javaweb入门实例---servlet例子

1.编写servlet: TreeDataServlet.java

package com.maggie.tree;  

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 TreeDataServlet extends HttpServlet{  

    private String getData(){
        StringBuffer sb = new StringBuffer();
        sb.append("Hello~First Servlet!");
        return sb.toString();
    }  

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
//      super.doGet(req, resp);
        String data = this.getData();
        resp.setContentType("text/html;charset=GBK");
        resp.getOutputStream().write(data.getBytes("GBK"));
    }  

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
//      super.doPost(req, resp);
    }
}

　　

2.配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <servlet>
        <servlet-name>treeServlet</servlet-name>
        <servlet-class>
            com.maggie.tree.TreeDataServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>treeServlet</servlet-name>
        <url-pattern>/servlet/treeServlet</url-pattern>
    </servlet-mapping>
</web-app>

不针对此例子，例如如下：

<servlet>
    <description>任意</description>
    <display-name>任意</display-name>
    <servlet-name>ServletDemoFirst</servlet-name>
    <servlet-class>cn.dragon.servlet.ServletDemoFirst</servlet-class>
  </servlet>

　<servlet-mapping>
    <servlet-name>ServletDemoFirst</servlet-name>
    <url-pattern>/servlet/ServletDemoFirst</url-pattern>
  </servlet-mapping>　

①　上面的两个<servlet-name>必须相同
　　②　<servlet-class>后面指在对应的类上面．　　技巧：你可以直接在你的servlet类中复制过来，这样可以避免出错！
　　③　<url-pattern>　必须是/servlet 再加servlet名字.大家现在就这么记.　

3.测试，访问地址：http://localhost:8080/fistServlet/treeServlet

页面显示如下：

Hello~First Servlet!

自己实例：

1：编写servlet：

package xjl;

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 TreeDataServlet extends HttpServlet{

	private String getData(){
		StringBuffer sb= new StringBuffer();
		sb.append("Hello xjl World!");
		return sb.toString();
	}

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException{
        // super.doGet(req, resp);一定要注释掉这句，否则会出错
		String data=this.getData();
		resp.setContentType("text/html;charset=GBK");
        resp.getOutputStream().write(data.getBytes("GBK"));
    }

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // super.doPost(req, resp);一定要注释掉这句，否则会出错

       doGet(req, resp); } }

2 web.xml:

<?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">

	<servlet>
        <servlet-name>TreeDataServlet</servlet-name>
        <servlet-class>
            xjl.TreeDataServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>TreeDataServlet</servlet-name>
        <url-pattern>/servlet/xjl.TreeDataServlet</url-pattern>//注意这里url-pattern格式必须为：/servlet/包名.类名
    </servlet-mapping>
</web-app>

3:访问：http://localhost:8080/helloworld/servlet/xjl.TreeDataServlet

Hello xjl World!