20个Java程序片段(1-5)

1. 字符串有整型的相互转换

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

2. 向文件末尾添加内容

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. 得到当前方法的名字

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

4. 转字符串到日期

java.util.Date = java.text.DateFormat.getDateInstance().parse(date String);

或者是：

SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy" );
Date date = format.parse( myString );

5. 使用JDBC链接Oracle

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();
}
}