Request-获取请求参数中文乱码问题处理、请求转发

Request-获取请求参数中文乱码问题处理

　　中文乱码问题：

　　　　get方式：tomcat 8 已经将get方式乱码问题解决了

　　　　post方式：会乱码

　　　　解决：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

package com.example.request;

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("/requestDemo7")
public class RequestDemo7 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.设置流的编码
        request.setCharacterEncoding("utf-8");

        //获取请求参数username
        String username = request.getParameter("username");

        System.out.println(username);
    }

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

        this.doPost(request,response);
    }
}

Request-请求转发

　　请求转发：一种在服务器内部的资源跳转方式

　　　　1. 步骤：

　　　　　　1. 通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)

　　　　　　2. 使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response)

　　　　2. 特点：

　　　　　　1. 浏览器地址栏路径不发生变化

　　　　　　2. 只能转发到当前服务器内部资源中。

　　　　　　3. 转发是一次请求

package com.example.request;

import javax.servlet.RequestDispatcher;
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;

@WebServlet("/requestDemo8")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo8888被访问了。。。");
        //转发到demo9资源
/*
        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");
        requestDispatcher.forward(request,response);
        */

        //存储数据到request域中
        request.setAttribute("msg","hello");

        request.getRequestDispatcher("/requestDemo9").forward(request,response);
        //request.getRequestDispatcher("http://www.itcast.cn").forward(request,response);

    }

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

        this.doPost(request,response);
    }
}

package com.example.request;

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;

@WebServlet("/requestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取数据
        Object msg = request.getAttribute("msg");
        System.out.println(msg);

        System.out.println("demo9999被访问了。。。");

    }

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

        this.doPost(request,response);
    }
}