泛型化单例模式实例-MyEclipse, Maven, Junit

深碍√TFBOYSˉ_ 2022-09-25 08:21 4阅读 0赞

泛型化单例模式，关键点为Class.newInstance()，构建无参的Class类的实例。写个例子记录一下（MyEclipse maven）：

src/main/java源文件夹下：

club.younge.demo下新建单例获取类和实体类（Singleton, Student）

Singleton:

package club.younge.demo;
    
    import java.util.concurrent.ConcurrentHashMap;
    
    /**
     * 泛型化单例模式
     * 
     * @author Younge
     *
     */
    public class Singleton {
    	@SuppressWarnings("rawtypes")
    	private static final ConcurrentHashMap<Class, Object> MAP = new ConcurrentHashMap<Class, Object>();
    
    	@SuppressWarnings("unchecked")
    	public static <T> T getInstance(Class<T> type) {
    		Object object = MAP.get(type);
    		if (object == null) {
    			try {
    				synchronized (MAP) {
    					object = type.newInstance(); //关键部分，通过类型创建无参实例
    					MAP.put(type, object);
    				}
    			} catch (InstantiationException e) {
    				e.printStackTrace();
    			} catch (IllegalAccessException e) {
    
    				e.printStackTrace();
    			}
    		}
    		return (T) object;
    	}
    	public static <T> void remove(Class<T> type){
    		MAP.remove(type);
    	}
    }

Student:

package club.younge.demo;
    
    public class Student {
    	private String number;
    	private String name;
    	public String getNumber() {
    		return number;
    	}
    	public void setNumberAndName(String number, String name){
    		this.number = number;
    		this.name = name;
    	}
    	public void setNumber(String number) {
    		this.number = number;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	@Override
    	public String toString() {
    		return new StringBuilder()
    		.append("I am a student, my number is ")
    		.append(this.number).append(",my name is ")
    		.append(this.name).toString();
    	}
    	
    }

src/test/java源文件夹下：

club.younge.demo下新建测试类（TestCC）

TestCC:

package club.younge.demo;
    
    import org.junit.Test;
    
    public class TestCC {
    
    	@Test
    	public void testSingleTon(){
    		Student student = Singleton.getInstance(Student.class);
    		student.setNumberAndName("123", "Haha");
    		System.out.println(student);
    	}
    }

测试结果：

I am a student, my number is 123,my name is Haha