日期:2014-05-16  浏览次数:20440 次

通过JDBC来理解反射机制
//将ResultSet中的数据转换为相应的对象
	@SuppressWarnings("unchecked")
	private <T> T buildAlarm(T pojo, ResultSet rs) {
		ResultSetMetaData rsmd;
		try {
			rsmd = rs.getMetaData();
			int columnsCount = rsmd.getColumnCount();
			for (int i = 1; i <= columnsCount; i++) {
				String fieldName = rsmd.getColumnLabel(i).toLowerCase();
				Object value = rs.getObject(fieldName);
				if(value instanceof java.sql.Date){
					value = new java.util.Date(((java.sql.Date) value).getTime());
				}
				if(value instanceof java.sql.Timestamp){
					value = new java.util.Date(((java.sql.Timestamp) value).getTime());
				}
				BeanUtils.setProperty(pojo, fieldName, value);
			}
		} catch (Exception e1) {
		}
		return pojo;
	}
	
	
	
	
	
	
	private <T> T buildAlarm(T pojo, ResultSet rs) {
		ResultSetMetaData rsmd;
		try {
			rsmd = rs.getMetaData();
			int columnsCount = rsmd.getColumnCount();
			for (int i = 1; i <= columnsCount; i++) {
				String fieldName = rsmd.getColumnLabel(i).toLowerCase();
				Object value = rs.getObject(fieldName);
				if(value instanceof java.sql.Date){
					value = new java.util.Date(((java.sql.Date) value).getTime());
				}
				if(value instanceof java.sql.Timestamp){
					value = new java.util.Date(((java.sql.Timestamp) value).getTime());
				}
				BeanUtils.setProperty(pojo, fieldName, value);
			}
		} catch (Exception e1) {
		}
		return pojo;
	}
	
	
	
	
	//将ResultSet中的数据转换为相应的对象
	@SuppressWarnings("unchecked")
	private <T> T buildAlarm_rs(T pojo, ResultSet rs) {

		Class classType = pojo.getClass();
		ResultSetMetaData rsmd;
		try {
			rsmd = rs.getMetaData();
			int columnsCount = rsmd.getColumnCount();

			for (int i = 1; i <= columnsCount; i++) {
				String fieldName = rsmd.getColumnLabel(i).toLowerCase();
				String stringLetter = fieldName.substring(0, 1).toUpperCase();

				String setName = "set" + stringLetter + fieldName.substring(1);
				String getName = "get" + stringLetter + fieldName.substring(1);

				Method getMethod = classType.getMethod(getName, new Class[] {});
				Method setMethod = classType.getMethod(setName,
						new Class[] { getMethod.getReturnType() });
				Class fieldType = setMethod.getParameterTypes()[0];
				Object value = null;
				if (fieldType == Integer.class || "int".equals(fieldType.getName())){
					if(rs.getObject(fieldName)!=null)
						value = rs.getInt(fieldName);
				}
				else if (fieldType == Float.class || "float".equals(fieldType.getName())){
					if(rs.getObject(fieldName)!=null)
						value = rs.getFloat(fieldName);
				}
				else if (fieldType == Double.class || "double".equals(fieldType.getName())){
					if(rs.getObject(fieldName)!=null)
						value = rs.getDouble(fieldName);
				}
				else if (fieldType == Timestamp.class || fieldType == java.util.Date.class){
					value = rs.getTimestamp(fieldName);
				}
				else
					value = rs.getString(fieldName);

				// 赋值操作

				setMethod.invoke(pojo, new Object[] { value });
			}
		} catch (Exception e1) {
			e1.printStackTrace();
		}
		return pojo;
	}
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