org.springframework.beans.BeanUtils学习笔记

时间：2019-03-18 12:26:51 阅读：148 评论：0 收藏：0 [点我收藏+]

注：转自：https://www.cnblogs.com/dongfangshenhua/p/7099970.html

仅仅只是拿来作为笔记，方便以后自己查看。

知识点

org.springframework.beans.BeanUtils与org.apache.commons.beanutils.BeanUtils都提供了copyProperties方法，作用是将一个Bean对象中的数据封装到另一个属性结构相似的Bean对象中

1）两者的copyProperties方法参数位置不同

　　org.springframework.beans.BeanUtils:　　copyProperties(sourceDemo, targetDemo)

　　org.apache.commons.beanutils.BeanUtils:　　copyProperties(targetDemo, sourceDemo)

2）要求两个Bean的属性名相同，且有对应的setXxx方法和getXxx方法。其实底层原理是使用sourceDemo的getXxx方法和targetDemo的setXxx方法

3）sourceDemo有的属性而targetDemo没有的属性，不会封装到targetDemo对象中；

　 targetDemo有的属性而sourceDemo没有的属性，会封装到targetDemo中，数据为默认值（注意基本类型默认值与引用类型默认值不同）

4）类型转换问题

　 a）基本类型与其对应的封装类型可以相互转换

　 b）org.springframework.beans.BeanUtils与org.apache.commons.beanutils.BeanUtils对于String和Date类型转换的情况是不同的，具体看以下案例

案例一

SourceDemo

package com.fortis.customer.test;

import java.util.Date;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class SourceDemo {
    
    private int id;
    
    private String name;
    
    private String address;
    
    private Date createTime;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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 Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

TargetDemo

package com.fortis.customer.test;

import java.util.Date;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class TargetDemo {
    
    private Integer id;
    
    private String name;
    
    private String email;
    
    private Date createTime;
    
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }
    
    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

Test

package com.fortis.customer.test;

import java.lang.reflect.InvocationTargetException;
import java.util.Date;

public class Test {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
        
        SourceDemo sourceDemo = new SourceDemo();
        sourceDemo.setId(10);
        sourceDemo.setName("姓名");
        sourceDemo.setAddress("地址");
        sourceDemo.setCreateTime(new Date());
        
        TargetDemo targetDemo = new TargetDemo();
        org.springframework.beans.BeanUtils.copyProperties(sourceDemo, targetDemo);
        System.out.println(targetDemo);
        
        org.apache.commons.beanutils.BeanUtils.copyProperties(targetDemo, sourceDemo);
        System.out.println(targetDemo);
    }
}

测试效果：

[id=10,name=姓名,email=<null>,createTime=Fri Jun 30 16:19:31 CST 2017]
[id=10,name=姓名,email=<null>,createTime=Fri Jun 30 16:19:31 CST 2017]

结论：基本类型与其对应的封装类型是可以相互转换的

案例二

SourceDemo

package com.fortis.customer.test;

import java.util.Date;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class SourceDemo {
    
    private int id;
    
    private String name;
    
    private String address;
    
    private Date createTime;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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 Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

TargetDemo

package com.fortis.customer.test;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class TargetDemo {
    
    private Integer id;
    
    private String name;
    
    private String email;
    
    private String createTime;
    
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getCreateTime() {
        return createTime;
    }

    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }
    
    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

Test

package com.fortis.customer.test;

import java.lang.reflect.InvocationTargetException;
import java.util.Date;

public class Test {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
        
        SourceDemo sourceDemo = new SourceDemo();
        sourceDemo.setId(10);
        sourceDemo.setName("姓名");
        sourceDemo.setAddress("地址");
        sourceDemo.setCreateTime(new Date(0));
        
        TargetDemo targetDemo = new TargetDemo();
        org.springframework.beans.BeanUtils.copyProperties(sourceDemo, targetDemo);
        System.out.println(targetDemo);
        
        //org.apache.commons.beanutils.BeanUtils.copyProperties(targetDemo, sourceDemo);
        //System.out.println(targetDemo);
    }
}

测试效果：

Exception in thread "main" org.springframework.beans.FatalBeanException: Could not copy properties from source to target; nested exception is java.lang.IllegalArgumentException: argument type mismatch
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:599)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:509)
    at com.fortis.customer.test.Test.main(Test.java:17)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:596)
    ... 2 more

结论：org.springframework.beans.BeanUtils.copyProperties不可以将java.util.Date类型转换成String类型

同时：也不可将java.sql.Date类型转换成String类型（因为网上搜的说可以支持java.sql.Date类型，我自己测试了一下发现不可以，还是信自己靠谱）

Exception in thread "main" org.springframework.beans.FatalBeanException: Could not copy properties from source to target; nested exception is java.lang.IllegalArgumentException: argument type mismatch
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:599)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:509)
    at com.fortis.customer.test.Test.main(Test.java:17)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:596)
    ... 2 more

案例三

Test

package com.fortis.customer.test;

import java.lang.reflect.InvocationTargetException;
import java.util.Date;

public class Test {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
        
        SourceDemo sourceDemo = new SourceDemo();
        sourceDemo.setId(10);
        sourceDemo.setName("姓名");
        sourceDemo.setAddress("地址");
        sourceDemo.setCreateTime(new Date(0));
        
        TargetDemo targetDemo = new TargetDemo();
        //org.springframework.beans.BeanUtils.copyProperties(sourceDemo, targetDemo);
        //System.out.println(targetDemo);
        
        org.apache.commons.beanutils.BeanUtils.copyProperties(targetDemo, sourceDemo);
        System.out.println(targetDemo);
    }
}

注：SourceDemo和TargetDemo与案例二相同

测试效果：java.util.Date

[id=10,name=姓名,email=<null>,createTime=Thu Jan 01 08:00:00 CST 1970]

结论：org.apache.commons.beanutils.BeanUtils.copyProperties可以将java.util.Date类型转换成String类型

测试效果：java.sql.Date

[id=10,name=姓名,email=<null>,createTime=1970-01-01]

结论：org.apache.commons.beanutils.BeanUtils.copyProperties可以将java.sql.Date类型转换成String类型

注意：虽然都可以转换，但发现两者的日期格式还是不同的

案例四：

SourceDemo

package com.fortis.customer.test;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class SourceDemo {
    
    private int id;
    
    private String name;
    
    private String address;
    
    private String createTime;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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 String getCreateTime() {
        return createTime;
    }

    public void setCreateTime(String createTime) {
        this.createTime = createTime;
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

TargetDemo

package com.fortis.customer.test;

import java.util.Date;

import org.apache.commons.lang3.builder.ToStringBuilder;

public class TargetDemo {
    
    private Integer id;
    
    private String name;
    
    private String email;
    
    private Date createTime;
    
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }
    
    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
    
}

Test

package com.fortis.customer.test;

import java.lang.reflect.InvocationTargetException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Test {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
        
        SourceDemo sourceDemo = new SourceDemo();
        sourceDemo.setId(10);
        sourceDemo.setName("姓名");
        sourceDemo.setAddress("地址");
        sourceDemo.setCreateTime(new SimpleDateFormat("yyyyMMddHHmmss").format(new Date(0)));
        
        TargetDemo targetDemo = new TargetDemo();
        org.springframework.beans.BeanUtils.copyProperties(sourceDemo, targetDemo);
        System.out.println(targetDemo);
        
        //org.apache.commons.beanutils.BeanUtils.copyProperties(targetDemo, sourceDemo);
        //System.out.println(targetDemo);
    }
}

测试效果：

Exception in thread "main" org.springframework.beans.FatalBeanException: Could not copy properties from source to target; nested exception is java.lang.IllegalArgumentException: argument type mismatch
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:599)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:509)
    at com.fortis.customer.test.Test.main(Test.java:18)
Caused by: java.lang.IllegalArgumentException: argument type mismatch
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:596)
    ... 2 more

结论：org.springframework.beans.BeanUtils.copyProperties不可以将String类型转换成java.util.Date类型

同时：也不可将String类型转换成java.sql.Date类型

案例五

Test

package com.fortis.customer.test;

import java.lang.reflect.InvocationTargetException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Test {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
        
        SourceDemo sourceDemo = new SourceDemo();
        sourceDemo.setId(10);
        sourceDemo.setName("姓名");
        sourceDemo.setAddress("地址");
        sourceDemo.setCreateTime(new SimpleDateFormat("yyyyMMddHHmmss").format(new Date(0)));
        
        TargetDemo targetDemo = new TargetDemo();
        //org.springframework.beans.BeanUtils.copyProperties(sourceDemo, targetDemo);
        //System.out.println(targetDemo);
        
        org.apache.commons.beanutils.BeanUtils.copyProperties(targetDemo, sourceDemo);
        System.out.println(targetDemo);
    }
}

测试效果：java.util.Date

log4j:WARN No appenders could be found for logger (org.apache.commons.beanutils.converters.BooleanConverter).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.apache.commons.beanutils.ConversionException: DateConverter does not support default String to ‘Date‘ conversion.
    at org.apache.commons.beanutils.converters.DateTimeConverter.toDate(DateTimeConverter.java:468)
    at org.apache.commons.beanutils.converters.DateTimeConverter.convertToType(DateTimeConverter.java:343)
    at org.apache.commons.beanutils.converters.AbstractConverter.convert(AbstractConverter.java:156)
    at org.apache.commons.beanutils.converters.ConverterFacade.convert(ConverterFacade.java:60)
    at org.apache.commons.beanutils.BeanUtilsBean.convert(BeanUtilsBean.java:1078)
    at org.apache.commons.beanutils.BeanUtilsBean.copyProperty(BeanUtilsBean.java:437)
    at org.apache.commons.beanutils.BeanUtilsBean.copyProperties(BeanUtilsBean.java:286)
    at org.apache.commons.beanutils.BeanUtils.copyProperties(BeanUtils.java:137)
    at com.fortis.customer.test.Test.main(Test.java:21)

结论：org.apache.commons.beanutils.BeanUtils

看错误日志，发现说是默认的转换器是不可以将String类型转换成java.util.Date，可能自己配置一个转换器就可以转了吧，我没有测试过

测试效果：java.sql.Date

log4j:WARN No appenders could be found for logger (org.apache.commons.beanutils.converters.BooleanConverter).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.apache.commons.beanutils.ConversionException: String must be in JDBC format [yyyy-MM-dd] to create a java.sql.Date
    at org.apache.commons.beanutils.converters.DateTimeConverter.toDate(DateTimeConverter.java:436)
    at org.apache.commons.beanutils.converters.DateTimeConverter.convertToType(DateTimeConverter.java:343)
    at org.apache.commons.beanutils.converters.AbstractConverter.convert(AbstractConverter.java:156)
    at org.apache.commons.beanutils.converters.ConverterFacade.convert(ConverterFacade.java:60)
    at org.apache.commons.beanutils.BeanUtilsBean.convert(BeanUtilsBean.java:1078)
    at org.apache.commons.beanutils.BeanUtilsBean.copyProperty(BeanUtilsBean.java:437)
    at org.apache.commons.beanutils.BeanUtilsBean.copyProperties(BeanUtilsBean.java:286)
    at org.apache.commons.beanutils.BeanUtils.copyProperties(BeanUtils.java:137)
    at com.fortis.customer.test.Test.main(Test.java:21)

结论：org.apache.commons.beanutils.BeanUtils

看错误日志，发现说是需要将String类型转成java.sql.Date，使用simpleDateFormat是将String类型转成java.util.Date，可能转成java.sql.Date就可以了吧，我没测试过

注意：我这里说的转换，单纯是指这一行代码sourceDemo.setCreateTime(new SimpleDateFormat("yyyyMMddHHmmss").format(new Date(0)));而不是两个Bean的类型转换

总之，无论是org.springframework.beans.BeanUtils还是org.apache.commons.beanutils.BeanUtils，默认情况下都不能将String类型转成Date类型

案例六：

SourceDemo：

　　private String name;

TargetDemo：

　　private String name = “马超”;

　　private String email = "张飞";

复制之后的结果：name = null，email = “张飞”

SourceDemo：

　　private String name = “诸葛亮”;

TargetDemo：

　　private String name = “马超”;

　　private String email = "张飞";

复制之后的结果：name = “诸葛亮”，email = “张飞”

注：使用两种BeanUtils效果相同

org.springframework.beans.BeanUtils学习笔记

原文：https://www.cnblogs.com/ahri-gx/p/10551340.html

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