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Predicate 实现 And 和 Or的逻辑

需求

给一个集合，找到满足添加的对象，一下条件可能会动态的变化，有时候只需要满足一个，有时候需要满足两个。。。

 1、大于。。
 2、小于。。
 3、是偶数

使用 Predicate完成需求

Predicate主要作用就是输入一个参数，输出一个Boolean值，用于判断这个输入的参数是否满足某个条件 Predicate 接口里面一个默认方法，可以完成多个条件的组合

 default Predicate<T> and(Predicate<? super T> other) {
 Objects.requireNonNull(other);
 return (t) -> test(t) && other.test(t);
 }
 
 default Predicate<T> or(Predicate<? super T> other) {
 Objects.requireNonNull(other);
 return (t) -> test(t) || other.test(t);
 }

测试代码：

public class RequestParam {
    private String packageId;
    private String data;
    private boolean isFlow;
    public RequestParam(String packageId, String data, boolean isFlow)  {
        try {
            this.packageId = packageId;
            this.data = URLEncoder.encode(data, "UTF-8");
            this.isFlow = isFlow;
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public String getPackageId() {
        return packageId;
    }

    public String getData() {
        return data;
    }

    public boolean isFlow() {
        return isFlow;
    }

    @Override
    public String toString() {
        return "packageId="+packageId+"&data="+data+"&isFlow="+isFlow+"";
    }
}

public class PredicateTest {
 
    public static void main(String[] args) {
        List<RequestParam>  list =  new ArrayList<>();
        RequestParam  requestParam1 =  new RequestParam("test/111","111",true);
        RequestParam  requestParam2 =  new RequestParam("test/222","222",false);
        RequestParam  requestParam3 =  new RequestParam("test/333","333",false);
        list.add(requestParam1);
        list.add(requestParam2);
        list.add(requestParam3);

        Predicate<RequestParam> condition1 = value -> value.getPackageId().startsWith("test") ;
        Predicate<RequestParam> condition2 = value -> value.getData().length()==3;
        Predicate<RequestParam> condition3 = value -> value.isFlow() == false ;
        Predicate<RequestParam> predicate = condition1.and(condition2.or(condition3));
        AtomicInteger count= new AtomicInteger();
        list.forEach(v -> {
            if(predicate.test(v)){
                count.getAndIncrement();
            }
        });
        System.out.println("符合帅选条件的数量："+count);
    
    }
}

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