首页
学习
活动
专区
工具
TVP
发布
社区首页 >专栏 >JavaWeb(三)servlet

JavaWeb(三)servlet

作者头像
二十三年蝉
发布2018-02-28 11:39:56
1.1K0
发布2018-02-28 11:39:56
举报
文章被收录于专栏:闻道于事闻道于事

Servlet

* 什么是Servlet

是运行在web服务器端的Java应用程序,它使用JAVA语言编写,具有Java语言的优点。与Java程序的区别:Servlet对象主要封装了对Http请求的处理,并且他的运行需要Servlet容器的支持。

Servlet实质上就是按Servlet规范编写的Java类,他可以处理Web应用中的相关请求。Servlet是一个标准,由Sun公司定义,具体实现细节由Servlet容器进行实现,如Tomcat,JBoss等。

Servlet和JSP的区别:

1, 角色不同(视图层和控制层) 2, 编程方法不同 3, 是否需要重新编译 4, 运行速度不同

Servlet代码结构

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<a href="TestServlet2?username=aaaa">测试Servlet链接</a><br>
<form action="TestServlet" method="post">
<input type="submit" value="aaa">
</form>
</body>
</html>

Servlet类作为处理层

package com.hanqi.servlet;

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("")
public class TestServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //get方法接受的请求传到这里
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //post方法接受的请求传到这里
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        String username = config.getInitParameter("username");
        String password = config.getInitParameter("password");
        
        System.out.println(username);
        System.out.println(password);
    }

/*    @Override
    public void destroy() {
        System.out.println("servlet被销毁");
    }

    @Override
    public void init() throws ServletException {
        System.out.println("初始化servlet");
    }*/
    
}

web.xml配置,服务器启动先加载

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">


    <servlet>
        <servlet-name>TestServlet</servlet-name>
        <servlet-class>com.hanqi.servlet.TestServlet</servlet-class>
        <!-- 当这个标签中的数字是0或者不配置这个标签的时候, servlet默认使用的时候加载 -->
        <!-- 数字不是0的时候, 为启动服务器时加载, 数字越小, 优先级越高 -->
        <load-on-startup>1</load-on-startup>
        <init-param>
            <param-name>username</param-name>
            <param-value>admin</param-value>
        </init-param>
        <init-param>
            <param-name>password</param-name>
            <param-value>123456</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>TestServlet</servlet-name>
        <url-pattern>/TestServlet</url-pattern>
    </servlet-mapping>
</web-app>

用Servlet传入信息并打印

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
    <form action="TestServlet2" method="post">
        <input name="username" type="text" /><br> 
        <input name="password" type="text" /><br> 
        <input name="realname" type="text" /><br>
        <input type="submit" value="提交" />
    </form>
</body>
</html>
package com.hanqi.servlet;

import java.io.IOException;
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 TestServlet2
 */
@WebServlet("/TestServlet2")
public class TestServlet2 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
         //String name = request.getParameter("username");
         //request.getServletContext(); 
         //request.getSession();
         //request.getpagecontext
         
         out response.getWriter(); 
         System.out.println(name);
         
        
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");

        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String realname = request.getParameter("realname");

        response.getWriter()
                .append("username: " + username + "\npassword: " 
                        + password + "\nrealname: " + realname);
    }

    /**
     * @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);
    }

}

例子:

使用Servlet+JDBC实现登录注册

首先准备页面

注册页面:

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
    
    <form action="ZhueServlet" method="post">
        用户名:<input type="text" name="username"><br>
        密码:<input type="password" name="password"><br>
        确认密码:<input type="password" name="password1"><br>
        真实姓名:<input type="text" name="realname"><br>
        <input type="submit" value="提交"><br>
    </form>
</body>
</html>

登录页面:

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
    
    <form action="DengluServlet" method="post">
        用户名:<input type="text" name="username"><br>
        密码:<input type="password" name="password"><br>
        <input type="submit" value="提交"><br>
    </form>
</body>
</html>

主页:

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
    
    电话本
</body>
</html>

提示页面:

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
    
<%
    String code=request.getParameter("code");
    if("1".equals(code)){
        out.print("<h1>注册成功</h1><br>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if("2".equals(code)){
        out.print("<h1>密码不一致</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if("3".equals(code)){
        out.print("<h1>输入有误</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if("4".equals(code)){
        out.print("<h1>用户名已存在</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if("5".equals(code)){
        out.print("<h1>用户名不存在</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if("6".equals(code)){
        out.print("<h1>登录成功</h1>");
        out.print("<a href=index.jsp >查看电话本</a>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if(" ".equals(code)){
        out.print("<h1>注册成功</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
    if(" ".equals(code)){
        out.print("<h1>注册成功</h1>");
        out.print("<a href=denglu.jsp >登录</a><br>");
        out.print("<a href=zhuce.jsp >注册</a><br>");
    }
%>
</body>
</html>

然后准备工具:

JDBC初始化数据库类:

package com.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import com.util.JdbcConnectionUtil;

public class JdbcConnectionUtil {
    private static final String USERNAME = "test";
    private static final String PASSWORD = "test";
    private static final String URL = "jdbc:oracle:thin:@localhost:1521:xe";
    private static final String DRIVERCLASSNAME = "oracle.jdbc.OracleDriver";

    public static Connection getConnection(){
        Connection conn=null;
        try {
            Class.forName(DRIVERCLASSNAME);
            conn=DriverManager.getConnection(URL,USERNAME,PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
    public static void destroy(Connection conn){
        if(conn!=null){
            try {
                conn.close();
                conn=null;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            
        }
    }
    public static void main(String[] args) {
        System.out.println(JdbcConnectionUtil.getConnection());
    }
}

数据库操作类:

package com.util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Date;

import com.util.JdbcConnectionUtil;
import com.util.User;

public class MethodDal {
    private Connection con;
    private PreparedStatement pste;
    private ResultSet rs;
    //向表中添加数据
    public int insertData(){
        init();
        int i=-1;
        String sql="insert into puser values('c','c')";
        
        try {
            pste=con.prepareStatement(sql);
            i=pste.executeUpdate();//针对于增删改数据吗,返回受影响的行数
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return i;
    }
    //向表中添加数据
    public int insertData(User user){
        init();
        int i=-1;
        String sql="insert into puser values(?,?)";
        try {
            pste=con.prepareStatement(sql);
            pste.setString(1,user.getUsername());
            pste.setString(2, user.getPassword());
            i=pste.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return i;
    }
    //删除记录
    public int deleteDate(int id){
        
        return 0;
    }
    //查现有姓名
    public String selectName(String name){
        init();
        String sql="select * from puser p where p.pname=?";
        try {
            pste=con.prepareStatement(sql);
            pste.setString(1,name);
            rs = pste.executeQuery();
            while(rs.next()) {
                String pname=rs.getString("pname");
                if(pname!=null){
                    return pname;
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return "no";
    }
    //根据姓名查密码
    public String selectPwd(String name){
        init();
        String sql="select * from puser p where p.pname=?";
        try {
            pste=con.prepareStatement(sql);
            pste.setString(1,name);
            rs = pste.executeQuery();
            while(rs.next()) {
                String pwd=rs.getString("ppassword");
                return pwd;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return "wu";
    }
    public void init(){
        con=JdbcConnectionUtil.getConnection();
    }
}

用户类:

package com.util;

public class User {
    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

然后准备逻辑处理Servlet页面:

注册的Servlet页面:

package com.servlet;

import java.io.IOException;
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 com.util.MethodDal;
import com.util.User;

/**
 * Servlet implementation class ZhueServlet
 */
@WebServlet("/ZhueServlet")
public class ZhueServlet extends HttpServlet {
    
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ZhueServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");
        
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String password1=request.getParameter("password1");
        String realname=request.getParameter("realname");
        //调用方法判断传入的参数有没有空,都不为空才可以执行下去
        if(checkParam(username,password,password1)){
            if(password.equals(password1)){
                MethodDal m=new MethodDal();
                if(m.selectName(username).equals("no")){//调用方法根据用户名查询,如果返回no说明数据库没有此用户名,可以注册
                    User user=new User();//实例化用户类并添加信息
                    user.setUsername(username);
                    user.setPassword(password);
                    m.insertData(user);//将实例化的用户传到添加用户的方法
                    response.sendRedirect("message.jsp?code=1");
                }else{
                    response.sendRedirect("message.jsp?code=4");
                }
            }else{
                response.sendRedirect("message.jsp?code=2");
            }
        }else{
            response.sendRedirect("message.jsp?code=3");
        }
    }

    /**
     * @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);
    }
    //判断传入的参数有没有空的方法,只要有空的就返回false
    public boolean checkParam(String... args){//这样传参数代表参数个数不确定,传几个都可以
        for(String s : args){
            if("".equals(s)||s==null){
                return false;
            }
        }
        return true;
    }

}

登陆的Servlet页面:

package com.servlet;

import java.io.IOException;
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 com.util.MethodDal;
import com.util.User;

/**
 * Servlet implementation class DengluServlet
 */
@WebServlet("/DengluServlet")
public class DengluServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public DengluServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html; charset=utf-8");
        
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        
        MethodDal m=new MethodDal();
        //调用方法判断传入的参数有没有空,都不为空才可以执行下去
        if(checkParam(username,password)){
            if(!(m.selectName(username).equals("no"))){//调用方法根据用户名查询,如果返回不为no说明数据库有此用户
                if((m.selectPwd(username)).equals(password)){//根据用户名查询密码,并对比输入的密码和数据库的密码
                    
                    response.sendRedirect("message.jsp?code=6");
                }else{
                    response.sendRedirect("message.jsp?code=4");
                }
            }else{
                response.sendRedirect("message.jsp?code=5");
            }
        }else{
            response.sendRedirect("message.jsp?code=3");
        }
    }
    

    /**
     * @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);
    }
    //判断传入的参数有没有空的方法,只要有空的就返回false
    public boolean checkParam(String... args){//这样传参数代表参数个数不确定,传几个都可以
        for(String s : args){
            if("".equals(s)||s==null){
                return false;
            }
        }
        return true;
    }

}
本文参与 腾讯云自媒体分享计划,分享自作者个人站点/博客。
原始发表:2017-08-23 ,如有侵权请联系 cloudcommunity@tencent.com 删除

本文分享自 作者个人站点/博客 前往查看

如有侵权,请联系 cloudcommunity@tencent.com 删除。

本文参与 腾讯云自媒体分享计划  ,欢迎热爱写作的你一起参与!

评论
登录后参与评论
0 条评论
热度
最新
推荐阅读
目录
  • 例子:
  • 使用Servlet+JDBC实现登录注册
相关产品与服务
容器服务
腾讯云容器服务(Tencent Kubernetes Engine, TKE)基于原生 kubernetes 提供以容器为核心的、高度可扩展的高性能容器管理服务,覆盖 Serverless、边缘计算、分布式云等多种业务部署场景,业内首创单个集群兼容多种计算节点的容器资源管理模式。同时产品作为云原生 Finops 领先布道者,主导开源项目Crane,全面助力客户实现资源优化、成本控制。
领券
问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档