海外制作网站,WordPress维护模式退出,h5页面制作素材,建设部网站建筑工程质保期一、过滤器模式 概述 过滤器模式#xff08;Filter Pattern#xff09;或标准模式#xff08;Criteria Pattern#xff09;是一种设计模式#xff0c;这种模式允许开发人员使用不同的标准来过滤一组对象#xff0c;通过逻辑运算以解耦的方式把它们连接起来。这种类型的…一、过滤器模式 概述 过滤器模式Filter Pattern或标准模式Criteria Pattern是一种设计模式这种模式允许开发人员使用不同的标准来过滤一组对象通过逻辑运算以解耦的方式把它们连接起来。这种类型的设计模式属于结构型模式它结合多个标准来获得单一标准
主要解决在众多数据中根据特定的标准在一组数据中筛选出不同标准的数据 优缺点 优点
将对象的过滤、校验逻辑抽离出来降低系统的复杂度过滤规则可实现重复利用
缺点
性能较低每个过滤器对每一个元素都会进行遍历。如果有n个元素m个过滤器则时间复杂度为O(mn)
1. 各个角色介绍
1.1 过滤器接口Filter
定义了过滤器的基本方法具体的实现还要具体过滤器角色去参与在实际应用中可以扩展该接口以适应不同的过滤条件
1.2 具体命过滤器ConcreteFilter
实现了过滤器接口负责执行具体的过滤操作。对数据进行过滤
1.3 过滤链FilterChain 将多个过滤器按照一定的顺序组合起来形成一个过滤器链依次对数据进行过滤
2. UML图
首先创建一个 Shape 对象作为过滤的接口 IFilter然后实现该接口创建对应的 CornerFilter、CurveFilter、EdgeFilter具体过滤器。然后创建带有过滤器的过滤链 FilterChain基于各种标准和它们的结合来过滤 Shape 对象的列表
3. 具体例子和代码 角色分配 Shape形状IFilter过滤器接口 CornerFilter角过滤器实现过滤器接口EdgeFilter边过滤器实现过滤器接口CurveFilter曲线过滤器实现过滤器接口 FilterChain过滤链
3.1 形状
Instruction
package com.vinjcent.prototype.filter;import io.swagger.annotations.ApiModelProperty;/*** author vinjcent* description 形状*/
public class Shape {ApiModelProperty(形状名称)private String name;ApiModelProperty(是否有角)private Boolean isCorner;ApiModelProperty(边数)private Integer edges;ApiModelProperty(线构成类型)private String type;public Shape(String name, Boolean isCorner, Integer edges, String type) {this.name name;this.isCorner isCorner;this.edges edges;this.type type;}public String getName() {return name;}public void setName(String name) {this.name name;}public Boolean getCorner() {return isCorner;}public void setCorner(Boolean corner) {isCorner corner;}public Integer getEdges() {return edges;}public void setEdges(Integer edges) {this.edges edges;}public String getType() {return type;}public void setType(String type) {this.type type;}
}
3.2 过滤接口及其实现类
IFilter
package com.vinjcent.prototype.filter;import java.util.List;/*** author vinjcent* description 过滤接口*/
public interface IFilter {/*** 适配标准形状** param shapes 形状列表* return 适配的形状列表*/ListShape adaptFilter(ListShape shapes);
}
CornerFilter
package com.vinjcent.prototype.filter;import java.util.ArrayList;
import java.util.List;/*** author vinjcent* /* description 角过滤器*/
public class CornerFilter implements IFilter {Overridepublic ListShape adaptFilter(ListShape shapes) {// 符合具有角的形状ListShape cornerFilter new ArrayList();for (Shape shape : shapes) {if (shape.getIsCorner()) {cornerFilter.add(shape);}}return cornerFilter;}}
EdgeFilter
package com.vinjcent.prototype.filter;import java.util.ArrayList;
import java.util.List;/*** author vinjcent* /* description 边过滤器*/
public class EdgeFilter implements IFilter {Overridepublic ListShape adaptFilter(ListShape shapes) {// 边数大于0的形状ListShape edgeFilter new ArrayList();for (Shape shape : shapes) {if (shape.getEdges() 0) {edgeFilter.add(shape);}}return edgeFilter;}}
CurveFilter
package com.vinjcent.prototype.filter;import java.util.ArrayList;
import java.util.List;/*** author vinjcent* /* description 曲线过滤器*/
public class CurveFilter implements IFilter {Overridepublic ListShape adaptFilter(ListShape shapes) {// 曲线ListShape curveFilter new ArrayList();for (Shape shape : shapes) {if (shape.getType().toLowerCase().contains(curve)) {curveFilter.add(shape);}}return curveFilter;}}
3.3 过滤链
FilterChain
package com.vinjcent.prototype.filter;import com.vinjcent.api.utils.CollectionUtils;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;import java.util.ArrayList;
import java.util.List;/*** author vinjcent* description 过滤链*/
Data
public class FilterChain {ApiModelProperty(过滤器集合)private ListIFilter filters;public FilterChain(ListIFilter filters) {this.filters filters;}public ListShape doFilter(ListShape shapes) {if (CollectionUtils.isEmpty(filters) || CollectionUtils.isEmpty(shapes)) {return new ArrayList();}ListShape afterFilterShapes new ArrayList(shapes);// 执行过滤for (IFilter filter : filters) {afterFilterShapes filter.adaptFilter(afterFilterShapes);}return afterFilterShapes;}
}
3.4 测试主函数
package com.vinjcent.prototype.filter;import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;/*** author vinjcent* 过滤模式*/
public class Main {public static void main(String[] args) {ListShape shapes new ArrayList();shapes.add(new Shape(Circle, false, 0, Curve));shapes.add(new Shape(Triangle, true, 3, Straight));shapes.add(new Shape(Rectangle, true, 4, Straight));shapes.add(new Shape(Square, true, 4, Straight));shapes.add(new Shape(Oval, false, 0, Curve));shapes.add(new Shape(Sector, true, 2, Curve and Straight));CornerFilter cornerFilter new CornerFilter();EdgeFilter edgeFilter new EdgeFilter();CurveFilter curveFilter new CurveFilter();// 具有角、边的形状FilterChain cornerAndEdgeFilterChain new FilterChain(Arrays.asList(cornerFilter, edgeFilter));ListShape cornerAndEdgeShapes cornerAndEdgeFilterChain.doFilter(shapes);System.out.println(具有角、边的形状:);printResult(cornerAndEdgeShapes);// 具有角、曲线的形状FilterChain cornerAndCurveFilterChain new FilterChain(Arrays.asList(cornerFilter, curveFilter));ListShape cornerAndCurveShapes cornerAndCurveFilterChain.doFilter(shapes);System.out.println(\n具有角、曲线的形状:);printResult(cornerAndCurveShapes);// 具有边、曲线的形状FilterChain edgeAndCurveFilterChain new FilterChain(Arrays.asList(edgeFilter, curveFilter));ListShape edgeAndCurveShapes edgeAndCurveFilterChain.doFilter(shapes);System.out.println(\n具有边、曲线的形状:);printResult(edgeAndCurveShapes);}public static void printResult(ListShape shapes) {for (Shape shape : shapes) {System.out.println(Shape{ name shape.getName() \ , isCorner shape.getIsCorner() , edges shape.getEdges() , type shape.getType() \ });}}}
测试结果 4. 使用场景
在某些场合比如要对数据进行过滤不仅仅局限于一个标准的情况下进行分组例如数据查询、日志过滤、请求过滤
