使用Apache HttpClient 4.x发送Json数据

Apache HttpClient是Apache提供的一个开源组件，使用HttpClient可以很方便地进行Http请求的调用。自4.1版本开始，HttpClient的API发生了较大的改变，很多方法的调用方式已经和3.x版本不同。本文使用的是当前最新的4.5.3版本。

首先在pom文件中引入httpcomponents依赖包：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
</dependency>

本文展示的是POST请求。

import java.io.IOException;

import org.apache.commons.lang3.ObjectUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.Consts;
import org.apache.http.HttpStatus;
import org.apache.http.ParseException;
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.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

/**
 * @author 
 *
 * @date 2017年5月18日 上午9:17:30
 *
 * @Description
 */
public class HttpPostUtils {
    /**
     * 
     * @param uri
     *            the request address
     * @param json
     *            the request data that must be a JSON string
     * @param connectTimeout
     *            the timeout in milliseconds until a connection is established
     * @param connectionRequestTimeout
     *            the timeout in milliseconds used when requesting a connection
     *            from the connection manager
     * @param socketTimeout
     *            the socket timeout in milliseconds, which is the timeout for
     *            waiting for data or, put differently, a maximum period
     *            inactivity between two consecutive data packets
     * @return null when method parameter is null, "", " "
     * @throws IOException
     *             if HTTP connection can not opened or closed successfully
     * @throws ParseException
     *             if response data can not be parsed successfully
     */
    public String postJson(String uri, String json, int connectTimeout, int connectionRequestTimeout, int socketTimeout)
            throws IOException, ParseException {
        if (StringUtils.isAnyBlank(uri, json)) {
            return null;
        }

        CloseableHttpClient client = HttpClients.createDefault();
        HttpPost post = new HttpPost(uri);
        // Create request data
        StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
        // Set request body
        post.setEntity(entity);

        RequestConfig config = RequestConfig.custom().setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout).build();
        post.setConfig(config);
        // Response content
        String responseContent = null;
        CloseableHttpResponse response = null;
        try {
            response = client.execute(post);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                responseContent = EntityUtils.toString(response.getEntity(), Consts.UTF_8.name());
            }
        } finally {
            if (ObjectUtils.anyNotNull(response)) {
                response.close();
            }
            if (ObjectUtils.anyNotNull(client)) {
                client.close();
            }
        }
        return responseContent;
    }
}