Servlet检索请求参数

Servlet为检索请求参数提供几种方法;

（1）getParameterMap()获取的参数是Map类型的，我们需要通过循环遍历来把它取出来

（2）getParameterVaules（）根据Vaule的值获取的参数是String类型的数组，

（3）getParameter（）通过name来获取请求的参数。

package com.zhengshanming;

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.net.URLDecoder;
import java.net.URLEncoder;
import java.net.UnknownServiceException;
import java.util.Map;

@WebServlet("/req")
public class ReqAndRes extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");  //POST中文乱码姐解决问你题
        //request对象 获取请求数据
        String name = req.getParameter("name"); //url?name = zhangsan
        resp.setHeader("content-type", "text/html;charset=utf-8");
        resp.getWriter().write("" + name + ", 欢迎你！" + "");
        //getParameterMap
        Map map = req.getParameterMap();
        for (String key : map.keySet()) {
            //username:zhangsan
            System.out.print(key + ":");
            //获取值
            String[] vaules = map.get(key);
            for (String vaule : vaules) {
                vaule = new String(vaule.getBytes("ISO-8859-1"), "utf-8");
                System.out.print(vaule + " ");
            }
            System.out.println();
        }
        //getParameterVaules
        String[] agr = req.getParameterValues("hobby");
        for (String a : agr) {
            System.out.println(a);
        }
        //getParameter
        String username = req.getParameter("username");
        String password = req.getParameter("password");


        //解决乱码问题
        

        username = new String(username.getBytes("ISO-8859-1"), "utf-8");
        System.out.println("username :" + username);
        System.out.println("password: " + password);


    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}