Java:使用HttpClient进行POST和GET请求以及文件上传和下载

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转载最新推荐文章于 2026-09-20 12:43:44 发布 8.1k 阅读 AI 写同款· GEO 优化 ›

java调用下载接口下载文件 4.从HttpsURLConnection中获取文件名,在本示例中传入的参数就是文件名则不需要去获取文件名。1.设置请求头，如果需要token验证的话，也需要在请求头中设置。2.设置url地址，在get请求中，请求参数在路径中体现。3.获取url连接HttpsURLConnection。5.从HttpsURLConnection中获取输入流。6.循环读取输入流，写入输出流，将文件下载到本地。剩余的是主方法中调用的方法。二是主方法，主要流程。阅读详情

转载自：https://blog.youkuaiyun.com/nupt123456789/article/details/42721003/

1.HttpClient

大家可以先看一下HttpClient的介绍，这篇博文写的还算不错：http://blog.youkuaiyun.com/wangpeng047/article/details/19624529

当然，详细的文档，你可以去官方网站查看和下载：http://hc.apache.org/httpclient-3.x/

2.本博客简单介绍一下POST和GET以及文件下载的应用。

代码如下：

package net.mobctrl;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
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.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
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;

/**
 * @web http://www.mobctrl.net
 * @author Zheng Haibo
 * @Description: 文件下载 POST GET
 */
public class HttpClientUtils {

	/**
	 * 最大线程池
	 */
	public static final int THREAD_POOL_SIZE = 5;

	public interface HttpClientDownLoadProgress {
		public void onProgress(int progress);
	}

	private static HttpClientUtils httpClientDownload;

	private ExecutorService downloadExcutorService;

	private HttpClientUtils() {
		downloadExcutorService = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
	}

	public static HttpClientUtils getInstance() {
		if (httpClientDownload == null) {
			httpClientDownload = new HttpClientUtils();
		}
		return httpClientDownload;
	}

	/**
	 * 下载文件
	 * 
	 * @param url
	 * @param filePath
	 */
	public void download(final String url, final String filePath) {
		downloadExcutorService.execute(new Runnable() {

			@Override
			public void run() {
				httpDownloadFile(url, filePath, null, null);
			}
		});
	}

	/**
	 * 下载文件
	 * 
	 * @param url
	 * @param filePath
	 * @param progress
	 *            进度回调
	 */
	public void download(final String url, final String filePath,
			final HttpClientDownLoadProgress progress) {
		downloadExcutorService.execute(new Runnable() {

			@Override
			public void run() {
				httpDownloadFile(url, filePath, progress, null);
			}
		});
	}

	/**
	 * 下载文件
	 * 
	 * @param url
	 * @param filePath
	 */
	private void httpDownloadFile(String url, String filePath,
			HttpClientDownLoadProgress progress, Map<String, String> headMap) {
		CloseableHttpClient httpclient = HttpClients.createDefault();
		try {
			HttpGet httpGet = new HttpGet(url);
			setGetHead(httpGet, headMap);
			CloseableHttpResponse response1 = httpclient.execute(httpGet);
			try {
				System.out.println(response1.getStatusLine());
				HttpEntity httpEntity = response1.getEntity();
				long contentLength = httpEntity.getContentLength();
				InputStream is = httpEntity.getContent();
				// 根据InputStream 下载文件
				ByteArrayOutputStream output = new ByteArrayOutputStream();
				byte[] buffer = new byte[4096];
				int r = 0;
				long totalRead = 0;
				while ((r = is.read(buffer)) > 0) {
					output.write(buffer, 0, r);
					totalRead += r;
					if (progress != null) {// 回调进度
						progress.onProgress((int) (totalRead * 100 / contentLength));
					}
				}
				FileOutputStream fos = new FileOutputStream(filePath);
				output.writeTo(fos);
				output.flush();
				output.close();
				fos.close();
				EntityUtils.consume(httpEntity);
			} finally {
				response1.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				httpclient.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * get请求
	 * 
	 * @param url
	 * @return
	 */
	public String httpGet(String url) {
		return httpGet(url, null);
	}

	/**
	 * http get请求
	 * 
	 * @param url
	 * @return
	 */
	public String httpGet(String url, Map<String, String> headMap) {
		String responseContent = null;
		CloseableHttpClient httpclient = HttpClients.createDefault();
		try {
			HttpGet httpGet = new HttpGet(url);
			CloseableHttpResponse response1 = httpclient.execute(httpGet);
			setGetHead(httpGet, headMap);
			try {
				System.out.println(response1.getStatusLine());
				HttpEntity entity = response1.getEntity();
				responseContent = getRespString(entity);
				System.out.println("debug:" + responseContent);
				EntityUtils.consume(entity);
			} finally {
				response1.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				httpclient.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return responseContent;
	}

	public String httpPost(String url, Map<String, String> paramsMap) {
		return httpPost(url, paramsMap, null);
	}

	/**
	 * http的post请求
	 * 
	 * @param url
	 * @param paramsMap
	 * @return
	 */
	public String httpPost(String url, Map<String, String> paramsMap,
			Map<String, String> headMap) {
		String responseContent = null;
		CloseableHttpClient httpclient = HttpClients.createDefault();
		try {
			HttpPost httpPost = new HttpPost(url);
			setPostHead(httpPost, headMap);
			setPostParams(httpPost, paramsMap);
			CloseableHttpResponse response = httpclient.execute(httpPost);
			try {
				System.out.println(response.getStatusLine());
				HttpEntity entity = response.getEntity();
				responseContent = getRespString(entity);
				EntityUtils.consume(entity);
			} finally {
				response.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				httpclient.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		System.out.println("responseContent = " + responseContent);
		return responseContent;
	}

	/**
	 * 设置POST的参数
	 * 
	 * @param httpPost
	 * @param paramsMap
	 * @throws Exception
	 */
	private void setPostParams(HttpPost httpPost, Map<String, String> paramsMap)
			throws Exception {
		if (paramsMap != null && paramsMap.size() > 0) {
			List<NameValuePair> nvps = new ArrayList<NameValuePair>();
			Set<String> keySet = paramsMap.keySet();
			for (String key : keySet) {
				nvps.add(new BasicNameValuePair(key, paramsMap.get(key)));
			}
			httpPost.setEntity(new UrlEncodedFormEntity(nvps));
		}
	}

	/**
	 * 设置http的HEAD
	 * 
	 * @param httpPost
	 * @param headMap
	 */
	private void setPostHead(HttpPost httpPost, Map<String, String> headMap) {
		if (headMap != null && headMap.size() > 0) {
			Set<String> keySet = headMap.keySet();
			for (String key : keySet) {
				httpPost.addHeader(key, headMap.get(key));
			}
		}
	}

	/**
	 * 设置http的HEAD
	 * 
	 * @param httpGet
	 * @param headMap
	 */
	private void setGetHead(HttpGet httpGet, Map<String, String> headMap) {
		if (headMap != null && headMap.size() > 0) {
			Set<String> keySet = headMap.keySet();
			for (String key : keySet) {
				httpGet.addHeader(key, headMap.get(key));
			}
		}
	}

	/**
	 * 上传文件
	 * 
	 * @param serverUrl
	 *            服务器地址
	 * @param localFilePath
	 *            本地文件路径
	 * @param serverFieldName
	 * @param params
	 * @return
	 * @throws Exception
	 */
	public String uploadFileImpl(String serverUrl, String localFilePath,
			String serverFieldName, Map<String, String> params)
			throws Exception {
		String respStr = null;
		CloseableHttpClient httpclient = HttpClients.createDefault();
		try {
			HttpPost httppost = new HttpPost(serverUrl);
			FileBody binFileBody = new FileBody(new File(localFilePath));

			MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder
					.create();
			// add the file params
			multipartEntityBuilder.addPart(serverFieldName, binFileBody);
			// 设置上传的其他参数
			setUploadParams(multipartEntityBuilder, params);

			HttpEntity reqEntity = multipartEntityBuilder.build();
			httppost.setEntity(reqEntity);

			CloseableHttpResponse response = httpclient.execute(httppost);
			try {
				System.out.println(response.getStatusLine());
				HttpEntity resEntity = response.getEntity();
				respStr = getRespString(resEntity);
				EntityUtils.consume(resEntity);
			} finally {
				response.close();
			}
		} finally {
			httpclient.close();
		}
		System.out.println("resp=" + respStr);
		return respStr;
	}

	/**
	 * 设置上传文件时所附带的其他参数
	 * 
	 * @param multipartEntityBuilder
	 * @param params
	 */
	private void setUploadParams(MultipartEntityBuilder multipartEntityBuilder,
			Map<String, String> params) {
		if (params != null && params.size() > 0) {
			Set<String> keys = params.keySet();
			for (String key : keys) {
				multipartEntityBuilder
						.addPart(key, new StringBody(params.get(key),
								ContentType.TEXT_PLAIN));
			}
		}
	}

	/**
	 * 将返回结果转化为String
	 * 
	 * @param entity
	 * @return
	 * @throws Exception
	 */
	private String getRespString(HttpEntity entity) throws Exception {
		if (entity == null) {
			return null;
		}
		InputStream is = entity.getContent();
		StringBuffer strBuf = new StringBuffer();
		byte[] buffer = new byte[4096];
		int r = 0;
		while ((r = is.read(buffer)) > 0) {
			strBuf.append(new String(buffer, 0, r, "UTF-8"));
		}
		return strBuf.toString();
	}
}

我们可以使用如下代码进行测试：

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;

import net.mobctrl.HttpClientUtils;
import net.mobctrl.HttpClientUtils.HttpClientDownLoadProgress;

/**
 * @date 2015年1月14日 下午1:49:50
 * @author Zheng Haibo
 * @Description: 测试
 */
public class Main {

	public static void main(String[] args) {
		/**
		 * 测试下载文件 异步下载
		 */
		HttpClientUtils.getInstance().download(
				"http://newbbs.qiniudn.com/phone.png", "test.png",
				new HttpClientDownLoadProgress() {

					@Override
					public void onProgress(int progress) {
						System.out.println("download progress = " + progress);
					}
				});

		// POST 同步方法
		Map<String, String> params = new HashMap<String, String>();
		params.put("username", "admin");
		params.put("password", "admin");
		HttpClientUtils.getInstance().httpPost(
				"http://192.168.31.183:8080/SSHMySql/register", params);

		// GET 同步方法
		HttpClientUtils.getInstance().httpGet(
				"http://wthrcdn.etouch.cn/weather_mini?city=北京");

		// 上传文件 POST 同步方法
		try {
			Map<String,String> uploadParams = new LinkedHashMap<String, String>();
			uploadParams.put("userImageContentType", "image");
			uploadParams.put("userImageFileName", "testaa.png");
			HttpClientUtils.getInstance().uploadFileImpl(
					"http://192.168.31.183:8080/SSHMySql/upload", "android_bug_1.png",
					"userImage", uploadParams);
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

运行结果为：

HTTP/1.1 200 OK
responseContent = {"id":"-2","msg":"添加失败!用户名已经存在！"}
HTTP/1.1 200 OK
download progress = 6
download progress = 11
download progress = 13
download progress = 20
download progress = 22
download progress = 26
download progress = 31
download progress = 33
download progress = 35
download progress = 38
download progress = 40
download progress = 42
download progress = 44
download progress = 49
download progress = 53
download progress = 55
download progress = 57
download progress = 60
download progress = 62
download progress = 64
download progress = 66
download progress = 71
download progress = 77
download progress = 77
download progress = 80
download progress = 82
HTTP/1.1 200 OK
debug:{"desc":"OK","status":1000,"data":{"wendu":"3","ganmao":"昼夜温差很大，易发生感冒，请注意适当增减衣服，加强自我防护避免感冒。","forecast":[{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 6℃","type":"晴","low":"低温 -6℃","date":"22日星期四"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 6℃","type":"多云","low":"低温 -3℃","date":"23日星期五"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 5℃","type":"多云","low":"低温 -3℃","date":"24日星期六"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 5℃","type":"阴","low":"低温 -2℃","date":"25日星期天"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 4℃","type":"多云","low":"低温 -2℃","date":"26日星期一"}],"yesterday":{"fl":"3-4级","fx":"北风","high":"高温 5℃","type":"晴","low":"低温 -6℃","date":"21日星期三"},"aqi":"124","city":"北京"}}
download progress = 84
download progress = 86
download progress = 88
download progress = 91
download progress = 93
download progress = 95
download progress = 99
download progress = 100
HTTP/1.1 200 OK
resp={"error_code":2000,"msg":"OK","filepath":"uploadfiles/192.168.31.72_android_bug_1.png"}

下载过程有进度回调。

相关的libs包，可以在如下链接中下载：http://download.youkuaiyun.com/detail/nuptboyzhb/8362801

上述代码，既可以在J2SE,J2EE中使用，也可以在Android中使用，在android中使用时，需要相关的权限。

另外，测试所使用的Web项目为：https://github.com/nuptboyzhb/SSHMySQLDemo

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