开发人员非常有用的Java功能代码

1. 把Strings转换成int和把int转换成String

String a = String.valueOf(2); 
//integer to numeric string   
int i = Integer.parseInt(a); //numeric 
string to an int 
String a = String.valueOf(2);   
//integer to numeric string
int i = Integer.parseInt(a); //numeric string to an int

2. 向Java文件中添加文本

Updated: Thanks Simone for pointing to exception. I have changed the code. 
 
BufferedWriter out = null;   
try 
{   
   out = new BufferedWriter(new FileWriter("filename", true));   
   out.write("aString");   
}
catch (IOException e)
{   
   //error processing code   
}
finally 
{   
   if (out != null)
   {   
      out.close();   
   }   
}  

3. 获取Java现在正调用的方法名

String methodName =Thread.currentThread().getStackTrace()[1].getMethodName();  
String methodName =Thread.currentThread().getStackTrace()[1].getMethodName();

4. 在Java中将String型转换成Date型

java.util.Date = java.text.DateFormat.getDateInstance().parse(date String);  
java.util.Date = java.text.DateFormat.getDateInstance().parse(date String);
  
SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy");   
Date date = format.parse( myString );  
SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy" );
Date date= format.parse( myString );

5. 通过Java JDBC链接Oracle数据库

public class OracleJdbcTest   
{   
   String driverClass ="oracle.jdbc.driver.OracleDriver";   
   Connection con;   
   public void init(FileInputStream fs) throws ClassNotFoundException,SQLException, FileNotFoundException, IOException   
{   
   Properties props = new Properties();   
   props.load(fs);   
   String url = props.getProperty("db.url");   
   String userName = props.getProperty("db.user");   
   String password = props.getProperty("db.password");   
   Class.forName(driverClass);   
   con=DriverManager.getConnection(url,userName,password);   
}   

public void fetch() throws SQLException,IOException   
{   
   PreparedStatement ps =con.prepareStatement("select SYSDATE from dual");   
   ResultSet rs = ps.executeQuery();   
   while (rs.next())   
   {   
      // do the thing you do   
   }
   rs.close();
   ps.close();   
}   

public static void main(String[] args)
{   
   OracleJdbcTest test = new OracleJdbcTest();   
   test.init();   
   test.fetch();
}   
}  

6.将Java中的util.Date转换成sql.Date

java.util.Date utilDate = new java.util.Date();   
java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());