Java：準備沒有連接的語句

public Connection connectToDatabase() { 

// connect to the database (creates new if not found) 
try { 
    Class.forName("org.sqlite.JDBC"); 
    conn = DriverManager.getConnection("jdbc:sqlite:mydatabase.db"); 

    // initialise the tables if necessary 
    this.createDatabase(conn); 
} 
catch (java.lang.ClassNotFoundException e) { 
    System.out.println(e.getMessage()); 
} 
catch (java.sql.SQLException e) { 
    System.out.println(e.getMessage()); 
} 

return conn; 

}

來源

2010-05-20 12:31:15 blissapp

那麼，如何創建一個沒有連接的連接？ – r3zn1k 2010-05-20 12:42:38

sqlite會爲你創建一個新的數據庫，如果它不存在 - 增加了概念證明代碼片段 – blissapp 2010-05-20 13:43:27

更新，剛剛得知SQLite數據庫可以在內存中創建只有連接字符串「jdbc：sqlite :: memory：」 – blissapp 2010-06-02 18:51:37

嘗試實施PreparedStatement。

實施例：類YourOwnClass實現的PreparedStatement {

// 1.不要執行所有方法， 2.獲取最小邏輯從OraclePreparedStatement（classes12.jar）或 sun.jdbc.odbc.JdbcOdbcCallableStatement實施

}

來源

2010-05-20 12:33:20 srinannapa

使用正則表達式或類似的東西會容易得多... – r3zn1k 2010-05-20 12:44:11

@ r3zn1k：實現這一點的優點是代碼可以重用：它可以生成文本SQL或直接執行SQL。不過，如果你不需要這種靈活性，我不會感到驚訝。 :) – 2010-05-20 12:58:03

這是一個卑鄙狡猾的問題，謝謝完全它很容易應付：

public class PreparedStatementBuilder 
{ 
    private String sql; // the sql to be executed 

    public PreparedStatementBuilder(final String sql) { this.sql = sql; } 

    protected void preparePrepared(final PreparedStatement preparedStatement) 
      throws SQLException 
    { 
     // this virtual method lets us declare how, when we do generate our 
     // PreparedStatement, we want it to be setup. 

     // note that at the time this method is overridden, the 
     // PreparedStatement has not yet been created. 
    } 

    public PreparedStatement build(final Connection conn) 
      throws SQLException 
    { 
     // fetch the PreparedStatement 
     final PreparedStatement returnable = conn.prepareStatement(sql); 
     // perform our setup directives 
     preparePrepared(returnable); 
     return returnable; 
    } 
}

要使用，只寫一個匿名類中的覆蓋空洞preparePrepared（PreparedStatement的）：

final String sql = "SELECT * FROM FOO WHERE USER = ?"; 
    PreparedStatementBuilder psBuilder = new PreparedStatementBuilder(sql){ 
     @Override 
     protected void preparePrepared(PreparedStatement preparedStatement) 
      throws SQLException 
     { 
      preparedStatement.setString(1, "randal"); 
     }}; 
    return obtainResultSet(psBuilder);

的Presto！您現在可以使用PreparedStatement進行工作，但尚未構建它。下面是顯示的最小樣板，否則你不得不復制粘貼到國降臨爲例，每次你需要時間來寫不同的說法：

public ResultSet obtainResultSet(final PreparedStatementBuilder builder) 
     throws SQLException { 
    final Connection conn = this.connectionSource.getConnection(); 
    try 
    { 
     // your "virtual" preparePrepared is called here, doing the work 
     // you've laid out for your PreparedStatement now that it's time 
     // to actually build it. 
     return builder.build(conn).executeQuery(); 
    } 
    finally 
    { 
     try { conn.close(); } 
     catch (SQLException e) { log.error("f7u12!", e); } 
    } 
}

你真的真的不希望複製粘貼到處都有，你做？

來源

2011-08-19 20:43:30 rektide

Java：準備沒有連接的語句

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