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Servlet与JSP进阶

请求与响应

请求的结构

  • Post具有请求体，Get无请求体

多端开发技巧

package com.jesse.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 UserAgentServlet
 */
@WebServlet("/ua")
public class UserAgentServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public UserAgentServlet() {
        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
        String  userAgent = request.getHeader("User-Agent");
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().println(userAgent);
        String output = "";
        if(userAgent.indexOf("Windows NT") != -1) {
            output = "<h1>这是PC端首页</h1>";
        }else  if(userAgent.indexOf("iPhone") != -1 || userAgent.indexOf("Android") != -1) {
            output = "<h1>这是移动端首页</h1>";
        }
        response.getWriter().println(output);
    }

}

响应的结构

HTTP常见状态码

ContentType的作用

请求转发与重定向

内容

Example

package com.jesse.servlet.direct;

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 CheckLoginServlet
 */
@WebServlet("/direct/check")
public class CheckLoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("用户登陆成功");

        //实现了请求转发的功能
        //request.getRequestDispatcher("/direct/index").forward(request, response);
        //响应重定向需要增加contextPath
        response.sendRedirect("/servlet_advanced/direct/index");
    }

}

请求转发和响应重定向的区别

设置请求自带属性

Example

package com.jesse.servlet.direct;

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 CheckLoginServlet
 */
@WebServlet("/direct/check")
public class CheckLoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("用户登陆成功");
        request.setAttribute("username", "admin");
        //实现了请求转发的功能
        request.getRequestDispatcher("/direct/index").forward(request, response);
        //响应重定向需要增加contextPath
        //response.sendRedirect("/servlet_advanced/direct/index");
    }

}

package com.jesse.servlet.direct;

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 IndexServlet
 */
@WebServlet("/direct/index")
public class IndexServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = (String)request.getAttribute("username");
        response.getWriter().println("This is index page!current username is " + username);
    }
}

Cookie与Session

Example

package com.jesse.servlet.cookie;

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

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

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("用户登录成功");
        Cookie cookie = new Cookie("user", "admin");
        cookie.setMaxAge(60*60*24*7);
        response.addCookie(cookie);
        response.getWriter().println("login success");
    }

}

package com.jesse.servlet.cookie;

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

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

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie[] cs = request.getCookies();
        if(cs == null) {
            response.getWriter().println("user not login");
            return;
        }
        String user = null;
        for(Cookie c : cs) {
            System.out.println(c.getName() + " : " +  c.getValue() );
            if(c.getName().equals("user")) {
                user = c.getValue();
                break;
            }
        }
        if(user == null) {
            response.getWriter().println("user not login");
        }else {
            response.getWriter().println("user:" + user);
        }
    }

}

Session

Session原理

Example

package com.jesse.servlet.session;

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 javax.servlet.http.HttpSession;

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

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("用户登录成功");
        //获取到用户会话Session对象
        HttpSession session = request.getSession();
        session.setAttribute("name", "张三");
        //request.getRequestDispatcher("/session/index").forward(request, response);
    }

}

package com.jesse.servlet.session;

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 javax.servlet.http.HttpSession;

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

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session =request.getSession();
        String name = (String)session.getAttribute("name");
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().println("这是首页，当前用户为：" + name);
    }

}

ServletContext

Example

package com.jessee.servlet.servletcontext;

import java.io.IOException;

import javax.servlet.ServletContext;
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 ServletContextInitServlet
 */
@WebServlet("/servletcontext/init")
public class ServletContextInitServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext context = request.getServletContext();
        context.setAttribute("copy", "jesse");
        response.getWriter().println("init success");
    }
}

package com.jessee.servlet.servletcontext;

import java.io.IOException;

import javax.servlet.ServletContext;
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 ServletContextDefalutServlet
 */
@WebServlet("/servletcontext/default")
public class ServletContextDefalutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

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

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext context = request.getServletContext();
        String copy = (String)context.getAttribute("copy");
        response.getWriter().println("<h1>"  + copy +  "</h1>");
    }

}

Java Web三大作用域对象

中文乱码解决

web.xml配置详解

JSP内置对象

Java Web打包与发布

posted @ 2020-04-27 20:35  JesseKkk  阅读(188)  评论(0)    收藏  举报