jsp-连接数据库
jsp连接数据库
index.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
import="java.util.*,rbook.DAO"
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>home</title>
</head>
<%! //可以声明方法 不调用不运行 几乎不用 因为import 考试考
public String username="someone";
public static void test(){
System.out.println(123);
}
%>
<body>
<%
List list=new Vector();
DAO.test();
String name=(String)session.getAttribute("name");
request.setCharacterEncoding("UTF-8");
String form_name=request.getParameter("name");
// response.sendRedirect("http://www.baidu.com");
%>
hello
<% if(name!=null){
out.println(name);
}else{
out.println(username);
}
%>
<form action="login.jsp" method="post">
用户名：<input name="name" type="text"><br>
密码：<input name="password" type="password"><br>
<input type="reset">
<input type="submit">
</form>
</body>
</html>login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="rbook.*,java.sql.*"%>
<!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>Insert title here</title>
</head>
<body>
<%
request.setCharacterEncoding("UTF-8");//习惯
String name = request.getParameter("name");
String password = request.getParameter("password");
if(null!=name){
Connection conn=DB.getConnection();
String sql="SELECT *FROM tb_user where name=‘"+name+"‘ and password=‘"+password+"‘";
Statement stmt =conn.createStatement();
sql="SELECT *FROM tb_user where name=? and password=?";
PreparedStatement pstmt =conn.prepareStatement(sql);
pstmt.setString(1,name);
pstmt.setString(2,password);
System.out.println("name"+name);
System.out.println("password"+password);
System.out.println("sql"+sql);
ResultSet rs= pstmt.executeQuery();
if(rs.next()){//结果不为空
session.setAttribute("name",rs.getString("name"));
response.sendRedirect("index.jsp");
}else{
response.sendRedirect("index.jsp");
}
DB.close(stmt);
DB.close(conn);
}else{
response.sendRedirect("index.jsp");
}
%>
</body>
</html>DB.java
package rbook;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;
public class DB {
private static final String driver ="com.mysql.jdbc.Driver";
private static final String password="";
private static final String url="jdbc:mysql://localhost:3306/chat?useUnicode=true&characterEncoding=UTF-8";
private static final String user="root";
public static Connection getConnection(){
Connection conn=null;
try {
Class<?> theClass = Class.forName(driver);//反射加载mysql的jdbc驱动，注册到DriveManager
conn = DriverManager.getConnection(url,user,password);//用账号密码连接到数据库
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
System.out.println("mysql驱动未找到，请复制java文件到lib目录");
e.printStackTrace();
} catch (SQLException e) { //驱动程序版本不对 账号密码不对 网络超时（忘记去启动mysql -nt
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
public static List<List> queryList(String sql,Object ...values){
Connection conn=null;
PreparedStatement pstmt=null;
List<List> ret = new LinkedList();//末尾增加
System.out.println("execute sql:"+sql); //出错方便调试
try{
conn=getConnection();
pstmt = conn.prepareStatement(sql);
for(int i=0;i < values.length;i++){
pstmt.setObject(i+1, values[i]);//从1开始 设置参数
}
ResultSet rs = pstmt.executeQuery();//执行查询，返回结果集
ResultSetMetaData rsmt = pstmt.getMetaData(); //获得结果集元数据对象
int cloNum =rsmt.getColumnCount();//结果集的列数
while(rs.next()){ //查询到的结果集 默认指针位置是在首记录之前
//返回值表明指针向后移动后，只想的位置是否存在有效记录
List row =new Vector(cloNum); //根据列的数量初始化list实现
for(int i=1;i<=cloNum;i++){
row.add(rs.getObject(i));//为了通用性，以object类型获取
}
ret.add(row);//加入总表
}
System.out.println("return:"+ret.size());//总表多少行
}catch(SQLException e){
e.printStackTrace();
}
DB.close(pstmt); //数据库操作后释放资源 消耗光不能使用
DB.close(conn);
return ret;
}
public static int executeUpdate(String sql,Object ...values){
Connection conn=null; //
PreparedStatement pstmt=null;
int ret =-1;
System.out.println("execute sql:"+sql);
try{//数据库所有操作 都有可能出现异常
conn=getConnection();//获得数据库连接
pstmt = conn.prepareStatement(sql);//预编译sql
for(int i=0;i < values.length;i++){
pstmt.setObject(i+1, values[i]);//从1开始
}
ret = pstmt.executeUpdate();//返回一个数 代表改变多少行（影响的记录行数
System.out.println("return:"+ret);
}catch(SQLException e){
e.printStackTrace(); //打印函数调用栈
}
DB.close(pstmt);
DB.close(conn);
return ret;
}
public static void main(String [] args){
int ret=0;
// String sql ="insert into tb_user(name,email,password) values(?,?,?)";
// ret=executeUpdate(sql,"test","","789");
// System.out.println(ret);
String select ="select * from tb_user";
List<List> data=queryList(select);
for(List list :data){
for(Object object :list){
System.out.print(object+" ");
}
System.out.println();
}
}
public static void close(Object toClose){
//利用反射机制
if(toClose==null) return;
Class theClass=toClose.getClass();//得到参数的类
try {
Method close = theClass.getMethod("close");//找到这个类叫colse的方法
close.invoke(toClose);//对某个对象做close方法
//规律 改变方法属性时要用方法确定这些方法属性从属于哪个对象
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}register.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"
import="rbook.*,java.sql.*"%>
<!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>注册用户</title>
</head>
<body>
<%
request.setCharacterEncoding("UTF-8");//习惯
String name = request.getParameter("name");
String password = request.getParameter("password");
String password2 = request.getParameter("password2");
String email = request.getParameter("email");
if(null!=name){
if(password!=null&&password2!=null&&password.equals(password2)){
String sql = "insert into tb_user(name,password,email) values (‘"+name+"‘,‘"+password+"‘,‘"+email+"‘)";
int ret = DB.executeUpdate(sql);
if(ret>0){
response.sendRedirect("index.jsp");
}else{
out.println("用户名被占用");
}
}else{
out.println("两次密码不一致");
}
}
%>
<form action="register.jsp" method="post">
用户名：<input name="name" type="text" value="<%=name==null?"":name%>"><br>
密码：<input name="password" type="password"><br>
再次输入密码：<input name="password2" type="password"><br>
email：<input name="email" type="text"><br>
<input type="reset">
<input type="submit">
</form>
</body>
</html>list.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.sql.*,rbook.*,java.util.*"%>
<!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>Insert title here</title>
</head>
<body>
<table border="1">
<%
String select ="select * from tb_user";
List<List> data=DB.queryList(select);
for(List list :data){
out.print("<tr>");
for(Object object :list){
out.print("<td>");
System.out.print(object+" ");
out.print("</td>");
}
System.out.println("<br>");//html
}
%>
</table>
</body>
</html>DAO.java
package rbook;
public class DAO extends DB{
public String username="someone";
public static void test(){
System.out.println(123);
}
}
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