浅析JDBC的使用方法

public class JDBCUtils {
 private static String url;
 private static String user;
 private static String password;
 private static String driver;
 /**
  * 文件的读取，只需要读取一次即可拿到这些值。使用静态代码块
  */
 static{
  //读取资源文件，获取值。
 
  try {
  //1. 创建Properties集合类。
  Properties pro = new Properties();
 
  //获取src路径下的文件的方式--->ClassLoader 类加载器
  ClassLoader classLoader = JDBCUtils.class.getClassLoader();
  URL res = classLoader.getResource("jdbc.properties");
  String path = res.getPath();
  
  //2. 加载文件
  pro.load(new FileReader(path));
 
  //3. 获取数据，赋值
  url = pro.getProperty("url");
  user = pro.getProperty("user");
  password = pro.getProperty("password");
  driver = pro.getProperty("driver");
  //4. 注册驱动
  Class.forName(driver);
  } catch (IOException e) {
  e.printStackTrace();
  } catch (ClassNotFoundException e) {
  e.printStackTrace();
  }
 }
 
 
 /**
  * 获取连接
  * @return 连接对象
  */
 public static Connection getConnection() throws SQLException {
 
  return DriverManager.getConnection(url, user, password);
 }
 
 /**
  * 释放资源
  * @param stmt
  * @param conn
  */
 public static void close(Statement stmt,Connection conn){
  if( stmt != null){
  try {
   stmt.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  }
 
  if( conn != null){
  try {
   conn.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  }
 }
 
 
 /**
  * 释放资源
  * @param stmt
  * @param conn
  */
 public static void close(ResultSet rs,Statement stmt, Connection conn){
  if( rs != null){
  try {
   rs.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  }
 
  if( stmt != null){
  try {
   stmt.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  }
 
  if( conn != null){
  try {
   conn.close();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  }
 }
 
 }

public static void main(String[] args) {
 PreparedStatement pstmt1 = null;
 PreparedStatement pstmt2 = null;
 Connection con = null;


 try {
 con = JDBCUtils.getConnection();
 //开启事务
 con.setAutoCommit(false);
 //2.1 张三 - 500
 String sql1 = "update account set balance = balance - ? where id = ?";
 //2.2 李四 + 500
 String sql2 = "update account set balance = balance + ? where id = ?";


 pstmt1 = con.prepareStatement(sql1);
 pstmt2 = con.prepareStatement(sql2);


 //4. 设置参数,sql语句里的问号
 pstmt1.setDouble(1,500);//填第一个数据
 pstmt1.setInt(2,1);//填第二个数据


 pstmt2.setDouble(1,500);
 pstmt2.setInt(2,2);
 //5.执行sql
 pstmt1.executeUpdate();
 // 手动制造异常
 int i = 3/0;


 pstmt2.executeUpdate();
 //提交事务
 con.commit();
 } catch (SQLException e) {
 e.printStackTrace();
 } catch (Exception e){
 try {
  con.rollback();
 } catch (SQLException ex) {
  ex.printStackTrace();
 }
 } finally{
 JDBCUtils.close(con,pstmt1);
 JDBCUtils.close(con,pstmt2);
 }
}

//1.创建数据库连接池对象
 DataSource ds = new ComboPooledDataSource();
 //2. 获取连接对象
 Connection conn = ds.getConnection();

//3.加载配置文件
Properties pro = new Properties();
InputStream is = DruidDemo.class.getClassLoader().getResourceAsStream("druid.properties");
pro.load(is);
//4.获取连接池对象
DataSource ds = DruidDataSourceFactory.createDataSource(pro);
//5.获取连接
Connection conn = ds.getConnection();

public class JDBCUtils {

    //1.定义成员变量 DataSource
    private static DataSource ds ;
   
    static{
     try {
      //1.加载配置文件
      Properties pro = new Properties();
      pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
      //2.获取DataSource
      ds = DruidDataSourceFactory.createDataSource(pro);
     } catch (IOException e) {
      e.printStackTrace();
     } catch (Exception e) {
      e.printStackTrace();
     }
    }
   
    /**
     * 获取连接
     */
    public static Connection getConnection() throws SQLException {
     return ds.getConnection();
    }

//2. 定义sql
 
//1. 获取JDBCTemplate对象
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
String sql = "update emp set salary = 10000 where id = 1001";
//3. 执行sql
int count = template.update(sql);
System.out.println(count);