数据库中多字段的排序 java实现

多个字段排序的时候，按照你在order by 之中指定的顺序进行排列的。
select  * form tbl1 order by col1 desc, col2, col3
如上面， 先按照col1 的值递减排列，
如果col1的值相同，则按照col2来排列，
如果col1和col2的值都相同，则按照col3的值进行排列。

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.HashMap;
import java.util.List;
import java.util.Map;

public class SortTest {

static Map<String, Integer> sortNameMap = new HashMap<String, Integer>();
static {
sortNameMap.put("张三", 1);
sortNameMap.put("王五", 2);
sortNameMap.put("赵六", 3);
sortNameMap.put("李四", 4);
}

public static Integer getSortNameMapByKey(String key) {
for (String s : sortNameMap.keySet()) {
if (key.contains(s)) {
return sortNameMap.get(s);
}
}
return sortNameMap.size() + 1;
}

public static <T> void sort(List<T> list,
final List<Comparator<T>> comparatorList) {
if (comparatorList.isEmpty()) {// Always equals, if no Comparator.
throw new IllegalArgumentException("comparatorList is empty.");
}
Comparator<T> comparator = new Comparator<T>() {
public int compare(T o1, T o2) {
for (Comparator<T> c : comparatorList) {
if (c.compare(o1, o2) > 0) {
return 1;
} else if (c.compare(o1, o2) < 0) {
return -1;
}
}
return 0;
}
};
Collections.sort(list, comparator);
}

public static <E> void sortByMethod(List<E> list, final String method,
final boolean reverseFlag) {
Collections.sort(list, new Comparator<Object>() {
@SuppressWarnings("unchecked")
public int compare(Object arg1, Object arg2) {
int result = 0;
try {
Method m1 = ((E) arg1).getClass().getMethod(method, null);
Method m2 = ((E) arg2).getClass().getMethod(method, null);
Object obj1 = m1.invoke(((E) arg1), null);
Object obj2 = m2.invoke(((E) arg2), null);
if (obj1 instanceof String) {
if (method.toLowerCase().contains("name")) {
Integer sort1 = getSortNameMapByKey((String) (obj1));
Integer sort2 = getSortNameMapByKey((String) (obj2));
result = sort1.compareTo(sort2);
} else {
// 字符串
result = obj1.toString().compareTo(obj2.toString());
}
} else if (obj1 instanceof Date) {
// 日期
long l = ((Date) obj1).getTime()
- ((Date) obj2).getTime();
if (l > 0) {
result = 1;
} else if (l < 0) {
result = -1;
} else {
result = 0;
}
} else if (obj1 instanceof Integer) {
// 整型（Method的返回参数可以是int的，因为JDK1.5之后，Integer与int可以自动转换了）
result = (Integer) obj1 - (Integer) obj2;
} else {
// 目前尚不支持的对象，直接转换为String，然后比较，后果未知
result = obj1.toString().compareTo(obj2.toString());

System.err
.println("MySortList.sortByMethod方法接受到不可识别的对象类型，转换为字符串后比较返回...");
}

if (reverseFlag) {
// 倒序
result = -result;
}
} catch (NoSuchMethodException nsme) {
nsme.printStackTrace();
} catch (IllegalAccessException iae) {
iae.printStackTrace();
} catch (InvocationTargetException ite) {
ite.printStackTrace();
}

return result;
}
});
}

public static <E> int compareTo(Object arg1, Object arg2, String method,
boolean reverseFlag) {
int result = 0;
try {
Method m1 = ((E) arg1).getClass().getMethod(method, null);
Method m2 = ((E) arg2).getClass().getMethod(method, null);
Object obj1 = m1.invoke(((E) arg1), null);
Object obj2 = m2.invoke(((E) arg2), null);
if (obj1 instanceof String) {
if (method.toLowerCase().contains("name")) {
Integer sort1 = getSortNameMapByKey((String) (obj1));
Integer sort2 = getSortNameMapByKey((String) (obj2));
result = sort1.compareTo(sort2);
} else {
// 字符串
result = obj1.toString().compareTo(obj2.toString());
}
} else if (obj1 instanceof Date) {
// 日期
long l = ((Date) obj1).getTime() - ((Date) obj2).getTime();
if (l > 0) {
result = 1;
} else if (l < 0) {
result = -1;
} else {
result = 0;
}
} else if (obj1 instanceof Integer) {
// 整型（Method的返回参数可以是int的，因为JDK1.5之后，Integer与int可以自动转换了）
result = (Integer) obj1 - (Integer) obj2;
} else {
// 目前尚不支持的对象，直接转换为String，然后比较，后果未知
result = obj1.toString().compareTo(obj2.toString());

System.err
.println("MySortList.sortByMethod方法接受到不可识别的对象类型，转换为字符串后比较返回...");
}

if (reverseFlag) {
// 倒序
result = -result;
}
} catch (NoSuchMethodException nsme) {
nsme.printStackTrace();
} catch (IllegalAccessException iae) {
iae.printStackTrace();
} catch (InvocationTargetException ite) {
ite.printStackTrace();
}

return result;
}

public static <E> void sortByMethods(List<E> list,
final boolean reverseFlag, final String... methods) {
Collections.sort(list, new Comparator<Object>() {
@SuppressWarnings("unchecked")
public int compare(Object arg1, Object arg2) {
int result = 0;
for (String m : methods) {
result = compareTo(arg1, arg2, m, reverseFlag);
if (result != 0) {
return result;
} else {
result = compareTo(arg1, arg2, m, reverseFlag);
}
}

return result;
}
});
}

public static void main(String[] args) {
System.out.println("2".compareTo("1"));
List<Person> list = new ArrayList<Person>();
Person p = new Person();
p.setId(1);
p.setName("张三111");
list.add(p);
p = new Person();
p.setId(2);
p.setName("李四111");
list.add(p);
p = new Person();
p.setId(3);
p.setName("王五111");
list.add(p);

p = new Person();
p.setId(4);
p.setName("王五111");
list.add(p);

p = new Person();
p.setId(40);
p.setName("赵六1111");
list.add(p);

p = new Person();
p.setId(5);
p.setName("赵六1111");
list.add(p);

p = new Person();
p.setId(5);
p.setName("小王1111");
list.add(p);
p = new Person();
p.setId(6);
p.setName("老王1111");
list.add(p);

sortByMethods(list, false, "getName","getId");
System.out.println("中文名称正序排列：");
for (Person pp : list) {
System.out.println(pp.getId() + "," + pp.getName());
}

/*
* sortByMethod(list, "getName", false);
* System.out.println("中文名称正序排列："); for (Person pp : list) {
* System.out.println(pp.getId() + "," + pp.getName()); }
*
* sortByMethod(list, "getId", false); System.out.println("中文名称正序排列：");
* for (Person pp : list) { System.out.println(pp.getId() + "," +
* pp.getName()); }
*/

}

}

class Person {
private int id;
private String name;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

}