java - Java中声明静态常量会影响编译后的类

Question

好吧，这是我的疑问......

我有一个 blazeDS (tomcat) 应用程序，其中包含一些类，每个类都使用 Config 和 DB 类进行配置和数据库连接...

这是一个示例

配置类

public class Config {
    public static final String DBClass = "oracle.jdbc.driver.OracleDriver";
    public static final String ConnectString = "jdbc:oracle:thin:@//127.0.0.1:1521/xe";
    public static final String UserDB = "user";
    public static final String PasswordDB = "pass"; 
}

数据库类

public class DB
{       
    public DB() {}

    public static Connection dbConnect(Connection c)
    {
                try
                {      if (c == null || c.isClosed()){                                  
                            Class.forName(Config.DBClass);
                            c = DriverManager.getConnection(Config.ConnectString,Config.UserDB,Config.PasswordDB);
                        }
                return c;                        
                }
                catch (Exception e)
                {
                        System.out.println(e.getMessage());
                        return null;
                }
    }

    public static void closeConnection(Connection connection) throws SQLException
    {
        if (!connection.isClosed())
            connection.close();
    }
}

我有一个测试和生产环境，每个数据库访问都有不同的用户/密码。 我注意到，当使用测试类更新生产文件时(我不覆盖 Config.class )，我从数据库收到错误...

那么，编译版本中的静态最终值(用户/密码)是否直接保存在类本身中(在我的例子中是DB.class)？？？

Answer 1

简而言之，是的。

摘自Java specs :

"References to fields that are constant variables (§4.12.4) are resolved at compile-time to the constant value that is denoted. No reference to such a field should be present in the code in a binary file (except in the class or interface containing the field, which will have code to initialize it). Such a field must always appear to have been initialized (§12.4.2); the default initial value for the type of such a field must never be observed. See §13.4.9 for a discussion." (p. 339)