加载驱动+建立连接+创建sql语句+执行并获取结果+释放连接 增删改查

package com.hp.dao;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.hp.bean.Menus;
import com.hp.util.DBCon;

public class MenusDao {

public List<Menus> selectAll(){

String sql = "select * from menus";
try {
ResultSet rs = DBCon.executeQuery(sql);
List<Menus> menus = new ArrayList<Menus>();
while(rs.next()){
Menus menu = new Menus();
menu.setId(rs.getInt(1));
menu.setName(rs.getString(2));
menu.setBurden(rs.getString(3));
menu.setPrice(rs.getFloat(4));
menus.add(menu);
}
return menus;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}

public int insert(Menus m){

String sql = "insert into menus (name,burden,price) values ('"
+m.getName()+"','"+m.getBurden()+"',"+m.getPrice()+")";
try {
int i = DBCon.executeUpdate(sql);
return i;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return 0;
}
}

public Menus selectById(Menus m){

String sql = "select * from menus where id="+m.getId();
try {
ResultSet rs = DBCon.executeQuery(sql);
Menus menu = new Menus();
while(rs.next()){
menu.setId(rs.getInt(1));
menu.setName(rs.getString(2));
menu.setBurden(rs.getString(3));
menu.setPrice(rs.getFloat(4));
}
return menu;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}

public int update(Menus m){

String sql = "update menus set name='"+m.getName()
+"',burden='"+m.getBurden()+"',price="+m.getPrice()+" where id="+m.getId();
try {
int i = DBCon.executeUpdate(sql);
return i;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return 0;
}
}

public int delete(Menus m){

String sql = "delete from menus where id="+m.getId();
try {
int i = DBCon.executeUpdate(sql);
return i;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return 0;
}
}
package com.hp.util;

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

public class DBCon {

private static String DBConDriver = "com.mysql.jdbc.Driver";
private static String DBConURL = "jdbc:mysql://localhost/apsfc";
private static String user = "root";
private static String pass = "123456";
private static Connection con = null;

private DBCon(){
try {
Class.forName(DBConDriver);
if(con==null){
con = DriverManager.getConnection(DBConURL,user,pass);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static ResultSet executeQuery(String sql){
new DBCon();
ResultSet rs = null;
try {
rs = con.createStatement().executeQuery(sql);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return rs;
}

public static int executeUpdate(String sql){
new DBCon();
int i = 0;
try {
i = con.createStatement().executeUpdate(sql);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return i;
}

public static void close(){
try {
con.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
con = null;
}
}
}

贾琏欲执事
加载驱动+建立连接+创建sql语句+执行并获取结果+释放连接
增删改查
package ch16;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.DriverManager;
import java.sql.SQLException;

publicclass Test {
publicstaticvoid main(String[] arge) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
// 1.注册驱动
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
// 增删改查
try {
// 2.建立连接
conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/test", "root", "123");
// 3.创建语句
stmt = conn.createStatement();
// 4.执行语句
// 增加
stmt.executeUpdate("insert into text(id,name,xuehao)values(7,'李刚',65)");
// 删除多条
stmt.executeUpdate("delete from text where name in('王五','赵六') ");
// 删除一条
stmt.executeUpdate("delete from text where name='王五' ");
// 改
stmt.executeUpdate(" update text set id=150 where name='陈二' ");
// 查询
//条件查询rs = stmt.executeQuery("select * from text where id=6");
//全部查询rs = stmt.executeQuery("select * from text ");
// 5.处理结果
while (rs.next()) {
System.out.println(rs.getInt("id") + "\t"
+ rs.getString("name") + "\t" + rs.getInt("xuehao")
+ "\t");
}
} catch (SQLException e) {
e.printStackTrace();
}
// 6.释放资源
finally {
if (rs != null)
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
if (stmt != null)
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
if (conn != null)
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}