利用XML来向服务器发送数据

今天写一篇关于利用Ajax技术，通过客户端将请求参数放入XML文件，然后将XML发送给服务器端。最后，服务器端将请求的处理结果返回给客户端。

1、首先在做一个Ajax程序的时候，必须了解Ajax其运行原理（或是工作机制）
（1）创建XMLHTTPRequest对象

（2）向服务器端发出请求

（3）服务器端接受请求并做出处理

（4）服务器端返回请求结果给客户端

（5）利用ajax接收服务器端请求结果

（6）将请求结果显示给用户（或是客户端）

2、一个登录验证例子

技术要求：

（1）登录验证采用的技术Ajax+Spring+Servlet+JavaBean

（2）采用数据库SQL Server

（3）程序实现必须采用分层结构。（即表现层+控制层+业务逻辑层+数据持久层+数据库层）

（4）那么各个层采用的技术如下：

表现层：JSP+JavaScript+Ajax

控制层：Servlet

业务逻辑层：Spring的IOC容器

数据持久层：Spring中的JDBC

数据库层：由SQL Server提供支持

程序实现步骤：
（1）先从数据库持久层开始

package com.gxa.edu.spring.dao;

import java.util.List;

import com.gxa.edu.spring.bean.Student;

public interface StudentDao {
		
	List queryStudent(String stuId, String stuName);
}

（2）接着创建一个实现StudentDao接口的StudentDaoImpl类

package com.gxa.edu.spring.dao.impl;

import java.util.List;

import org.springframework.core.io.Resource;
import org.springframework.jdbc.core.support.JdbcDaoSupport;

import com.gxa.edu.spring.bean.Student;
import com.gxa.edu.spring.dao.StudentDao;
import com.gxa.edu.spring.rowmapper.StudentRowMapper;

/**
 * 该StudentDaoImpl是操作student表的StudentDao接口具体实现类
 * 1、该类继承了Spring框架提供的JdbcDaoSupport类。
 * 2、Spring框架中的JdbcDaoSupport类是一个对JDBC抽象封装的Dao
 * 3、继承JdbcDaoSupport类，必须设置DataSource、同时通过调用JdbcDaoSupport类的getJdbcTemplate()方法为其子类提供操作数据库的JdbcTemplate类
 * 4、JdbcTemplate类是操作JDBC的核心类，并且提供了执行SQL，执行存储过程，避免操作异常功能。
 * @author Administrator
 *
 */
public class StudentDaoImpl extends JdbcDaoSupport implements StudentDao{

	public List queryStudent(String stuId, String stuName) {
		// TODO Auto-generated method stub
		String sql = "select stuId, stuName from student " +
				"where stuId = ? and stuName = ?";
		Object[] obj = {stuId, stuName};
		return getJdbcTemplate().query(sql, obj, new StudentRowMapper());
	}
}

（3）接着创建一个实现RowMapper接口的StudentRowMapper类

package com.gxa.edu.spring.rowmapper;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.springframework.jdbc.core.RowMapper;

import com.gxa.edu.spring.bean.Student;

public class StudentRowMapper implements RowMapper{

	public Object mapRow(ResultSet arg0, int arg1) throws SQLException {
		// TODO Auto-generated method stub
		Student stu = new Student();
		stu.setStuId(arg0.getString("stuId"));
		stu.setStuName(arg0.getString("stuName"));
		return stu;
	}

}

（4）业务逻辑层实现

package com.gxa.edu.spring.logic;

import java.util.List;
import java.util.Map;

import com.gxa.edu.spring.bean.Student;
import com.gxa.edu.spring.dao.StudentDao;

public class StudentLogic {
	
	private StudentDao dao;

	public void setDao(StudentDao dao) {
		this.dao = dao;
	}
	
	public List queryStudent(String stuId, String stuName) {
		return dao.queryStudent(stuId, stuName);
	}
	
}

（5）控制层实现
创建一个LoginXMLServlet类，该Servlet主要是处理客户端提交过来的请求

package com.gxa.edu.servlet;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

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

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import com.gxa.edu.spring.logic.StudentLogic;

public class LoginXMLServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public LoginXMLServlet() {
		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 {

		doPost(request, response);
	}

	/**
	 * 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 {
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/xml; charset=UTF-8");
        response.setHeader("Cache-Control", "no-cache");
		List list = getRoot(readXML(request.getInputStream()));
		String stuId = "";
		String stuName = "";
		for (int i = 0; i < list.size(); i++) {
			if (i > 0) {
				stuName = (String) list.get(i);
			} else {
				stuId = (String) list.get(i);
			}
		}
		System.out.println("stuId === " + stuId);
		System.out.println("stuName === " + stuName);
		
		WebApplicationContext wc = WebApplicationContextUtils.getRequiredWebApplicationContext(this.getServletContext());
		StudentLogic logic = (StudentLogic) wc.getBean("transactionStudent");
		
		String info;
		
		if (logic.queryStudent(stuId, stuName).size() > 0) {
			info = "学生ID和姓名正确，验证通过";
		} else {
			info = "学生ID和姓名不正确，验证不通过";
		}
		
		PrintWriter out = response.getWriter();
		out.println(info);
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occure
	 */
	public void init() throws ServletException {
		// Put your code here
	}
	
	private Document readXML(InputStream in) {   
        Document document = null;   
        SAXReader saxReader = new SAXReader();   
        try {   
            document = saxReader.read(in);   
        } catch (DocumentException e) {   
            e.printStackTrace();   
        }   
        return document;   
    }
	
	private List getRoot(Document document) {   
        Element root = document.getRootElement();   
        return disXML_3(root);   
    }
	
	private List disXML_3(Element element) {   
        Iterator iterator = element.elementIterator();   
        List list = null;
        //一个泛型的使用
        List<String> list_str = new ArrayList<String>();
        while (iterator.hasNext()) {   
            Element node = (Element) iterator.next();   
            list = node.elements();   
            if (list != null && list.size() > 0) {   
                System.out.print(node.getName());   
                int count = node.attributeCount();   
                for (int i = 0; i < count; i++) {   
                    Attribute attr = node.attribute(i);   
                    System.out.println("*****" + attr.getName() + " " + attr.getText());   
                }   
                disXML_3(node);   
            } else {   
                //System.out.println(node.getName() + " " + node.getText());
                list_str.add(node.getText());
            }   
        }
        return list_str;
    } 

}

（6）表现层实现

<%@ page language="java" pageEncoding="gb2312"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    
    <title>利用XML来向服务器发送数据</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	
	<script type="text/javascript">
		var XMLHttpReq = false;
		var stuId;
		var stuName;
	 	//创建XMLHttpRequest对象       
	    function createXMLHttpRequest() {
			if(window.XMLHttpRequest) { //Mozilla 浏览器
				XMLHttpReq = new XMLHttpRequest();
			}
			else if (window.ActiveXObject) { // IE浏览器
				try {
					XMLHttpReq = new ActiveXObject("Msxml2.XMLHTTP");
				} catch (e) {
					try {
						XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
					} catch (e) {}
				}
			}
		}
		//发送请求函数
		function sendRequest() {
			createXMLHttpRequest();
	    	var xml = createXML();
	        XMLHttpReq.open("POST", "LoginXMLServlet", true);
			XMLHttpReq.onreadystatechange = processResponse;//指定响应函数
	    	XMLHttpReq.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");    
			XMLHttpReq.send(xml);
		}
		// 处理返回信息函数
	    function processResponse() {
	    	if (XMLHttpReq.readyState == 4) { // 判断对象状态
	        	if (XMLHttpReq.status == 200) { // 信息已经成功返回，开始处理信息
		            var res=XMLHttpReq.responseText;
		            window.alert(res);                
		        } else { //页面不正常
		           window.alert("您所请求的页面有异常。");
		        }
       		}
	    }
		function userCheck() {
			stuId = document.form1.stuId.value;
			stuName = document.form1.stuName.value;
			sendRequest();
		}
		
			//创建XML
		function createXML() {
		    var xml = "<user>";
		    xml = xml + "<stuId>" +stuId + "<\/stuId>";
		    xml = xml + "<stuName>" + stuName + "<\/stuName>";
		    xml = xml + "<\/user>";
		    return xml;
		}
	</script>

  </head>
  
  <body>
    <form name="form1">
		学生ID：
		<input type="text" name="stuId">
		<br>
		学生姓名：
		<input type="text" name="stuName">
		<br>
		<input type="button" value="登录" onclick="userCheck()">
	</form>
  </body>
</html>

（7）Spring的application.xml文件，该配置文件用的Spring 1.2版本的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
	
	<!-- 配置SQL Server数据源 -->
	<bean id="dataSource"
		class="org.apache.commons.dbcp.BasicDataSource"
		destroy-method="close">
		<property name="driverClassName">
			<value>com.microsoft.jdbc.sqlserver.SQLServerDriver</value>
		</property>
		<property name="url">
			<value>jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=stu</value>
		</property>
		<property name="username">
			<value>sa</value>
		</property>
		<property name="password">
			<value>12345</value>
		</property>
	</bean>

	<bean id="studentDao"
		class="com.gxa.edu.spring.dao.impl.StudentDaoImpl">
		<!-- 为studentDao注入dataSource实例 -->
		<property name="dataSource">
			<ref local="dataSource" />
		</property>
	</bean>
	
	<!-- =====DataSourceTransactionManager来对数据源进行事务管理===== -->
	<bean id="transactionManager"
		class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource">
			<ref local="dataSource" />
		</property>
	</bean>

	<!-- =====TransactionProxyFactoryBean一个事务管理代理工厂bean，它是我们Spring中一个拦截器====== -->
	<bean id="basicTransactionProxy"
		class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"
		abstract="true">
		<property name="transactionManager">
			<ref local="transactionManager" />
		</property>
		<property name="transactionAttributes">
			<props>
				<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
				<prop key="insert*">PROPAGATION_REQUIRED</prop>
				<prop key="update*">PROPAGATION_REQUIRED</prop>
			</props>
		</property>
		<!-- <property name="proxyTargetClass" value="true"></property> -->
	</bean>

	<!-- =====为一个操作数据库对象织入事务管理===== -->
	<bean id="transactionStudent" parent="basicTransactionProxy">
		<property name="target">
			<bean class="com.gxa.edu.spring.logic.StudentLogic">
				<property name="dao">
					<ref local="studentDao"/>
				</property>
			</bean>
		</property>
	</bean>
				
</beans>