结合阿里代码规范约定+源码剖析属性拷贝性能安全问题

org.springframework.beans.BeanUtils源码为例　　　　　　

第一个标记处校验了源对象中是否有目标对象中需要更新的某属性，如果有就往下执行了
第二个标记处从原对象中把该属性值取出，然后设置到目标对象中相应属性上

对比了其他几种BeanUtils源码基本都是这个实现思路，大同小异，并不会检查原对象的属性是否为null，我想这可能是因为BeanUtils拷贝属性的设计初衷就是null也是一种属性值的状态
【不是不可以使用，请大家使用前务必多做了解，测试；再投入使用】

public interface PropertiesCopier {
    void copyProperties(Object source, Object target) throws Exception;
}
public class CglibBeanCopierPropertiesCopier implements PropertiesCopier {
    @Override
    public void copyProperties(Object source, Object target) throws Exception {
        BeanCopier copier = BeanCopier.create(source.getClass(), target.getClass(), false);
        copier.copy(source, target, null);
    }
}
// 全局静态 BeanCopier，避免每次都生成新的对象
public class StaticCglibBeanCopierPropertiesCopier implements PropertiesCopier {
    private static BeanCopier copier = BeanCopier.create(Account.class, Account.class, false);
    @Override
    public void copyProperties(Object source, Object target) throws Exception {
        copier.copy(source, target, null);
    }
}
public class SpringBeanUtilsPropertiesCopier implements PropertiesCopier {
    @Override
    public void copyProperties(Object source, Object target) throws Exception {
        org.springframework.beans.BeanUtils.copyProperties(source, target);
    }
}
public class CommonsBeanUtilsPropertiesCopier implements PropertiesCopier {
    @Override
    public void copyProperties(Object source, Object target) throws Exception {
        org.apache.commons.beanutils.BeanUtils.copyProperties(target, source);
    }
}
public class CommonsPropertyUtilsPropertiesCopier implements PropertiesCopier {
    @Override
    public void copyProperties(Object source, Object target) throws Exception {
        org.apache.commons.beanutils.PropertyUtils.copyProperties(target, source);
    }
}

@RunWith(Parameterized.class)
public class PropertiesCopierTest {
    @Parameterized.Parameter(0)
    public PropertiesCopier propertiesCopier;
    // 测试次数
    private static List<Integer> testTimes = Arrays.asList(100, 1000, 10_000, 100_000, 1_000_000);
    // 测试结果以 markdown 表格的形式输出
    private static StringBuilder resultBuilder = new StringBuilder("|实现|100|1,000|10,000|100,000|1,000,000|\n").append("|----|----|----|----|----|----|\n");

    @Parameterized.Parameters
    public static Collection<Object[]> data() {
        Collection<Object[]> params = new ArrayList<>();
        params.add(new Object[]{new StaticCglibBeanCopierPropertiesCopier()});
        params.add(new Object[]{new CglibBeanCopierPropertiesCopier()});
        params.add(new Object[]{new SpringBeanUtilsPropertiesCopier()});
        params.add(new Object[]{new CommonsPropertyUtilsPropertiesCopier()});
        params.add(new Object[]{new CommonsBeanUtilsPropertiesCopier()});
        return params;
    }

    @Before
    public void setUp() throws Exception {
        String name = propertiesCopier.getClass().getSimpleName().replace("PropertiesCopier", "");
        resultBuilder.append("|").append(name).append("|");
    }

    @Test
    public void copyProperties() throws Exception {
        Account source = new Account(1, "test1", 30D);
        Account target = new Account();
        // 预热一次
        propertiesCopier.copyProperties(source, target);
        for (Integer time : testTimes) {
            long start = System.nanoTime();
            for (int i = 0; i < time; i++) {
                propertiesCopier.copyProperties(source, target);
            }
            resultBuilder.append((System.nanoTime() - start) / 1_000_000D).append("|");
        }
        resultBuilder.append("\n");
    }

    @AfterClass
    public static void tearDown() throws Exception {
        System.out.println("测试结果：");
        System.out.println(resultBuilder);
    }
}

/**
 * 
* @ClassName: CacheBeanCopier
* <b>Copyright xxxx
* @Description: 缓存 Bean Copier提升性能
* @author liuhanlin
* @date 2020年5月20日 下午4:01:34
*
 */
public class CacheBeanCopier {
    
    private static final Map<String, BeanCopier> BEAN_COPIERS = new HashMap<String, BeanCopier>();

    public static void copy(Object source, Object target){
        String key = genKey(source.getClass(), target.getClass());
        BeanCopier copier = null;
        if(!BEAN_COPIERS.containsKey(key)){
            copier = BeanCopier.create(source.getClass(), target.getClass(), false);
            BEAN_COPIERS.put(key, copier);
        }else{
            copier = BEAN_COPIERS.get(key);
        }
        copier.copy(source, target, null);
    }
    
    private static String genKey(Class<?> sourceClz, Class<?> targetClz){
        return sourceClz.toString() + targetClz.toString();
    }
    
    public static void main(String[] args) {
        Param1  p1 = new Param1();
        p1.setPrd("TOD");
        p1.setCntrctNm("you");
        p1.setOptnHdgSpotFwdIndctr("1");
        p1.setOptnSpotIndctr("0");
        p1.setIntrNlegBaseCcyTrdngDir("S");
        p1.setFrLegBaseAmnt(new BigDecimal(1500));
        p1.setFrLegTermAmnt(new BigDecimal(899));
        p1.setNrLegBaseAmnt(new BigDecimal(100));
        p1.setNrLegTermAmnt(new BigDecimal(56));
        p1.setIntrFlegBaseCcyDir("B");
        p1.setNlegSpotExchngRate(new BigDecimal(2));
        p1.setFlegSpotExchngRate(new BigDecimal(0.5));
        p1.setNrLegVlDt(new Date());
        p1.setFrLegVlDt(new Date());    
        p1.setNtngAmnt(new BigDecimal(2.3));
        p1.setClrngCcy("CNY");
        p1.setTcktTp("2");
        p1.setTcktId("6.25654313");
        Param2  p2 = new Param2();
        CacheBeanCopier.copy(p1, p2);
        System.out.println(new Gson().toJson(p2));
    }

}

本文最后才想起来，依赖也给大家贴出来：

1. <dependency>  
2.             <groupId>asm</groupId>  
3.             <artifactId>asm</artifactId>  
4.             <version>3.3.1</version>  
5.         </dependency>  
6.         <dependency>  
7.             <groupId>asm</groupId>  
8.             <artifactId>asm-commons</artifactId>  
9.             <version>3.3.1</version>  
10.         </dependency>  
11.         <dependency>  
12.             <groupId>asm</groupId>  
13.             <artifactId>asm-util</artifactId>  
14.             <version>3.3.1</version>  
15.         </dependency>  
16.         <dependency>  
17.             <groupId>cglib</groupId>  
18.             <artifactId>cglib-nodep</artifactId>  
19.             <version>2.2.2</version>  
20.         </dependency>