Java基础中用到的代码片段

Java基础中用到的代码片段

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( \ ); Date date = format.parse( myString );

5. 使用JDBC链接Oracle

public class OracleJdbcTest

{

String driverClass = \;

Connection con;

public void init(FileInputStream fs) throws ClassNotFoundException, SQLException, FileNotFoundException, IOException {

Properties props = new Properties(); props.load(fs);

String url = props.getProperty(\); String userName = props.getProperty(\); String password = props.getProperty(\); Class.forName(driverClass);

con=DriverManager.getConnection(url, userName, password); }

public void fetch() throws SQLException, IOException {

PreparedStatement ps = con.prepareStatement(\ 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. 把 Java util.Date 转成 sql.Date

java.util.Date utilDate = new java.util.Date();

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

7. 使用NIO进行快速的文件拷贝

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

// magic number for Windows, 64Mb - 32Kb)

int maxCount = (64 * 1024 * 1024) - (32 * 1024); long size = inChannel.size(); long position = 0;

while ( position < size ) {

position += inChannel.transferTo( position, maxCount, outChannel );