从cursor中提取bean 列表(反射的使用)

BeanUtil.java

package com.android.orm;

import android.database.Cursor;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Created by kai.wang on 1/13/14.
 */
class BeanUtil {

	/**
	 * 从cursor中提取bean
	 * @param cursor
	 * @param cls
	 * @param <T>
	 * @return
	 */
	public static <T> T cursorToBean(Cursor cursor, Class<T> cls) {
		T bean = null;
		if (cursor != null && cursor.getCount() > 0) {
			Field[] fields = cls.getDeclaredFields();
			String[] columns = cursor.getColumnNames();
			try {
				while (cursor.moveToNext()) {
					bean = cls.newInstance();
					for(String column : columns){
						Field field = findFieldByName(fields,column);
						String letter=column.substring(0, 1).toUpperCase();
						String setter = "set" + letter + column.substring(1);
						Method setMethod = cls.getMethod(setter,new Class[]{field.getType()});
						setMethod.invoke(bean,getValueByField(cursor,column,field));
					}
				}
			} catch (NoSuchMethodException e) {
				e.printStackTrace();
			} catch (InvocationTargetException e) {
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				e.printStackTrace();
			} catch (InstantiationException e) {
				e.printStackTrace();
			}
		}
		return bean;
	}

	/**
	 * 从cursor中提取bean 列表
	 * @param cursor
	 * @param cls
	 * @param <T>
	 * @return
	 */
	public static <T> List<T> cursorToBeans(Cursor cursor, Class<T> cls) {
		List<T> beans = new ArrayList<T>();
		if (cursor != null && cursor.getCount() > 0) {
			Field[] fields = cls.getDeclaredFields();
			String[] columns = cursor.getColumnNames();
			try {
				while (cursor.moveToNext()) {
					T bean = cls.newInstance();
					for(String column : columns){
						Field field = findFieldByName(fields,column);
						String letter=column.substring(0, 1).toUpperCase();
						String setter = "set" + letter + column.substring(1);
						Method setMethod = cls.getMethod(setter,new Class[]{field.getType()});
						setMethod.invoke(bean,getValueByField(cursor,column,field));
					}
					beans.add(bean);
				}
			} catch (NoSuchMethodException e) {
				e.printStackTrace();
			} catch (InvocationTargetException e) {
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				e.printStackTrace();
			} catch (InstantiationException e) {
				e.printStackTrace();
			}
		}
		return beans;
	}

	/**
	 * 根据字段取出值
	 * @param cursor
	 * @param columnName
	 * @param field
	 * @return
	 */
	private static Object getValueByField(Cursor cursor,String columnName, Field field){
		int index = cursor.getColumnIndex(columnName);
		if (index == -1) return null;// 如果不存在此列则返回null
		Class fieldClass = field.getType();
		// 根据属性类型从Cursor中获取值
		if (fieldClass == String.class) return cursor.getString(index);

		else if (fieldClass == int.class || fieldClass == Integer.class)
			return cursor.getInt(index);
		else if (fieldClass == Long.class) return cursor.getLong(index);

		else if (fieldClass == Double.class) return cursor.getDouble(index);

		else if (fieldClass == Float.class) return cursor.getFloat(index);

		else if (fieldClass == Short.class) return cursor.getShort(index);

		return null;
	}

	private static Field findFieldByName(Field[] fields, String name){
		for (Field field : fields) {
			if (field.getName().equals(name)) {
				return field;
			}
		}
		return null;
	}
}