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一个程序的必备代码

1.一个用timer设定的时间控键
private void getTime() {
int delay = 1000; //milliseconds
ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
Calendar cal = Calendar.getInstance();
SimpleDateFormat time = new SimpleDateFormat("yyyy-MM-dd hh:mm.s");
sysTime.setText(time.format(cal.getTime()).toString());
}
};
new Timer(delay, taskPerformer).start();

2.使用SimpleDateFormat实现Date,Calendar的格式化和在程序与数据库之间的日期转化!
--------//设定日期格式:
SimpleDateFormat time = new SimpleDateFormat("yyyy-MM-dd hh:mm.s");
--------
Calendar的getTime();方法反回一个Date对象,
Calendar的add(),set(),get(),用来增加，设置，获得,Calendar中具体日期部分的值
实例：
Calendar time1 = Calendar.getInstance();
int timeLimite = Integer.parseInt(bookVO.getTimeLimit());
Date time2 = bookVO.getLendTime();
time1.set(Calendar.DAY_OF_YEAR, time1.get(Calendar.DAY_OF_YEAR) - timeLimite);

3.实现jTree的基本代码：
jTree1.addTreeSelectionListener(new TreeSelectionListener() {
public void valueChanged(TreeSelectionEvent arg0) {
DefaultMutableTreeNode node = (DefaultMutableTreeNode) jTree1.
getLastSelectedPathComponent();
try {
if (node.isLeaf()) {
table.clear();
getTable();
}
if (node != null && !node.isRoot() && !node.isLeaf()) {
table.clear();
getTable();
}
if (node.isRoot()) {
table.clear();
getTable();
}
}
catch (Exception ex) {
}

}
});

4.实现jTable的基本代码:
实例：
Hashtable table = new Hashtable();
private void getTable() {
BookVO book = new BookVO();
obj = new Object[table.size()][13];
int i = 0;
for (Enumeration e = table.elements(); e.hasMoreElements(); ) {
book = (BookVO) e.nextElement();
obj[i][0] = book.getNo();
i++;
}
jdbTable2 = new JdbTable(obj, head);
//实现对表中的数据只可选中而不可修改：
jdbTable2.setEditable(false);
jdbTable2.setFocusable(true);
//实现对表格的单击事件调用
jdbTable2.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
jdbTable1_mouseClicked(e);
}
});
}

5.HashTable与jTable的连用(HashTable比HashMap更灵活)
(1)
用于与表连用.实现表中的数据是唯一的，以HashTable建表可方便表中数据的增，删，改，查;
以表中的主键作为key,以一个对象作为Value;
(2)
for (Enumeration e = table.elements(); e.hasMoreElements(); ) {
book = (BookVO) e.nextElement();}
HashTable 与 Enumeration的连用实现实现数据的操作

6.使用ArrayList代替结果集反回
ArrayList用于代替结果集返回，一般存放一个对象
实例:
public ArrayList selectBook(String Stype, String Scontent, String isMoHu) {
DBConn db = new DBConn();
ArrayList list = new ArrayList();
db.strSQL = "exec bookfind ?,?,?";
try {
db.cstmt = db.con.prepareCall(db.strSQL);
// db.cstmt.setNull(1,java.sql.Types.str);
db.cstmt.setString(1, Stype);
db.cstmt.setString(2, Scontent);
db.cstmt.setString(3, isMoHu);
db.rs = db.cstmt.executeQuery();
while (db.rs.next()) {
BookVO book = new BookVO();
book.setNo(db.rs.getString(1));
book.setName(db.rs.getString(2));
book.setSort(db.rs.getString(3));
book.setPrice("" + db.rs.getFloat(4));
book.setFactorname(db.rs.getString(5));
book.setConcernSort(db.rs.getString(6));
book.setAuthor(db.rs.getString(7));
book.setTranslate(db.rs.getString(8));
book.setLeavePlace(db.rs.getString(9));
book.setAccessory(db.rs.getString(10));
book.setState(db.rs.getString(11));
book.setEmpName(db.rs.getString(12));
book.setRendMoney("" + db.rs.getFloat(13));
list.add(book);
}
db.rs.close();
}
catch (SQLException ex) {
}
finally {
db.closeConn();
}
return list;
}

7.RunTime实现从一个程序打开另一个程序:
1.打开一个*.exe程序:
Runtime.getRuntime().exec("C:\WINDOWS\system32\notepad.exe");
2.打开一个*.chm:
Runtime.getRuntime().exec("hh.exe E:\JavaScript.chm");