初探 java反射機制

java可以通過反射機制獲取類的各種信息和創建類的實例,就算將構造方法用private修飾,也可以創建,通過反射能創建很多強大的功能,算是寫框架的常用方法和技巧

這裏只介紹通過反射獲取類的各種信息

實驗類

package learn.reflect;

public class UserBean {

    private Integer id;
    private String usrname;
    private String phone;

    public UserBean(Integer id, String usrname, String phone) {
        super();
        this.id = id;
        this.usrname = usrname;
        this.phone = phone;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsrname() {
        return usrname;
    }

    public void setUsrname(String usrname) {
        this.usrname = usrname;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

}

啓動類

package learn.reflect;

public class Main {

    public static void main(String[] args) {
        Class u = null;
        try {
            // 運行時加載以編譯好的xxx.class文件,默認路徑在classPath
            u = Class.forName("learn.reflect.UserBean");
            System.out.println("找到xxx.class文件");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // 獲取class後,能獲取該類的一切信息進行判斷或查看,有很多getxxx方法和isxxx方法
        System.out.println("class文件和包路徑: " + u.getName());
        System.out.println(u.getComponentType());
        System.out.println(u.getCanonicalName());
        System.out.println(u.getModifiers());
        System.out.println(u.getSimpleName());
        System.out.println(u.getTypeName());
        System.out.println(u.getAnnotatedInterfaces());
        System.out.println(u.getAnnotatedSuperclass());
        System.out.println(u.getAnnotations());
        System.out.println(u.getConstructors());
        System.out.println(u.getDeclaredAnnotations());
        System.out.println(u.getFields());
        System.out.println(u.getMethods());
        System.out.println();


        u.getMethods();

    }

}