java拓展集合工具类CollectionUtils

拓展集合工具类collectionutils，供大家参考，具体内容如下

package com.demo.utils;

import java.lang.reflect.method;
import java.util.arraylist;
import java.util.collection;
import java.util.hashset;
import java.util.iterator;
import java.util.linkedhashmap;
import java.util.linkedhashset;
import java.util.list;
import java.util.map;
import java.util.set;
import org.slf4j.logger;
import org.slf4j.loggerfactory;

import com.demo.bean.employeeentity;

/**
 * 
 * <p>自定义集合工具类拓展常用方法</p>
 * @autho 董杨炀
 * @time 2017-4-10 上午11:33:36
 */
public class collectionutils extends org.apache.commons.collections.collectionutils {

 private static final logger logger = loggerfactory.getlogger(collectionutils.class);

 private static final int default_size = 1000;

 /**
  * 
  * <p>拆分list为固定大小的多个集合</p>
  * <p>推荐使用</p>
  * <p>返回集合的size越小,此方法性能越高</p>
  * @param baselist
  * @param size
  * @return arraylist
  * @autho 董杨炀
  * @time 2017-4-10 上午11:30:43
  */
 @suppresswarnings("unchecked")
 public static <t> list<list<t>> fastsplitlist(list<t> baselist, int size) {
  if (baselist == null || baselist.size() == 0) {
   return null;
  }
  if (size <= 0) {
   size = default_size;
  }
  int arrsize = baselist.size() % size == 0 ? baselist.size() / size : baselist.size() / size + 1;
  list<list<t>> resultlist = new arraylist<list<t>>();
  for (int i = 0; i < arrsize; i++) {
   if (arrsize - 1 == i) {
    resultlist.add((list<t>) new arraylist<object>( baselist.sublist(i * size, baselist.size())));
   } else {
    resultlist.add((list<t>) new arraylist<object>( baselist.sublist(i * size, size * (i + 1))));
   }
  }
  return resultlist;
 }

 /**
  * 
  * <p>拆分list为固定大小的多个集合</p>
  * <p>返回集合的size越大,此方法性能越高</p>
  * @param baselist
  * @param size
  * @return arraylist
  * @autho 董杨炀
  * @time 2017-4-10 上午11:30:43
  */
 public static <t> list<list<t>> splitlist(list<t> baselist, int size) {
  if (baselist == null || baselist.size() == 0) {
   return null;
  }
  if (size <= 0) {
   size = default_size;
  }
  list<list<t>> resultlist = new arraylist<list<t>>();
  for (int i = 0; i < baselist.size(); ++i) {
   if (i % size == 0) {
    list<t> result = new arraylist<t>();
    resultlist.add(result);
   }
   resultlist.get(i / size).add(baselist.get(i));
  }
  return resultlist;
 }

 /**
  * 
  * <p>集合转set</p>
  * @param coll 源集合
  * @param keytype 属性类型
  * @param keymethodname 属性get方法
  * @return linkedhashset
  * @autho 董杨炀
  * @time 2017-4-10 上午11:31:50
  */
 public static <k, v> set<k> asset(final java.util.collection<v> coll,final class<k> keytype
   ,final string keymethodname) {
  if (collectionutils.isempty(coll)) {
   return new hashset<k>(0);
  }
  final set<k> set = new linkedhashset<k>(coll.size());
  try {
   for (final v value : coll) {
    object object;
    method method = value.getclass().getmethod(keymethodname);
    object = method.invoke(value);
    @suppresswarnings("unchecked")
    final k key = (k) object;
    set.add(key);
   }
  } catch (exception e) {
   logger.error(e.getmessage(), e);
   throw new collectionutilsexception("collection conversion set exceptions");
  }
  return set;
 }

 /**
  * 
  * <p>集合转map</p>
  * <p>比如:list<employeeentity>,讲employeeentity的name属性作为key,转换成map</p>
  * @param coll 源集合
  * @param keytype 属性类型
  * @param valuetype 源数据类型(实体类型)
  * @param keymethodname 属性get方法
  * @return linkedhashmap
  * @autho 董杨炀
  * @time 2017-4-10 上午11:32:01
  */
 public static <k, v> map<k, v> asmap(final java.util.collection<v> coll,final class<k> keytype
   ,final class<v> valuetype,final string keymethodname) {
  if (collectionutils.isempty(coll)) {
   return new linkedhashmap<k, v>(0);
  }
  final map<k, v> map = new linkedhashmap<k, v>(coll.size());
  try {
   method method = valuetype.getmethod(keymethodname);
   for (final v value : coll) {
    object object;
    object = method.invoke(value);
    @suppresswarnings("unchecked")
    final k key = (k) object;
    map.put(key, value);
   }
  } catch (exception e) {
   logger.error(e.getmessage(), e);
   throw new collectionutilsexception("collection conversion map exceptions");
  }
  return map;
 }

 /**
  * 
  * <p>集合转list</p>
  * @param coll
  * @return arraylist
  * @autho 董杨炀
  * @time 2017-4-10 上午11:32:56
  */
 public static <v> list<v> aslist(final java.util.collection<v> coll) {
  if (collectionutils.isempty(coll)) {
   return new arraylist<v>(0);
  }
  final list<v> list = new arraylist<v>();
  for (final v value : coll) {
   if (value != null) {
    list.add(value);
   }
  }
  return list;
 }

 /**
  * <p>集合<string>tostring</p>
  * @param collection 泛型必须为string类型
  * @param split 比如连接符","
  * @return
  * @autho 董杨炀
  * @time 2017-4-10 下午3:22:24
  */
 public static string colltostring(collection<string> collection, string split) {
  stringbuilder sb = new stringbuilder();
  if (collection != null) {
   int i = 0, size = collection.size();
   for (iterator<string> iterator = collection.iterator(); iterator.hasnext();) {
    string str = iterator.next();
    sb.append(str);
    if (++i < size) {
     sb.append(split);
    }
   }
  }
  return sb.tostring();
 }

 static class collectionutilsexception extends runtimeexception{

  private static final long serialversionuid = 1l;

  public collectionutilsexception(string s) {
   super(s);
  }

  public collectionutilsexception(string s, throwable e) {
   super(s, e);
  }

  public collectionutilsexception(throwable e) {
   super(e);
  }

 }

 public static void main(string[] args) {
  list<string> baselist = new arraylist<string>(1000000);
  for (int i = 0; i < 1000000; i++) {
   baselist.add("data:"+" i");
  }
  long currenttimemillis1 = system.currenttimemillis();
  list<list<string>> splitlist = splitlist(baselist, 1000);
  long currenttimemillis2 = system.currenttimemillis();
  system.out.println(splitlist.size());
  system.out.println("切割完成时间为:"+string.valueof(currenttimemillis2-currenttimemillis1)+"毫秒");
  long currenttimemillis3 = system.currenttimemillis();
  list<list<string>> newlist = fastsplitlist(baselist,1000);
  long currenttimemillis4 = system.currenttimemillis();
  system.out.println(newlist.size());
  system.out.println("快速切割完成时间为:"+string.valueof(currenttimemillis4-currenttimemillis3)+"毫秒");

  list<employeeentity> employeelist = new arraylist<employeeentity>();
  for (int i = 1; i < 11; i++) {
   employeeentity entity = new employeeentity();
   entity.setname("名字"+string.valueof(i));
   employeelist.add(entity);
  }
  system.out.println(employeelist.size());
  set<string> set = collectionutils.asset(employeelist, string.class, "getname");
  for (string name : set) {
   system.out.println(name);
  }

  map<string, employeeentity> map = collectionutils.asmap(employeelist, string.class, employeeentity.class, "getname");
  set<string> keyset = map.keyset();
  for (string key : keyset) {
   system.out.println(key);
   system.out.println(map.get(key));
  }

  list<employeeentity> list = collectionutils.aslist(map.values());
  for (employeeentity employeeentity : list) {
   system.out.println(employeeentity);
  }
 }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。