java 设置内存地址_如何获得java对象的内存地址
展开全部
在java中内存中的对象地址是可变的，所以获得的内存地e68a843231313335323631343130323136353331333363373639址有可能会变化。要获得内存地址也只能通过Unsafe的方法来获得，如下代码示例：
package com.bijian.study;
import java.lang.reflect.Field;
import sun.misc.Unsafe;
public class Addresser {
//实例化Unsafe 类
private static Unsafe unsafe;
static {
try {
//得到field对象
Field field = Unsafe.class.getDeclaredField("theUnsafe");
//设置获取地址
field.setAccessible(true);
unsafe = (Unsafe) field.get(null);
} catch (Exception e) {
e.printStackTrace();
}
}
public static long addressOf(Object o) throws Exception {
Object[] array = new Object[] { o };
long baseOffset = unsafe.arrayBaseOffset(Object[].class);
int addressSize = unsafe.addressSize();
long objectAddress;
switch (addressSize) {
case 4:
objectAddress = unsafe.getInt(array, baseOffset);
break;
case 8:
objectAddress = unsafe.getLong(array, baseOffset);
break;
default:
throw new Error("unsupported address size: " + addressSize);
}
return (objectAddress);
}
//打印地址的长度
public static void main(String... args) throws Exception {
Object mine = "Hi there".toCharArray();
long address = addressOf(mine);
System.out.println("Addess: " + address);
// Verify address works - should see the characters in the array in the output
printBytes(address, 27);
}
//调用此方法得到地址
public static void printBytes(long objectAddress, int num) {
//循环打印得到的地址。
for (long i = 0; i
int cur = unsafe.getByte(objectAddress + i);
System.out.print((char) cur);
}
System.out.println();
}
}
运行结果：
展开全部 在java中内存中的对象地址是可变的，所以获得的内存地e68a843231313335323631343130323136353331333363373639址有可能会变化。要获得内存地址也只能通过Unsafe的方法来获得，如下代码示例： package com.bijian.study; import java.lang.reflect.Field; import sun.misc.Unsafe; public class Addresser { //实例化Unsafe 类 private static Unsafe unsafe; static { try { //得到field对象 Field field = Unsafe.class.getDeclaredField("theUnsafe"); //设置获取地址 field.setAccessible(true); unsafe = (Unsafe) field.get(null); } catch (Exception e) { e.printStackTrace(); } } public static long addressOf(Object o) throws Exception { Object[] array = new Object[] { o }; long baseOffset = unsafe.arrayBaseOffset(Object[].class); int addressSize = unsafe.addressSize(); long objectAddress; switch (addressSize) { case 4: objectAddress = unsafe.getInt(array, baseOffset); break; case 8: objectAddress = unsafe.getLong(array, baseOffset); break; default: throw new Error("unsupported address size: " + addressSize); } return (objectAddress); } //打印地址的长度 public static void main(String... args) throws Exception { Object mine = "Hi there".toCharArray(); long address = addressOf(mine); System.out.println("Addess: " + address); // Verify address works - should see the characters in the array in the output printBytes(address, 27); } //调用此方法得到地址 public static void printBytes(long objectAddress, int num) { //循环打印得到的地址。 for (long i = 0; i int cur = unsafe.getByte(objectAddress + i); System.out.print((char) cur); } System.out.println(); } } 运行结果：