Java tutorial
/* * Copyright 2010-2012 Ning, Inc. * * Ning licenses this file to you under the Apache License, version 2.0 * (the "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. */ package com.ning.billing.util.dao; import java.beans.BeanInfo; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.PropertyDescriptor; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.math.BigDecimal; import java.sql.Date; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Time; import java.sql.Timestamp; import java.util.HashMap; import java.util.Map; import java.util.UUID; import org.joda.time.DateTime; import org.joda.time.DateTimeZone; import org.joda.time.LocalDate; import org.skife.jdbi.v2.StatementContext; import org.skife.jdbi.v2.tweak.ResultSetMapper; import com.google.common.base.CaseFormat; // Identical to org.skife.jdbi.v2.BeanMapper but maps created_date to createdDate public class LowerToCamelBeanMapper<T> implements ResultSetMapper<T> { private final Class<T> type; private final Map<String, PropertyDescriptor> properties = new HashMap<String, PropertyDescriptor>(); public LowerToCamelBeanMapper(final Class<T> type) { this.type = type; try { final BeanInfo info = Introspector.getBeanInfo(type); for (final PropertyDescriptor descriptor : info.getPropertyDescriptors()) { properties.put( CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, descriptor.getName()).toLowerCase(), descriptor); } } catch (IntrospectionException e) { throw new IllegalArgumentException(e); } } public T map(final int row, final ResultSet rs, final StatementContext ctx) throws SQLException { final T bean; try { bean = type.newInstance(); } catch (Exception e) { throw new IllegalArgumentException( String.format("A bean, %s, was mapped " + "which was not instantiable", type.getName()), e); } final Class beanClass = bean.getClass(); final ResultSetMetaData metadata = rs.getMetaData(); for (int i = 1; i <= metadata.getColumnCount(); ++i) { final String name = metadata.getColumnLabel(i).toLowerCase(); final PropertyDescriptor descriptor = properties.get(name); if (descriptor != null) { final Class<?> type = descriptor.getPropertyType(); Object value; if (type.isAssignableFrom(Boolean.class) || type.isAssignableFrom(boolean.class)) { value = rs.getBoolean(i); } else if (type.isAssignableFrom(Byte.class) || type.isAssignableFrom(byte.class)) { value = rs.getByte(i); } else if (type.isAssignableFrom(Short.class) || type.isAssignableFrom(short.class)) { value = rs.getShort(i); } else if (type.isAssignableFrom(Integer.class) || type.isAssignableFrom(int.class)) { value = rs.getInt(i); } else if (type.isAssignableFrom(Long.class) || type.isAssignableFrom(long.class)) { value = rs.getLong(i); } else if (type.isAssignableFrom(Float.class) || type.isAssignableFrom(float.class)) { value = rs.getFloat(i); } else if (type.isAssignableFrom(Double.class) || type.isAssignableFrom(double.class)) { value = rs.getDouble(i); } else if (type.isAssignableFrom(BigDecimal.class)) { value = rs.getBigDecimal(i); } else if (type.isAssignableFrom(DateTime.class)) { final Timestamp timestamp = rs.getTimestamp(i); value = timestamp == null ? null : new DateTime(timestamp).toDateTime(DateTimeZone.UTC); } else if (type.isAssignableFrom(Time.class)) { value = rs.getTime(i); } else if (type.isAssignableFrom(LocalDate.class)) { final Date date = rs.getDate(i); value = date == null ? null : new LocalDate(date, DateTimeZone.UTC); } else if (type.isAssignableFrom(DateTimeZone.class)) { final String dateTimeZoneString = rs.getString(i); value = dateTimeZoneString == null ? null : DateTimeZone.forID(dateTimeZoneString); } else if (type.isAssignableFrom(String.class)) { value = rs.getString(i); } else if (type.isAssignableFrom(UUID.class)) { final String uuidString = rs.getString(i); value = uuidString == null ? null : UUID.fromString(uuidString); } else if (type.isEnum()) { final String enumString = rs.getString(i); //noinspection unchecked value = enumString == null ? null : Enum.valueOf((Class<Enum>) type, enumString); } else { value = rs.getObject(i); } if (rs.wasNull() && !type.isPrimitive()) { value = null; } try { final Method writeMethod = descriptor.getWriteMethod(); if (writeMethod != null) { writeMethod.invoke(bean, value); } else { final String camelCasedName = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, name); final Field field = getField(beanClass, camelCasedName); field.setAccessible(true); // Often private... field.set(bean, value); } } catch (NoSuchFieldException e) { throw new IllegalArgumentException( String.format("Unable to find field for " + "property, %s", name), e); } catch (IllegalAccessException e) { throw new IllegalArgumentException( String.format("Unable to access setter for " + "property, %s", name), e); } catch (InvocationTargetException e) { throw new IllegalArgumentException(String.format( "Invocation target exception trying to " + "invoker setter for the %s property", name), e); } catch (NullPointerException e) { throw new IllegalArgumentException( String.format("No appropriate method to " + "write value %s ", value.toString()), e); } } } return bean; } private static Field getField(final Class clazz, final String fieldName) throws NoSuchFieldException { try { return clazz.getDeclaredField(fieldName); } catch (NoSuchFieldException e) { // Go up in the hierarchy final Class superClass = clazz.getSuperclass(); if (superClass == null) { throw e; } else { return getField(superClass, fieldName); } } } }