JSP基础--servlet

墨蓝 2022-07-14 00:40 168阅读 0赞

创建一个JavaWeb项目  
  
  
1、eclipse新建 Dynamic Web Project，名字为  jsp

2、helloservlet类

package com.jsp;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    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 helloservlet
     */
    // @WebServlet("/helloservlet")
    public class helloservlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
    
    	@Override
    	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    		System.out.println("doget");
    		//可以取得一些request的信息
    		System.out.println(req.getRequestURI());
    		System.out.println(req.getRequestURL());
    		System.out.println(req.getRemoteAddr());
    		//Response返回给页面的信息
    		resp.setContentType("text/html;charset=utf-8");
    		PrintWriter out = resp.getWriter();
    		out.write("<h1>我是一个servlet页面！</h1>");
    		out.flush();
    		out.close();
    	}
    
    	@Override
    	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    		System.out.println("dopost");
    	}
    
    	@Override
    	public void destroy() {
    		System.out.println("destroy");
    		super.destroy();
    	}
    
    	@Override
    	public void init() throws ServletException {
    		System.out.println("init");
    		super.init();
    	}
    
    }

3、web.xml文件配置servlet

<servlet>
      	<servlet-name>helloservlet</servlet-name>
      	<servlet-class>com.jsp.helloservlet</servlet-class>   //servlet类，Ctrl点击，能跳转OK
      </servlet>
      <servlet-mapping>
      	
      	<servlet-name>helloservlet</servlet-name>         //<servlet>中的<servlet-name>
      	
      	<url-pattern>/hello</url-pattern>                 //url路径
      </servlet-mapping>

4、访问流程

页面访问：http://127.0.0.1:8080/jsp/hello
    http://127.0.0.1:8080    IP+PORT
    /jsp    项目名称
    /hello  web.xml==拦截<url-pattern>/hello</url-pattern>==跳转<servlet-name>helloservlet</servlet-name>==执行com.jsp.helloservlet类

5、doGet与doPost

访问doGet
    直接访问servlet            http://127.0.0.1:8080/jsp/hello
    在servlet后加参数          http://127.0.0.1:8080/jsp/hello?username=haha 
    在form表单提交method="get"    <form name="login" method="get" action="hello">
    网页链接的弹出窗口         <a href="hello?userName=haaa">测试连接</a>
    
    访问doPost
    在form表单提交method="post"    <form name="login" method="post" action="hello">