数据库连接步骤
1.注册驱动driver
2.建立连接connection
3.创建sql语句通常是创建statement或者statem的子类PreparedStatement
4.执行语句
5.处理执行结果(在非查询语句中，这一步可以省略)
6.释放相关资源
第一种连接数据库的方法
BaseDao包里的basedao类
importjava.sql.Connection;
importjava.sql.DriverManager;
importjava.sql.SQLException;
publicclassBaseDao {
// private String dbDriver = "oracle.jdbc.driver.OracleDriver";
// private String dbUrl = "jdbc:oracle:thin:@localhost:1521:orcl";
// private String dbUser ="scott";
// private String dbPass ="tiger";
privatestaticfinalStringdriver="com.mysql.jdbc.Driver";
privatestaticfinalStringurl="jdbc:mysql://localhost:3306/area";
privatestaticfinalStringusername="root";
privatestaticfinalStringpassword="accp";
privatestaticConnectioncon;
static{
try{
Class.forName(driver);
con=DriverManager.getConnection(url,username,password);
}catch(Exception e) {
e.printStackTrace();
}
}
publicstaticConnection getCon(){
returncon;
}
publicstaticvoidmain(String[] args) {
Connection con1=BaseDao.getCon();
System.out.println(con1);
}
}
第二种连接数据库的方法
1.创建database文件
jdbc.driver_class=oracle.jdbc.driver.OracleDriver
jdbc.connection.url=jdbc\:oracle\:thin\:@localhost\:1521\:orcl
jdbc.connection.username=scott
jdbc.connection.password=tiger
2.创建ConfigManager类
importjava.io.InputStream;
importjava.util.Properties;
//在这个类是用来读取database.properties文件的
publicclassConfigManager{
privatestaticConfigManagerconfigManager;
privatestaticPropertiesproperties;
//创建构造方法
privateConfigManager(){
String datafile="database.properties";
//实例化我的properties
properties=newProperties();
//通过我的当前类读取到我的属性文件返回一个输入流
InputStream in=ConfigManager.class.getClassLoader().getResourceAsStream(datafile);
try{
properties.load(in);
in.close();
}catch(Exception e) {
System.out.println(e);
}
}
//保证只创建一个configManager对象
publicstaticConfigManagergetIntance(){
if(configManager==null){
configManager=newConfigManager();
}
returnconfigManager;
}
//通过键返回值
publicString getString(String key){
returnproperties.getProperty(key);
}
}
2.创建basedao类建立数据库连接
importjava.sql.Connection;
importjava.sql.DriverManager;
importjava.sql.SQLException;
importjavax.naming.NamingException;
importcom.dbqn.JDBC.util.ConfigManager;
//用来连接数据库的基础类，里面包含一个getCon()方法
publicclassBaseDao {
publicstaticConnection getCon(){
//通过键得到值driver驱动,url地址username用户名password密码
String driver=ConfigManager.getIntance().getString("jdbc.driver_class");
String url=ConfigManager.getIntance().getString("jdbc.connection.url");
String username=ConfigManager.getIntance().getString("jdbc.connection.username");
String password=ConfigManager.getIntance().getString("jdbc.connection.password");
System.out.println(driver);
System.out.println(url);
Connection con=null;
try{
//加载驱动
Class.forName(driver);
//连接数据库
con=DriverManager.getConnection(url, username,password);
}catch(Exception e) {
System.out.println(e);
}
returncon;//返回
}
//当前页测试
publicstaticvoidmain(String[] args)throwsNamingException, SQLException{
Connection con=BaseDao.getCon();
System.out.println(con);
}
}
注册驱动的三种方法
1.使用DriverManager的registerDriver方法进行加载驱动
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
2.使用System.setProperty(“jdbc.driver”,”com.mysql.jdbc.Driver”)
3.Class.forName(“com.mysql.jdbc.Driver”)