设计模式--享元模式

文章目录

• 1. 概述
• 2. 代码解析
• 3. 源码使用

1. 概述

2. 代码解析

public interface Employee {

    void report();
}


public class Manager implements Employee {

    private String department; // 内部状态

    private String reportContent; // 外部状态

    public Manager(String department) {
        this.department = department;
    }

    public void setReportContent(String reportContent) {
        this.reportContent = reportContent;
    }

    @Override
    public void report() {
        System.out.println(reportContent);
    }
}



/**
 * 享元模式:
 * 1. 减少创建对象的次数.
 * 2. 内部状态：就是不通过外部修改、传入的属性.
 * 3. 外部状态：就是通过外部修改值, 影响对象的属性.
 */
public class EmployeeFactory {
    private static Map<String, Employee> EMPLOYEE_GROUP = new HashMap<>();

    public static Manager getManager(String department) {
        Manager manager = (Manager) EMPLOYEE_GROUP.get(department);
        if (manager == null) {
            manager = new Manager(department);
            System.out.println("Create manager: " + department);
            String reportContent = "Report Content: .........";
            manager.setReportContent(department + " ---> " + reportContent);
            EMPLOYEE_GROUP.put(department, manager);
        }

        return manager;
    }
}


public class FlyWeightTest {
    public static void main(String[] args) {
        String[] departments = {"RD", "QA", "PM"};

        IntStream.range(0, 10).forEach(item -> {
            String department = departments[(int)(Math.random() * departments.length)];
            Manager manager = EmployeeFactory.getManager(department);
            manager.report();
        });
    }
}

3. 源码使用

1. JDK中Integer的IntegerCache；只要Integer不是new出来的，在-128~127中，都不会产生新的对象，而是从IntegerCache中获取Integer对象，达到对象的重用。

来源：https://blog.csdn.net/weixin_38608626/article/details/100538130