[Commons beanautils topic] 005- convertutils topic

【commons-beanutils project 】005- ConvertUtils project

One 、 Get ready

0、ConvertUtils The main role

Mainly used for type conversion , Customizable converter ！

1、 introduce commons-beanutils rely on

<!-- Introduce dependencies commons-beanutils-->
<dependency>
    <groupId>commons-beanutils</groupId>
    <artifactId>commons-beanutils</artifactId>
    <version>1.9.4</version>
</dependency>

2、pom.xml file

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zibo</groupId>
    <artifactId>zibo2022</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>zibo2022</name>
    <description>zibo2022</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- Introduce dependencies commons-beanutils-->
        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.4</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.7.1</version>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

3、 Entity class

Cat

package com.zibo.zibo2022.convert_utils.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Cat {
    

    private String name;

    private Integer age;

}

CatDto

package com.zibo.zibo2022.convert_utils.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/** * @author zibo * @date 2022/7/20 0020 18:56 */
@Data
@NoArgsConstructor
@AllArgsConstructor
public class CatDto {
    

    private String name;

    private Integer age;

}

4、 Custom converter

package com.zibo.zibo2022.convert_utils.converter;

import com.zibo.zibo2022.convert_utils.entity.Cat;
import com.zibo.zibo2022.convert_utils.entity.CatDto;
import java.lang.reflect.InvocationTargetException;
import org.apache.commons.beanutils.Converter;
import org.apache.commons.beanutils.PropertyUtils;

/** *  Here simply write a converter , Is used to  Cat  Object to  CatDto  object  * * @author zibo * @date 2022/7/20 0020 19:00 */
public class CatConverter implements Converter {
    
    @Override
    public <T> T convert(Class<T> type, Object value) {
    
        try {
    
            if (!(value instanceof Cat)) {
    
                throw new IllegalArgumentException(" Wrong parameter type ！");
            }
            if (type != CatDto.class) {
    
                throw new IllegalArgumentException(" Wrong parameter type ！");
            }
            String name = (String) PropertyUtils.getProperty(value, "name");
            Integer age = (Integer) PropertyUtils.getProperty(value, "age");
            T newInstance = type.getDeclaredConstructor().newInstance();
            PropertyUtils.setProperty(newInstance, "name", name);
            PropertyUtils.setProperty(newInstance, "age", age);
            return newInstance;
        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException | InstantiationException e) {
    
            throw new RuntimeException(e);
        }
    }
}

5、 Pre code

Cat cat = new Cat(" kitten ", 1);
Cat cat2 = new Cat(" kitten 2", 2);

Two 、 Type conversion

1、 Convert objects to strings

// 1、 Convert objects to strings 
String convert = ConvertUtils.convert(cat);
System.out.println(convert); // Cat(name= kitten , age=1)
//  The following is noteworthy , If it's an array , Convert only the first element 
String convert20 = ConvertUtils.convert(new Cat[] {
    cat, cat2});
System.out.println(convert20); // Cat(name= kitten , age=1)
String convert40 = ConvertUtils.convert(new String[] {
    " kitten ", "1", " Casually written content "});
System.out.println(convert40);
String convert10 = ConvertUtils.convert(new Long[] {
    1L, 2L, 3L});
System.out.println(convert10); // 1

2、 Converts a string to an object of the specified data type

// 2、 Converts a string to an object of the specified data type 
String one = "1";
Integer convert1 = (Integer) ConvertUtils.convert(one, Integer.class);
System.out.println(convert1); // 1
Object convert2 = ConvertUtils.convert(one, Boolean.class);
System.out.println(convert2); // true
Object convert4 = ConvertUtils.convert("true", Boolean.class);
System.out.println(convert4); // true
Integer[] convert5 = (Integer[]) ConvertUtils.convert("[1, 2, 3]", Integer[].class);
for (Integer integer : convert5) {
    
    System.out.println(integer);
}
// 1
// 2
// 3
//  The following cannot be converted ！！！
// Cat convert6 = (Cat)ConvertUtils.convert("Cat(name= kitten , age=1)", Cat.class);
// System.out.println(convert6);
// org.apache.commons.beanutils.ConversionException: Default conversion to com.zibo.zibo2022.convert_utils.entity.Cat failed.

3、 Converts an array of specified values to an array of objects of the specified class （ If possible ）

// 3、 Converts an array of specified values to an array of objects of the specified class （ If possible ）
String[] array = {
    " Eating rats ", " Eat fish "};
String[] convert3 = (String[]) ConvertUtils.convert(array, String.class);
System.out.println(Arrays.toString(convert3)); // [ Eating rats ,  Eat fish ]
String[] arr = {
    "true", "false"};
Boolean[] conver4 = (Boolean[]) ConvertUtils.convert(arr, Boolean.class);
System.out.println(Arrays.toString(conver4)); // [true, false]

4、 Converts an object to an object of the specified data type

// 4、 Converts an object to an object of the specified data type 
Boolean convert7 = (Boolean) ConvertUtils.convert("true", Boolean.class);
System.out.println(convert7); // true

5、 Convert basic type to wrapper class

// 10、 Convert basic type to wrapper class 
int i = 1;
Integer i2 = (Integer) ConvertUtils.convert(i, Integer.class);
System.out.println(i2); // 1

3、 ... and 、 converter

1、 Register custom converter

See the preparation section for the converter ！

// 5、 Register converter 
//  Here is the custom converter , Then register 
ConvertUtils.register(new CatConverter(), Cat.class);
CatConverter catConverter = new CatConverter();
CatDto catDto = catConverter.convert(CatDto.class, cat);
System.out.println(catDto); // CatDto(name= kitten , age=1)

2、 Find a converter of the specified type

// 6、 Find a converter of the specified type 
Converter lookup = ConvertUtils.lookup(Cat.class);
System.out.println(lookup); // [email protected]

3、 Find a converter that converts a specified type to another type

// 7、 Find a converter that converts a specified type to another type 
Converter lookup2 = ConvertUtils.lookup(String.class, Boolean.class);
System.out.println(lookup2); // ConverterFacade[BooleanConverter[UseDefault=true]]
Converter converter = ConvertUtils.lookup(CatDto.class, Cat.class);
System.out.println(converter); // [email protected]
//  Pay attention to the following 
Converter lookup3 = ConvertUtils.lookup(Cat.class, CatDto.class);
System.out.println(lookup3); // null

4、 Remove the converter of the specified type

// 8、 Remove the converter of the specified type 
ConvertUtils.deregister(Cat.class);
Converter converter1 = ConvertUtils.lookup(CatDto.class, Cat.class);
System.out.println(converter1); // null

5、 Remove all registered converters

// 9、 Remove all registered converters 
ConvertUtils.deregister();

Four 、 Complete code

package com.zibo.zibo2022.convert_utils.main;

import com.zibo.zibo2022.convert_utils.converter.CatConverter;
import com.zibo.zibo2022.convert_utils.entity.Cat;
import com.zibo.zibo2022.convert_utils.entity.CatDto;
import java.util.Arrays;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;

public class Main {
    

    public static void main(String[] args) {
    
        Cat cat = new Cat(" kitten ", 1);
        Cat cat2 = new Cat(" kitten 2", 2);

        // 1、 Convert objects to strings 
        String convert = ConvertUtils.convert(cat);
        System.out.println(convert); // Cat(name= kitten , age=1)
        //  The following is noteworthy , If it's an array , Convert only the first element 
        String convert20 = ConvertUtils.convert(new Cat[] {
    cat, cat2});
        System.out.println(convert20); // Cat(name= kitten , age=1)
        String convert40 = ConvertUtils.convert(new String[] {
    " kitten ", "1", " Casually written content "});
        System.out.println(convert40);
        String convert10 = ConvertUtils.convert(new Long[] {
    1L, 2L, 3L});
        System.out.println(convert10); // 1

        // 2、 Converts a string to an object of the specified data type 
        String one = "1";
        Integer convert1 = (Integer) ConvertUtils.convert(one, Integer.class);
        System.out.println(convert1); // 1
        Object convert2 = ConvertUtils.convert(one, Boolean.class);
        System.out.println(convert2); // true
        Object convert4 = ConvertUtils.convert("true", Boolean.class);
        System.out.println(convert4); // true
        Integer[] convert5 = (Integer[]) ConvertUtils.convert("[1, 2, 3]", Integer[].class);
        for (Integer integer : convert5) {
    
            System.out.println(integer);
        }
        // 1
        // 2
        // 3
        //  The following cannot be converted ！！！
        // Cat convert6 = (Cat)ConvertUtils.convert("Cat(name= kitten , age=1)", Cat.class);
        // System.out.println(convert6);
        // org.apache.commons.beanutils.ConversionException: Default conversion to com.zibo.zibo2022.convert_utils.entity.Cat failed.

        // 3、 Converts an array of specified values to an array of objects of the specified class （ If possible ）
        String[] array = {
    " Eating rats ", " Eat fish "};
        String[] convert3 = (String[]) ConvertUtils.convert(array, String.class);
        System.out.println(Arrays.toString(convert3)); // [ Eating rats ,  Eat fish ]
        String[] arr = {
    "true", "false"};
        Boolean[] conver4 = (Boolean[]) ConvertUtils.convert(arr, Boolean.class);
        System.out.println(Arrays.toString(conver4)); // [true, false]

        // 4、 Converts an object to an object of the specified data type 
        Boolean convert7 = (Boolean) ConvertUtils.convert("true", Boolean.class);
        System.out.println(convert7); // true

        // 5、 Register converter 
        //  Here is the custom converter , Then register 
        ConvertUtils.register(new CatConverter(), Cat.class);
        CatConverter catConverter = new CatConverter();
        CatDto catDto = catConverter.convert(CatDto.class, cat);
        System.out.println(catDto); // CatDto(name= kitten , age=1)

        // 6、 Find a converter of the specified type 
        Converter lookup = ConvertUtils.lookup(Cat.class);
        System.out.println(lookup); // [email protected]

        // 7、 Find a converter that converts a specified type to another type 
        Converter lookup2 = ConvertUtils.lookup(String.class, Boolean.class);
        System.out.println(lookup2); // ConverterFacade[BooleanConverter[UseDefault=true]]
        Converter converter = ConvertUtils.lookup(CatDto.class, Cat.class);
        System.out.println(converter); // [email protected]
        //  Pay attention to the following 
        Converter lookup3 = ConvertUtils.lookup(Cat.class, CatDto.class);
        System.out.println(lookup3); // null

        // 8、 Remove the converter of the specified type 
        ConvertUtils.deregister(Cat.class);
        Converter converter1 = ConvertUtils.lookup(CatDto.class, Cat.class);
        System.out.println(converter1); // null

        // 9、 Remove all registered converters 
        ConvertUtils.deregister();

        // 10、 Convert basic type to wrapper class 
        int i = 1;
        Integer i2 = (Integer) ConvertUtils.convert(i, Integer.class);
        System.out.println(i2); // 1
    }

}