestJson
     * @return
     * @throws Exception
     */
    public static String sendPostJson(String url, String requestJson) throws Exception {
        // 创建HttpClientBuilder
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        // HttpClient
        CloseableHttpClient closeableHttpClient = httpClientBuilder.build();
        HttpPost httpPost = new HttpPost(url);
        // 设置请求和传输超时时间
        RequestConfig requestConfig = RequestConfig.custom()
                .setSocketTimeout(60000)
                .setConnectionRequestTimeout(60000)
                .setConnectTimeout(60000)
                .build();
        httpPost.setConfig(requestConfig);

        CloseableHttpResponse response = null;

        try {
            //设置post请求方式为JSON
            httpPost.addHeader("Authorization", "Basic" + encryptBASE64("username", "password"));
            StringEntity data = new StringEntity(requestJson, "UTF-8");
            data.setContentType("application/json; charset=UTF-8");
            httpPost.setEntity(data);

            //发送post请求
            response = closeableHttpClient.execute(httpPost);
            if (response == null || response.getStatusLine() == null) {
                throw new Exception("发送POST请求失败，返回结果为空！");
            }

            //返回状态是否200
            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == HttpStatus.SC_OK) {
                //得到请求结果
                HttpEntity entityRes = response.getEntity();
                if (entityRes != null) {
                    String responsetData = EntityUtils.toString(entityRes, "UTF-8");
                    return responsetData;
                }
            } else {
                throw new Exception("发送POST-JSON请求出错：" + response);
            }
        } catch (Exception e) {
            throw new Exception("发送POST请求出现异常,"+e.getMessage());
        } finally {
            try {
                // 关闭连接释放资源
                if (response != null) {
                    response.close();
                }
                if (closeableHttpClient != null) {
                    closeableHttpClient.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return "";
    }

    public static String encryptBASE64(String username, String password) {
        byte[] key = (username+":"+password).getBytes();
        return  new String(Base64.encodeBase64(key));
    }
}