Java实现http（post、get）请求

package com.wolaidai.credit.management.utils;

import com.alibaba.fastjson.JSON;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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.client.methods.HttpRequestBase;
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.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.BasicHeader;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.net.URI;
import java.nio.charset.Charset;
import java.util.*;
import java.util.Map.Entry;

public class HttpClientUtil {
	
	protected final Log LOG = LogFactory.getLog(HttpClientUtil.class);
	private static HttpClientUtil instance;
	protected Charset charset;
	
	private HttpClientUtil(){}
	
	public static HttpClientUtil getInstance() {
		return getInstance(Charset.defaultCharset());
	}
	
	public static HttpClientUtil getInstance(Charset charset){
        if(instance == null){
            instance = new HttpClientUtil();
        }
        instance.setCharset(charset);
        return instance;
    }
	
	public void setCharset(Charset charset) {
		this.charset = charset;
	}

	/**
	 * post请求 
	 */
    public String doPost(String url) throws Exception {
    	return doPost(url, null, null);
    }
        
	public String doPost(String url, Map params) throws Exception {
		return doPost(url, params, null);
	}
	
	public String doPost(String url, Map params, Map header) throws Exception {
		String body = null;
		try {
			// Post请求
			LOG.debug(" protocol: POST");
			LOG.debug("      url: " + url);
	        HttpPost httpPost = new HttpPost(url.trim());
	        // 设置参数
	        LOG.debug("   params: " + JSON.toJSONString(params));
	        httpPost.setEntity(new UrlEncodedFormEntity(map2NameValuePairList(params), charset));
	        // 设置Header
	        if (header != null && !header.isEmpty()) {
	        	LOG.debug("   header: " + JSON.toJSONString(header));
	        	for (Iterator> it = header.entrySet().iterator(); it.hasNext();) {
	        		Entry entry = (Entry) it.next();
	        		httpPost.setHeader(new BasicHeader(entry.getKey(), entry.getValue()));
	        	}
	        }
	        // 发送请求,获取返回数据
	        body = execute(httpPost);
		} catch (Exception e) {
			throw e;
		}
		LOG.debug("   result: " + body);
		return body;
	}

	/**
	 * postJson请求
	 */
	public String doPostJson(String url, Map params) throws Exception {
		return doPostJson(url, params, null);
	}

	public String doPostJson(String url, Map params, Map header) throws Exception {
		String json = null;
        if (params != null && !params.isEmpty()) {
        	for (Iterator> it = params.entrySet().iterator(); it.hasNext();) {
				Entry entry = (Entry) it.next();
				Object object = entry.getValue();
				if (object == null) {
					it.remove();
				}
			}
        	json = JSON.toJSONString(params);
		}
		return postJson(url, json, header);
	}

	public String doPostJson(String url, String json) throws Exception {
		return doPostJson(url, json, null);
	}

	public String doPostJson(String url, String json, Map header) throws Exception {
		return postJson(url, json, header);
	}

	private String postJson(String url, String json, Map header) throws Exception {
		String body = null;
		try {
			// Post请求
			LOG.debug(" protocol: POST");
			LOG.debug("      url: " + url);
	        HttpPost httpPost = new HttpPost(url.trim());
	        // 设置参数
	        LOG.debug("   params: " + json);
	        httpPost.setEntity(new StringEntity(json, ContentType.DEFAULT_TEXT.withCharset(charset)));
	        httpPost.setHeader(new BasicHeader("Content-Type", "application/json"));
	        LOG.debug("     type: JSON");
	        // 设置Header
	        if (header != null && !header.isEmpty()) {
	        	LOG.debug("   header: " + JSON.toJSONString(header));
	        	for (Iterator> it = header.entrySet().iterator(); it.hasNext();) {
	        		Entry entry = (Entry) it.next();
	        		httpPost.setHeader(new BasicHeader(entry.getKey(), entry.getValue()));
	        	}
	        }
	        // 发送请求,获取返回数据
	        body = execute(httpPost);
		} catch (Exception e) {
			throw e;
		}
		LOG.debug("  result: " + body);
		return body;
	}

	/**
	 * get请求
	 */
	public String doGet(String url) throws Exception {
		return doGet(url, null, null);
	}

	public String doGet(String url, Map header) throws Exception {
		return doGet(url, null, header);
	}

	public String doGet(String url, Map params, Map header) throws Exception {
		String body = null;
		try {
			// Get请求
			LOG.debug("protocol: GET");
			HttpGet httpGet = new HttpGet(url.trim());
			// 设置参数
			if (params != null && !params.isEmpty()) {
	            String str = EntityUtils.toString(new UrlEncodedFormEntity(map2NameValuePairList(params), charset));
	            String uri = httpGet.getURI().toString();
	            if(uri.indexOf("?") >= 0){
	            	httpGet.setURI(new URI(httpGet.getURI().toString() + "&" + str));
	            }else {
	            	httpGet.setURI(new URI(httpGet.getURI().toString() + "?" + str));
	            }
			}
			LOG.debug("     url: " + httpGet.getURI());
			// 设置Header
	        if (header != null && !header.isEmpty()) {
	        	LOG.debug("   header: " + header);
	        	for (Iterator> it = header.entrySet().iterator(); it.hasNext();) {
	        		Entry entry = (Entry) it.next();
	        		httpGet.setHeader(new BasicHeader(entry.getKey(), entry.getValue()));
	        	}
	        }
			// 发送请求,获取返回数据
			body =  execute(httpGet);
		} catch (Exception e) {
			throw e;
		}
		LOG.debug("  result: " + body);
		return body;
	}

	/**
	 * 下载文件
	 */
	public void doDownload(String url, String path) throws Exception {
		download(url, null, path);
	}
	
	public void doDownload(String url, Map params, String path) throws Exception {
		download(url, params, path);
	}
	
	/**
	 * 上传文件
	 */
	public String doUpload(String url, String name, String path) throws Exception {
		Map params = new HashMap();
		params.put(name, new File(path));
		return doUpload(url, params);
	}
	
	public String doUpload(String url, Map params) throws Exception {
		String body = null;
		// Post请求
        HttpPost httpPost = new HttpPost(url.trim());
        // 设置参数
        MultipartEntityBuilder entityBuilder = MultipartEntityBuilder.create();
        entityBuilder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
        entityBuilder.setCharset(charset);
        if (params != null && !params.isEmpty()) {
        	Iterator it = params.keySet().iterator();
			while (it.hasNext()) {
				String key = it.next();
				Object value = params.get(key);
				if (value instanceof File) {
					FileBody fileBody = new FileBody((File) value);
    		        entityBuilder.addPart(key, fileBody);
				} else {
					entityBuilder.addPart(key, new StringBody(String.valueOf(value), ContentType.DEFAULT_TEXT.withCharset(charset)));
				}
			}
        }
        HttpEntity entity = entityBuilder.build();
        httpPost.setEntity(entity);
        // 发送请求,获取返回数据
        body = execute(httpPost);
		return body;
	}
	
	private void download(String url, Map params, String path) throws Exception {
		// Get请求
		HttpGet httpGet = new HttpGet(url.trim());
		if (params != null && !params.isEmpty()) {
			// 设置参数
			String str = EntityUtils.toString(new UrlEncodedFormEntity(map2NameValuePairList(params)));
			String uri = httpGet.getURI().toString();
			if (uri.indexOf("?") >= 0) {
				httpGet.setURI(new URI(httpGet.getURI().toString() + "&" + str));
			} else {
				httpGet.setURI(new URI(httpGet.getURI().toString() + "?" + str));
			}
		}
        // 发送请求,下载文件
        downloadFile(httpGet, path);
	}
 
	private void downloadFile(HttpRequestBase requestBase, String path) throws Exception {
		CloseableHttpClient httpclient = HttpClients.createDefault();
		try {
			CloseableHttpResponse response = httpclient.execute(requestBase);
			try {
				HttpEntity entity = response.getEntity();
				
				if (entity != null) {
					byte[] b = EntityUtils.toByteArray(entity);
					OutputStream out = new BufferedOutputStream(new FileOutputStream(new File(path)));
					out.write(b);
					out.flush();
					out.close();
                }
				EntityUtils.consume(entity);
			} catch (Exception e) {
				throw e;
			} finally {
				response.close();
			}
		} catch (Exception e) {
			throw e;
		} finally {
			httpclient.close();
		}
	}
 
	private String execute(HttpRequestBase requestBase) throws Exception {
		CloseableHttpClient httpclient = HttpClients.createDefault();
		String body = null;
		try {
			CloseableHttpResponse response = httpclient.execute(requestBase);
			try {
				HttpEntity entity = response.getEntity();
				
				if (entity != null) {
					body = EntityUtils.toString(entity, charset.toString());
                }
				EntityUtils.consume(entity);
			} catch (Exception e) {
				throw e;
			}finally {
				response.close();
			}
		} catch (Exception e) {
			throw e;
		} finally {
			httpclient.close();
		}
		return body;
	}
	
	private List map2NameValuePairList(Map params) {
		if (params != null && !params.isEmpty()) {
			List list = new ArrayList();
			Iterator it = params.keySet().iterator();
			while (it.hasNext()) {
				String key = it.next();
				if(params.get(key) != null) {
					String value = String.valueOf(params.get(key));
					list.add(new BasicNameValuePair(key, value));
				}
			}
			return list;
		}
		return null;
	}
}

直接调用即可

HttpClientUtil.getInstance().doPost(url,Data);