Java：准备没有连接的语句

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; 

}

来源

2010-05-20 12:31:15 blissapp

那么，如何创建一个没有连接的连接？ – r3zn1k 2010-05-20 12:42:38

sqlite会为你创建一个新的数据库，如果它不存在 - 增加了概念证明代码片段 – blissapp 2010-05-20 13:43:27

更新，刚刚得知SQLite数据库可以在内存中创建只有连接字符串“jdbc：sqlite :: memory：” – blissapp 2010-06-02 18:51:37

尝试实施PreparedStatement。

实施例：类YourOwnClass实现的PreparedStatement {

// 1.不要执行所有方法， 2.获取最小逻辑从OraclePreparedStatement（classes12.jar）或 sun.jdbc.odbc.JdbcOdbcCallableStatement实施

}

来源

2010-05-20 12:33:20 srinannapa

使用正则表达式或类似的东西会容易得多... – r3zn1k 2010-05-20 12:44:11

@ r3zn1k：实现这一点的优点是代码可以重用：它可以生成文本SQL或直接执行SQL。不过，如果你不需要这种灵活性，我不会感到惊讶。 :) – 2010-05-20 12:58:03

这是一个卑鄙狡猾的问题，谢谢完全它很容易应付：

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，只写一个匿名类中的覆盖空洞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！您现在可以使用PreparedStatement进行工作，但尚未构建它。下面是显示的最小样板，否则你不得不复制粘贴到国降临为例，每次你需要时间来写不同的说法：

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); } 
    } 
}

你真的真的不希望复制粘贴到处都有，你做？

来源

2011-08-19 20:43:30 rektide

Java：准备没有连接的语句

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