org.springframework.beans.BeanUtils學習筆記

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

僅僅只是拿來作為筆記，方便以后自己查看。

 

知識點

org.springframework.beans.BeanUtils與org.apache.commons.beanutils.BeanUtils都提供了copyProperties方法，作用是將一個Bean對象中的數據封裝到另一個屬性結構相似的Bean對象中

1）兩者的copyProperties方法參數位置不同

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

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

2）要求兩個Bean的屬性名相同，且有對應的setXxx方法和getXxx方法。其實底層原理是使用sourceDemo的getXxx方法和targetDemo的setXxx方法

3）sourceDemo有的屬性而targetDemo沒有的屬性，不會封裝到targetDemo對象中；

　  targetDemo有的屬性而sourceDemo沒有的屬性，會封裝到targetDemo中，數據為默認值（注意基本類型默認值與引用類型默認值不同）

4）類型轉換問題

　 a）基本類型與其對應的封裝類型可以相互轉換

　 b）org.springframework.beans.BeanUtils與org.apache.commons.beanutils.BeanUtils對於String和Date類型轉換的情況是不同的，具體看以下案例

　

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); } }

 

測試效果：

[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]

結論：基本類型與其對應的封裝類型是可以相互轉換的

 

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);  } }

 

測試效果：

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

結論：org.springframework.beans.BeanUtils.copyProperties不可以將java.util.Date類型轉換成String類型

同時：也不可將java.sql.Date類型轉換成String類型（因為網上搜的說可以支持java.sql.Date類型，我自己測試了一下發現不可以，還是信自己靠譜）

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與案例二相同

 

測試效果：java.util.Date

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

結論：org.apache.commons.beanutils.BeanUtils.copyProperties可以將java.util.Date類型轉換成String類型

 

測試效果：java.sql.Date

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

結論：org.apache.commons.beanutils.BeanUtils.copyProperties可以將java.sql.Date類型轉換成String類型

注意：雖然都可以轉換，但發現兩者的日期格式還是不同的

 

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); } }

測試效果：

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

結論：org.springframework.beans.BeanUtils.copyProperties不可以將String類型轉換成java.util.Date類型

同時：也不可將String類型轉換成java.sql.Date類型

 

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);
    }
}

 

測試效果：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)

結論：org.apache.commons.beanutils.BeanUtils

看錯誤日志，發現說是默認的轉換器是不可以將String類型轉換成java.util.Date，可能自己配置一個轉換器就可以轉了吧，我沒有測試過

 

測試效果：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)

結論：org.apache.commons.beanutils.BeanUtils

看錯誤日志，發現說是需要將String類型轉成java.sql.Date，使用simpleDateFormat是將String類型轉成java.util.Date，可能轉成java.sql.Date就可以了吧，我沒測試過

 注意：我這里說的轉換，單純是指這一行代碼sourceDemo.setCreateTime(new SimpleDateFormat("yyyyMMddHHmmss").format(new Date(0)));而不是兩個Bean的類型轉換

 

總之，無論是org.springframework.beans.BeanUtils還是org.apache.commons.beanutils.BeanUtils，默認情況下都不能將String類型轉成Date類型

 

案例六：

SourceDemo：

　　private String name;

TargetDemo：

　　private String name = “馬超”;

　　private String email = "張飛";

復制之后的結果：name = null，email = “張飛”

 

SourceDemo：

　　private String name = “諸葛亮”;

TargetDemo：

　　private String name = “馬超”;

　　private String email = "張飛";

復制之后的結果：name = “諸葛亮”，email = “張飛”

注：使用兩種BeanUtils效果相同