使用DWR框架处理下拉列表的级联

package dao.common; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.List; import javax.servlet.jsp.jstl.sql.Result; import javax.servlet.jsp.jstl.sql.ResultSupport; /** * * 通用的JDBC数据库访问类 * */ @SuppressWarnings({"unchecked"}) public class SQLCommandBean { private Connection conn; private String sqlValue; private List values; /** * 设定连接类 */ public void setConnection(Connection conn) { this.conn = conn; } /** * 设定SQL语句 */ public void setSqlValue(String sqlValue) { this.sqlValue = sqlValue; } /** * 设定SQL语句的参数 */ public void setValues(List values) { this.values = values; } /** * 设定语句的参数 * * @param PreparedStatement对象 * @param values参数列表 * @exception SQLException */ private void setValues(PreparedStatement pstmt, List values) throws SQLException { for (int i = 0; i < values.size(); i++) { Object v = values.get(i); pstmt.setObject(i + 1, v); } } /** * 执行查询 * * @return Result对象 * @exception SQLException */ public Result executeQuery(){ Result result = null; ResultSet rs = null; PreparedStatement pstmt = null; Statement stmt = null; try { if (values != null && values.size() > 0) { pstmt = conn.prepareStatement(sqlValue); setValues(pstmt, values); rs = pstmt.executeQuery(); } else { stmt = conn.createStatement(); rs = stmt.executeQuery(sqlValue); } result = ResultSupport.toResult(rs); } catch (SQLException e) { e.printStackTrace(); } finally { if (rs != null) { try { rs.close(); } catch (SQLException e) { } } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { } } if (pstmt != null) { try { pstmt.close(); } catch (SQLException e) { } } } return result; } /** * 执行Update语句 * * @return 执行影响的行数 * @exception SQLException */ public int executeUpdate() { int noOfRows = 0; ResultSet rs = null; PreparedStatement pstmt = null; Statement stmt = null; try { if (values != null && values.size() > 0) { pstmt = conn.prepareStatement(sqlValue); setValues(pstmt, values); noOfRows = pstmt.executeUpdate(); } else { stmt = conn.createStatement(); noOfRows = stmt.executeUpdate(sqlValue); } } catch (SQLException e) { e.printStackTrace(); } finally { if (rs != null) { try { rs.close(); } catch (SQLException e) { } } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { } } if (pstmt != null) { try { pstmt.close(); } catch (SQLException e) { } } } return noOfRows; } }