Servlet

获取请求参数通用方式：
不论get还是post请求方式都可以使用下列方法来获取请求参数
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
3. Enumeration 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
* 中文乱码问题：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        //根据参数名称获取值
        String username = request.getParameter("username");
        System.out.println(username);
        //根据参数获取值的数组
        String[] hobbies = request.getParameterValues("hobby");
//        for (String hobby : hobbies) {
//            System.out.println(hobby);
//        }
        //获取所有参数的名称
        Enumeration<String> parameterNames = request.getParameterNames();
//        while (parameterNames.hasMoreElements()) {
//            String s = parameterNames.nextElement();
//            System.out.println(s);
//        }
        //获取所有参数的map集合
        Map<String, String[]> parameterMap = request.getParameterMap();
//        Set<String> strings = parameterMap.keySet();
//        for (String string : strings) {
//            String[] strings1 = parameterMap.get(string);
//            System.out.println(string);
//            for (String s : strings1) {
//                System.out.println(s);
//            }
//        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}