java连接数据库
1.jdbc连接数据库
package com.hu.demo;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class DBHelper {
public static final String url = "jdbc:mysql://127.0.0.1/student";
public static final String name = "com.mysql.jdbc.Driver";
public static final String user = "root";
public static final String password = "root";
public Connection conn = null;
public PreparedStatement pst = null;
public DBHelper(String sql) {
try {
Class.forName(name);//指定连接类型
conn = DriverManager.getConnection(url, user, password);//获取连接
pst = conn.prepareStatement(sql);//准备执行语句
} catch (Exception e) {
e.printStackTrace();
}
}
public void close() {
try {
this.conn.close();
this.pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
package com.hu.demo;
import java.sql.ResultSet;
import java.sql.SQLException;
public class Demo {
static String sql = null;
static DBHelper db1 = null;
static ResultSet ret = null;
public static void main(String[] args) {
sql = "select *from stuinfo";//SQL语句
db1 = new DBHelper(sql);//创建DBHelper对象
try {
ret = db1.pst.executeQuery();//执行语句，得到结果集
while (ret.next()) {
String uid = ret.getString(1);
String ufname = ret.getString(2);
String ulname = ret.getString(3);
String udate = ret.getString(4);
System.out.println(uid + "\t" + ufname + "\t" + ulname + "\t" + udate );
}//显示数据
ret.close();
db1.close();//关闭连接
} catch (SQLException e) {
e.printStackTrace();
}
}
}
2.Spring + JdbcTemplate + JdbcDaoSupport
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean id="test" class="jdbc.Test"> <property name="dataSource" ref="dataSource"></property> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/testspring" /> <property name="username" value="root" /> <property name="password" value="" /> </bean> </beans>
spring
package jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
private DataSource dataSource;
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public void insert(User u) {
String sql = "insert into _user " + "values(null, ?, ?)";//普通的sql语句
Connection conn = null;
try {
conn = dataSource.getConnection();
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, u.getName());
ps.setString(2, u.getPassword());
ps.executeUpdate();
ps.close();
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
}
}
}
}
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"applicationContext.xml");
Test t = (Test) ctx.getBean("test");
User u = new User();
u.setName("dd");
u.setPassword("dd");
t.insert(u);
}
}
JdbcTemplate
package jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;
public class Test {
private DataSource dataSource;
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public void insert(User u) {
String sql = "insert into _user " + "values(null, ?, ?)";//普通的sql语句
JdbcTemplate template = new JdbcTemplate(dataSource);
template.update(sql, new Object[]{u.getName(), u.getPassword()});
}
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"applicationContext.xml");
Test t = (Test) ctx.getBean("test");
User u = new User();
u.setName("dd");
u.setPassword("dd");
t.insert(u);
}
}
JdbcDaoSupport
package jdbc;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
public class Test extends JdbcDaoSupport {
//JdbcDaoSupport类已经有了public final void setDataSource(DataSource dataSource)了
//不用重写也不能重写
public void insert(User u) {
String sql = "insert into _user " + "values(null, ?, ?)";//普通的sql语句
this.getJdbcTemplate().update(sql, new Object[]{u.getName(), u.getPassword()});
}
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"applicationContext.xml");
Test t = (Test) ctx.getBean("test");
User u = new User();
u.setName("dd");
u.setPassword("dd");
t.insert(u);
}
}
参考博文http://hzy3774.iteye.com/blog/1689525
hibernate
public List<UserPO> LoginUser(UserPO up)throws Exception{
Session session = HibernateSessionFactory.getSession();
String hql = "from UserPO where name = ? and pwd= ?";
Query query = session.createQuery(hql);
query.setString(0, up.getName());
query.setString(1, up.getPwd());
List<UserPO> list = query.list();
session.close();
return list;
}
// 建工厂类HibernateUtil
package com.historycreator.hibernate;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
return new Configuration().configure().buildSessionFactory();
}
catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
//建类EventManager
package com.historycreator.hibernate;
import java.util.Date;
import org.hibernate.classic.Session;
public class EventManager {
public static void main(String[] args) {
EventManager mgr = new EventManager();
mgr.createAndStoreEvent("My Event", new Date());
HibernateUtil.getSessionFactory().close();
}
private void createAndStoreEvent(String title, Date theDate) {
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
Event theEvent = new Event();
theEvent.setTitle(title);
theEvent.setDate(theDate);
session.save(theEvent);
session.getTransaction().commit();
}
}