经常会遇到一些管理后台，需要详细的记录每次操作更新的内容，具体到字段，以及修改前修改后的内容；

利用反射写了一个通用工具类

定义一个简单的PO：

@Data
@NoArgsConstructor
public class SimplePO {

    @Record(name = "唯一键")
    private Integer id;

    @Record(name = "名字")
    private String name;

    @Record(isRecord = false)
    private String desc;
}

字段注解，能够有针对性的记录字段内容：

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Record {

    boolean isRecord() default true;
    String name() default "";
}

工具类：

public class RecordUtil<T> {

    public String record(Class<T> clazz,T newObj,T oldObj) throws IllegalAccessException {

        if(oldObj.equals(newObj)){
            return "";

        }
        StringBuffer sb = new StringBuffer();

        Field[] fields = clazz.getDeclaredFields();

        for(Field field : fields){
            field.setAccessible(true);
            boolean isHasAnnotation = field.isAnnotationPresent(Record.class);
            if( !isHasAnnotation ){
                continue;
            }
            Record  record =  field.getAnnotation(Record.class);
            if(!record.isRecord()){
              continue;
            }
            if(field.get(oldObj) == field.get(newObj)){
                continue;
            }

            if(field.get(oldObj) != null){
                String oldValue = String.valueOf(field.get(oldObj));
                String newValue = String.valueOf(field.get(newObj));

                String name = record.name();
                String fieldName = field.getName();

                if( !oldValue.equalsIgnoreCase(newValue)){
                    sb.append(name).append("(").append(fieldName).append(")").append("修改前：").append(oldValue).
                            append(" 修改后：").append(newValue).append("\n");
                }
            }else {
                String newValue = String.valueOf(field.get(newObj));

                String name = record.name();
                String fieldName = field.getName();

                sb.append(name).append("(").append(fieldName).append(")").append("修改前：").append("null").
                        append(" 修改后：").append(newValue).append("\n");

            }
        }

        System.out.printf(sb.toString());

        return sb.toString();
    }

测试用例：

 public static void main(String[] args) {
        try {
            SimplePO newPO = new SimplePO();
            newPO.setId(1);
            newPO.setName("测试");
            newPO.setDesc("星期一");

            SimplePO oldPO = new SimplePO();
            oldPO.setId(2);
            oldPO.setName("上线");
            oldPO.setDesc("星期二");
            System.out.printf("test");
            RecordUtil<SimplePO> recordUtil = new RecordUtil<>();

            recordUtil.record(SimplePO.class,newPO,oldPO);
            System.out.printf("执行到这了");
        } catch (Exception e) {
            e.printStackTrace();
        }


    }

测试结果：

唯一键(id)修改前：2 修改后：1
名字(name)修改前：上线 修改后：测试