【Servlet使用1】

建立包cn.rs.javaweb

建立a.html

    <form action="http://localhost:8080/Javaweb_war_exploded/hello3" method="post">
    <input type="hidden" name="action" value="login"/>
    <input type="hidden" name="username" value="root"/>
    <input type="submit">
</form>

内容

Web1

、package cn.rs.javaweb;

import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

public class Web1 implements Servlet {

    public Web1() {
        System.out.println("1.构造器方法！");
    }

    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("2.init！");
        //1.获取servlet程序的别名servlet-name的值
        System.out.println("HelloServlet程序的别名是：" + servletConfig.getServletName());
        //2.获取初始化参数init-param
        System.out.println("初始化参数username的值是：" + servletConfig.getInitParameter("username"));
        System.out.println("初始化参数url的值是：" + servletConfig.getInitParameter("url"));
        //获取ServletContext对象
        System.out.println(servletConfig.getServletContext());

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("3.Hello Servlet 被访问了！");

        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String method = httpServletRequest.getMethod();

        if ("GET".equals(method)) {
            doGet();
        } else if ("POST".equals(method)) {
            doPost();
        }
    }


    public void doGet() {
        System.out.println("get请求");
        System.out.println("get请求");
    }

    public void doPost() {
        System.out.println("post请求");
        System.out.println("post请求");
    }


    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {
        System.out.println("4.destroy!");
    }
}

Web2

package cn.rs.javaweb;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class Web2 extends HttpServlet {


    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        System.out.println("重写了init初始化方法！");
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        System.out.println("HelloServlet2的doGet方法");
//      也可以使用
        ServletConfig servletConfig = getServletConfig();
        System.out.println(servletConfig);

        System.out.println("初始化参数username的值是：" + servletConfig.getInitParameter("username"));
        System.out.println("初始化参数url的值是：" + servletConfig.getInitParameter("url"));
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("HelloServlet2的doPost方法");
    }
}

HelloServlet3

package cn.rs.javaweb;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HelloServlet3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("HelloServlet3的doPost方法");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("HelloServlet3的doGet方法");
    }
}

ContextServlet

package cn.rs.javaweb;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ContextServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        1.获取web。xml中配置的上下文参数context-param
        ServletContext context = getServletConfig().getServletContext();

        String username = context.getInitParameter("username");
        System.out.println("context-param参数username的值是：" + username);
        System.out.println("context-param参数password的值是：" + context.getInitParameter("password"));

//        2.获取当前的工程路径，格式：/工程路径
        System.out.println("当前工程路径:" + context.getContextPath());

//        3.获取工程部署后在服务器硬盘上的绝对路径
        System.out.println("工程部署的路径是：" + context.getRealPath("/"));

    }
}

ContextServlet1

package cn.rs.javaweb;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ContextServlet1 extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext context = getServletContext();

        System.out.println("保存之前：Context1 获取key1的值是：" + context.getAttribute("key1"));

        context.setAttribute("key1", "value1");

        System.out.println("Context1 中获取域数据key1的值是：" + context.getAttribute("key1"));
        System.out.println("Context1 中获取域数据key1的值是：" + context.getAttribute("key1"));
        System.out.println("Context1 中获取域数据key1的值是：" + context.getAttribute("key1"));
        System.out.println("Context1 中获取域数据key1的值是：" + context.getAttribute("key1"));
    }
}

ContextServlet2

package cn.rs.javaweb;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ContextServlet2 extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext context = getServletContext();
        System.out.println("Context2 中获取域数据key1的值是：" + context.getAttribute("key1"));
    }
}