JSP和Servlet学习笔记1

1. 访问 WebContent 目录下的 JSP 文件

在 WebContent 目录下的文件可以直接在浏览器中访问。新建一个 test.jsp 文件

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    <% int value = 100; %>
    <h1>value is <%= value %></h1>
</body>
</html>

访问结果：

2. 访问 Servlet 需要配置 web.xml

新建一个类并继承 HttpServlet 或直接新建一个 Servlet

package indi.tracine.servlet.test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html; charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.print("This is TestServlet");
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //doGet(req, resp);
    }
}

在 web.xml 中配置该 Servlet 的 <servlet> 节点和 </servlet-mapping> 节点

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    version="3.1">
    <display-name>jee-proj</display-name>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
    <servlet>
        <servlet-name>TestServlet</servlet-name>
        <servlet-class>indi.tracine.servlet.test.TestServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>TestServlet</servlet-name>
        <url-pattern>/test</url-pattern>
    </servlet-mapping>
</web-app>

访问结果：

3. 访问 WEB-INF 目录下的 JSP 文件

WEB-INF是一个安全目录，客户端请求是无法访问该目录了下的文件，需要配置 web.xm l或利用 Servlet 跳转到该 jsp 文件

方法 1). 在 web.xm l中配置 WEB-INF 目录下的 jsp（output.jsp）文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    version="3.1">
    <display-name>jee-proj</display-name>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
    <servlet>
        <servlet-name>output</servlet-name>
        <jsp-file>/WEB-INF/output.jsp</jsp-file>
    </servlet>
    <servlet-mapping>
        <servlet-name>output</servlet-name>
        <url-pattern>/output</url-pattern>
    </servlet-mapping>
</web-app>

方法 2). 访问某个 Servlet，在 Servlet 内部转发到 jsp（output.jsp）文件（不是重定向）

package indi.tracine.servlet.test;

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

public class OutputServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        
        request.getRequestDispatcher("/WEB-INF/output.jsp").forward(request,response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //doGet(req, resp);
    }
}