HttpServletRequest

总结：

1、queryString就是附加在URL中带的参数，这部分参数会被URLEncode。

2、url中带的参数可以和body中带的参数相同，body中的多个参数也可以相同。request.getParameter(name)只能返回一个值，如果url中包含该参数则返回url中的值，否则返回body中所带的参数（如果body存在多个相同的，则取第一个）。

3、GET 不能通过Body传输数据。post采取x-www-form-urlencoded时，body编码为：paramA=valueA&paramB=valueB&......

4、只有使用的API需要从body读流（如：request.getParameter()），则会把body中所有的流读完，读完之后，后续从流中再也读不出数据。

5、如果先从流中读取数据，则后续的可能利用流中数据的API（如：request.getParameter()）得不到数据。

6、post的body编码为form-data时，具体的body输出为：

 

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

Content-Type: text/plain

 

hello world!

 

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

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

 

违法而发weee

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

一、示例一

doPost()如下：

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         //后从body读流
         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:请求如下

A:执行结果如下：

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:请求如下

B:执行结果如下：

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

二、示例二

doPost()代码如下：

protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 先从body读流
        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:请求如下：

A:执行结果如下：

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:请求如下：

B:执行结果如下：

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