httpclient如何实现在一个连接中发送多次请求？

如题，最好能给个简单的demo,几行也可以，就是核心的在一个连接中允许多次发送请求的代码！谢谢各位了！我用的连接池，如下，就是想实现多次调用post均使用同一个打开的连接，如何实现？测试发现老是会重新建立连接（即新开端口进行通信）！

public class HttpClientTestDemo {

    public static final int MAX_TOTAL_CONNECTIONS = 400;

    public static final int MAX_ROUTE_CONNECTIONS = 100;

    public static final int CONNECT_TIMEOUT = 10000;

    public static final int SOCKET_TIMEOUT = 20000;

    public static final long CONN_MANAGER_TIMEOUT = 10000;

    public static HttpParams parentParams;

    public static PoolingClientConnectionManager cm;

    private static final HttpHost DEFAULT_TARGETHOST = new HttpHost("123.456.789.101", 80);
    public static HttpRequestRetryHandler httpRequestRetryHandler;

    static {

        SchemeRegistry schemeRegistry = new SchemeRegistry();

        schemeRegistry.register(
                new Scheme("http", 80, PlainSocketFactory.getSocketFactory()));

        schemeRegistry.register(
                new Scheme("https", 443, SSLSocketFactory.getSocketFactory()));

        cm = new PoolingClientConnectionManager(schemeRegistry);

        cm.setMaxTotal(MAX_TOTAL_CONNECTIONS);

        cm.setDefaultMaxPerRoute(MAX_ROUTE_CONNECTIONS);

        cm.setMaxPerRoute(new HttpRoute(DEFAULT_TARGETHOST), 20);        

        parentParams = new BasicHttpParams();

        parentParams.setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);

        parentParams.setParameter(ClientPNames.DEFAULT_HOST, DEFAULT_TARGETHOST);    //设置默认targetHost

        parentParams.setParameter(ClientPNames.COOKIE_POLICY, CookiePolicy.BROWSER_COMPATIBILITY);

        parentParams.setParameter(ClientPNames.CONN_MANAGER_TIMEOUT, CONN_MANAGER_TIMEOUT);

        parentParams.setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, CONNECT_TIMEOUT);

        parentParams.setParameter(CoreConnectionPNames.SO_TIMEOUT, SOCKET_TIMEOUT);

        parentParams.setParameter(ClientPNames.ALLOW_CIRCULAR_REDIRECTS, true);

        parentParams.setParameter(ClientPNames.HANDLE_REDIRECTS, true);

        //设置头信息,模拟浏览器
        Collection collection = new ArrayList();

        collection.add(new BasicHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)"));

        collection.add(new BasicHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"));

        collection.add(new BasicHeader("Accept-Language", "zh-cn,zh,en-US,en;q=0.5"));

        collection.add(new BasicHeader("Accept-Charset", "ISO-8859-1,utf-8,gbk,gb2312;q=0.7,*;q=0.7"));

        collection.add(new BasicHeader("Accept-Encoding", "gzip, deflate"));

        parentParams.setParameter(ClientPNames.DEFAULT_HEADERS, collection);

        //请求重试处理
        httpRequestRetryHandler = new HttpRequestRetryHandler() {

            @Override
            public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
                if (executionCount >= 3) {
                    // 如果超过最大重试次数，那么就不要继续了
                    return false;
                }
                if (exception instanceof NoHttpResponseException) {
                    // 如果服务器丢掉了连接，那么就重试
                    return true;
                }
                if (exception instanceof SSLHandshakeException) {
                    // 不要重试SSL握手异常
                    return false;
                }
                HttpRequest request = (HttpRequest) context.getAttribute(ExecutionContext.HTTP_REQUEST);
                boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
                if (idempotent) {
                    // 如果请求被认为是幂等的，那么就重试
                    return true;
                }
                return false;
            }

           
        };
    }
    private static String readHtmlContentFromEntity(HttpEntity httpEntity) throws ParseException, IOException {
        String html = "";
        Header header = httpEntity.getContentEncoding();
        {
            InputStream in = httpEntity.getContent();
            if (header != null && "gzip".equals(header.getValue())) {
                html = unZip(in);
            } else {
                html = readInStreamToString(in);
            }
            if (in != null) {
                in.close();
            }
        }
        return html;
    }
    private static String unZip(InputStream in) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        GZIPInputStream gis = null;
        try {
            gis = new GZIPInputStream(in);
            byte[] _byte = new byte[1024];
            int len = 0;
            while ((len = gis.read(_byte)) != -1) {
                baos.write(_byte, 0, len);
            }
            String unzipString = new String(baos.toByteArray(), "utf-8");
            return unzipString;
        } finally {
            if (gis != null) {
                gis.close();
            }
            if (baos != null) {
                baos.close();
            }
            if(in!=null)
            {
                in.close();
            }
        }
    }

    private static String readInStreamToString(InputStream in) throws IOException {
        StringBuilder str = new StringBuilder();
        String line;
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in, "utf-8"));
        while ((line = bufferedReader.readLine()) != null) {
            str.append(line);
            str.append("\r\n");
        }
        if (bufferedReader != null) {
            bufferedReader.close();
        }
        if(in!=null)
            in.close();
        return str.toString();
    }

    public static String post(DefaultHttpClient httpClient, String url) throws UnsupportedEncodingException {
        HttpGet httpGet = new HttpGet(url);
        String result = "";
        httpGet.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, DEFAULT_TARGETHOST);
         HttpResponse httpResponse;
        try {
            httpResponse = httpClient.execute(httpGet);//建立端口映射
            if (httpResponse.getStatusLine().getStatusCode() != 200) {
                httpGet.abort();
                return result;
            }
            result = readHtmlContentFromEntity(httpResponse.getEntity());
        } catch (ClientProtocolException e) {
            httpGet.abort();
            return e.toString();
        } catch (IOException ex) {
            httpGet.abort();
            return ex.toString();
        } finally {
            httpGet.releaseConnection();
            httpClient.close();
        }
        return result;
    }

    public static void main(String[] args) throws InterruptedException {
        Date start = new Date();
        DefaultHttpClient httpClient = new DefaultHttpClient(cm, parentParams);
        httpClient.setHttpRequestRetryHandler(httpRequestRetryHandler);
        try {
            post(httpClient, "https://www.baidu.com/index1.php");//这里的几个网址是随便举例的，实际页面是纯txt，没有任何其他元素
            post(httpClient, "https://www.baidu.com/index2.php");
            post(httpClient, "https://www.baidu.com/index3.php");
        } catch (UnsupportedEncodingException ex) {
            Logger.getLogger(HttpClientTestDemo.class.getName()).log(Level.SEVERE, null, ex);
        }
        Date end = new Date();
        System.out.println((end.getTime() - start.getTime()) / 1000.0 + " 秒");

    }
}