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!