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Java EE WEB工程师培训-JDBC+Servlet+JSP整合开发之12.Servlet基础(2)

2009-06-19 21:43 609 查看

–提交表单的方法
• get
• post
–Servlet 生命周期
–使用Servlet 输出HTML页面
–获得Servlet初始化参数
–页面导航
• 请求重定向
–response.sendRedirect(“url”);
• 请求转发
–request.getRequestDispatcher(“url”).forward(request,response);
• 请求包含
–request.getRequestDispatcher(“url”).include(request,response); ############Michael分割线################ 全局参数对全局生效，我们来测试一下 ServletBasic2.java package com.michael.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

public class ServletBasic2 extends HttpServlet {

        /**
         * Constructor of the object.
         */
        public ServletBasic2() {
                super();
        }

        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
                super.destroy(); // Just puts "destroy" string in log
                // Put your code here
        }

        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the GET method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the POST method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occure
         */
        public void init() throws ServletException {
                Enumeration enu = this.getServletContext().getInitParameterNames();
                while(enu.hasMoreElements()){
                        String name = (String) enu.nextElement();
                        String value = this.getServletContext().getInitParameter(name);
                        System.out.println(name+":"+value);
                }
        }

}
< 1c6f3 /div> 测试一下

–局部参数
• web.xml 配置

• 获得

web.xml <?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
        xmlns="http://java.sun.com/xml/ns/j2ee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
        <context-param>
                <param-name>driver</param-name>
                <param-value>com.mysql.jdbc.Driver</param-value>
        </context-param>
        <context-param>
                <param-name>url</param-name>
                <param-value>jdbc:mysql://localhost:3306/jdbc_db</param-value>
        </context-param>
    <servlet>
        <servlet-name>ServletBasic</servlet-name>
        <servlet-class>com.michael.servlet.ServletBasic</servlet-class>
        <init-param>
                <param-name>username</param-name>
                <param-value>michael</param-value>
        </init-param>
        <init-param>
                <param-name>password</param-name>
                <param-value>111222</param-value>
        </init-param>
    </servlet>
    <servlet>
        <servlet-name>ServletBasic2</servlet-name>
        <servlet-class>com.michael.servlet.ServletBasic2</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ServletBasic</servlet-name>
        <url-pattern>/servlet/ServletBasic</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>ServletBasic2</servlet-name>
        <url-pattern>/servlet/ServletBasic2</url-pattern>
    </servlet-mapping>

</web-app>

ServletBasic.java package com.michael.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

public class ServletBasic extends HttpServlet {

        /**
         * Constructor of the object.
         */
        public ServletBasic() {
                super();
                System.out.println("-----ServletBasic-----");
        }

        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
                super.destroy();
                System.out.println("-----destroy-----");
        }

        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
                System.out.println("-----doGet-----");

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the GET method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
                System.out.println("-----doPost-----");
                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the POST method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occure
         */
        public void init() throws ServletException {
                /*
                //第一种方法
                String driver = this.getServletContext().getInitParameter("driver");
                String url = this.getServletContext().getInitParameter("url");
                System.out.println(driver);
                System.out.println(url);
                //第二种方法
                Enumeration enu = this.getServletContext().getInitParameterNames();
                while(enu.hasMoreElements()){
                        String name = (String) enu.nextElement();
                        String value = this.getServletContext().getInitParameter(name);
                        System.out.println(name+":"+value);
                }
                */
                String username = this.getInitParameter("username");
                String password = this.getInitParameter("password");
                System.out.println(username);
                System.out.println(password);
                System.out.println("-----init-----");
        }

        @Override
        protected void service(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException {
                // TODO Auto-generated method stub
                System.out.println("-----service-----");
        }
}

ServletBasic2.java package com.michael.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

public class ServletBasic2 extends HttpServlet {

        /**
         * Constructor of the object.
         */
        public ServletBasic2() {
                super();
        }

        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
                super.destroy(); // Just puts "destroy" string in log
                // Put your code here
        }

        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the GET method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the POST method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occure
         */
        public void init() throws ServletException {
                /*
                Enumeration enu = this.getServletContext().getInitParameterNames();
                while(enu.hasMoreElements()){
                        String name = (String) enu.nextElement();
                        String value = this.getServletContext().getInitParameter(name);
                        System.out.println(name+":"+value);
                }
                */
                String username = this.getInitParameter("username");
                String password = this.getInitParameter("password");
                System.out.println(username);
                System.out.println(password);
        }

}

测试

现在调用第二个

• 页面导航
– 请求重定向
• response.sendRedirect(“url”);
– 请求转发
• request.getRequestDispatcher(“url”).forward(request,response);
– 请求包含
• request.getRequestDispatcher(“url”).forward(request,response); ServletBasic.java package com.michael.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

public class ServletBasic extends HttpServlet {

        /**
         * Constructor of the object.
         */
        public ServletBasic() {
                super();
                System.out.println("-----ServletBasic-----");
        }

        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
                super.destroy();
                System.out.println("-----destroy-----");
        }

        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
                String username = request.getParameter("username");
                String password = request.getParameter("password");
                System.out.println("username="+username);
                if(username!=null&&username.equals("redking")){
                        request.getRequestDispatcher("/successfull.html").forward(request,response);
                }else{
                        request.getRequestDispatcher("/failure.html").forward(request,response);
                }
                /*
                System.out.println("-----doGet-----");

                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the GET method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        */
        }

        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
                System.out.println("-----doPost-----");
                response.setContentType("text/html");
                PrintWriter out = response.getWriter();
                out
                                .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
                out.println("<HTML>");
                out.println("    <HEAD><TITLE>A Servlet</TITLE></HEAD>");
                out.println("    <BODY>");
                out.print("        This is ");
                out.print(this.getClass());
                out.println(", using the POST method");
                out.println("    </BODY>");
                out.println("</HTML>");
                out.flush();
                out.close();
        }

        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occure
         */
        public void init() throws ServletException {
                /*
                //第一种方法
                String driver = this.getServletContext().getInitParameter("driver");
                String url = this.getServletContext().getInitParameter("url");
                System.out.println(driver);
                System.out.println(url);
                //第二种方法
                Enumeration enu = this.getServletContext().getInitParameterNames();
                while(enu.hasMoreElements()){
                        String name = (String) enu.nextElement();
                        String value = this.getServletContext().getInitParameter(name);
                        System.out.println(name+":"+value);
                }
                */
                String username = this.getInitParameter("username");
                String password = this.getInitParameter("password");
                System.out.println(username);
                System.out.println(password);
                System.out.println("-----init-----");
        }
        /*
        @Override
        protected void service(HttpServletRequest arg0, HttpServletResponse arg1) throws ServletException, IOException {
                // TODO Auto-generated method stub
                System.out.println("-----service-----");
        }
        */
}

successfull.html <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <title>successfull.html</title>
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="this is my page">
        <meta http-equiv="content-type" content="text/html; charset=UTF-8">
        

    </head>
    <body>
        <h1>successfull!!!</h1>
    </body>
</html>

failure.html <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <title>failure.html</title>
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="this is my page">
        <meta http-equiv="content-type" content="text/html; charset=UTF-8">
        

    </head>
    <body>
        <h1>failure!!!</h1>
    </body>
</html>

输入用户名为redking进行测试

显示successfull!!!

输入其他用户名测试

显示failure!!!

看下显示信息

############Michael分割线################ 阅读更多

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