DWR级联菜单下拉框

package czw; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Properties; public class DB { private static String driver; private static String url; private static String user; private static String password; static{ try { Properties pro = new Properties(); InputStream in = DB.class.getClassLoader().getResourceAsStream("czw.properties"); pro.load(in); driver = pro.getProperty("driver"); url = pro.getProperty("url"); user = pro.getProperty("user"); password = pro.getProperty("password"); Class.forName(driver); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public DB(){} public static Connection getConnection() throws SQLException{ return DriverManager.getConnection(url,user,password); } public static String[] getColumnNames(ResultSet rs) throws SQLException{ String[] columnNames = null; ResultSetMetaData rsma = rs.getMetaData(); int count = rsma.getColumnCount(); columnNames = new String[count]; for(int i=0;i<count;i++){ columnNames[i] = rsma.getColumnLabel(i+1); //System.out.println(columnNames[i]); } return columnNames; } public List<Map<String, Object> > getList(String sql,Object[] args) throws Exception{ List<Map<String, Object> > list = new ArrayList<Map<String, Object> >(); Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; try{ conn = getConnection(); ps = conn.prepareStatement(sql); if(null!= args && args.length>0){ for(int i=0;i<args.length;i++){ ps.setObject(i+1, args[i]); } } rs = ps.executeQuery(); String[] columnLabel = getColumnNames(rs); while(rs.next()){ Map<String, Object> map = new HashMap<String, Object>(); for(int j=0;j<columnLabel.length;j++){ map.put(columnLabel[j], rs.getObject(columnLabel[j])); } list.add(map); } }catch(Exception e){ e.printStackTrace(); throw new RuntimeException(); }finally{ close(rs,ps,conn); } return list; } public static void close(ResultSet rs,Statement st, Connection conn){ try { if (rs != null) rs.close(); } catch (SQLException e) { e.printStackTrace(); } finally { try { if (st != null) st.close(); } catch (SQLException e) { e.printStackTrace(); } finally { if (conn != null) try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } public static void main(String[] args) throws Exception{ DB db = new DB(); // String sql = "select id ID, sname SNAME, pid PID from S"; // sql = "select id ID, sname SNAME, pid PID from S where s.id = ?"; // List list = db.getList(sql, new Object[]{1}); // for(int i=0;i<list.size();i++){ // Map map = (Map)list.get(i); // System.out.println(map.get("ID")+" , "+map.get("SNAME")+" , "+map.get("PID")); // } String sql = "select id , sname SNAME, pid PID from S"; ResultSet rs = db.getConnection().createStatement().executeQuery(sql); String[] columnNames = db.getColumnNames(rs); for(int i=0;i<columnNames.length;i++){ System.out.println(columnNames[i]); } } }