Request获取请求体数据和Request获取请求参数通用方式介绍

Request获取请求体数据

获取请求体数据：

　　请求体：只要POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数

　　步骤：

　　　　1.获取流对象

　　　　　　BufferedReader getReader()：获取字符输入流，只能操作字符数据

　　　　　　ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据

　　　　2.再从流对象中拿数据

regist.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>
<form action="/servlet/requestD5" method="post">
    <input type="text" placeholder="请输入用户名" name="username"><br>
    <input type="text" placeholder="请输入密码" name="password">
    <input type="submit" value="注册">
</form>
</body>
</html>

@WebServlet("/requestD5")
public class RequestD5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求消息体

        //获取字符流
        BufferedReader br = request.getReader();
        //读取数据
        String len = null;
        while ((len=br.readLine())!=null){
            System.out.println(len);
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    }
}

Request获取请求参数通用方式介绍

1.获取请求参数通用方式：

　　1.String getParameter(String name)：根据参数名称获取参数值

　　2.String[] getParameterValues(String name)：根据参数名称获取参数值的数组 hobby=xx&hobby=game

　　3.Enumeration<String> getParameterNames()：获取所有请求的参数名称

　　4.Map<String,String[]> getParameterMap():获取所有参数的map集合

Request获取请求参数通用方式演示

@WebServlet("/requestD6")
public class RequestD6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //post获取请求参数

        //根据参数名称获取参数值
        String username = request.getParameter("username");
        /*System.out.println("post");
        System.out.println(username);*/
        //根据参数名称获取参数值的数组
        String[] hobbies = request.getParameterValues("hobby");
        /*for (String hobby : hobbies) {
            System.out.println(hobby);
        }*/

        //获取所有请求的参数名称
        Enumeration<String> parameterNames = request.getParameterNames();
        /*while (parameterNames.hasMoreElements()){
            String name = parameterNames.nextElement();
            System.out.println(name);
            String value = request.getParameter(name);
            System.out.println(value);
            System.out.println("--------------");
        }*/

        //获取所有参数的map集合
        Map<String, String[]> parameterMap = request.getParameterMap();
        //遍历
        Set<String> keyset = parameterMap.keySet();
        for (String name : keyset) {
            //获取键获取值
            String[] values = parameterMap.get(name);
            System.out.println(name);
            for (String value : values) {
                System.out.println(value);
            }
            System.out.println("-------------");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        /*String username = request.getParameter("username");
        System.out.println("post");
        System.out.println(username);*/
        this.doPost(request, response);
    }
}