如何使用Java HttpClient发送HTTP请求

1、导入依赖

    org.apache.httpcomponents
    httpclient
    4.5.3



    com.alibaba
    fastjson
    1.2.58


 
     org.apache.httpcomponents
     httpmime
     4.5.3
 

 
     org.apache.httpcomponents
     httpcore
     4.4.13
 
 

    org.slf4j
    slf4j-api
    1.7.7

2、使用工具类

该工具类将get请求和post请求当中几种传参方式都写了，其中有get地址栏传参、get的params传参、post的params传参、post的json传参。

import com.alibaba.fastjson.JSONObject;
import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
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.client.utils.URIBuilder;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.MultipartEntityBuilder;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class HttpClientUtil {

    private static Logger logger = LoggerFactory.getLogger(HttpClientUtil.class);

    private static final int DEFULT_TIMEOUT = 30 * 1000;//默认超时时间20秒

    /**
     * 可以访问  http://localhost:9005/yzhwsj/addPersonal/1/2 这样的接口
     * @param url
     * @param headers
     * @param urlParam
     * @param timeout
     * @return
     */
    private static String doUrlGet(String url, Map headers, List urlParam, Integer timeout) {
        //创建httpClient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String resultString = null;
        CloseableHttpResponse response = null;
        try {
            //创建uri
            if (urlParam != null){
                for (String param : urlParam) {
                    url = url + "/" + param;
                }
            }
            //创建hTTP get请求
            HttpGet httpGet = new HttpGet(url);
            //设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpGet.setConfig(requestConfig);
            //设置头信息
            if (null != headers) {
                for (String key : headers.keySet()) {
                    httpGet.setHeader(key, headers.get(key));
                }
            }
            //执行请求
            response = httpClient.execute(httpGet);
            if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (IOException e) {
            logger.error("http调用异常" + e.toString(), e);
        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                logger.error("response关闭异常" + e.toString(), e);
            }
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("httpClient关闭异常" + e.toString(), e);
            }
        }
        return resultString;
    }

    /**
     * @param url
     * @param headers
     * @param params
     * @param timeout
     * @return
     */
    private static String doGet(String url, Map headers, Map params, Integer timeout) {
        //创建httpClient对象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        String resultString = null;
        CloseableHttpResponse response = null;
        try {
            // 1.创建uri
            URIBuilder builder = new URIBuilder(url);
            if (params != null) {
                //uri添加参数
                for (String key : params.keySet()) {
                    builder.addParameter(key, String.valueOf(params.get(key)));
                }
            }
            URI uri = builder.build();
            // 2.创建hTTP get请求
            HttpGet httpGet = new HttpGet(uri);
            // 3.设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpGet.setConfig(requestConfig);
            // 4.设置头信息
            if (null != headers) {
                for (String key : headers.keySet()) {
                    httpGet.setHeader(key, headers.get(key));
                }
            }
            // 5.执行请求
            response = httpClient.execute(httpGet);
            if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (URISyntaxException e) {
            logger.error("http调用异常" + e.toString(), e);
        } catch (IOException e) {
            logger.error("http调用异常" + e.toString(), e);

        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                logger.error("response关闭异常" + e.toString(), e);
            }
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("httpClient关闭异常" + e.toString(), e);
            }
        }
        return resultString;
    }

    /**
     * 调用http post请求（json数据）
     *
     * @param url
     * @param headers
     * @param json
     * @return
     */
    public static String doJsonPost(String url, Map headers, JSONObject json, Integer timeout) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            // 1.创建http post请求
            HttpPost httpPost = new HttpPost(url);
            // 2.设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpPost.setConfig(requestConfig);
            // 3.设置参数信息
            StringEntity s = new StringEntity(json.toString(), Consts.UTF_8);
            // 发送json数据需要设置的contentType
            s.setContentType("application/json");
            httpPost.setEntity(s);
            // 4.设置头信息
            if (headers != null) {
                for (String key : headers.keySet()) {
                    httpPost.setHeader(key, headers.get(key));
                }
            }
            // 5.执行http请求
            response = httpClient.execute(httpPost);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (UnsupportedEncodingException e) {
            logger.error("调用http异常" + e.toString(), e);
        } catch (ClientProtocolException e) {
            logger.error("调用http异常" + e.toString(), e);
        } catch (IOException e) {
            logger.error("调用http异常" + e.toString(), e);
        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                logger.error("关闭response异常" + e.toString(), e);
            }
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("关闭httpClient异常" + e.toString(), e);
            }
        }
        return resultString;
    }

    /**
     * 调用http post请求 基础方法
     *
     * @param url     请求的url
     * @param headers 请求头
     * @param params  参数
     * @param timeout 超时时间
     * @return
     */
    public static String doPost(String url, Map headers, Map params, Integer timeout) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            // 1.创建http post请求
            HttpPost httpPost = new HttpPost(url);
            // 2.设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpPost.setConfig(requestConfig);
            // 3.设置参数信息
            if (params != null) {
                List paramList = new ArrayList<>();
                for (String key : params.keySet()) {
                    paramList.add(new BasicNameValuePair(key, String.valueOf(params.get(key))));
                }
                // 模拟表单
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList, Consts.UTF_8);
                httpPost.setEntity(entity);
            }
            // 4.设置头信息
            if (headers != null) {
                for (String key : headers.keySet()) {
                    httpPost.setHeader(key, headers.get(key));
                }
            }
            // 5.执行http请求
            response = httpClient.execute(httpPost);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (UnsupportedEncodingException e) {
            logger.error("调用http异常" + e.toString(), e);
        } catch (ClientProtocolException e) {
            logger.error("调用http异常" + e.toString(), e);
        } catch (IOException e) {
            logger.error("调用http异常" + e.toString(), e);
        } finally {
            try {
                if (null != response) {
                    response.close();
                }
            } catch (IOException e) {
                logger.error("关闭response异常" + e.toString(), e);
            }
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("关闭httpClient异常" + e.toString(), e);
            }
        }
        return resultString;
    }
    
	/**
     * 通过httpClient上传文件
     *
     * @param url      请求的URL
     * @param headers  请求头参数
     * @param path     文件路径
     * @param fileName 文件名称
     * @param timeout  超时时间
     * @return
     */
    public static String UploadFileByHttpClient(String url, Map headers, String path, String fileName, Integer timeout) {
        String resultString = "";
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        InputStream content = null;
        BufferedReader in = null;
        try {
            // 1.创建http post请求
            HttpPost httpPost = new HttpPost(url);

            // 2.设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpPost.setConfig(requestConfig);

            // 3.设置参数信息
            // HttpMultipartMode.RFC6532参数的设定是为避免文件名为中文时乱码
            MultipartEntityBuilder builder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.RFC6532);
            // 上传文件的路径
            File file = new File(path + File.separator + fileName);
            builder.setCharset(Charset.forName("UTF-8"));
            builder.addBinaryBody("file", file, ContentType.MULTIPART_FORM_DATA, fileName);
            HttpEntity entity = builder.build();
            httpPost.setEntity(entity);

            // 4.设置头信息
            if (headers != null) {
                for (String key : headers.keySet()) {
                    httpPost.setHeader(key, headers.get(key));
                }
            }

            // 5.执行http请求
            response = httpClient.execute(httpPost);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (Exception e) {
            logger.error("上传文件失败：", e);
        } finally {
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("关闭httpClient异常" + e.toString(), e);
            }
            try {
                if (null != content) {
                    content.close();
                }
            } catch (IOException e) {
                logger.error("关闭content异常" + e.toString(), e);
            }
            try {
                if (null != in) {
                    in.close();
                }
            } catch (IOException e) {
                logger.error("关闭in异常" + e.toString(), e);
            }
        }

        return resultString;
    }
 }

	/**
     * 通过httpClient批量上传文件
     *
     * @param url     请求的URL
     * @param headers 请求头参数
     * @param params  参数
     * @param paths   文件路径(key文件名称，value路径)
     * @param timeout 超时时间
     * @return
     */
    public static String UploadFilesByHttpClient(String url, Map headers, Map params, Map paths, Integer timeout) {
        String resultString = "";
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        InputStream content = null;
        BufferedReader in = null;
        try {
            // 1.创建http post请求
            HttpPost httpPost = new HttpPost(url);

            // 2.设置超时时间
            int timeoutTmp = DEFULT_TIMEOUT;
            if (timeout != null) {
                timeoutTmp = timeout;
            }
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(timeoutTmp)
                    .setConnectionRequestTimeout(timeoutTmp).setSocketTimeout(timeoutTmp).build();
            httpPost.setConfig(requestConfig);

            // 3.设置文件信息
            // HttpMultipartMode.RFC6532参数的设定是为避免文件名为中文时乱码
            MultipartEntityBuilder builder = MultipartEntityBuilder.create().setMode(HttpMultipartMode.RFC6532);
            builder.setCharset(Charset.forName("UTF-8"));
            // 上传文件的路径
            for (Map.Entry m : paths.entrySet()) {
                File file = new File(m.getValue() + File.separator + m.getKey());
                builder.addBinaryBody("files", file, ContentType.MULTIPART_FORM_DATA, m.getKey());
            }

            // 4.设置参数信息
            ContentType contentType = ContentType.create("text/plain", Charset.forName("UTF-8"));
            for (Map.Entry param : params.entrySet()) {
                builder.addTextBody(param.getKey(), param.getValue(), contentType);
            }
            HttpEntity entity = builder.build();
            httpPost.setEntity(entity);

            // 5.设置头信息
            if (headers != null) {
                for (String key : headers.keySet()) {
                    httpPost.setHeader(key, headers.get(key));
                }
            }

            // 6.执行http请求
            response = httpClient.execute(httpPost);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                resultString = EntityUtils.toString(response.getEntity(), Consts.UTF_8);
            }
        } catch (Exception e) {
            logger.error("上传文件失败：", e);
        } finally {
            try {
                if (null != httpClient) {
                    httpClient.close();
                }
            } catch (IOException e) {
                logger.error("关闭httpClient异常" + e.toString(), e);
            }
            try {
                if (null != content) {
                    content.close();
                }
            } catch (IOException e) {
                logger.error("关闭content异常" + e.toString(), e);
            }
            try {
                if (null != in) {
                    in.close();
                }
            } catch (IOException e) {
                logger.error("关闭in异常" + e.toString(), e);
            }
        }

        return resultString;
    }

3、扩展

上面的工具类，方法都携带了token和超时时间，假如接口用不到可以做接口拓展。例如：

/**
 * 调用http get请求
 *
 * @param url
 * @param params
 * @return
 */
public static String doGet(String url, Map params) {
    return doGet(url, null, params, null);
}

如果涉及到put请求和delete请求，跟上面都差不多，只不过创建请求的时候改为:

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HttpDelete httpDelete = new HttpDelete();

HttpPut httpPut = new HttpPut();