1.初学 servlet

2023-09-24 16:15:04

Servlet核心接口和类

创建servlet，除了实现Servlet接口之外，还可以继承 GenericServlet 或 HttpServlet。

HttpServlet类

继承HttpServlet类创建Servlet

package com.ws.servlet_;

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 HttpsServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("get请求");
    }

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

Servlet配置方法

注解方式配置

package com.ws.Servlet2;

import com.ws.servlet_.HttpsServlet;

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

@WebServlet(value = "/hello_http")//注解方式配置，value的值为请求的路径
public class BasicServlet extends HttpsServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("GET");
    }

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

requests对象

servlet中，get和post请求的数据都在HttpServletRequest对象中，两个核心接口是 ServletRequest、HttpServletRequ

方法

方法名	说明
String getParameter(String name)	根据表单组件名称获取提交的数据
void setCharacterEncoding(String charset)	指定每个请求的编码

get和post请求

通过get和post请求来获取注册页面的数据。

get方式

package com.ws.Servlet2;

import com.ws.servlet_.HttpsServlet;

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

@WebServlet(value = "/register")
public class RegisterServlet extends HttpsServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取用户请求发送的数据
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println("提交的数据"+username+"\t"+password);
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>
    <form action="/servlet_war_exploded/register" method="get">
        用户名：<input type="text" name="username"><br/>
        密码：<input type="password" name="password"><br/>
        <input type="submit" value="注册">
    </form>
</body>
</html>

post方式

package com.ws.Servlet2;

import com.ws.servlet_.HttpsServlet;

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

@WebServlet(value = "/register")
public class RegisterServlet extends HttpsServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //对request请求对象设置统一的编码，中文服务器端接收会乱码
        req.setCharacterEncoding("utf-8");
        //获取用户请求发送的数据
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println("提交的数据"+username+"\t"+password);
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>
    <form action="/servlet_war_exploded/register" method="post">
        用户名：<input type="text" name="username"><br/>
        密码：<input type="password" name="password"><br/>
        <input type="submit" value="注册">
    </form>
</body>
</html>

response对象

response对象用于响应客户端请求病向客户端输出信息。

response主要方法

方法名称	作用
setHeader(name,value)	设置响应信息头
setContentType(String)	设置响应文件类型、响应式的编码格式
setCharacterEncoding(String)	设置服务端响应内容编码格式
getWriter()	获取字符输出流

package com.ws.Servlet2;

import com.ws.servlet_.HttpsServlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(value = "/register")
public class RegisterServlet extends HttpsServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //对request请求对象设置统一的编码
        req.setCharacterEncoding("utf-8");
        //获取用户请求发送的数据
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        System.out.println("提交的数据"+username+"\t"+password);

//        //设置服务器端响应的编码格式
//        resp.setCharacterEncoding("utf-8");
//        //设置客户端响应内容的头内容的文件类型及编码格式
//        resp.setHeader("Content-type","text/html;charset=UTF-8");
        //同时设置服务器端的响应格式和客户端的头内容编码
        resp.setContentType("text/html;charset=UTF-8");

        //响应数据给客户端
        PrintWriter writer = resp.getWriter();
        writer.println("登录成功！");
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>
    <form action="/servlet_war_exploded/register" method="post">
        用户名：<input type="text" name="username"><br/>
        密码：<input type="password" name="password"><br/>
        <input type="submit" value="注册">
    </form>
</body>
</html>

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