java工具类之按对象中某属性排序

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

/**
 * java工具类之按对象中某属性排序
 * @author李坤 交流博客:http://blog.csdn.net/lk_blog
 */
public class SortListUtil {
	
	public static final String DESC = "desc";
	public static final String ASC = "asc";

	/**
	 * 对list中的元素按升序排列.
	 * 
	 * @param list
	 *            排序集合
	 * @param field
	 *            排序字段
	 * @return
	 */
	public static List<?> sort(List<?> list, final String field) {
		return sort(list, field, null);
	}

	/**
	 * 对list中的元素进行排序.
	 * 
	 * @param list
	 *            排序集合
	 * @param field
	 *            排序字段
	 * @param sort
	 *            排序方式: SortList.DESC(降序) SortList.ASC(升序).
	 * @return
	 */
	@SuppressWarnings("unchecked")
	public static List<?> sort(List<?> list, final String field,
			final String sort) {
		Collections.sort(list, new Comparator() {
			public int compare(Object a, Object b) {
				int ret = 0;
				try {
					Field f = a.getClass().getDeclaredField(field);
					f.setAccessible(true);
					Class<?> type = f.getType();

					if (type == int.class) {
						ret = ((Integer) f.getInt(a)).compareTo((Integer) f
								.getInt(b));
					} else if (type == double.class) {
						ret = ((Double) f.getDouble(a)).compareTo((Double) f
								.getDouble(b));
					} else if (type == long.class) {
						ret = ((Long) f.getLong(a)).compareTo((Long) f
								.getLong(b));
					} else if (type == float.class) {
						ret = ((Float) f.getFloat(a)).compareTo((Float) f
								.getFloat(b));
					} else if (type == Date.class) {
						ret = ((Date) f.get(a)).compareTo((Date) f.get(b));
					} else if (isImplementsOf(type, Comparable.class)) {
						ret = ((Comparable) f.get(a)).compareTo((Comparable) f
								.get(b));
					} else {
						ret = String.valueOf(f.get(a)).compareTo(
								String.valueOf(f.get(b)));
					}

				}catch (Exception e) {
					e.printStackTrace();
				}
				if (sort != null && sort.toLowerCase().equals(DESC)) {
					return -ret;
				} else {
					return ret;
				}

			}
		});
		return list;
	}

	/**
	 * 对list中的元素按fields和sorts进行排序,
	 * fields[i]指定排序字段,sorts[i]指定排序方式.如果sorts[i]为空则默认按升序排列.
	 * 
	 * @param list
	 * @param fields
	 * @param sorts
	 * @return
	 */
	@SuppressWarnings("unchecked")
	public static List<?> sort(List<?> list, String[] fields, String[] sorts) {
		if (fields != null && fields.length > 0) {
			for (int i = fields.length - 1; i >= 0; i--) {
				final String field = fields[i];
				String tmpSort = ASC;
				if (sorts != null && sorts.length > i && sorts[i] != null) {
					tmpSort = sorts[i];
				}
				final String sort = tmpSort;
				Collections.sort(list, new Comparator() {
					public int compare(Object a, Object b) {
						int ret = 0;
						try {
							Field f = a.getClass().getDeclaredField(field);
							f.setAccessible(true);
							Class<?> type = f.getType();
							if (type == int.class) {
								ret = ((Integer) f.getInt(a))
										.compareTo((Integer) f.getInt(b));
							} else if (type == double.class) {
								ret = ((Double) f.getDouble(a))
										.compareTo((Double) f.getDouble(b));
							} else if (type == long.class) {
								ret = ((Long) f.getLong(a)).compareTo((Long) f
										.getLong(b));
							} else if (type == float.class) {
								ret = ((Float) f.getFloat(a))
										.compareTo((Float) f.getFloat(b));
							} else if (type == Date.class) {
								ret = ((Date) f.get(a)).compareTo((Date) f
										.get(b));
							} else if (isImplementsOf(type, Comparable.class)) {
								ret = ((Comparable) f.get(a))
										.compareTo((Comparable) f.get(b));
							} else {
								ret = String.valueOf(f.get(a)).compareTo(
										String.valueOf(f.get(b)));
							}

						} catch (SecurityException e) {
							e.printStackTrace();
						} catch (NoSuchFieldException e) {
							e.printStackTrace();
						} catch (IllegalArgumentException e) {
							e.printStackTrace();
						} catch (IllegalAccessException e) {
							e.printStackTrace();
						}

						if (sort != null && sort.toLowerCase().equals(DESC)) {
							return -ret;
						} else {
							return ret;
						}
					}
				});
			}
		}
		return list;
	}

	/**
	 * 默认按正序排列
	 * 
	 * @param list
	 * @param method
	 * @return
	 */
	public static List<?> sortByMethod(List<?> list, final String method) {
		return sortByMethod(list, method, null);
	}

	@SuppressWarnings("unchecked")
	public static List<?> sortByMethod(List<?> list, final String method,
			final String sort) {
		Collections.sort(list, new Comparator() {
			public int compare(Object a, Object b) {
				int ret = 0;
				try {
					Method m = a.getClass().getMethod(method, null);
					m.setAccessible(true);
					Class<?> type = m.getReturnType();
					if (type == int.class) {
						ret = ((Integer) m.invoke(a, null))
								.compareTo((Integer) m.invoke(b, null));
					} else if (type == double.class) {
						ret = ((Double) m.invoke(a, null)).compareTo((Double) m
								.invoke(b, null));
					} else if (type == long.class) {
						ret = ((Long) m.invoke(a, null)).compareTo((Long) m
								.invoke(b, null));
					} else if (type == float.class) {
						ret = ((Float) m.invoke(a, null)).compareTo((Float) m
								.invoke(b, null));
					} else if (type == Date.class) {
						ret = ((Date) m.invoke(a, null)).compareTo((Date) m
								.invoke(b, null));
					} else if (isImplementsOf(type, Comparable.class)) {
						ret = ((Comparable) m.invoke(a, null))
								.compareTo((Comparable) m.invoke(b, null));
					} else {
						ret = String.valueOf(m.invoke(a, null)).compareTo(
								String.valueOf(m.invoke(b, null)));
					}

					if (isImplementsOf(type, Comparable.class)) {
						ret = ((Comparable) m.invoke(a, null))
								.compareTo((Comparable) m.invoke(b, null));
					} else {
						ret = String.valueOf(m.invoke(a, null)).compareTo(
								String.valueOf(m.invoke(b, null)));
					}

				}catch (Exception it) {
					System.out.println(it);
				}

				if (sort != null && sort.toLowerCase().equals(DESC)) {
					return -ret;
				} else {
					return ret;
				}
			}
		});
		return list;
	}

	@SuppressWarnings("unchecked")
	public static List<?> sortByMethod(List<?> list, final String methods[],
			final String sorts[]) {
		if (methods != null && methods.length > 0) {
			for (int i = methods.length - 1; i >= 0; i--) {
				final String method = methods[i];
				String tmpSort = ASC;
				if (sorts != null && sorts.length > i && sorts[i] != null) {
					tmpSort = sorts[i];
				}
				final String sort = tmpSort;
				Collections.sort(list, new Comparator() {
					public int compare(Object a, Object b) {
						int ret = 0;
						try {
							Method m = a.getClass().getMethod(method, null);
							m.setAccessible(true);
							Class<?> type = m.getReturnType();
							if (type == int.class) {
								ret = ((Integer) m.invoke(a, null))
										.compareTo((Integer) m.invoke(b, null));
							} else if (type == double.class) {
								ret = ((Double) m.invoke(a, null))
										.compareTo((Double) m.invoke(b, null));
							} else if (type == long.class) {
								ret = ((Long) m.invoke(a, null))
										.compareTo((Long) m.invoke(b, null));
							} else if (type == float.class) {
								ret = ((Float) m.invoke(a, null))
										.compareTo((Float) m.invoke(b, null));
							} else if (type == Date.class) {
								ret = ((Date) m.invoke(a, null))
										.compareTo((Date) m.invoke(b, null));
							} else if (isImplementsOf(type, Comparable.class)) {
								ret = ((Comparable) m.invoke(a, null))
										.compareTo((Comparable) m.invoke(b,
												null));
							} else {
								ret = String.valueOf(m.invoke(a, null))
										.compareTo(
												String.valueOf(m
														.invoke(b, null)));
							}

						} catch (NoSuchMethodException ne) {
							System.out.println(ne);
						} catch (IllegalAccessException ie) {
							System.out.println(ie);
						} catch (InvocationTargetException it) {
							System.out.println(it);
						}

						if (sort != null && sort.toLowerCase().equals(DESC)) {
							return -ret;
						} else {
							return ret;
						}
					}
				});
			}
		}
		return list;
	}

	/**
	 * 判断对象实现的所有接口中是否包含szInterface
	 * 
	 * @param clazz
	 * @param szInterface
	 * @return
	 */
	public static boolean isImplementsOf(Class<?> clazz, Class<?> szInterface) {
		boolean flag = false;

		Class<?>[] face = clazz.getInterfaces();
		for (Class<?> c : face) {
			if (c == szInterface) {
				flag = true;
			} else {
				flag = isImplementsOf(c, szInterface);
			}
		}

		if (!flag && null != clazz.getSuperclass()) {
			return isImplementsOf(clazz.getSuperclass(), szInterface);
		}

		return flag;
	}

	public static void main(String[] args) throws Exception {
		List<Student> list = new ArrayList<Student>();

		list.add(new Student(3, "b", 1, new Date(11110000)));
		list.add(new Student(1, "c", 3, new Date(44440000)));
		list.add(new Student(2, "a", 2, new Date(22210000)));
		list.add(new Student(4, "a", 11, new Date(33330000)));
		System.out.println("-------原来序列-------------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// 按age正序排序,注意结果排完后是1,2,3,11. 不是1,11,2,3(如果是String类型正序排序是这样)
		SortListUtil.sort(list, "age", null);
		System.out.println("---------测试Integer和正序,按age正序排序-----------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// 按id倒序
		SortListUtil.sort(list, "id", SortListUtil.DESC);
		System.out.println("--------测试int和倒序,按id倒序------------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// 先按name正序排序,再按id正序排序
		SortListUtil.sort(list, new String[] { "name", "id" }, new String[] {});
		System.out
				.println("---------测试多个排序字段,先按name正序,name相同时再按id正序-----------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// 先按name正序排序,再按id倒序排序
		SortListUtil.sort(list, new String[] { "name", "id" }, new String[] {
				SortListUtil.ASC, SortListUtil.DESC });
		System.out
				.println("---------测试多个排序字段,先按name正序,name相同时再按id倒序-----------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// 按birthday排序
		SortListUtil.sort(list, "birthday");
		System.out
				.println("---------测试实现了Comparable接口的对象排序,按birthday正序-----------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

		// sortByMethod
		SortListUtil.sortByMethod(list, "getId", null);
		System.out.println("---------测试sortByMethod,按getId方法正序-----------------");
		for (Student stu : list) {
			System.out.println(stu.toString());
		}

	}
}