List進行去重 排序

接到任務 進行一個菜單去重排序的功能 還是比較有意思的

背景：一個用戶 存在 多個角色  一個角色分別有對應的菜單  所以要進行合併 去重 排序處理 並且菜單擁有二級甚至三級菜單

先定義一個Menu類  並且重寫它的hashcode和equals

package com.sitech.smartcity.common.entity;

import java.util.List;

public class Menu {
   private String menuName;
   private String url;
   private List<Menu> menus;
   private String openType;//0:iframe嵌套  1： load加載 ；2 ：window.location打開新界面
   private String logourl;
   private String code;//app業務編碼
   private String classCode;//分類編碼
   private String appid;
   private Integer classPriority;//排序字段

   public Integer getClassPriority() {
      return classPriority;
   }

   public void setClassPriority(Integer classPriority) {
      this.classPriority = classPriority;
   }

   public String getMenuName() {
      return menuName;
   }

   public void setMenuName(String menuName) {
      this.menuName = menuName;
   }

   public String getUrl() {
      return url;
   }

   public void setUrl(String url) {
      this.url = url;
   }

   public List<Menu> getMenus() {
      return menus;
   }

   public void setMenus(List<Menu> menus) {
      this.menus = menus;
   }

   public String getOpenType() {
      return openType;
   }

   public void setOpenType(String openType) {
      this.openType = openType;
   }

   public String getLogourl() {
      return logourl;
   }

   public void setLogourl(String logourl) {
      this.logourl = logourl;
   }

   public String getCode() {
      return code;
   }

   public void setCode(String code) {
      this.code = code;
   }

   public String getClassCode() {
      return classCode;
   }

   public void setClassCode(String classCode) {
      this.classCode = classCode;
   }

   public String getAppid() {
      return appid;
   }

   public void setAppid(String appid) {
      this.appid = appid;
   }

   @Override
   public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
      Menu menu = (Menu) o;
      if (menuName != null ? !menuName.equals(menu.menuName) : menu.menuName != null) return false;
      if (url != null ? !url.equals(menu.url) : menu.url != null) return false;
      if (openType != null ? !openType.equals(menu.openType) : menu.openType != null) return false;
      if (code != null ? !code.equals(menu.code) : menu.code != null) return false;
      if (classCode != null ? !classCode.equals(menu.classCode) : menu.classCode != null) return false;
      if (appid != null ? !appid.equals(menu.appid) : menu.appid != null) return false;
      return classPriority != null ? classPriority.equals(menu.classPriority) : menu.classPriority == null;
   }

   @Override
   public int hashCode() {
      int result = menuName != null ? menuName.hashCode() : 0;
      result = 31 * result + (url != null ? url.hashCode() : 0);
      result = 31 * result + (menus != null ? menus.hashCode() : 0);
      result = 31 * result + (openType != null ? openType.hashCode() : 0);
      result = 31 * result + (logourl != null ? logourl.hashCode() : 0);
      result = 31 * result + (code != null ? code.hashCode() : 0);
      result = 31 * result + (classCode != null ? classCode.hashCode() : 0);
      result = 31 * result + (appid != null ? appid.hashCode() : 0);
      result = 31 * result + (classPriority != null ? classPriority.hashCode() : 0);
      return result;
   }
}

然後 寫幾個 方法 用來合併 去重 排序的方法

//清除重複數據 利用set集合的 無重複特點 
public static List removeDuplicate(List list) {
   HashSet h = new HashSet(list);
   list.clear();
   list.addAll(h);
   return list;
}

//根據排序字段進行排序
public static List compareList(List<Menu> list){
   Collections.sort(list, new Comparator<Menu>() {
      @Override
      public int compare(Menu m1,Menu m2) {
         if (m1.getClassPriority() > m2.getClassPriority()) {
            return 1;
         }
         if (m1.getClassPriority() == m2.getClassPriority()) {
            return 0;
         }
         return -1;
      }
   });
   return list;
}


//遞歸  合併  去重
public static void trecursive(List<Menu> list){
   try {
      for(Iterator<Menu> oneIter = list.iterator(); oneIter.hasNext();){
         Menu one = oneIter.next();

         for(Iterator<Menu> twoIter = list.iterator(); twoIter.hasNext();){
            Menu two = twoIter.next();
            //classcode爲菜單的唯一標識  此處使用剛纔重寫的equals比較兩個Menu對象也可
            if(one.getClassCode()!=null&&one.getClassCode().equals(two.getClassCode())){
               //如果進入 說明存在兩個相同菜單  子菜單爲空的情況  填充菜單  再去重
               if (one.getMenus() == null && two.getMenus() != null) {
                  one.setMenus(two.getMenus());
               }
               if (two.getMenus() == null && one.getMenus() != null) {
                  two.setMenus(one.getMenus());
               }
               if (two.getMenus() == null && one.getMenus() == null) {
                  continue;
               }
               //否則合併  去重被合併菜單
               one.getMenus().addAll(two.getMenus());
               two.setMenus(one.getMenus());
               removeDuplicate(one.getMenus());
               compareList(one.getMenus());
               //遞歸
               trecursive(one.getMenus());
            }
         }
      }
   }catch (Exception e){
      e.printStackTrace();
   }
}