概念&入门
public static void main(String[] args) throws Exception {
//1 导入jar包
//2注册驱动
Class.forName("com.mysql.jdbc.Driver");
//3 获取连接
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1/db4", "root", "root");
//4.获取执行者对象
Statement stat = conn.createStatement();
//5.执行sql 语句,且接收结果
String sql = "select * from user";
ResultSet rs = stat.executeQuery(sql);
//处理结果
while (rs.next()){
System.out.println(rs.getInt("id")+"----"+rs.getString("NAME")+"----"+rs.getInt("age"));
}
//释放资源
rs.close();
conn.close();
} 工具类
public class JDBCUtils {
//私有构造方法
private JDBCUtils(){}
//声明所需要的配置变量
private static String driverClass;
private static String url;
private static String username;
private static String password;
private static Connection conn;
static {
try {
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("config.properties");
// InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("config.properties");
Properties prop = new Properties();
prop.load(is);
driverClass = prop.getProperty("driverClass");
url = prop.getProperty("url");
username = prop.getProperty("username");
password = prop.getProperty("password");
Class.forName(driverClass);
} catch (Exception e) {
e.printStackTrace();
}
}
//连接方法
public static Connection getConnection() {
try {
conn = DriverManager.getConnection(url, username, password);
} catch (SQLException throwables) {
throwables.printStackTrace();
}
return conn;
}
//释放资源
public static void close(Connection conn, Statement stat, ResultSet rs){
if(conn!=null){
try {
conn.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(stat!=null){
try {
stat.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(rs!=null){
try {
rs.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
public static void close(Connection conn, Statement stat){
if(conn!=null){
try {
conn.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if(stat!=null){
try {
stat.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
} sql注入攻击
JDBC管理事务
连接池
dataSource
private static Connection conn;
private static List<Connection> pool;
public MyDataSource1(String hostToConnectTo, int portToConnectTo, Properties info, String databaseToConnectTo, String url,Connection conn,List<Connection> pool) throws SQLException {
super(hostToConnectTo, portToConnectTo, info, databaseToConnectTo, url);
this.conn = conn;
this.pool = pool;
}
@Override
public void close() throws SQLException {
pool.add(conn);
}
动态代理
public static void main(String[] args) {
Student stu = new Student();
/*
要求：在不改动Student类中任何的代码的前提下，通过study方法输出一句话：来黑马学习
类加载器：和被代理对象使用相同的类加载器
接口类型Class数组：和被代理对象使用相同接口
代理规则：完成代理增强的功能
*/
StudentInterface proxyStu = (StudentInterface) Proxy.newProxyInstance(stu.getClass().getClassLoader(), new Class[]{StudentInterface.class}, new InvocationHandler() {
/*
执行Student类中所有的方法都会经过invoke方法
对method方法进行判断
如果是study，则对其增强
如果不是，还调用学生对象原有的功能即可
*/
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (method.getName().equals("eat")) {
System.out.println("来黑马学习");
return null;
} else {
return method.invoke(stu, args);
}
}
});
proxyStu.eat("面条");
proxyStu.study();
} 
c3p0
<!-- c3p0-config.xml-->
<c3p0-config>
<!-- 使用默认的配置读取连接池对象 -->
<default-config>
<!-- 连接参数 -->
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/db14</property>
<property name="user">root</property>
<property name="password">root</property>
<!-- 连接池参数 -->
<!--初始化的连接数量-->
<property name="initialPoolSize">5</property>
<!--最大连接数量-->
<property name="maxPoolSize">10</property>
<!--超时时间-->
<property name="checkoutTimeout">3000</property>
</default-config>
</c3p0-config>
//测试
public static void main(String[] args) throws SQLException {
DataSource dataSource = new ComboPooledDataSource();
Connection conn = dataSource.getConnection();
System.out.println(conn.getClass());
String sql = "SELECT * FROM student";
PreparedStatement pst = conn.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
while (rs.next()){
System.out.println(rs.getString("name"));
}
rs.close();
pst.close();
conn.close();
} Druid
//测试
public static void main(String[] args) {
try {
Connection conn = DataSourceUtils.getConnection();
System.out.println(conn.getClass());
String sql ="SELECT * FROM student";
PreparedStatement pst = conn.prepareStatement(sql);
ResultSet rs = pst.executeQuery();
while (rs.next()){
System.out.println(rs.getString("name"));
}
DataSourceUtils.close(conn,pst,rs);
} catch (Exception e) {
e.printStackTrace();
}
} /*
数据库连接池的工具类
*/
public class DataSourceUtils {
//1.私有构造方法
private DataSourceUtils(){}
//2.声明数据源变量
private static DataSource dataSource;
//3.提供静态代码块，完成配置文件的加载和获取数据库连接池对象
static{
try{
//完成配置文件的加载
InputStream is = DataSourceUtils.class.getClassLoader().getResourceAsStream("druid.properties");
Properties prop = new Properties();
prop.load(is);
//获取数据库连接池对象
dataSource = DruidDataSourceFactory.createDataSource(prop);
} catch (Exception e) {
e.printStackTrace();
}
}
//4.提供一个获取数据库连接的方法
public static Connection getConnection() {
Connection con = null;
try {
con = dataSource.getConnection();
} catch (SQLException e) {
e.printStackTrace();
}
return con;
}
//5.提供一个获取数据库连接池对象的方法
public static DataSource getDataSource() {
return dataSource;
}
//6.释放资源
public static void close(Connection con, Statement stat, ResultSet rs) {
if(con != null) {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(stat != null) {
try {
stat.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void close(Connection con, Statement stat) {
if(con != null) {
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(stat != null) {
try {
stat.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
} 自定义JDBC框架
京公网安备 11010502036488号