概念:存放数据库连接的一个容器(集合)Connection
当系统运行起来之后,这个连接池就被创建,在这个连接池当中,会申请一些对象,当有用户来访问数据库的时候,就从这个连接池当中获取连接对象,用户访问结束之后,连接池对象会归还给容器
java官方提供了标准接口 DataSource(javax.sql包下)
//常用方法
getConnection();//获取连接对象
conn.close();//归还连接池对象
此接口由数据库厂商为我们实现
①C3P0 ②Druid阿里巴巴开发的数据库连接池
public class demo1 {
public static void main(String[] args) {
try {
//3. 创建数据源连接对象 DataSource
DataSource dataSource = new ComboPooledDataSource();
//4. 获取连接
Connection connection = dataSource.getConnection();
System.out.println(connection.toString());
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
public class demo1 {
public static void main(String[] args) {
DataSource dataSource = null;
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
//3. 创建数据源连接对象 DataSource
dataSource = new ComboPooledDataSource();
//4. 获取连接
connection = dataSource.getConnection();
String sql = "select * from mytest";
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
while (resultSet.next()){
int id = resultSet.getInt("id");
String name = resultSet.getString("sname");
String pass = resultSet.getString("spwd");
System.out.println(id+name+pass);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
try {
preparedStatement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
}
1.导入jar包
2.定义配置文件, 任意的名称和任意的位置 eg:xxx.properties
3.加载配置文件
4.创建数据源对象
5.获取连接
public class DruidDemo1 {
public static void main(String[] args) {
DataSource dataSource = null;
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
dataSource = new ComboPooledDataSource();
connection = dataSource.getConnection();
String sql = "select * from mytest";
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
while (resultSet.next()){
int i = resultSet.getInt(1);
String name = resultSet.getString("sname");
String pass = resultSet.getString("spwd");
System.out.println(i+"---"+name+"---"+pass);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
try {
preparedStatement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
}
创建实体类 user 和数据库表对应
定义一个工具类
提供静态代码块 加载配置文件 初始化连接池对象
提供方法
1.获取连接池对象的方法
2.释放资源的方法
3.获取数据源对象的方法
//工具类
public class DruidUtiles {
private static DataSource dataSource;
static {
//读取资源文件,获取值,执行一次
Properties properties = new Properties();
try {
//加载配置文件
properties.load(new FileReader("D:\\桌面\\JDBC\\JDBC-C3P0\\src\\druid.properties"));
//初始化连接池对象
dataSource = DruidDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
//1.获取连接池对象的方法
public static Connection getConnection() throws SQLException {
return dataSource.getConnection();
}
//2.释放资源的方法
public static void close(Connection connection, PreparedStatement preparedStatement){
if(connection!=null){
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(preparedStatement!=null){
try {
preparedStatement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
//2.释放资源的方法
public static void close(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet){
if(connection!=null){
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(preparedStatement!=null){
try {
preparedStatement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(resultSet!=null){
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
// 3.获取数据源对象的方法
public static DataSource getDataSource(){
return dataSource;
}
}
/**
* 添加操作
*/
public class DruidDemo2 {
public static void main(String[] args) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = DruidUtiles.getConnection();
String sql="insert into mytest values(null,?,?)";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1,"hhbh");
preparedStatement.setString(2,"821821");
int i = preparedStatement.executeUpdate();
System.out.println(i);
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
DruidUtiles.close(connection,preparedStatement);
}
}
}
//查询
public class DruidDemo3 {
public static void main(String[] args) {
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
connection = DruidUtiles.getConnection();
String sql="select * from mytest";
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
List<user> list = new ArrayList<>();
while (resultSet.next()){
user u = new user();
u.setId(resultSet.getInt("id"));
u.setName(resultSet.getString("sname"));
u.setPassword(resultSet.getString("spwd"));
System.out.println(u);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
DruidUtiles.close(connection,preparedStatement,resultSet);
}
}
}
Spring框架对JDBC的简单封装,提供了一个JdbcTemplate对象,大大的简化了开发
1.导入jar包 5个
2.创建一个JdbcTemPlate,依赖对象DataSource
3.调用JdbcTemPlate对象中的方法帮助我们实现增删改查
update();//执行增删改语句
queryForMap();//查询结束,并将结果封装成Map集合
queryForList();//查询结束,并将结果封装成Map集合,并将map存放在list当中
query();//查询结果,并将结果封装成JavaBean对象
queryForObject();//查询结果,并将结果封装成对象
修改 密码
添加
删除
查询所有记录 将结果封装成map------结果只有一条,列名为key,值为value
查询所有记录 将结果封装成list
查询所有记录 将结果封装成JavaBean
查询总记录数
public class jdbcTemplateDemo {
private JdbcTemplate jt = new JdbcTemplate(DruidUtiles.getDataSource());
//修改密码
public void test1(){
String sql = "update mytest set spwd = ? where id =?";
int update = jt.update(sql, 730730, 8);
System.out.println(update);
}
//添加
public void test2(){
String sql = "insert into mytest values(null,?,?)";
int update = jt.update(sql,"张三", 77777);
System.out.println(update);
}
//删除
public void test3(){
String sql = "delete from mytest where id = ?";
int update = jt.update(sql,9);
System.out.println(update);
}
//查询所有记录 将结果封装成map
public void test4(){
String sql = "select * from mytest where id = ?";
Map<String, Object> map = jt.queryForMap(sql,1);
System.out.println(map);
}
//查询所有记录 将结果封装成list
public void test5(){
String sql = "select * from mytest ";
List<Map<String, Object>> maps = jt.queryForList(sql);
System.out.println(maps);
}
//查询所有记录 将结果封装成JavaBean-----方法1
public void test6(){
String sql = "select * from mytest ";
List<user> query = jt.query(sql, new RowMapper<user>() {
@Override
public user mapRow(ResultSet resultSet, int i) throws SQLException {
user u = new user();
u.setId(resultSet.getInt("id"));
u.setName(resultSet.getString("sname"));
u.setPassword(resultSet.getString("spwd"));
return u;
}
});
System.out.println(query);
}
//查询所有记录 将结果封装成JavaBean-----方法2
public void test7(){
String sql = "select * from mytest ";
List<user> query = jt.query(sql, new BeanPropertyRowMapper<user>(user.class));
System.out.println(query);
}
//查询总记录数
public void test8(){
String sql = "select count (*) from mytest ";
Long aLong = jt.queryForObject(sql,Long.class);
System.out.println(aLong);
}
}
public class test {
public static void main(String[] args) {
jdbcTemplateDemo jdbcTemplateDemo = new jdbcTemplateDemo();
jdbcTemplateDemo.test1();
jdbcTemplateDemo.test2();
jdbcTemplateDemo.test3();
jdbcTemplateDemo.test4();
jdbcTemplateDemo.test5();
jdbcTemplateDemo.test6();
jdbcTemplateDemo.test7();
jdbcTemplateDemo.test8();
}
}