JDBC连接数据库例子--一般，封装，单例模式封装

一般：

Test.java

package day01;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

public class Test {

public static void main(String[] args) {

Jdbc();

}



public static void Jdbc(){

Connection conn=null;

java.sql.Statement st=null;

ResultSet rs=null;

PreparedStatement pst=null;



try{

Class.forName("oracle.jdbc.driver.OracleDriver");

}catch(ClassNotFoundException e){

e.printStackTrace();

}try{

conn=DriverManager.getConnection("jdbc:oracle:thin:@OWEYOJ5DU7AAHZZ:1521:ORCL", "jbit", "bdqn");

//Statement的使用

st=conn.createStatement();

String sql="select * from user1";

rs=st.executeQuery(sql);

while(rs.next()){

System.out.println(rs.getInt(1)+" ,"+rs.getString(2));

}

//PreparedStatement的使用

String sql1="insert into user1(id,name) values(?,?)";

pst=conn.prepareStatement(sql1);

pst.setInt(1, 2);

pst.setString(2, "niini");

pst.execute();

}catch(SQLException e){

e.printStackTrace();

}finally{

if(rs!=null){

try {

rs.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(st!=null){

try {

st.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(conn!=null){

try {

conn.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}

}

封装

JdbcTest.java

package day01;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class JdbcTest {

public static void main(String[] args){

Connection conn=null;

Statement st=null;

ResultSet rs=null;

/*

JdbcUnit.Driver();

conn=JdbcUnit.conn();

*/

//调用单例模式

JdbcUnitSing.getJdbcUnitSing().Driver();

conn=JdbcUnitSing.getJdbcUnitSing().conn();

try {

st=conn.createStatement();

String sql="select * from user1";

rs=st.executeQuery(sql);

while(rs.next()){

System.out.println(rs.getInt("id")+","+rs.getString("name"));

}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

JdbcUnit.closeConn(conn, st, rs);



}

}

用static 封装

jdbcUnit.java

package day01;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public final class JdbcUnit {

private static String url="jdbc:oracle:thin:@OWEYOJ5DU7AAHZZ:1521:ORCL";

private static String name="jbit";

private static String password="bdqn";

private static Connection conn=null;



//实例化一次

private JdbcUnit(){

}



public static void Driver(){

try{

Class.forName("oracle.jdbc.driver.OracleDriver");

}catch(ClassNotFoundException e){

e.printStackTrace();

}

}



public static Connection conn(){

try {

return conn=DriverManager.getConnection(url,name,password);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return conn;

}



public static void closeConn(Connection conn,Statement st,ResultSet rs){

if(rs!=null){

try {

rs.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(st!=null){

try {

st.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(conn!=null){

try {

conn.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}



}



单例模式封装

JdbcUintSing.java

package day01;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public final class JdbcUnitSing {

private static String url="jdbc:oracle:thin:@OWEYOJ5DU7AAHZZ:1521:ORCL";

private static String name="jbit";

private static String password="bdqn";

private static Connection conn=null;



//实例化一次

private JdbcUnitSing(){

}

//只创建一个实例

private static JdbcUnitSing jus = new JdbcUnitSing();

//给外界提供实例的访问对象

public static JdbcUnitSing getJdbcUnitSing(){

return jus;

}



public void Driver(){

try{

Class.forName("oracle.jdbc.driver.OracleDriver");

}catch(ClassNotFoundException e){

e.printStackTrace();

}

}



public Connection conn(){

try {

return conn=DriverManager.getConnection(url,name,password);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return conn;

}



public void closeConn(Connection conn,Statement st,ResultSet rs){

if(rs!=null){

try {

rs.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(st!=null){

try {

st.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if(conn!=null){

try {

conn.close();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}



}