Java HTTP请求

import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.util.ArrayList;import java.util.List;import java.util.Map;import org.apache.http.HeaderElement;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;import org.apache.http.message.BasicNameValuePair;import org.apache.http.params.CoreConnectionPNames;public class HttpHelper {	public static String postRequest(String url, Map
     
       parameters) throws Exception {		DefaultHttpClient httpclient = new DefaultHttpClient();		httpclient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 3000);		httpclient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, 3000);		httpclient.setHttpRequestRetryHandler(new DefaultHttpRequestRetryHandler(0, false));		HttpPost httpPost = new HttpPost(url);		List
      
        nvps = new ArrayList
       
        ();		for (String key : parameters.keySet()) {			nvps.add(new BasicNameValuePair(key, (String) parameters.get(key)));		}		//UrlEncodedFormEntity   将请求参数格式化为 http请求需要的格式		httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));		httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");						String charset = "utf-8";		InputStream is = null;		BufferedReader br = null;		try {			HttpResponse response = httpclient.execute(httpPost);			HttpEntity entity = response.getEntity();			int statusCode = response.getStatusLine().getStatusCode();			if (statusCode != 200) {				System.err.println("Method failed: " + response.getStatusLine().getStatusCode());				System.err.println("Http服务链路异常:服务器状态码为" + statusCode);			}			String responseCharSet = getContentCharSet(entity);			if ("ISO-8859-1".equals(responseCharSet)) {				charset = responseCharSet;			}			StringBuffer buf = new StringBuffer();// 拼接返回的字符串			if (entity != null) {				is = entity.getContent();				// 转换为字节输入流				br = new BufferedReader(new InputStreamReader(is, charset));				String body = null;				while ((body = br.readLine()) != null) {					buf.append(body);				}			}			return buf.toString();		} catch (Exception e) {			throw e;		} finally {			if (is != null) {                                //IO流一定要关闭  不然会耗费资源				is.close();				httpPost.releaseConnection();			}			if(br != null) {				br.close();			}		}	}        //获取请求连接的编码格式	private static String getContentCharSet(final HttpEntity entity) {		if (entity == null) {			throw new IllegalArgumentException("HTTP entity may not be null");		}		String charset = null;		if (entity.getContentType() != null) {			HeaderElement values[] = entity.getContentType().getElements();			if (values.length > 0) {				NameValuePair param = values[0].getParameterByName("charset");				if (param != null) {					charset = param.getValue();				}			}		}		return charset;	}}