import java.lang.reflect.Field;
/**
* description:
*
* @author: dawn.he QQ: 905845006
* @email: dawn.he@cloudwise.com
* @email: 905845006@qq.com
* @date: 2019/12/4 11:19 PM
*/
public class aa {
public static void main(String[] args) {
ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
System.out.println("main线程:" + Thread.currentThread().getId() + ":");
Field threadsField = null;
Field nthreadsField = null;
nthreadsField = getField(currentGroup, "nthreads");
threadsField = getField(currentGroup, "threads");
try {
Object nthread = nthreadsField.get(currentGroup);
int a = Integer.parseInt(nthread.toString());
Object[] o = (Object[]) threadsField.get(currentGroup);
System.out.println(o.length);
Thread[] thread = (Thread[]) o;
if (a == 1) {
System.out.println("反射main线程：" + thread[a - 1].getId() + "------------");
System.out.println("反射main线程父线程：null-------");
} else {
System.out.println("反射当前线程：" + thread[a - 1].getId() + "------------");
System.out.println("反射当前父线程：" + thread[a - 2].getId() + "------------");
}
} catch (IllegalAccessException e) {
e.printStackTrace();
}
//-------------------------
new Thread(new Runnable() {
public void run() {
ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
System.out.println("线程1:" + Thread.currentThread().getId() + ":");
Field threadsField = null;
Field nthreadsField = null;
nthreadsField = getField(currentGroup, "nthreads");
threadsField = getField(currentGroup, "threads");
try {
Object nthread = nthreadsField.get(currentGroup);
int a = Integer.parseInt(nthread.toString());
Object[] o = (Object[]) threadsField.get(currentGroup);
System.out.println(o.length);
Thread[] thread = (Thread[]) o;
if (a == 1) {
System.out.println("反射main线程：" + thread[a - 1].getId() + "------------");
System.out.println("反射main线程父线程：null-------");
} else {
System.out.println("反射当前线程1：" + thread[a - 1].getId() + "------------");
System.out.println("反射当前父线程1：" + thread[a - 2].getId() + "------------");
}
} catch (IllegalAccessException e) {
e.printStackTrace();
}
new Thread(new Runnable() {
public void run() {
ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
System.out.println("线程2:" + Thread.currentThread().getId() + ":");
Field threadsField = null;
Field nthreadsField = null;
nthreadsField = getField(currentGroup, "nthreads");
threadsField = getField(currentGroup, "threads");
try {
Object nthread = nthreadsField.get(currentGroup);
int a = Integer.parseInt(nthread.toString());
Object[] o = (Object[]) threadsField.get(currentGroup);
System.out.println(o.length);
Thread[] thread = (Thread[]) o;
if (a == 1) {
System.out.println("反射main线程：" + thread[a - 1].getId() + "------------");
System.out.println("反射main线程父线程：null-------");
} else {
System.out.println("反射当前线程2：" + thread[a - 1].getId() + "------------");
System.out.println("反射当前父线程2：" + thread[a - 2].getId() + "------------");
}
} catch (IllegalAccessException e) {
e.printStackTrace();
}
new Thread(new Runnable() {
public void run() {
ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
System.out.println("线程3:" + Thread.currentThread().getId() + ":");
Field threadsField = null;
Field nthreadsField = null;
nthreadsField = getField(currentGroup, "nthreads");
threadsField = getField(currentGroup, "threads");
try {
Object nthread = nthreadsField.get(currentGroup);
int a = Integer.parseInt(nthread.toString());
Object[] o = (Object[]) threadsField.get(currentGroup);
System.out.println(o.length);
Thread[] thread = (Thread[]) o;
if (a == 1) {
System.out.println("反射main线程：" + thread[a - 1].getId() + "------------");
System.out.println("反射main线程父线程：null-------");
} else {
System.out.println("反射当前线程3：" + thread[a - 1].getId() + "------------");
System.out.println("反射当前父线程3：" + thread[a - 2].getId() + "------------");
}
} catch (IllegalAccessException e) {
e.printStackTrace();
}
while (true) {
}
}
}).start();
while (true) {
}
}
}).start();
while (true) {
}
}
}).start();
while (true) {
}
}
public static Field getField(ThreadGroup group, String field) {
try {
Field field1;
field1 = group.getClass().getDeclaredField(field);
if (!field1.isAccessible()) {
field1.setAccessible(true);
}
return field1;
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
return null;
}
}
