1.实现servlet打印日志#

开发一个动态web资源，即开发一个Java程序向浏览器输出数据，需要完成以下2个步骤：

1.编写一个Java类，实现Servlet接口#

开发一个动态web资源必须实现javax.servlet.Servlet接口，Servlet接口定义了Servlet引擎与Servlet程序之间通信的协议约定

以下是MyServlet.java文件中的代码（写的这个类的名字叫做MyServlet）：

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package org.MyServlet.MyServlet;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

//开发一个动态web资源必须实现javax.servlet.Servlet接口
//Servlet接口定义了Servlet引擎与Servlet程序之间通信的协议约定

//Q:MyServlet完成了一个动态网页程序，或者说是一个功能，如何让客户端能否准确得找到我们得这个Servlet服务
//A:服务器需要预先为我们预留出扩展接口，我们只需要按照一定的规则去提供相应的扩展功能

//Q:如何和服务器进行通讯
//A:web.xml就是服务器提供给我们的完成功能的地方
public class MyServlet implements Servlet{

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public ServletConfig getServletConfig() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public String getServletInfo() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void init(ServletConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        
    }

    //所有客户端请求会自动调用Service方法进行处理
    //ServletRequest    是一个对象，封装所有HTTP请求信息
    //ServletResponse    是一个对象，封装所有HTTP响应信息
    //这两个对象是Tomcat服务器给我们的
    @Override
    public void service(ServletRequest arg0, ServletResponse arg1)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        
        System.out.println("执行 MyServlet 的 service() 方法。。。。。");
    }

}

关于其中的Service方法的一些Tip：　　

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//所有客户端请求会自动调用Service方法进行处理
//ServletRequest 是一个对象，封装所有HTTP请求信息
//ServletResponse 是一个对象，封装所有HTTP响应信息
//这两个对象是Tomcat服务器给我们的

此外，如果是只实现service方法，则称为适配器模式

以下是web.xml文件中的代码：

MyServlet

index.html
index.htm
index.jsp
default.html
default.htm
default.jsp


//定义一个Servlet服务
//Servlet服务的名字叫做aaa

aaa
org.MyServlet.MyServlet.MyServlet


//定义一个Servlet服务的映射关系
//Servlet服务的名字叫做aaa
//请求的路径是/myServlet.do

//1.服务器启动模式加载webapps下面所有的应用，加载web应用的时候会读取每个应用的web。xml文件
//2.客户单发送请求http://127.0.0.1:8080/MyServlet/myServlet.do
//3.请求就找到http://127.0.0.1:8080，找到MyServlet(Context)
//去mapping里面查找/myServlet.do,如果找到，定位到aaa
//4.去Servlet的定义里面查找Servlet-name是aaa的Servlet服务
//然后定位到org.MyServlet.MyServlet.MyServlet,执行该class的service方法

aaa
/myServlet.do

然后在浏览器中输入

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http://127.0.0.1:8080/MyServlet/myServlet.do

便可以在Tomcat中看到

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执行 MyServlet 的 service() 方法。。。。。

2.把开发好的Java类部署到web服务器中#

2.实现servlet打印HelloWorld#

该工程的功能是在页面上输出一段话

首先在src里面新建一个class,在interface里面添加javax.servlet.Servlet

以下是HelloServlet.java中的代码：

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package org.common.Servlet;

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

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class HelloServlet implements Servlet {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

    @Override
    public ServletConfig getServletConfig() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public String getServletInfo() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void init(ServletConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }
    
    //开发完成之后要告诉服务器我的存在，就要在web。xml里面继续写代码
    @Override
    public void service(ServletRequest arg0, ServletResponse arg1)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        //获取一个输出流，就可以对页面写出内容
        PrintWriter pw = arg1.getWriter();
        pw.println("终于成功了！");
        pw.close();
    }

}

以下是web.xml文件中的代码：

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<?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">
  <display-name>HelloApp</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>
  
  <!-- 定义Servlet服务 -->
  <servlet>
      <servlet-name>hello</servlet-name>    <!--随便取-->    
      <servlet-class>org.common.Servlet.HelloServlet</servlet-class>    <!--取包名。类名-->
  </servlet>
  
  <!-- 定义映射关系 -->
  <servlet-mapping>
      <!-- 注意：mapping里面的servlet-name在Servlet的定义里面一定要有匹配的，否则启动报错 -->
      <servlet-name>hello</servlet-name>
      <url-pattern>/hello</url-pattern>
  </servlet-mapping>
</web-app>&nbsp;

访问的网址是

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http://127.0.0.1:8080/Helloapp/hello

其中Helloapp是Tomcat里面的文件夹的名字，hello是url-pattern里面写的名字

3.实现servlet打印当前时间#

该工程的功能是实现在页面中显示当前的时间

1.编写一个Java类，实现Servlet接口#

以下的代码是HelloServlet.java中的代码

package helloapp2;

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

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class HelloServlet extends GenericServlet {

@Override<br />    public void service(ServletRequest arg0, ServletResponse arg1)<br />            throws ServletException, IOException {<br />        // TODO Auto-generated method stub

    PrintWriter pw = arg1.getWriter();<br />        pw.println("Hello");<br />        pw.println(new Date().toLocaleString());<br />        pw.close();<br />    }

}

以下的代码是web.xml中的代码

helloapp2

index.html
index.htm
index.jsp
default.html
default.htm
default.jsp



Hello
helloapp2.HelloServlet



Hello
/Hello

2.把开发好的Java类部署到web服务器中#

使用myeclipse自动部署的方法(使用myeclipse 2015自动部署有问题，待解决)(换成2014的便可以自动部署)：

　　1.Window->preferences->Myeclipse->Servers->Runtime Ecvironment->add->Tomcat 6.0，要选中添加local的那个选项

　　2.在manage deployment的module里面选择要部署的工程

　　3.重新安装Tomcat出现的问题解决，但是还是要手动部署

自动部署设置，参考：Eclipse中的Web项目自动部署到Tomcat

自动部署后要把网页的文件放在根目录下

该工程的名称是testhttp，功能是在页面中表格打印浏览过程中的相关头信息。

 　　新建一个工程，然后在这个工程里面新建一个servlet，这样便可以省去编写web.xml的过程

3.实现servlet打印header#

以下是TestHttpServlet.java中的代码

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package org.common.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 TestHttpServlet extends HttpServlet {

    /**
     * Constructor of the object.
     */
    public TestHttpServlet() {
        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
     */
    
    //Servlet接口的参数service(ServletRequest arg0, ServletResponse arg1)
    
    //HttpServletRequest封装了所有的请求信息，其实就是Tomcat将请求信息按照JAVA EE的Servlet的规范
    //封装好给我们
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        //设置返回类型
        //response.setContentType("text/html;charset=GBK");
        response.setContentType("text/html");
        response.setCharacterEncoding("GBK");
        
        //获取输出流
        PrintWriter out = response.getWriter();
        out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
        out.println("<HTML>");
        out.println("  <HEAD><TITLE>testhttp Servlet</TITLE></HEAD>");
        out.println("  <BODY>");
        
        out.print("<center>");
        out.print(" <h2>请求头信息列表<h2> ");
        
        out.print(" <table border=1> ");
        out.print(" |名字|值
 ");
        //返回头消息名字集合，返回的是一个枚举
        Enumeration enums = request.getHeaderNames();
        //遍历获取所有头信息名和值
        while(enums.hasMoreElements()){
            //获取每一个头消息的名字
            String headName = (String)enums.nextElement();
            out.println(" <tr> ");
            out.println(" | " + headName + "  ");
            //getHeader(java.lang.String name) 
            //Returns the value of the specified request header as a String.
            //返回这个名字的头信息的值
            out.println(" | " + request.getHeaders(headName) + "  ");
            out.println(" </tr> ");
        }
        out.println(" </table> ");
        
        out.println(" <hr> ");
        //测试HttpServletRequest的方法
        out.println("Method： " + request.getMethod() + "<br>");
        out.println("Request URI： " + request.getRequestURI() + "<br>");
        out.println("Protocol： " + request.getProtocol() + "<br>");
        out.println("PathInfo： " + request.getPathInfo() + "<br>");
        out.println("Remote Address： " + request.getRemoteAddr() + "<br>");
        out.println("ContextPath： " + request.getContextPath() + "<br>");
        out.println("getScheme： " + request.getScheme() + "<br>");
        out.println("getServerName： " + request.getServerName() + "<br>");
        out.println("getServerPort： " + request.getServerPort() + "<br>");
        out.println("getRequestURI： " + request.getRequestURI() + "<br>");
        String path = request.getContextPath();
        //请求全路径
        String basePath
            = request.getScheme() + "://" + request.getServerName() + ":"
            + request.getServerPort() + request.getRequestURI();
        out.println(" path: " + path + "<br>");
        out.println(" basePath: " + basePath + "<br>");
        
        //out.print(this.getClass());
        //out.println(", using the GET method");
        
        out.print("</center>");
        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 {
        
        //调用doGet方法
        this.doGet(request, response);
    }

    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }

}

请求头信息列表

“);#

    out.print(" <table border=1> ");
    out.print(" |名字|值

“);
//返回头消息名字集合，返回的是一个枚举
Enumeration enums = request.getHeaderNames();
//遍历获取所有头信息名和值
while(enums.hasMoreElements()){
//获取每一个头消息的名字
String headName = (String)enums.nextElement();
out.println(“ “);
out.println(“ | “ + headName + “ “);
//getHeader(java.lang.String name)
//Returns the value of the specified request header as a String.
//返回这个名字的头信息的值
out.println(“ | “ + request.getHeaders(headName) + “ “);
out.println(“ “);
}
out.println(“ “);

    out.println(" <hr> ");
    //测试HttpServletRequest的方法
    out.println("Method： " + request.getMethod() + "<br>");
    out.println("Request URI： " + request.getRequestURI() + "<br>");
    out.println("Protocol： " + request.getProtocol() + "<br>");
    out.println("PathInfo： " + request.getPathInfo() + "<br>");
    out.println("Remote Address： " + request.getRemoteAddr() + "<br>");
    out.println("ContextPath： " + request.getContextPath() + "<br>");
    out.println("getScheme： " + request.getScheme() + "<br>");
    out.println("getServerName： " + request.getServerName() + "<br>");
    out.println("getServerPort： " + request.getServerPort() + "<br>");
    out.println("getRequestURI： " + request.getRequestURI() + "<br>");
    String path = request.getContextPath();
    //请求全路径
    String basePath
        = request.getScheme() + "://" + request.getServerName() + ":"
        + request.getServerPort() + request.getRequestURI();
    out.println(" path: " + path + "<br>");
    out.println(" basePath: " + basePath + "<br>");
    
    //out.print(this.getClass());
    //out.println(", using the GET method");
    
    out.print("</center>");
    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 {
    
    //调用doGet方法
    this.doGet(request, response);
}

/**
 * Initialization of the servlet. <br>
 *
 * @throws ServletException if an error occurs
 */
public void init() throws ServletException {
    // Put your code here
}

}

然后部署并启动Tomcat服务器，在浏览器中输入

http://127.0.0.1:8080/testhttp/servlet/TestHttpServlet

4.使用servlet实现简单的login

本工程的功能是实现Javaweb的servlet身份验证

 

一下是login.html文件中的代码

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<!DOCTYPE html> <html> <head> <title>login.html</title> <meta name="keywords" content="keyword1,keyword2,keyword3"> <meta name="description" content="this is my page"> <meta name="content-type" content="text/html; charset=GBK"> <!--<link rel="stylesheet" type="text/css" href="./styles.css">--> <script type="text/javascript"> function check(){ //获取控件内容 var loginname = document.getElementById("loginname").value; if(loginname == ""){ alert("用户名不能为空"); document.getElementById("loginname").focus();//获取焦点 return false; } var password = document.getElementById("password").value; if(password == ""){ alert("密码不能为空"); document.getElementById("password").focus(); return false; } //验证成功 document.loginform.submit(); } </script> </head> <body> <center> <h2>登陆页面</h2> <br> <!-- html数据由两种传输方式 1.get 从地址栏传递 2.form表单传输 form代表表单 --action属性代表提交的url action="login.do",那么在web.xml里面定义<servlet-mapping>的<url-pattern> 的时候也是login.do --method属性代表提交表单的方式，http里面重点是get和post，默认get方式提交 --name属性给表单其名字 --id属性代表唯一标示该表单的名字，主要是javascript脚本使用 --> <form action="login.do" method="get" name="loginform" id="loginform"> <table> <tr> <td>登录名：</td> <td><input type="text" name="loginname" id="loginname"/></td> </tr> <tr> <td>密码：</td> <td><input type="password" name="password" id="password"/></td> </tr> </table> <table> <tr> <td><input type="button" value="提交" onclick="check();"></td> &amp;nbsp;&amp;nbsp; <td><input type="reset" value="重置"></td> </tr> </table> </form> </center> </body> </html>

 

以下代码是LoginServlet.java中的代码

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package org.common.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.Enumeration; import java.util.Properties; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class LoginServlet extends HttpServlet { /** * Constructor of the object. */ public LoginServlet() { 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 { System.out.println("执行 doGet 方法..."); // //1.接收前台传递过来的参数 // Enumeration enums = request.getParameterNames(); // while(enums.hasMoreElements()){ // System.out.println(enums.nextElement()); // // } //转换编码的第2种方式，配合doPost()方法使用 request.setCharacterEncoding("GBK"); //提交的name可以在后台使用request.getParameter("loginname")获取值 String loginname = request.getParameter("loginname"); System.out.println("转换前loginname:" + loginname); //String password = request.getParameter("password"); //把loginname这个字符串转成GBK，前提你要确定编码 loginname = new String(loginname.getBytes("iso-8859-1"),"GBK"); System.out.println("转换后loginname:" + loginname); String password = request.getParameter("password"); //properties文件是java的默认配置文件，以key-value的形式存储数据 //增加了一个user.properties文件存储用户名密码 Properties pro = new Properties(); //load方法从输入流中读取属性列表（键和元素对） pro.load(this.getClass().getResourceAsStream("/user.properties")); //System.out.print(pro); response.setContentType("text/html;charset=GBK"); 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(" loginname: " + loginname); //out.print(" password: " + password); if(loginname.equals(pro.getProperty("loginname")) &amp;&amp; password.equals(pro.getProperty("password"))){ out.println(" 欢迎["+pro.getProperty("username")+"]登陆"); }else{ out.println("用户名密码错误"); } 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 { this.doGet(request, response); } /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */ public void init() throws ServletException { // Put your code here } }

 

doGet()方法不安全，所以尽量使用doPost()方法

#