Ajax的小案例

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查询数据库客户是否存在

连接数据库

db.properties

url=jdbc\:MysqL\://localhost\:3306/csdn?useUnicode\=true&characterEncoding\=UTF-8
user=root
pass=113
driverClassName=com.MysqL.jdbc.Driver

工具包DBConn.java

package util;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.sqlException;
import java.util.Properties;

public class DBConn {
	private static Connection conn;

	private DBConn() {

	}

	public static Connection getConn() {
		if (conn == null) {
			// 创建集合对象
			Properties properties = new Properties();
			try {
				// 装载
				properties.load(DBConn.class.getClassLoader()
						.getResourceAsStream("db.properties"));
				// 加载驱动程序
				Class.forName(properties.getProperty("driverClassName"));
				// 获取连接对象
				conn = DriverManager.getConnection(
						properties.getProperty("url"),properties.getProperty("user"),properties.getProperty("pass"));
				conn.setAutoCommit(false);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return conn;
	}

	/**
	 * 单个数据的增加更新删除的事务处理
	 * @param sql
	 * @param params
	 * @param pstmt
	 */
	public static void update(String sql,Object params[],PreparedStatement pstmt) {
		try {
			pstmt = getConn().prepareStatement(sql);
			for (int i = 0; i < params.length; i++) {
				pstmt.setObject(i + 1,params[i]);
			}
			pstmt.executeUpdate();
			conn.commit();
		} catch (Exception e) {
			try {
				conn.rollback();
			} catch (sqlException e1) {
				e1.printStackTrace();
			}
			e.printStackTrace();
		} finally {
			release(null,pstmt);
		}
	}

	public static void release(ResultSet rs,PreparedStatement pstmt) {
		if (rs != null) {
			try {
				rs.close();
			} catch (sqlException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (pstmt != null) {
			try {
				pstmt.close();
			} catch (sqlException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}


读取数据库的信息

UserDomian.java

package www.csdn.net.user.domian;

public class UserDomian {
private Integer id;
private String name;
private String pass;
public UserDomian() {
	// TODO Auto-generated constructor stub
}
public UserDomian(Integer id,String name,String pass) {
	super();
	this.id = id;
	this.name = name;
	this.pass = pass;
}
public Integer getId() {
	return id;
}
public void setId(Integer id) {
	this.id = id;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public String getPass() {
	return pass;
}
public void setPass(String pass) {
	this.pass = pass;
}
@Override
public String toString() {
	return "UserDomian [id=" + id + ",name=" + name + ",pass=" + pass + "]";
}

}



实现增删查改功能

UserDo.java

package www.csdn.net.user.dao;

import java.util.List;

import www.csdn.net.user.domian.UserDomian;

public interface UserDo {
 void insert(UserDomian entity) throws Exception;
 void update(UserDomian entity) throws Exception;
 void delete(UserDomian entity) throws Exception;
 void deleteById(Integer id) throws Exception;
 List<UserDomian> findAll() throws Exception;
 UserDomian findById(Integer id) throws Exception;
 
 /**
  * 用户登录验证
  */
 UserDomian checkLogin(String name,String pass) throws Exception;
/**
 * 批量删除操作
 */
 void deletes(Integer ids[])  throws Exception;
 /**
  * 分页处理
  */
 List<UserDomian> findNowPageInfo(int nowpage) throws Exception;
/**
 * 总页
 */
 Integer getCountPage()  throws Exception;
 /**
  * 判断用户信息是否存在
  */
 boolean checkName(String name) throws Exception;
}


实现接口的类UserDoImpl.java

package www.csdn.net.user.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import util.DBConn;
import www.csdn.net.user.dao.UserDo;
import www.csdn.net.user.domian.UserDomian;

public class UserDoImpl implements UserDo {
	private Connection conn;
	private PreparedStatement pstmt;
	private ResultSet rs;
	final int PAGESIZE = 10;

	@Override
	public void insert(UserDomian entity) throws Exception {
		String sql = "insert into user (name,pass) values(?,?)";
		DBConn.update(sql,new Object[] { entity.getName(),entity.getPass() },pstmt);

	}

	@Override
	public void update(UserDomian entity) throws Exception {
		String sql = "update user set name=?,pass=? where id=?";
		DBConn.update(sql,entity.getPass(),entity.getId() },pstmt);

	}

	@Override
	public void delete(UserDomian entity) throws Exception {
		String sql = "delete from user where id=?";
		DBConn.update(sql,new Object[] { entity.getId() },pstmt);

	}

	@Override
	public void deleteById(Integer id) throws Exception {
		String sql = "delete from user where id=?";
		DBConn.update(sql,new Object[] { id },pstmt);
	}

	@Override
	public List<UserDomian> findAll() throws Exception {
		List<UserDomian> entities = new ArrayList<UserDomian>();
		String sql = "select id,name,pass from user ";
		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);
		rs = pstmt.executeQuery();
		while (rs.next()) {
			UserDomian entity = new UserDomian();
			entity.setId(rs.getInt("id"));
			entity.setName(rs.getString("name"));
			entity.setPass(rs.getString("pass"));
			entities.add(entity);
		}
		return entities;
	}

	@Override
	public UserDomian findById(Integer id) throws Exception {
		UserDomian entity = null;
		String sql = "select id,pass  from user  where id=?";
		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);
		int index = 1;
		pstmt.setInt(index++,id);
		rs = pstmt.executeQuery();
		if (rs.next()) {
			entity = new UserDomian();
			entity.setId(rs.getInt("id"));
			entity.setName(rs.getString("name"));
			entity.setPass(rs.getString("pass"));
		}
		return entity;
	}

	@Override
	public UserDomian checkLogin(String name,String pass) throws Exception {
		UserDomian entity = null;
		String sql = "select id,pass from user where name=? and pass=?";
		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);
		int index = 1;
		pstmt.setString(index++,name);
		pstmt.setString(index++,pass);
		rs = pstmt.executeQuery();
		if (rs.next()) {
			entity = new UserDomian();
			entity.setId(rs.getInt("id"));
			entity.setName(rs.getString("name"));
			entity.setPass(rs.getString("pass"));
		}

		return entity;
	}

	@Override
	public void deletes(Integer[] ids) throws Exception {
		conn = DBConn.getConn();
		try {
			for (int i = 0; i < ids.length; i++) {
				String sql = "delete from user where id=?";
				pstmt = conn.prepareStatement(sql);
				pstmt.setInt(1,ids[i]);
				pstmt.executeUpdate();
				// pstmt.addBatch();
			}
			// pstmt.executeBatch();
			conn.commit();
		} catch (Exception e) {
			conn.rollback();
			e.printStackTrace();
		}
	}

	@Override
	public List<UserDomian> findNowPageInfo(int nowpage) throws Exception {
		List<UserDomian> entities = new ArrayList<UserDomian>();
		String sql = "select id,pass from user limit ?,?";

		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);
		int index = 1;
		pstmt.setInt(index++,(nowpage - 1) * PAGESIZE);
		pstmt.setInt(index++,PAGESIZE);
		rs = pstmt.executeQuery();
		while (rs.next()) {
			UserDomian entity = new UserDomian();
			entity.setId(rs.getInt("id"));
			entity.setName(rs.getString("name"));
			entity.setPass(rs.getString("pass"));
			entities.add(entity);
		}
		return entities;

	}

	// 总页数
	@Override
	public Integer getCountPage() throws Exception {
		String sql = "select count(*) as c from user";

		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);

		rs = pstmt.executeQuery();
		while (rs.next()) {
			int countsize = rs.getInt("c");
			return countsize % PAGESIZE == 0 ? countsize / PAGESIZE : countsize
					/ PAGESIZE + 1;
		}
		return null;
	}

	@Override
	public boolean checkName(String name) throws Exception {
		boolean flag = false;
		String sql = "select id,pass from user where name=?";
		conn = DBConn.getConn();
		pstmt = conn.prepareStatement(sql);
		int index = 1;
		pstmt.setString(index++,name);
		rs = pstmt.executeQuery();
		if (rs.next()) {
			flag = true;
		}
		return flag;
	}

}


验证码RandomImage .java

package img;

import java.awt.Color;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

/**
 * 验证码
 * @author yanmei
 *
 */
public class RandomImage {
private final static int W=80;
private final static int H=30;
public static BufferedImage createImage(){
	//创建图片
	BufferedImage image=new BufferedImage(W,H,BufferedImage.TYPE_INT_RGB);
	//得到图形绘制的对象
	Graphics g=image.getGraphics();
	//设置背景颜色
	setBackGroud(g);
	//设置边框
	setBorder(g);
	//绘制内容
	drawContent(g);
	//绘制干扰线
	drawDisturbline(g);
	return image;
}
private static void drawDisturbline(Graphics g) {
	g.setColor(Color.blue);
	Random r=new Random();
	for (int i = 0; i < 4; i++) {
		int x1 = r.nextInt(W);
		int y1 = r.nextInt(H);
		int x2 = r.nextInt(W);
		int y2 = r.nextInt(H);
		g.drawLine(x1,y1,x2,y2);
	}
}
private static void drawContent(Graphics g) {
	// TODO Auto-generated method stub
	
	//字节资源
	String re = "u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
	//获取字符的长度
	int length=re.length();
	//随机操作对象
	Random r=new Random();
	//存储字符的对象
	StringBuffer sb=new StringBuffer();
	for (int i = 0; i < 4; i++) {
		//随机产生数字
		int index=r.nextInt(length);
		//获取字符
		char c=re.charAt(index);
		sb.append(c);
	}
	g.setColor(Color.black);
	g.drawString(sb.toString(),20,20);
}
private static void setBorder(Graphics g) {
	g.setColor(Color.black);
	g.drawRect(0,W-2,H-2);
	
}
private static void setBackGroud(Graphics g) {
	// 绘制矩形
	g.setColor(Color.yellow);
	g.fillRect(0,W,H);
	
}
}


package www.csdn.net.ajax.servlet;

import java.awt.Color;
import java.awt.Graphics;
import java.io.IOException;
import java.util.Random;

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

import img.RandomImage;

public class ImageServlet extends HttpServlet {
	

	public void doGet(HttpServletRequest request,HttpServletResponse response)
			throws ServletException,IOException {
           //禁止浏览器缓存数据
		response.setHeader("expires","0");
		response.setHeader("Cache-Control","no-cache");
		response.setHeader("Pragma","no-cache");
		
		//1.通知浏览器以图片的方式打开数据
		response.setContentType("image/jpeg");
		
		
		//把图片显示给浏览器
	     ImageIO.write(RandomImage.createImage(),"jpeg",response.getOutputStream());
		
		
	}

	public void doPost(HttpServletRequest request,IOException {
		this.doGet(request,response);
	}

}


login.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'login.jsp' starting page</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">
	-->
	<!-- 引入js文件 -->
<script type="text/javascript" >
//当窗体加载完毕后触发该函数
window.onload = function(){
	//获取name输入框的Dom对象
	var inputName = document.getElementById("uname");
	//注册事件
	inputName.onblur= checkName;
};

function checkName(){
	var name = this.value;
	
	//1.第一步获取XMLHttpRequest对象
	 var xmlHttp = getXMLHttp();
	//2. 第二步:打开请求
	 xmlHttp.open("GET","./checkName.do?name="+name+"&oper=checkName");
	//3.第三步:发送请求
	xmlHttp.send(null);//checkName.do
	//4.第四步:函数处理
	xmlHttp.onreadystatechange= processProgram;
	
}

function processProgram(){
	//判断是否处理完成,响应的是否正常
	//alert("11111111111111111111");
	if(this.readyState==4&&this.status==200){
		//服务器端响应过来的文本
	    var content = this.responseText;
	    //alert("---"+content);
	    //获取显示文本的span,Dom节点对象
	    var msgDom = document.getElementById("msg");
	    //清除操作
	   var childNodes =  msgDom.childNodes;
	   for(var i=0;i<childNodes.length;i++){
		   //删除所有的孩子节点
		   msgDom.removeChild(childNodes[i]);
	   }
	    //创建一个文本节点对象
	    var textDom =document.createTextNode(content);
	    //在显示文本的span,Dom节点中添加textDom的孩子节点
	    msgDom.appendChild(textDom);
	}
	
}
function getXMLHttp() {
	// 第一步:声明返回值
	var xmlHttp;
	// 第二步:实例化xmlHttp对象
	try {
		// firefox Opera等
		xmlHttp = new XMLHttpRequest();
	} catch (e) {
		try {
			// IE浏览器
			xmlHttp = new ActiveXObject("MSXML2.XMLHTTP5.0");
		} catch (ex) {
			xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}

</script>
</head>

<body>
	<div align="center">
		<form action="./login.action" method="post">
			<table border="1px" cellpadding="0" cellspacing="0">
				<tr>
					<td>用户名:</td>
					<td><input  type="text" name="name" id="uname"/></td>
					<td><span id="msg"></span></td>
				</tr>
				<tr>
					<td>密码:</td>
					<td colspan="2"><input type="password" name="pass" /></td>
				</tr>
				<tr>
					<td>验证码:</td>
					<td><input type="text" name="code" /></td>
					<td><img alt="验证码" src="./servlet/ImageServlet"></td>
				</tr>
				<tr>
					<td colspan="3" align="center"><input type="reset" value="重置" />
						 <input type="submit" value="登录" /></td>
				</tr>
			</table>
		</form>

	</div>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 
	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_3_0.xsd">
  <display-name></display-name>
  <servlet>
    <servlet-name>AjaxServlet</servlet-name>
    <servlet-class>www.csdn.net.ajax.servlet.AjaxServlet</servlet-class>
  </servlet>
    <servlet>
    <servlet-name>ImageServlet</servlet-name>
    <servlet-class>www.csdn.net.ajax.servlet.ImageServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>AdminServlet</servlet-name>
    <servlet-class>www.csdn.net.ajax.servlet.AdminServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>AjaxServlet</servlet-name>
    <url-pattern>/ajaxServlet.do</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>AdminServlet</servlet-name>
    <url-pattern>/checkName.do</url-pattern>
  </servlet-mapping>

 <servlet-mapping>
    <servlet-name>ImageServlet</servlet-name>
    <url-pattern>/servlet/ImageServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>
package www.csdn.net.ajax.servlet;

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

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

import www.csdn.net.user.dao.UserDo;
import www.csdn.net.user.dao.impl.UserDoImpl;



public class AdminServlet extends HttpServlet {
	private UserDo userDo=new UserDoImpl();
	public void doGet(HttpServletRequest request,IOException {
		String oper = request.getParameter("oper");
		if ("checkName".equals(oper))			
		// 验证用户操作
		checkName(request,response);
		// System.out.println(oper);
	}

	public void checkName(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {

		String name = request.getParameter("name");
		boolean flag=false;
		try {
			flag=userDo.checkName(name);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//设置响应
		response.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=UTF-8");
	    PrintWriter out=response.getWriter();
	    if (flag) {
			out.write("用户名被占用");
		}else{
			out.write("用户名可用");
		}
	    //System.out.println("----------------------");
	    out.flush();
	    out.close();
	}

	public void doPost(HttpServletRequest request,IOException {

		this.doGet(request,response);
	}

}



原文链接:https://www.f2er.com/ajax/165622.html

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