java 创建对象的方式

1: new
2:Constructor反射
3:Test.class.newInstance() 须有默认构造函数
4:Objenesis 是否存在默认构造函数都可以创建,但没有参数无法init

public class Test {
    private String string;

    public Test(String string) {
        this.string = string;
    }

    public String getString() {
        return string;
    }

    public void setString(String string) {
        this.string = string;
    }

    @Override
    public String toString() {
        return "Test{" +
                "string='" + string + '\'' +
                '}';
    }

    public static void main(String[] args) {
        Test o1 = new Test("test1");
        System.out.println("o1:" + o1);
        Objenesis objenesis = new ObjenesisStd();

        try {
            Test o2 = Test.class.newInstance(); //报错，须有默认构造函数
            System.out.println("o2:" + o2);
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            Constructor constructor = Test.class.getConstructor(String.class);
            constructor.setAccessible(true);
            Test o3 = constructor.newInstance("test2");
            System.out.println("o3:" + o3);
        } catch (Exception e) {
            e.printStackTrace();
        }

        ObjectInstantiator objectInstantiator = objenesis.getInstantiatorOf(Test.class);
        Test o4 = objectInstantiator.newInstance();
        System.out.println("o4:" + o4);
        Test o5 = objectInstantiator.newInstance();
        System.out.println("o5:" + o5);
    }
}