遇到了若干问题：

1.从oracle返回的列名都是大写，再用反射，就找不到相对应得 名字

2.oracle 中number类型 返回来，就变成了BigDecimal

    public static void main(String[] args){  String sql = "SELECT IDCARD , examcard , "  + "studentname ,"  + "lacation LoCATION,grade "  + " FROM student WHERE IDCARD = ?";  Student s = get(Student.class, sql, 7);  System.out.println(s);  }  //String sql = "SELECT id, name, email, birth "  <span style="white-space:pre">    </span>//<span style="white-space:pre">         </span>+ "FROM customers WHERE id = ?";  public static <T> T get(Class<T> clazz, String sql, Object... args) {  T entity = null;  Connection connection = null;  PreparedStatement preparedStatement = null;  ResultSet resultSet = null;  try {  //1. 得到 ResultSet 对象  connection = JDBC_Tools.getConnection();  preparedStatement = connection.prepareStatement(sql);  for (int i = 0; i < args.length; i++) {  preparedStatement.setObject(i + 1, args[i]);  }  resultSet = preparedStatement.executeQuery();  //2. 得到 ResultSetMetaData 对象  ResultSetMetaData rsmd = resultSet.getMetaData();  //3. 创建一个 Map<String, Object> 对象, 键: SQL 查询的列的别名,   //值: 列的值  Map<String, Object> values = new HashMap<>();  //4. 处理结果集. 利用 ResultSetMetaData 填充 3 对应的 Map 对象  if(resultSet.next()){  for(int i = 0; i < rsmd.getColumnCount(); i++){  //从 ResultSetMetaData 获取列的别名  String columnLabel = rsmd.getColumnLabel(i + 1);  //从 结果集 中获取列的值  Object columnValue = resultSet.getObject(i + 1);  values.put(columnLabel, columnValue);  }  }  //5. 若 Map 不为空集, 利用反射创建 clazz 对应的对象  if(values.size() > 0){  entity = clazz.newInstance();  //5. 遍历 Map 对象, 利用反射为 Class 对象的对应的属性赋值.   for(Map.Entry<String, Object> entry: values.entrySet()){  String fieldName = entry.getKey();  Object value = entry.getValue();  //System.out.println(fieldName+":"+value);  ReflectionUtils.setFieldValue(entity, fieldName, value); //出问题  //System.out.println(ReflectionUtils.getDeclaredField(entity,fieldName));  }  }  } catch (Exception e) {  e.printStackTrace();  } finally {  JDBC_Tools.relaseSource(resultSet, connection, preparedStatement);  }  return entity;  }  }     

ReflectionUtils.setFieldValue(entity, fieldName, value);出问题

java.lang.IllegalArgumentException: Can not set int field xuezaipiao3.Student.GRADE to java.math.BigDecimal
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:164)
at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:168)
at sun.reflect.UnsafeIntegerFieldAccessorImpl.set(UnsafeIntegerFieldAccessorImpl.java:98)
at java.lang.reflect.Field.set(Field.java:741)
at xuezaipiao3.ReflectionUtils.setFieldValue(ReflectionUtils.java:156)
at xuezaipiao3.ThinkInJDBC.get(ThinkInJDBC.java:77)
at xuezaipiao3.ThinkInJDBC.main(ThinkInJDBC.java:45)
Student [IDCARD=0, EXAMCARD=0, STUDENTNAME=null, LOCATION=7, GRADE=0]

Oracle  中 number类型 通过ResultSet 的 getObject() 返回的是 BigDecimal ，无法强制转化，而且 ResultSetMetaData 的 getColumnLabel() 取回的 列的别名是大写

MySQL不存在这样的问题

用的  Oracle 10g

ReflectionUtils

    package xuezaipiao3;  import java.lang.reflect.Field;  import java.lang.reflect.InvocationTargetException;  import java.lang.reflect.Method;  import java.lang.reflect.Modifier;  import java.lang.reflect.ParameterizedType;  import java.lang.reflect.Type;  /** * 反射的 Utils 函数集合 * 提供访问私有变量, 获取泛型类型 Class, 提取集合中元素属性等 Utils 函数 * @author Administrator * */  public class ReflectionUtils {  /** * 通过反射, 获得定义 Class 时声明的父类的泛型参数的类型 * 如: public EmployeeDao extends BaseDao<Employee, String> * @param <T> * @param clazz * @param index * @return */  @SuppressWarnings("unchecked")  public static  Class getSuperClassGenricType(Class clazz, int index){  Type genType = clazz.getGenericSuperclass();  if(!(genType instanceof ParameterizedType)){  return Object.class;  }  Type [] params = ((ParameterizedType)genType).getActualTypeArguments();  if(index >= params.length || index < 0){  return Object.class;  }  if(!(params[index] instanceof Class)){  return Object.class;  }  return (Class) params[index];  }  /** * 通过反射, 获得 Class 定义中声明的父类的泛型参数类型 * 如: public EmployeeDao extends BaseDao<Employee, String> * @param <T> * @param clazz * @return */  @SuppressWarnings("unchecked")  public static<T> Class<T> getSuperGenericType(Class<T> clazz){  return getSuperClassGenricType(clazz, 0);  }  /** * 循环向上转型, 获取对象的 DeclaredMethod * @param object * @param methodName * @param parameterTypes * @return */  public static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes){  for(Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){  try {  //superClass.getMethod(methodName, parameterTypes);  return superClass.getDeclaredMethod(methodName, parameterTypes);  } catch (NoSuchMethodException e) {  //Method 不在当前类定义, 继续向上转型  }  //..  }  return null;  }  /** * 使 filed 变为可访问 * @param field */  public static void makeAccessible(Field field){  if(!Modifier.isPublic(field.getModifiers())){  field.setAccessible(true);  }  }  /** * 循环向上转型, 获取对象的 DeclaredField * @param object * @param filedName * @return */  public static Field getDeclaredField(Object object, String filedName){  for(Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()){  try {  return superClass.getDeclaredField(filedName);  } catch (NoSuchFieldException e) {  //Field 不在当前类定义, 继续向上转型  }  }  return null;  }  /** * 直接调用对象方法, 而忽略修饰符(private, protected) * @param object * @param methodName * @param parameterTypes * @param parameters * @return * @throws InvocationTargetException  * @throws IllegalArgumentException  */  public static Object invokeMethod(Object object, String methodName, Class<?> [] parameterTypes,  Object [] parameters) throws InvocationTargetException{  Method method = getDeclaredMethod(object, methodName, parameterTypes);  if(method == null){  throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + object + "]");  }  method.setAccessible(true);  try {  return method.invoke(object, parameters);  } catch(IllegalAccessException e) {  System.out.println("不可能抛出的异常");  }   return null;  }  /** * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter * @param object * @param fieldName * @param value */  public static void setFieldValue(Object object, String fieldName, Object value){  Field field = getDeclaredField(object, fieldName);  if (field == null)  throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");  makeAccessible(field);  try {  field.set(object, value);  } catch (IllegalAccessException e) {  System.out.println("不可能抛出的异常");  }  }  /** * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter * @param object * @param fieldName * @return */  public static Object getFieldValue(Object object, String fieldName){  Field field = getDeclaredField(object, fieldName);  if (field == null)  throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]");  makeAccessible(field);  Object result = null;  try {  result = field.get(object);  } catch (IllegalAccessException e) {  System.out.println("不可能抛出的异常");  }  return result;  }  }  

来自：http://blog.csdn.net/wjw0130/article/details/43760487