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JavaWeb学习——Servlet+表单提交

Posted on In Valine:
4.5k 4 mins.
在Ecplise中采用Servlet进行表单提交

网上写servlet的大神不少，记录一下遇到的问题。

配置是ecplise+tomcat9.0

关于servlet的创建方法：项目右键->new->servlet，然后package和class的名字随便命名，之后全部默认或者点finish就好。

  • servlet配置现在有两种，网上比较多的是用xml来的，但是新版的可以通过 @配置注解，新生成的servlet是自带的，不需要任何配置
  • 一开始找到了一个直接用service的，但似乎它直接扩展了底层的内容，可以用doget和dopost来解决
  • 中文字符乱码问题，需要设置response.setCharacterEncoding(“UTF-8”)和request.setCharacterEncoding(“UTF-8”)。需要放在最前面，否则可能在传入值了以后就没用了。

这里写的是一个实现登录功能的表单提交的servlet，项目名字叫做Servlet_try4，表单一共就user和password两个内容，最后跳转到hellp.jsp显示登录状态

关于表单部分，在form里加上这个就好

1
<form action="servlet"  method="post">

至于表单内部的内容，记得写上name，servlet是根据name来获取的。

原来代码：

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package servlet.study;

import java.io.IOException;

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;

/**
 * Servlet implementation class Servlet_try4
 */
@WebServlet("/Servlet_try4")
public class Servlet_try4 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public Servlet_try4() {
		super();
		// TODO Auto-generated constructor stub
	}

	public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 设置字符编码
		request.setCharacterEncoding("utf8");
		// 从request对象中获取username,password
		String username = request.getParameter("user");
		String password = request.getParameter("password");

		// 给将要request的对象写入信息
		request.setAttribute("user", username);
		request.setAttribute("password", password);

		// 将页面转发到欢迎页面
		RequestDispatcher dispatcher = request.getRequestDispatcher("/hello.jsp");
		dispatcher.forward(request, response);
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

改进代码：

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package servlet.study;

import java.io.IOException;

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;

/**
 * Servlet implementation class Servlet_try4
 */
@WebServlet("/Servlet_try4")
public class Servlet_try4 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public Servlet_try4() {
		super();
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		// TODO Auto-generated method stub
		response.getWriter().append("Served at: ").append(request.getContextPath());

		// 设置字符编码
		request.setCharacterEncoding("UTF-8");

		// 从request对象中获取username,password
		String username = request.getParameter("user");
		String password = request.getParameter("password");

		// 给将要request的对象写入信息
		request.setAttribute("user", username);
		request.setAttribute("password", password);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");

		// TODO Auto-generated method stub
		doGet(request, response);

		// 将页面转发到欢迎页面
		RequestDispatcher dispatcher = request.getRequestDispatcher("/hello.jsp");
		dispatcher.forward(request, response);
	}

}

唔。。虽然这个可以成功，但是在后续学习上发现对于表单提交，最好把doGet的内容全部写到doPost里，这里就不更新了，但是希望可以注意一下~

附：doGet()和doPost()的区别

ps.这里只能实现通过submit做一个表单提交，但是对于很多网页来说需要或许数据库也要调用servlet，又或者想要在提交前做一些什么判断，这样子的话可以尝试一下ajax来跳转到servlet。

搬运自CSDN：https://blog.csdn.net/yueyue200830/article/details/84984287