HttpClient4.x：Get和Post提交數據

HttpClient是一款用Java寫的很是好用的基於Http協議的客戶端編程工具包。具體舉例來說，用它能夠模擬form表單提交數據動做，能夠模擬訪問網頁動做及獲得網頁源碼內容等等，這兩點或許是咱們在工做中最經常使用到的。

這裏也主要是以介紹模擬form表單提交數據來介紹一下HttpClient，準確地講主要是4.x版本，由於我發如今平常中，HttpClient的使用都仍是使用3.x的版本，而如今HttpClient的官網上，都已是最新版本4.1.3了，3.x版本在官網不見絲毫蹤跡，進入到下載頁面也見不着3.x版本的下載。

HttpClient對於使用者而言，一個很是大的好處就是它的例子很是豐富，幾乎每一個功能都有對應的例子代碼，這裏講的模擬form表單提交數據也是來源於HttpClient自帶的例子。

1、Get提交方式

DefaultHttpClient httpclient = new DefaultHttpClient();
try {
//注：若是參數值爲中文的話，提交過去後可能會是亂碼
HttpGet httpget = new
HttpGet("http://www.xxx.com/x.jsp?username=zhangsan&age=20");
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
System.out.println("Login form get: " + response.getStatusLine());
//若是entity是流數據則關閉之
EntityUtils.consume(entity);
} finally {
// When HttpClient instance is no longer needed,
// shut down the connection manager to ensure
// immediate deallocation of all system resources
httpclient.getConnectionManager().shutdown();
}

2、Form表單Post提交方式

DefaultHttpClient httpclient = new DefaultHttpClient();
try {
HttpPost httpost = new HttpPost("http://www.xxx.com/x.jsp?");
List <NameValuePair> nvps = new ArrayList <NameValuePair>();
//提交兩個參數及值
nvps.add(new BasicNameValuePair("age", "20"));
nvps.add(new BasicNameValuePair("username", "張三"));
//設置表單提交編碼爲UTF-8
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));
HttpResponse response = httpclient.execute(httpost);
HttpEntity entity = response.getEntity();
System.out.println("Login form get: " + response.getStatusLine());
EntityUtils.consume(entity);
} finally {
// When HttpClient instance is no longer needed,
// shut down the connection manager to ensure
// immediate deallocation of all system resources
httpclient.getConnectionManager().shutdown();
}

在提交到的x.jsp中，咱們仍是像日常獲取一個form表單數據那樣處理就好了：

String username = request.getParameter("username");

 

HttpClient官方網址：http://hc.apache.org/

關於HttpClient的例子頁面，見：

http://hc.apache.org/httpcomponents-client-ga/examples.html

或者在下載後的目錄：

httpcomponents-client-4.1.3_src\httpclient\src\examples 。

目前HttpClient分兩部分，一部分是HttpClient，另外一部分是HttpCore，二者都要下載下來，上面的例子見：

httpcomponents-client-4.1.3_src\httpclient\src\examples\org\apache\http\examples\client\ClientFormLogin.java