Trang JSP Gọi Hàm Xử Lý Truy Vấn Dữ Liệu MySQL Từ Class Java

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Trang JSP gọi hàm xử lý truy vấn dữ liệu MySQL từ class Java

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Dữ liệu:

 Tạo database db_news

 Tạo table categories

Class Java:

Database.java

package nguyenhuuthe;

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 java.util.logging.Level;

import java.util.logging.Logger;

public class Database {

static final String url =

"jdbc:mysql://localhost:3306/db_news?useUnicode=true&characterEncoding=UTF-8";

static final String username = "root";

static final String password = "123456";

public static Connection conn(){

try{

Class.forName("com.mysql.jdbc.Driver");

Connection con =DriverManager.getConnection(url, username, password);

return con;

}

catch (Exception e) {

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return null; }

}

public static String toUTF8(String isoString)

{

String utf8String = null;

try

{ byte[] stringBytesISO = isoString.getBytes("ISO-8859-1");

utf8String = new String(stringBytesISO, "UTF-8");

}catch(Exception e) { System.out.println("Unsupported Encoding Exception is: " + e.getMessage()); utf8String = isoString;

}

return utf8String;

}

public static void insertCate(String id, String name) {

try {

Connection con = conn();

Statement st = con.createStatement();

String sql="insert into categories values ("+ id +", '"+ name +"')"; st.executeUpdate(sql);

st.close();

con.close();

} catch (Exception ex) {

Logger.getLogger(Database.class.getName()).log(

Level.SEVERE, null, ex);

}

}

public static List<String> selectCate() {

List<String> list = new ArrayList<String>();

try {

String sql = "select * from categories";

Connection con = conn();

Statement stmt = con.createStatement();

ResultSet result = stmt.executeQuery(sql);

while(result.next())

{

list.add(result.getString(1));

list.add(result.getString(2));

}

con.close();

} catch (Exception ex) {

Logger.getLogger(Database.class.getName()).log(

Level.SEVERE, null, ex);

}

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return list;

}

public static void deleteCate(String id) {

try {

String sql = "delete from categories where category_id = "+ id;

Connection con = conn();

Statement st = con.createStatement();

st.executeUpdate(sql);

st.close();

con.close();

} catch (Exception ex) {

Logger.getLogger(Database.class.getName()).log(

Level.SEVERE, null, ex);

}

}

}

add_categories.jsp

<%@page import="nguyenhuuthe.Database"%>

<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%@ page import="java.sql.*" %>

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Books database</title>

<link rel="stylesheet" href="style.css" type="text/css">

</head>

<body>

<br>

<div class="navigator">

< id="currenttab" href="add_categories.jsp">Add</a

< href="delete_categories.jsp">Delete</a

</div>

<%

String id = request.getParameter("id");

String name = request.getParameter("name");

if (id != null && name != null) {

name = nguyenhuuthe.Database.toUTF8(name);

nguyenhuuthe.Database.insertCate(id, name);

}

%>

<br> <br> <br>

<form method="post" action="add_categories.jsp">

<table>

<tr>

Gọi phương thức insertCate() trong class

Database, pakage nguyenhuuthe

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<td>ID</td><td><input type="text" name="id"></td>

</tr>

<tr>

<td>Name</td><td><input type="text" name="name"></td>

</tr>

</table>

<br>

<input type="submit" value="submit">

</form>

</body>

</html>

delete_categories.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>

<%@page import="java.util.*" %>

<html>

<head>

<title>Manager Categories</title>

<link rel="stylesheet" href="style.css" type="text/css">

</head>

<body>

<%

Enumeration<String> names = request.getParameterNames(); while (names.hasMoreElements()) {

String name = (String) names.nextElement();

StringBuffer sb = new StringBuffer(name);

sb.deleteCharAt(0);

nguyenhuuthe.Database.deleteCate(sb.toString()); }

%>

<br>

<div class="navigator">

< href="add_categories.jsp">Add</a

< id="currenttab" href="delete_categories.jsp">Delete</a

</div>

<br> <br> <br>

<form action="delete_categories.jsp" method="post">

<table>

<tr>

<th>ID</th>

<th>Name</th>

<th>Delete</th>

</tr>

<%

List<String> list = nguyenhuuthe.Database.selectCate();

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int id = 0;

String box = null;

Iterator<String> it = list.iterator();

while (it.hasNext()) {

out.print("<tr>");

out.print("<td>");

id = Integer.parseInt(it.next());

out.print(id);

out.print("</td>");

out.print("<td>");

out.print(it.next());

out.print("</td>");

out.print("<td>");

box = "<input name=r" + id + " type='checkbox'>";

out.print(box);

out.print("</td>");

out.print("</tr>");

}

%>

</table>

<br>

<input type="submit" value="Delete">

</form>

</body>

</html>

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