JAVA中对List进行查询

JAVA中从数据库中取数据，根据MyBits返回结果主要有两种类型的List,一种是List<Entity>,还一种是List<Map<String,Object>>，

那么怎样对List结果集进行查询操作呢？当然最常用的是用for循环遍历，但是这个效率比较低下，下面是我认为比较好的操作方式，

对List<Map<String,Object>>的查询

    /**
     * 从列表中找出包括Value值的列表
     * @param list
     * @param keyName
     * @param value
     * @return
     */
    public static List<Map<String,Object>> findDataFromListMap(List<Map<String,Object>> list,String keyName,Object value) {

        Predicate<Map<String,Object>>predicate = new Predicate<Map<String,Object>>() {

            @Override
            public boolean evaluate(Map<String,Object> map) {
                // TODO Auto-generated method stub
                try {
                    Object val = map.get(keyName);
                    if(value == null || val == null)
                        return false;

                    return val.equals(value);
                }
                catch (Exception e) {
                    return false;
                }
            }
        };

        List<Map<String,Object>> result = (List<Map<String,Object>>) CollectionUtils.select( list, predicate);
        return result;
    }

    /**
     * 多值将交叉查找
     * @param list
     * @param keyName2ValueMap
     * @return
     */
    public static List<Map<String,Object>> findDataFromListMapByKeyValues(
            List<Map<String,Object>> list,
            Map<String,Object> keyName2ValueMap) {

        Predicate<Map<String,Object>>predicate = new Predicate<Map<String,Object>>() {

            @Override
            public boolean evaluate(Map<String,Object> map) {
                // TODO Auto-generated method stub
                try {
                    for(Map.Entry<String,Object> entry : keyName2ValueMap.entrySet()){
                        String keyName  = entry.getKey();
                        Object value = entry.getValue();
                        Object val = map.get(keyName);
                        if(StringUtils.isBlank(keyName) || value == null || val == null)
                            return false;
                        if(!val.equals(value))
                            return  false;
                    }
                    return true;
                }
                catch (Exception e) {
                    return false;
                }
            }
        };

        List<Map<String,Object>> result = (List<Map<String,Object>>) CollectionUtils.select( list, predicate);
        return result;
    }

对List<Entity>的查询

    /**
     * 从列表中找出包括Value值的对象列表
     * @param list
     * @param methodName
     * @param value
     * @return
     */
    public static <T,V> List<T> findObjFromList(List<T> list,String methodName,V value) {
    	
    	Predicate<T>predicate = new Predicate<T>() {

			@Override
			public boolean evaluate(T obj) {
				// TODO Auto-generated method stub
				try {
					Method method = obj.getClass().getMethod(methodName);
					@SuppressWarnings("unchecked")
					V keyName = (V) method.invoke(obj);
					return keyName.equals(value);
				}
				catch (Exception e) {
					return false;
				}
			}
		};
		
		List<T> result = (List<T>) CollectionUtils.select( list, predicate);
		return result;
    		
    }

标签：return,List,list,value,查询,keyName,param,JAVA
来源： https://blog.csdn.net/octdream/article/details/88963179