HttpServletRequest

總結：

一、queryString就是附加在URL中帶的參數，這部分參數會被URLEncode。

二、url中帶的參數能夠和body中帶的參數相同，body中的多個參數也能夠相同。request.getParameter(name)只能返回一個值，若是url中包含該參數則返回url中的值，不然返回body中所帶的參數（若是body存在多個相同的，則取第一個）。

三、GET 不能經過Body傳輸數據。post採起x-www-form-urlencoded時，body編碼爲：paramA=valueA&paramB=valueB&......

四、只有使用的API須要從body讀流（如：request.getParameter()），則會把body中全部的流讀完，讀完以後，後續從流中再也讀不出數據。

五、若是先從流中讀取數據，則後續的可能利用流中數據的API（如：request.getParameter()）得不到數據。

六、post的body編碼爲form-data時，具體的body輸出爲：

 

Content-Disposition: form-data; name="ddd"; filename="test.txt"

Content-Type: text/plain

 

hello world!

 

----------------------------517080537389190054308391

Content-Disposition: form-data; name="dscsd"

 

違法而發weee

----------------------------517080537389190054308391--

 

1、示例一

doPost()以下：

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         //後從body讀流
         System.out.println("queryString:"+request.getQueryString());
         System.out.println("urI:"+request.getRequestURI());
         System.out.println("URL:"+request.getRequestURL());
         Map<String, String[]> params = request.getParameterMap();   
        for (String key : params.keySet()) {  
            String[] values = params.get(key);  
            for (int i = 0; i < values.length; i++) {  
                String value = values[i];  
            System.out.println("["+key+","+value+"]");   
            }  
        }  
         System.out.println("getParameter-name:"+request.getParameter("name"));
         System.out.println("getParameter-address:"+request.getParameter("address"));
         String body = getStreamAsString(request.getInputStream(), "utf-8");
        System.out.println("body:"+body+"|");
    }

A:請求以下

 

A:執行結果以下：

queryString:name=urlName urI:/Web
URL:http://localhost:8080/Web
[name,urlName]
[name,bodyname]
[name,duplicateName]
[address,bodyaddressaddress]
getParameter-name:urlName
getParameter-address:bodyaddressaddress
body:|

 

B:請求以下

 

B:執行結果以下：

queryString:null
urI:/Web
URL:http://localhost:8080/Web
[name,bodyname]
[name,duplicateName]
[address,bodyaddressaddress]
getParameter-name:bodyname
getParameter-address:bodyaddressaddress
body:|

 

2、示例二

doPost()代碼以下：

protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 先從body讀流
        String body = getStreamAsString(request.getInputStream(), "utf-8");
        System.out.println("body:" + body + "|");
        System.out.println("queryString:" + request.getQueryString());
        System.out.println("urI:" + request.getRequestURI());
        System.out.println("URL:" + request.getRequestURL());
        Map<String, String[]> params = request.getParameterMap();
        for (String key : params.keySet()) {
            String[] values = params.get(key);
            for (int i = 0; i < values.length; i++) {
                String value = values[i];
                System.out.println("[" + key + "," + value + "]");
            }
        }
        System.out.println("getParameter-name:" + request.getParameter("name"));
        System.out.println("getParameter-address:" + request.getParameter("address"));
    }

A:請求以下：

A:執行結果以下：

body:name=bodyname&name=duplicateName&address=bodyaddressaddress|
queryString:name=urlName
urI:/Web
URL:http://localhost:8080/Web
[name,urlName]
getParameter-name:urlName
getParameter-address:null

 

B:請求以下：

B:執行結果以下：

body:name=bodyname&name=duplicateName&address=bodyaddressaddress|
queryString:null
urI:/Web
URL:http://localhost:8080/Web
getParameter-name:null
getParameter-address:null