安道生網站技術練功房 - 分享經驗，累積智慧

預先安裝函式庫：Apache Commons HttpClient 3.x, Apache Commons Codec, Apache Commons Logging
程式碼：
httpclient.jsp:

<%@ page contentType="text/html;charset=big5" %>
<%@ page import="org.apache.commons.httpclient.*" %>
<%@ page import="org.apache.commons.httpclient.methods.*" %>
<%@ page import="org.apache.commons.httpclient.params.HttpMethodParams" %>
<%@ page import="java.io.*" %>
<%    
    String url = "http://tw.stock.yahoo.com/";
    
    String stockId = request.getParameter("stock_id");
    if (stockId != null) { 
      url += "q/q?s="+stockId;
    }
    
    // Create an instance of HttpClient.
    HttpClient client = new HttpClient();

    // Create a method instance.
    HttpMethod method = new GetMethod(url);
    
    // Provide custom retry handler is necessary
    method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, 
    		new DefaultHttpMethodRetryHandler(3, false));

    try {
      // Execute the method.
      int statusCode = client.executeMethod(method);

      if (statusCode != HttpStatus.SC_OK) {
        System.err.println("Method failed: " + method.getStatusLine());
      }

      // Read the response body.
      byte[] responseBody = method.getResponseBody();

      // Deal with the response.
      // Use caution: ensure correct character encoding and is not binary data
      //System.out.println(new String(responseBody));
      
      String result = new String(responseBody, "Big5");
      if (stockId != null) {        
        result = result.substring(result.indexOf("nowrap><b>")+"nowrap><b>".length());
        result = result.substring(0, result.indexOf("</b>"));
        out.println(stockId + " Price Now: " + result);
      } else {
        out.println(result);
      }
    } catch (HttpException e) {
      System.err.println("Fatal protocol violation: " + e.getMessage());
      e.printStackTrace();
    } catch (IOException e) {
      System.err.println("Fatal transport error: " + e.getMessage());
      e.printStackTrace();
    } finally {
      // Release the connection.
      method.releaseConnection();
    } 
%>

參考資料：
http://hc.apache.org/httpclient-3.x/tutorial.html

改用Apache HttpComponents HttpClient 4撰寫的版本：
httpclient4.jsp:

<%@ page contentType="text/html;charset=big5" %>
<%@ page import="java.io.IOException" %>
<%@ page import="org.apache.http.client.ClientProtocolException" %>
<%@ page import="org.apache.http.client.HttpClient" %>
<%@ page import="org.apache.http.client.ResponseHandler" %>
<%@ page import="org.apache.http.client.methods.HttpGet" %>
<%@ page import="org.apache.http.impl.client.BasicResponseHandler" %>
<%@ page import="org.apache.http.impl.client.DefaultHttpClient" %>
<%    
    String url = "http://tw.stock.yahoo.com/";
    
    String stockId = request.getParameter("stock_id");
    if (stockId != null) { 
      url += "q/q?s="+stockId;
    }
    
   // Create an instance of HttpClient.
    HttpClient httpclient = new DefaultHttpClient();
    try {
    	// Create an HttpGet method instance.
    	HttpGet httpget = new HttpGet(url);

        System.out.println("executing request " + httpget.getURI());

        // Create a response handler
        ResponseHandler<String> responseHandler = new BasicResponseHandler();
        String responseBody = httpclient.execute(httpget, responseHandler);
        if (stockId != null) {
        	responseBody = responseBody.substring(responseBody.indexOf("nowrap><b>")+"nowrap><b>".length());
        	responseBody = responseBody.substring(0, responseBody.indexOf("</b>"));					
    		out.println(stockId + " Price Now: " + responseBody);
        } else {
        	out.println(responseBody);
        }
    } catch (ClientProtocolException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	} finally {
        // When HttpClient instance is no longer needed,
        // shut down the connection manager to ensure
        // immediate deallocation of all system resources
        httpclient.getConnectionManager().shutdown();
    }   
%>