java计算object大小

maven

        <!-- size of-->
        <dependency>
            <groupId>com.carrotsearch</groupId>
            <artifactId>java-sizeof</artifactId>
            <version>0.0.3</version>
        </dependency>

util

public class SizeOfUtil {

    public static enum SizeEnum {
        B {
            @Override
            public double getFromByteSize(long byteSize) {
                return byteSize;
            }
        },K {
            @Override
            public double getFromByteSize(long byteSize) {
                return byteSize*1.0/1024;
            }
        },M {
            @Override
            public double getFromByteSize(long byteSize) {
                return byteSize*1.0/1024/1024;
            }
        },G {
            @Override
            public double getFromByteSize(long byteSize) {
                return byteSize*1.0/1024/1024/1024;
            }
        };

        public abstract double getFromByteSize(long byteSize);
    }

    /**
     * 默认
     * 返回bytes
     * @param o
     * @return
     */
    public static double getObjectSize(Object o,SizeEnum sizeEnum){
        long byteSize = 0;
        if(o instanceof Collection<?>){
            byteSize = RamUsageEstimator.sizeOfAll(o);
        }else{
            byteSize = RamUsageEstimator.sizeOf(o);
        }
        return sizeEnum.getFromByteSize(byteSize);
    }
}

使用

System.out.println(SizeOfUtil.getObjectSize(map, SizeOfUtil.SizeEnum.K));