一、jsp和servlet的简单介绍
1、servlet和jsp简介：
java开发web应用程序时用到的技术主要有两种，即servlet和jsp，servlet是在服务器端执行的java程序，一个被称为servlet容器的程序（其实就是服务器） 负责执行java程序，而jsp(java server page)则是一个页面， 由jsp容器负责执行.
2、servlet和jsp的区别：
servlet以java程序为主， 输出html代码时需要使用out.println函数，也就是说java中内嵌html； 而jsp则以html页面为主，需要写java代码时则在页面中直接插入java代码， 即html中内嵌java.
3、mvc模型
mvc模型就是将数据、逻辑处理、用户界面分离的一种方法
1）、m(model, 模型)：用于数据处理、逻辑处理
2）、v(view，视图)：用于显示用户界面
3）、c(controller，控制器)：根据客户端的请求控制逻辑走向和画面
而在java中，mvc这三个部分则分别对应于 javabeans、jsp和servlet
1）、m = javabeans：用于传递数据，拥有与数据相关的逻辑处理
2）、v = jsp：从model接收数据并生成html
3）、c = servlet：接收http请求并控制model和view
4、jdbc连接，可参考文章：点击打开链接
二、代码演示，实现了book的添加删除和修改功能
1、环境的配置
myeclipse+tomcat+mysql
2、book中bean类
package example.bean.book;
public class book {
// 编号
private int id;
// 图书名称
private string name;
// 价格
private double price;
// 数量
private int bookcount;
// 作者
private string author;
public int getid() {
return id;
}
public void setid(int id) {
this.id = id;
}
public string getname() {
return name;
}
public void setname(string name) {
this.name = name;
}
public double getprice() {
return price;
}
public void setprice(double price) {
this.price = price;
}
public int getbookcount() {
return bookcount;
}
public void setbookcount(int bookcount) {
this.bookcount = bookcount;
}
public string getauthor() {
return author;
}
public void setauthor(string author) {
this.author = author;
}
}
3、servlet类
1)、findservlet.java
package example.servlet.book;
import java.io.ioexception;
import java.sql.connection;
import java.sql.drivermanager;
import java.sql.resultset;
import java.sql.statement;
import java.util.arraylist;
import java.util.list;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import example.bean.book.book;
/**
* servlet implementation class findservlet
*/
public class findservlet extends httpservlet {
private static final long serialversionuid = 1l;
/**
* @see httpservlet#doget(httpservletrequest request, httpservletresponse
* response)
*/
protected void doget(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
try {
// 加载数据库驱动，注册到驱动管理器
class.forname("com.mysql.jdbc.driver");
// 数据库连接字符串
string url = "jdbc:mysql://localhost:3306/db_book?useunicode=true&characterencoding=utf-8";
// 数据库用户名
string username = "root";
// 数据库密码
string password = "";
// 创建connection连接
connection conn = drivermanager.getconnection(url, username,
password);
// 添加图书信息的sql语句
string sql = "select * from tb_books";
// 获取statement
statement statement = conn.createstatement();
resultset resultset = statement.executequery(sql);
list<book> list = new arraylist<book>();
while (resultset.next()) {
book book = new book();
book.setid(resultset.getint("id"));
book.setname(resultset.getstring("name"));
book.setprice(resultset.getdouble("price"));
book.setbookcount(resultset.getint("bookcount"));
book.setauthor(resultset.getstring("author"));
list.add(book);
}
request.setattribute("list", list);
resultset.close();
statement.close();
conn.close();
} catch (exception e) {
e.printstacktrace();
}
request.getrequestdispatcher("book_list.jsp")
.forward(request, response);
}
/**
* @see httpservlet#dopost(httpservletrequest request, httpservletresponse
* response)
*/
protected void dopost(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
// todo auto-generated method stub
doget(request, response);
}
}
2)、updateservlet.java类
package example.servlet.book;
import java.io.ioexception;
import java.sql.connection;
import java.sql.drivermanager;
import java.sql.preparedstatement;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
/**
* servlet implementation class updateservlet
*/
public class updateservlet extends httpservlet {
private static final long serialversionuid = 1l;
/**
* @see httpservlet#doget(httpservletrequest request, httpservletresponse
* response)
*/
protected void doget(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
int id = integer.valueof(request.getparameter("id"));
int bookcount = integer.valueof(request.getparameter("bookcount"));
try {
// 加载数据库驱动，注册到驱动管理器
class.forname("com.mysql.jdbc.driver");
// 数据库连接字符串
string url = "jdbc:mysql://localhost:3306/db_book";
// 数据库用户名
string username = "root";
// 数据库密码
string password = "";
// 创建connection连接
connection conn = drivermanager.getconnection(url, username,
password);
// 更新sql语句
string sql = "update tb_books set bookcount=? where id=?";
// 获取preparedstatement
preparedstatement ps = conn.preparestatement(sql);
// 对sql语句中的第一个参数赋值
ps.setint(1, bookcount);
// 对sql语句中的第二个参数赋值
ps.setint(2, id);
// 执行更新操作
ps.executeupdate();
// 关闭preparedstatement
ps.close();
// 关闭connection
conn.close();
} catch (exception e) {
e.printstacktrace();
}
// 重定向到findservlet
response.sendredirect("findservlet");
}
/**
* @see httpservlet#dopost(httpservletrequest request, httpservletresponse
* response)
*/
protected void dopost(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
// todo auto-generated method stub
doget(request, response);
}
}
3）、deleteservlet类
package example.servlet.book;
import java.io.ioexception;
import java.sql.connection;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import example.dao.book.bookjdbcdao;
import example.dao.book.connectionfactory;
/**
* servlet implementation class deleteservlet
*/
public class deleteservlet extends httpservlet {
private static final long serialversionuid = 1l;
/**
* @see httpservlet#doget(httpservletrequest request, httpservletresponse
* response)
*/
protected void doget(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
int id = integer.valueof(request.getparameter("id"));
try {
// // 加载数据库驱动，注册到驱动管理器
// class.forname("com.mysql.jdbc.driver");
// // 数据库连接字符串
// string url = "jdbc:mysql://localhost:3306/db_book";
// // 数据库用户名
// string username = "root";
// // 数据库密码
// string password = "";
// // 创建connection连接
// connection conn = drivermanager.getconnection(url, username,
// password);
// // 删除图书信息的sql语句
// string sql = "delete from tb_books where id=?";
// // 获取preparedstatement
// preparedstatement ps = conn.preparestatement(sql);
// // 对sql语句中的第一个占位符赋值
// ps.setint(1, id);
// // 执行更新操作
// ps.executeupdate();
// // 关闭preparedstatement
// ps.close();
// // 关闭connection
// conn.close();
bookjdbcdao bookdao=new bookjdbcdao();
connection conn=connectionfactory.getinstance().getconnection();
bookdao.delete(conn,id);
} catch (exception e) {
e.printstacktrace();
}
// 重定向到findservlet
response.sendredirect("findservlet");
}
/**
* @see httpservlet#dopost(httpservletrequest request, httpservletresponse
* response)
*/
protected void dopost(httpservletrequest request,
httpservletresponse response) throws servletexception, ioexception {
doget(request, response);
}
}
4、servlet访问url映射配置：
由于客户端是通过url地址访问web服务器中的资源，所以servlet程序若想被外界访问，必须把servlet程序映射到一个url地址上，这个工作在web.xml文件中使用<servlet>元素和<servlet-mapping>元素完成，<servlet>元素用于注册servlet，它包含有两个主要的子元素：<servlet-name>和<servlet-class>，分别用于设置servlet的注册名称和servlet的完整类名。
一个<servlet-mapping>元素用于映射一个已注册的servlet的一个对外访问路径，它包含有两个子元素：<servlet-name>和<url-pattern>，分别用于指定servlet的注册名称和servlet的对外访问路径.另外：同一个servlet可以被映射到多个url上，即多个<servlet-mapping>元素的<servlet-name>子元素的设置值可以是同一个servlet的注册名.
eg:上例中的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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="webapp_id" version="2.5"> <display-name>jdbcconnection</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> <servlet> <description></description> <display-name>findservlet</display-name> <servlet-name>findservlet</servlet-name> <servlet-class>example.servlet.book.findservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>findservlet</servlet-name> <url-pattern>/findservlet</url-pattern> </servlet-mapping> <servlet> <description></description> <display-name>updateservlet</display-name> <servlet-name>updateservlet</servlet-name> <servlet-class>example.servlet.book.updateservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>updateservlet</servlet-name> <url-pattern>/updateservlet</url-pattern> </servlet-mapping> <servlet> <description></description> <display-name>deleteservlet</display-name> <servlet-name>deleteservlet</servlet-name> <servlet-class>example.servlet.book.deleteservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>deleteservlet</servlet-name> <url-pattern>/deleteservlet</url-pattern> </servlet-mapping> </web-app>
5、jsp页面
1）、index.jsp web页面主界面
<%@page import="java.sql.sqlexception"%>
<%@page import="java.sql.drivermanager"%>
<%@page import="java.sql.connection"%>
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>添加图书信息</title>
<script type="text/javascript">
function check(form) {
with (form) {
if (name.value == "") {
alert("图书名称不能为空");
return false;
}
if (price.value == "") {
alert("图书价格不能为空");
return false;
}
if (author.value == "") {
alert("作者不能为空");
return false;
}
}
}
</script>
</head>
<body>
<form action="addbook.jsp" method="post" onsubmit="check(this)">
<table align="center" width="450">
<tr>
<td align="center" colspan="2">
<h2>添加图书信息</h2>
<hr>
</td>
</tr>
<tr>
<td align="right">图书名称：</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td align="right">价 格：</td>
<td><input type="text" name="price"></td>
</tr>
<tr>
<td align="right">数 量：</td>
<td><input type="text" name="bookcount" /></td>
</tr>
<tr>
<td align="right">作 者：</td>
<td><input type="text" name="author" /></td>
</tr>
<tr>
<td align="center" colspan="2"><input type="submit" value="添 加">
</td>
</tr>
</table>
</form>
<h2 align="center">
<a href="findservlet">查询图书信息</a>
</h2>
</body>
</html>
2)、addbook.jsp 添加书籍成功或者失败后的显示页面
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<%@page import="java.sql.connection"%>
<%@page import="java.sql.drivermanager"%>
<%@page import="java.sql.preparedstatement"%>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>添加结果</title>
</head>
<body>
<%
request.setcharacterencoding("utf-8");
%>
<jsp:usebean id="book" class="example.bean.book.book"></jsp:usebean>
<jsp:setproperty property="*" name="book" />
<%
try {
// 加载数据库驱动，注册到驱动管理器
class.forname("com.mysql.jdbc.driver");
// 数据库连接字符串
string url = "jdbc:mysql://localhost:3306/db_book?useunicode=true&characterencoding=utf-8";
// 数据库用户名
string username = "root";
// 数据库密码
string password = "";
// 创建connection连接
connection conn = drivermanager.getconnection(url, username,
password);
// 添加图书信息的sql语句
string sql = "insert into tb_books(name,price,bookcount,author) values(?,?,?,?)";
// 获取preparedstatement
preparedstatement ps = conn.preparestatement(sql);
// 对sql语句中的第1个参数赋值
ps.setstring(1, book.getname());
// 对sql语句中的第2个参数赋值
ps.setdouble(2, book.getprice());
// 对sql语句中的第3个参数赋值
ps.setint(3, book.getbookcount());
// 对sql语句中的第4个参数赋值
ps.setstring(4, book.getauthor());
// 执行更新操作，返回所影响的行数
int row = ps.executeupdate();
// 判断是否更新成功
if (row > 0) {
// 更新成输出信息
out.print("成功添加了 " + row + "条数据！");
}
// 关闭preparedstatement，释放资源
ps.close();
// 关闭connection，释放资源
conn.close();
} catch (exception e) {
out.print("图书信息添加失败！");
e.printstacktrace();
}
%>
<br>
<a href="index.jsp">返回</a>
</body>
</html>
3)、book_list.jsp 查找所有书籍信息的显示页面，以表格方式显示
<!--<%@page import="sun.awt.sunhints.value"%>-->
<%@ page language="java" contenttype="text/html; charset=utf-8"
pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<%@page import="java.util.list"%>
<%@page import="example.bean.book.book"%>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>所有图书信息</title>
<style type="text/css">
td {
font-size: 12px;
}
h2 {
margin: 0px
}
</style>
<script type="text/javascript">
function check(form) {
with (form) {
if (bookcount.value == "") {
alert("请输入更新数量！");
return false;
}
if (isnan(bookcount.value)) {
alert("格式错误！");
return false;
}
return true;
}
}
</script>
</head>
<body>
<table align="center" width="450" border="1" height="180"
bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1">
<tr bgcolor="white">
<td align="center" colspan="7">
<h2>所有图书信息</h2>
</td>
</tr>
<tr align="center" bgcolor="#e1ffc1">
<td><b>id</b></td>
<td><b>图书名称</b></td>
<td><b>价格</b></td>
<td><b>数量</b></td>
<td><b>作者</b></td>
<td><b>修改</b></td>
<td><b>删除</b></td>
</tr>
<%
// 获取图书信息集合
list<book> list = (list<book>) request.getattribute("list");
// 判断集合是否有效
if (list == null || list.size() < 1) {
out.print("没有数据！");
} else {
// 遍历图书集合中的数据
for (book book : list) {
%>
<tr align="center" bgcolor="white">
<td><%=book.getid()%></td>
<td><%=book.getname()%></td>
<td><%=book.getprice()%></td>
<td><%=book.getbookcount()%></td>
<td><%=book.getauthor()%></td>
<td >
<form style="align:center; background-color: gray" action="updateservlet" method="post"
onsubmit="return check(this);">
<input type="hidden" name="id" value="<%=book.getid()%>"> <input
type="text" name="bookcount" size="3">
<input type="submit" value="修改数量">
</form>
</td>
<td>
<a href="deleteservlet?id=<%=book.getid()%>">删除</a>
</td>
</tr>
<%
}
}
%>
</table>
<h2 align="center">
<a href="index.jsp">返回添加图书信息页面</a>
</h2>
</body>
</html>
6、jdbc简单的封装
1）、connectionfactory.java工厂类
package example.dao.book;
import java.sql.connection;
import java.sql.drivermanager;
import java.sql.sqlexception;
public class connectionfactory {
private string driverclassname = "com.mysql.jdbc.driver";
private string url = "jdbc:mysql://localhost:3306/db_book?useunicode=true&characterencoding=utf-8";
private string username = "root";
private string password = "";
private static connectionfactory connectionfactory=null;
private connectionfactory() {
try {
class.forname(driverclassname);
} catch (classnotfoundexception e) {
e.printstacktrace();
}
}
public connection getconnection() throws sqlexception
{
return drivermanager.getconnection(url, username, password);
}
public static connectionfactory getinstance()
{
if (null==connectionfactory) {
connectionfactory=new connectionfactory();
}
return connectionfactory;
}
}
2）、bookjdbcdao.java数据库操作封装类
package example.dao.book;
import java.sql.connection;
import java.sql.preparedstatement;
import java.sql.resultset;
import java.sql.sqlexception;
import example.bean.book.book;
public class bookjdbcdao {
private preparedstatement ptmt = null;
private resultset rs = null;
public bookjdbcdao() {
}
public void findall(connection conn) throws sqlexception
{
//to do
}
public void delete(connection conn, int id) throws sqlexception
{
string sql = "delete from tb_books where id=?";
try{
ptmt = conn.preparestatement(sql);
// 对sql语句中的第一个占位符赋值
ptmt.setint(1, id);
// 执行更新操作
ptmt.executeupdate();
}finally{
if (null!=ptmt) {
ptmt.close();
}
if (null!=conn) {
conn.close();
}
}
}
public void update(connection conn, int id ,int bookcount) throws sqlexception
{
//to do
}
}
源代码下载链接
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