Through a connection pool C3P0 write tools, operation mysql

1 导入 jia 包: c3p0-0.9.1.2.jar mchange-commons-java-0.2.11.jar mysql-connector-java-5.1.37-bin.jar

2 without using the configuration file c3p0-0.9.1.2.jar writing tools

public  class C3P0Utils { 

    Private  static ComboPooledDataSource DS = new new ComboPooledDataSource (); 
    
    // static database connection block disposed four elements of 
    static {
         the try { 
            ds.setDriverClass ( "com.mysql.jdbc.Driver" ); 
            ds.setJdbcUrl ( "JDBC : MySQL: // localhost: 3306 / day04 " ); 
            ds.setUser ( " the root " ); 
            ds.setPassword ( " 123 " ); 
        } the catch (Exception E) {
             // the TODO Auto-Generated Block the catch 
            e.printStackTrace ( ); 
        } 
    }
    
    public  static Connection getConnection () throws SQLException {
         // get a connection, do not get themselves to DriverManager, but taken from the C3P0 connection pool 
        return ds.getConnection (); 
    } 
    
    // close all the resources of the Uniform Code 
    public  static  void closeAll (Connection conn , the Statement ST, the ResultSet RS) {
         // is responsible for closing 
        IF (Conn =! null ) {
             the try { 
                conn.Close (); 
            } the catch (SQLException E) {
                 // the TODO Auto-Generated Block the catch 
                e.printStackTrace (); 
            }
        }
        if(st != null){
            try {
                st.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

3 using the configuration file c3p0-0.9.1.2.jar writing tools (Note: The configuration file name can not be changed)

public  class C3P0Utils02 { 

    Private  static ComboPooledDataSource DS = new new ComboPooledDataSource (); 
    
    // DS objects directly to load C3P0-config.xml file, which automatically loads the four elements is obtained with a loading database connection 
    
    public  static Connection the getConnection () throws SQLException {
         // get a connection, do not get themselves to DriverManager, but taken from the C3P0 connection pool 
        return ds.getConnection (); 
    } 
    
    // close all the resources of the uniform Code 
    public  static  void closeAll (connection conn, ST of Statement, ResultSet rs) {
         / / responsible for closing 
        IF (conn! = null ) {
             the try {
                conn.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(rs != null){
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

4 C3P0 test class

public  class C3P0UtilsTestDemo {
     public  static  void main (String [] args) throws SQLException {
 //         INSERT ();
 //         Delete (); 
        Query (); 
    } 
    
    // insert 
    public  static  void INSERT () throws SQLException {
         // . 1. obtaining a connection 
        connection Conn = C3P0Utils02.getConnection ();
         // 2. Get the object performs 
        the Statement ST = conn.createStatement ();
         // 3. SQL execution 
        int rows = st.executeUpdate("insert into users (username,password) values ('王八','123321')");
        System.out.println(rows);
        //4.
        C3P0Utils02.closeAll(conn, st, null);
    }
    //删除
    public static void delete() throws SQLException{
        //1.获取连接
        Connection conn = C3P0Utils02.getConnection();
        //2.获取执行对象
        Statement st = conn.createStatement();
        //3.执行sql
        int rows = st.executeUpdate("delete from users where uid = 7");
        System.out.println(rows);
        //4.
        C3P0Utils02.closeAll(conn, st, null);
    }
    //查询
    public static void query() throws SQLException{
        //1.获取连接
        Connection conn = C3P0Utils02.getConnection();
        //2.获取执行对象
        Statement st = conn.createStatement();
        //3.执行sql
        ResultSet rs = st.executeQuery("select * from users");
        while(rs.next()){
            System.out.println(rs.getObject("uid")+"\t"+rs.getObject("username")+"\t"+rs.getObject("password"));
        }
        //4.
        C3P0Utils02.closeAll(conn, st, null);
    }
    
}