java - 使用 BeanUtils.copyProperties 复制特定字段？

Question

springframework.beans.BeanUtils 对于复制对象非常有用，我经常使用“ignoreProperties”选项。但是，有时我只想复制特定的对象(基本上，与“忽略属性”相反)。有谁知道我该怎么做？任何帮助将不胜感激。

import org.springframework.beans.BeanUtils;

public class Sample {    
    public static void main(String[] args) {    
        DemoADto demoADto = new DemoADto();
        demoADto.setName("Name of Demo A");
        demoADto.setAddress("Address of Demo A");

        DemoBDto demoBDto = new DemoBDto();

        // This is "ignoreProperties" option
        // But I want to know how I can copy only name field by using BeanUtils or something.
        BeanUtils.copyProperties(demoADto, demoBDto, new String[] {"address"});

        System.out.println(demoBDto.getName());
        System.out.println(demoBDto.getAddress());    
    }    
}

public class DemoADto {    
    private String name;    
    private String address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }    
}

public class DemoBDto {    
    private String name;    
    private String address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }    
}

Answer 1

您可以使用 BeanWrapper技术。这是一个示例实现:

public static void copyProperties(Object src, Object trg, Iterable<String> props) {

    BeanWrapper srcWrap = PropertyAccessorFactory.forBeanPropertyAccess(src);
    BeanWrapper trgWrap = PropertyAccessorFactory.forBeanPropertyAccess(trg);

    props.forEach(p -> trgWrap.setPropertyValue(p, srcWrap.getPropertyValue(p)));

}

或者，如果你真的，真的想要使用 BeanUtils，这里有一个解决方案。反转逻辑，通过将完整属性列表与包含进行比较来收集排除项:

public static void copyProperties2(Object src, Object trg, Set<String> props) {
    String[] excludedProperties = 
            Arrays.stream(BeanUtils.getPropertyDescriptors(src.getClass()))
                  .map(PropertyDescriptor::getName)
                  .filter(name -> !props.contains(name))
                  .toArray(String[]::new);

    BeanUtils.copyProperties(src, trg, excludedProperties);
}