Java反射泛型，实现数据库的动态增删改查等功能

import java.lang.reflect.Field; 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.util.ArrayList; import java.util.List; public class OracleHelper { public static final String CLASS_NAME = "oracle.jdbc.driver.OracleDriver"; public static final String URL = "jdbc:oracle:thin:@localhost:1522:accp11g"; public static final String UID = "system"; public static final String PWD = "manager"; public static Connection getConnection() throws ClassNotFoundException, SQLException { Class.forName(CLASS_NAME); return DriverManager.getConnection(URL,UID,PWD); } public static int executeNonQuery(String cmdText) throws ClassNotFoundException, SQLException { int result = -1; Connection con = null; PreparedStatement ps = null; try { con = getConnection(); ps = con.prepareStatement(cmdText); result = ps.executeUpdate(); }catch (Exception e) { System.out.println(e); } finally { close(con, ps, null); } return result; } public static int executeScalar(String cmdText) throws SQLException, ClassNotFoundException { int result = -1; Connection con = null; PreparedStatement ps = null; ResultSet rs = null; try { con = getConnection(); ps = con.prepareStatement(cmdText); rs = ps.executeQuery(); if (rs.next()) { result = rs.getInt(1); } }catch (Exception e) { System.out.println(e); } finally { close(con, ps, rs); } return result; } public static <T> List<T> executeList(Class<T> cls, String cmdText) throws ClassNotFoundException, SQLException, InstantiationException, IllegalAccessException { List<T> list = new ArrayList<T>(); Connection con = null; PreparedStatement ps = null; ResultSet rs = null; try { con = getConnection(); ps = con.prepareStatement(cmdText); rs = ps.executeQuery(); while (rs.next()) { T obj = executeResultSet(cls, rs); list.add(obj); } } catch (Exception e) { System.out.println(e); }finally { close(con, ps, rs); } return list; } public static <T> T executeEntity(Class<T> cls, String cmdText) throws SQLException, ClassNotFoundException, InstantiationException, IllegalAccessException { T obj = null; Connection con = null; PreparedStatement ps = null; ResultSet rs = null; try { con = getConnection(); ps = con.prepareStatement(cmdText); rs = ps.executeQuery(); while (rs.next()) { obj = executeResultSet(cls, rs); break; } } catch (Exception e) { System.out.println(e); }finally { close(con, ps, rs); } return obj; } private static <T> T executeResultSet(Class<T> cls, ResultSet rs) throws InstantiationException, IllegalAccessException, SQLException { T obj = cls.newInstance(); ResultSetMetaData rsm = rs.getMetaData(); int columnCount = rsm.getColumnCount(); Field[] fields = cls.getFields(); for (int i = 0; i < fields.length; i++) { Field field = fields[i]; String fieldName = field.getName(); for (int j = 1; j <= columnCount; j++) { String columnName = rsm.getColumnName(j); if (fieldName.equalsIgnoreCase(columnName)) { Object value = rs.getObject(j); field.set(obj, value); break; } } } return obj; } private static void close(Connection con, PreparedStatement ps, ResultSet rs) throws SQLException { if (rs != null) { rs.close(); rs = null; } if (ps != null ) { ps.close(); ps = null; } if (con != null) { con.close(); con = null; } } }