developer.51cto/art/200905/124291.htm
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 stringint
i = Integer.parseInt(a); //numeric string to an int
2. 向Java文件中添加文本
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);
or
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.pass
word");
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());
java.util.Date utilDate = new java.util.Date();java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());
7. 使用NIO快速复制Java文件
public static void fileCopy( File in, File out ) throws IOException
{
FileChannel inChannel = new FileInputStream( in ).getChannel();
FileChannel outChannel = new FileOutputStream( out ).getChannel();
try
{
//
inChannel.transferTo(0, inChannel.size(), outChannel); // original -- apparently has
trouble copying large files on Windows
int maxCount = (64 * 1024 * 1024) - (32 * 1024); // magic number for Windows, 64Mb - 32Kb)
long size = inChannel.size();
long position = 0;
while ( position < size )
{
position += inChannel.transferTo( position, maxCount, outChannel );
}
}
finally
{
if ( inChannel != null )
{
inChannel.close();
}
if ( outChannel != null )
{
outChannel.close();
}
}
}
8. 在Java中创建缩略图
private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename) throws InterruptedException, FileNotFoundException, IOException
{
// load image from
filename Image image = Toolkit.getDefaultToolkit().getImag