javaweb servlet实例

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本文介绍的是一个简单的javaweb实例。通过jsp、xml、servlet实现数据和视图的传递。

编写工具：eclipse
目录结构：

webapp/          <-- 根目录  
+- src/          <-- java目录   
|  +- bo/     
|  +- dao/   
|  |  +- impl/   
|  +- filter/  
|  +- servlet/  
+- WebContent/   <-- Web目录   
|  +- web-inf/  
|  |  +- lib/    <-- jar存放位置   
|  |  +- web.xml <-- 配置文件   
|  +- web/       <-- jsp文件  
|  +- index.jsp  <-- 主页

xml配置 代码：

<?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">
<display-name>webapp</display-name>
<welcome-file-list>
	<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<filter>
	<display-name>CharacterFilter</display-name>
	<filter-name>CharacterFilter</filter-name>
	<filter-class>filter.CharacterFilter</filter-class>
</filter>
<filter-mapping>
	<filter-name>CharacterFilter</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

<servlet>
	<description></description>
	<display-name>LoginServlet</display-name>
	<servlet-name>LoginServlet</servlet-name>
	<servlet-class>servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
	<servlet-name>LoginServlet</servlet-name>
	<url-pattern>/login</url-pattern>
</servlet-mapping>

</web-app>

lib中存放的jar文件：

mysql.jar
jstl.jar

index.jsp 代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<form action="login" method="post">
	<table align="center">
		<tr>
			<td>用户名： <input type="text" name="name"></input>
			</td>
		</tr>
		<tr>
			<td>密&nbsp码： <input type="password" name="pass"></input>
			</td>
		</tr>
		<tr align="center">
			<td><input type="submit"></input></td>
		</tr>
	</table>
</form>
</body>
</html>

web/main.jsp 代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<table>
	<tr>
		<td>name:${user.name}</td>
	</tr>
</table>
</body>
</html>

filter/CharacterFilter.java 代码：

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class CharacterFilter implements Filter {
public CharacterFilter() {
}

/**
 * @see Filter#destroy()
 */
public void destroy() {
	System.out.println("-----End-----");
}

/**
 * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
 */
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
	request.setCharacterEncoding("utf-8");
	response.setCharacterEncoding("utf-8");	
	chain.doFilter(request, response);
}

/**
 * @see Filter#init(FilterConfig)
 */
public void init(FilterConfig fConfig) throws ServletException {
	System.out.println("-----Star-----");
}

}

databsae/DBHelp.java 代码：

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.PreparedStatement;
import java.sql.Connection;

public class DBHelp {
private final String DRIVER="com.mysql.jdbc.Driver";
private final String URL="jdbc:mysql://127.0.0.1:3306/数据库名称";
private final String USER="mysql用户名";
private final String PASS="mysql用户密码";
private Connection conn;
private PreparedStatement prep;
private Statement stmt;

public DBHelp() {
	try {
		Class.forName(DRIVER);
		conn=DriverManager.getConnection(URL,USER,PASS);
	} catch (ClassNotFoundException e) {
		e.printStackTrace();
	} catch (SQLException e) {
		e.printStackTrace();
	}
}
public int update(String sql) throws SQLException{
	stmt=conn.createStatement();
	int temp=stmt.executeUpdate(sql);
	return temp;
}
public int update(String sql,Object ... arr) throws SQLException{
	prep=conn.prepareStatement(sql);
	for(int i=0;i<arr.length;i++){
		prep.setObject(i+1, arr[i]);
	}
	int temp=prep.executeUpdate();
	return temp;
}
public ResultSet query(String sql) throws SQLException{
	stmt=conn.createStatement();
	ResultSet rs=stmt.executeQuery(sql);
	return rs;
}
public ResultSet query(String sql,Object ... arr) throws SQLException{
	prep=conn.prepareStatement(sql);
	for(int i=0;i<arr.length;i++){
		prep.setObject(i+1, arr[i]);
	}
	return prep.executeQuery();
}
public void close() throws SQLException{
	if(stmt!=null && !stmt.isClosed())stmt.close();
	if(prep!=null && !prep.isClosed())prep.close();
	if(conn!=null && !conn.isClosed())conn.close();
}
}

bo/User.java 代码：

public class User {
private String uid;
private String name;
private String pass;

public String getUid() {
	return uid;
}
public void setUid(String uid) {
	this.uid = uid;
}
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;
}
public User(String uid,String name, String pass) {
	super();
	this.uid=uid;
	this.name = name;
	this.pass = pass;
}
}

servlet/LoginServlet.java 代码：

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import bo.User;
import dao.impl.LoginDaoImpl;

public class LoginServlet extends HttpServlet{
/**
 * @see HttpServlet#HttpServlet()
 */
public LoginServlet() {
	super();
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, 
 * HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
	String name=request.getParameter("name");
	String pass=request.getParameter("pass");
	LoginDaoImpl impl=new LoginDaoImpl();
	User u=impl.view(name,pass);
	response.setContentType("text/html;charset=UTF-8"); 
	if(u==null){
		response.sendRedirect("index.jsp");
	}else{
		request.setAttribute("user",u);
		request.getRequestDispatcher("web/main.jsp").forward(request,response);
	}
}
}

dao/impl/LoginDaoImpl.java 代码：

import bo.User;
import dao.LoginDao;

public class LoginDaoImpl {
private LoginDao logindao;
public LoginDaoImpl(){
	logindao=new LoginDao();
}
public User view(String name,String pass){
	return logindao.view(name,pass);
}
}

dao/LoginDao.java 代码：

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

import bo.User;
import database.DBHelp;

public class LoginDao {
private DBHelp hp;
public User view(String name,String pass){
	String sql="select * from user where username='"+name+"' and password='"+pass+"'";
	hp=new DBHelp();
	User user=null;
	try {
		ResultSet rs=hp.query(sql);
		if(rs.next()){
			user=new User(rs.getString(1),rs.getString(2),rs.getString(3));
		}
	} catch (SQLException e) {
		e.printStackTrace();
	}finally{
		try {
			hp.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	return user;
}
}

数据库模型：

表名：user
列名 数据类型 长度
uid varchar 32
username varchar 32
password varchar 32

以上就是javaweb的一个简单实例。

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