【commons-beanutils专题】004- BeanUtils 专题

古城微笑少年丶 2023-09-28 16:02 47阅读 0赞

# 【commons-beanutils专题】004- BeanUtils 专题 #

### 文章目录 ###

*  【commons-beanutils专题】004- BeanUtils 专题
 *  一、准备
 *   *  0、BeanUtils 主要作用
     *  1、引入 commons-beanutils 依赖
     *  2、pom.xml 文件
     *  3、实体类
     *  4、前置代码
 *  二、克隆复制
 *   *  1、克隆对象 - 浅克隆
     *  2、复制属性 - 浅复制
     *  3、复制属性，相当于设置属性
 *  三、获取属性
 *   *  1、获取描述 - 获取属性列表（含属性名和属性值）
     *  2、获取指定属性的值，作为字符串数组返回
     *  3、获取指定索引属性值，适用于属性是list或者array的情况
     *  4、获取指定索引属性值，适用于属性是list或者array的情况
     *  5、获得Map属性，适用于属性是Map的情况
     *  6、获得Map属性，适用于属性是Map的情况
     *  7、获得嵌套属性，属性是对象的情况
     *  8、获得属性值作为字符串返回
     *  9、获得属性值作为字符串返回
 *  三、转换对象
 *   *  1、将Map转换成对象
 *  四、设置属性值
 *   *  1、设置属性值
 *  五、不知道有什么用的功能
 *   *  1、对异常进行包装
     *  2、创建缓存
     *  3、getCacheFast
     *  4、setCacheFast
 *  六、完整代码

# 一、准备 #

## 0、BeanUtils 主要作用 ##

**主要用于通过反射技术操作对象：克隆对象、获取属性等；**

这个工具类的功能有一些是调用其他工具类的！

## 1、引入 commons-beanutils 依赖 ##

<dependency>
        <groupId>commons-beanutils</groupId>
        <artifactId>commons-beanutils</artifactId>
        <version>1.9.4</version>
    </dependency>

## 2、pom.xml 文件 ##

<?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/> 
        </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>
    
            
            <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、实体类 ##

package com.zibo.zibo2022.bean_utils.entity;
    
    import lombok.AllArgsConstructor;
    import lombok.Data;
    import lombok.NoArgsConstructor;
    
    import java.util.List;
    import java.util.Map;
    
    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class Dog {
        
    
        private String name;
    
        private Integer age;
    
        private String color;
    
        private Dog son;
    
        private List<String> hobbies;
    
        private Map<String, String> habits;
    
    }

## 4、前置代码 ##

List<String> hobbies = Arrays.asList("swimming", "running", "sleeping");
    Map<String, String> habits = Map.of("drinking", "beer", "smoking", "tobacco");
    Dog littleDog = new Dog("小狗的儿子", 1, "黑色", null, null, null);
    Dog dog = new Dog("小狗", 2, "黄色", littleDog, hobbies, habits);

# 二、克隆复制 #

## 1、克隆对象 - 浅克隆 ##

// 1、克隆对象 - 浅克隆
    try {
        
        Dog cloneBean = (Dog) BeanUtils.cloneBean(dog);
        littleDog.setName("小狗的儿子cloneBean");
        System.out.println(cloneBean);
        // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子cloneBean, age=1, color=黑色, son=null, hobbies=null,
        // habits=null), hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
    } catch (IllegalAccessException | InstantiationException | InvocationTargetException |
             NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 2、复制属性 - 浅复制 ##

// 2、复制属性 - 浅复制
    try {
        
        Dog dog1 = new Dog();
        BeanUtils.copyProperties(dog1, dog);
        littleDog.setName("小狗的儿子dog1");
        System.out.println(dog1);
        // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null,
        // habits=null), hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
    } catch (IllegalAccessException | InvocationTargetException e) {
        
        throw new RuntimeException(e);
    }

## 3、复制属性，相当于设置属性 ##

// 3、复制属性，相当于设置属性
    // 这就是设置属性，没看出来跟复制属性有什么关系
    try {
        
        Dog dog2 = new Dog();
        BeanUtils.copyProperty(dog2, "name", "dog2");
        System.out.println(dog2);
        // Dog(name=dog2, age=null, color=null, son=null, hobbies=null, habits=null)
    } catch (IllegalAccessException | InvocationTargetException e) {
        
        throw new RuntimeException(e);
    }

# 三、获取属性 #

## 1、获取描述 - 获取属性列表（含属性名和属性值） ##

// 4、描述 - 获取属性列表（含属性名和属性值）
    // 可借此实现判断一个类对象的所有属性是否都有值
    try {
        
        Map<String, String> map = BeanUtils.describe(dog);
        map.forEach((key, value) -> System.out.println(key + ":" + value));
        // habits:{drinking=beer, smoking=tobacco}
        // son:Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null, habits=null)
        // color:黄色
        // hobbies:swimming
        // name:小狗
        // age:2
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 2、获取指定属性的值，作为字符串数组返回 ##

// 5、返回指定属性的值，作为字符串数组返回
    try {
        
        String[] names = BeanUtils.getArrayProperty(dog, "name");
        System.out.println(Arrays.toString(names)); // [小狗]
        String[] hobbies1 = BeanUtils.getArrayProperty(dog, "hobbies");
        System.out.println(Arrays.toString(hobbies1)); // [swimming, running, sleeping]
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 3、获取指定索引属性值，适用于属性是list或者array的情况 ##

// 6、获取指定索引属性值，适用于属性是list或者array的情况
    // 与 PropertyUtils 的 getIndexedProperty 本质上是同一个方法
    try {
        
        String name = BeanUtils.getIndexedProperty(dog, "hobbies[0]");
        System.out.println(name); // swimming
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 4、获取指定索引属性值，适用于属性是list或者array的情况 ##

// 7、获取指定索引属性值，适用于属性是list或者array的情况
    // 与 PropertyUtils 的 getIndexedProperty 本质上是同一个方法
    try {
        
        String hobby = BeanUtils.getIndexedProperty(dog, "hobbies", 0);
        System.out.println(hobby); // swimming
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 5、获得Map属性，适用于属性是Map的情况 ##

// 8、获得Map属性，适用于属性是Map的情况
    // 与 PropertyUtils 的 getMappedProperty 本质上是同一个方法
    try {
        
        String habit = BeanUtils.getProperty(dog, "habits.smoking");
        System.out.println(habit); // tobacco
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 6、获得Map属性，适用于属性是Map的情况 ##

// 9、获得Map属性，适用于属性是Map的情况
    // 与 PropertyUtils 的 getMappedProperty 本质上是同一个方法
    try {
        
        String habit = BeanUtils.getMappedProperty(dog, "habits", "smoking");
        System.out.println(habit); // tobacco
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 7、获得嵌套属性，属性是对象的情况 ##

// 10、获得嵌套属性，属性是对象的情况
    // 与 PropertyUtils 的 getNestedProperty 本质上是同一个方法
    try {
        
        String name = BeanUtils.getNestedProperty(dog, "son.name");
        System.out.println(name); // 小狗的儿子dog1
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 8、获得属性值作为字符串返回 ##

// 11、获得属性值作为字符串返回
    try {
        
        String name = BeanUtils.getProperty(dog, "name");
        System.out.println(name); // 小狗
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

## 9、获得属性值作为字符串返回 ##

// 12、获得属性值作为字符串返回
    // 备注：暂未发现与 getProperty 的区别
    try {
        
        String age = BeanUtils.getSimpleProperty(dog, "age");
        System.out.println(age); // 2
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

# 三、转换对象 #

## 1、将Map转换成对象 ##

// 13、将Map转换成对象
    try {
        
        Dog dog3 = new Dog();
        BeanUtils.populate(dog3, PropertyUtils.describe(dog));
        System.out.println(dog3);
        System.out.println("================");
        // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null, habits=null),
        // hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
    } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
        throw new RuntimeException(e);
    }

# 四、设置属性值 #

## 1、设置属性值 ##

// 14、设置属性值
    try {
        
        BeanUtils.setProperty(dog, "name", "大狗子");
        System.out.println(dog.getName()); // 大狗子
    } catch (IllegalAccessException | InvocationTargetException e) {
        
        throw new RuntimeException(e);
    }

# 五、不知道有什么用的功能 #

## 1、对异常进行包装 ##

// 15、对异常进行包装 - TODO 不知何用
    NullPointerException nullPointerException = new NullPointerException("情况一");
    NullPointerException nullPointerException1 = new NullPointerException("情况二");
    boolean initCause = BeanUtils.initCause(nullPointerException, nullPointerException1);
    System.out.println(initCause); // true

## 2、创建缓存 ##

// 16、创建缓存 - TODO 不知何用
    Map<Object, Object> cache = BeanUtils.createCache();
    System.out.println(cache); // {}

## 3、getCacheFast ##

// 17、getCacheFast - TODO 不知何用
    boolean fast = BeanUtils.getCacheFast(cache);
    System.out.println(fast); // false

## 4、setCacheFast ##

// 18、setCacheFast - TODO 不知何用
    BeanUtils.setCacheFast(cache, true);

# 六、完整代码 #

package com.zibo.zibo2022.bean_utils.main;
    
    import com.zibo.zibo2022.bean_utils.entity.Dog;
    import org.apache.commons.beanutils.BeanUtils;
    import org.apache.commons.beanutils.PropertyUtils;
    
    import java.lang.reflect.InvocationTargetException;
    import java.util.Arrays;
    import java.util.List;
    import java.util.Map;
    
    /**
     * 很多方法与 PropertyUtils 重复
     */
    public class Main {
        
    
        public static void main(String[] args) {
        
            List<String> hobbies = Arrays.asList("swimming", "running", "sleeping");
            Map<String, String> habits = Map.of("drinking", "beer", "smoking", "tobacco");
            Dog littleDog = new Dog("小狗的儿子", 1, "黑色", null, null, null);
            Dog dog = new Dog("小狗", 2, "黄色", littleDog, hobbies, habits);
    
            // 1、克隆对象 - 浅克隆
            try {
        
                Dog cloneBean = (Dog) BeanUtils.cloneBean(dog);
                littleDog.setName("小狗的儿子cloneBean");
                System.out.println(cloneBean);
                // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子cloneBean, age=1, color=黑色, son=null, hobbies=null,
                // habits=null), hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
            } catch (IllegalAccessException | InstantiationException | InvocationTargetException |
                     NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 2、复制属性 - 浅复制
            try {
        
                Dog dog1 = new Dog();
                BeanUtils.copyProperties(dog1, dog);
                littleDog.setName("小狗的儿子dog1");
                System.out.println(dog1);
                // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null,
                // habits=null), hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
            } catch (IllegalAccessException | InvocationTargetException e) {
        
                throw new RuntimeException(e);
            }
    
            // 3、复制属性，相当于设置属性
            // 这就是设置属性，没看出来跟复制属性有什么关系
            try {
        
                Dog dog2 = new Dog();
                BeanUtils.copyProperty(dog2, "name", "dog2");
                System.out.println(dog2);
                // Dog(name=dog2, age=null, color=null, son=null, hobbies=null, habits=null)
            } catch (IllegalAccessException | InvocationTargetException e) {
        
                throw new RuntimeException(e);
            }
    
            // 4、描述 - 获取属性列表（含属性名和属性值）
            // 可借此实现判断一个类对象的所有属性是否都有值
            try {
        
                Map<String, String> map = BeanUtils.describe(dog);
                map.forEach((key, value) -> System.out.println(key + ":" + value));
                // habits:{drinking=beer, smoking=tobacco}
                // son:Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null, habits=null)
                // color:黄色
                // hobbies:swimming
                // name:小狗
                // age:2
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 5、返回指定属性的值，作为字符串数组返回
            try {
        
                String[] names = BeanUtils.getArrayProperty(dog, "name");
                System.out.println(Arrays.toString(names)); // [小狗]
                String[] hobbies1 = BeanUtils.getArrayProperty(dog, "hobbies");
                System.out.println(Arrays.toString(hobbies1)); // [swimming, running, sleeping]
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 6、获取指定索引属性值，适用于属性是list或者array的情况
            // 与 PropertyUtils 的 getIndexedProperty 本质上是同一个方法
            try {
        
                String name = BeanUtils.getIndexedProperty(dog, "hobbies[0]");
                System.out.println(name); // swimming
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 7、获取指定索引属性值，适用于属性是list或者array的情况
            // 与 PropertyUtils 的 getIndexedProperty 本质上是同一个方法
            try {
        
                String hobby = BeanUtils.getIndexedProperty(dog, "hobbies", 0);
                System.out.println(hobby); // swimming
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 8、获得Map属性，适用于属性是Map的情况
            // 与 PropertyUtils 的 getMappedProperty 本质上是同一个方法
            try {
        
                String habit = BeanUtils.getProperty(dog, "habits.smoking");
                System.out.println(habit); // tobacco
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 9、获得Map属性，适用于属性是Map的情况
            // 与 PropertyUtils 的 getMappedProperty 本质上是同一个方法
            try {
        
                String habit = BeanUtils.getMappedProperty(dog, "habits", "smoking");
                System.out.println(habit); // tobacco
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 10、获得嵌套属性，属性是对象的情况
            // 与 PropertyUtils 的 getNestedProperty 本质上是同一个方法
            try {
        
                String name = BeanUtils.getNestedProperty(dog, "son.name");
                System.out.println(name); // 小狗的儿子dog1
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 11、获得属性值作为字符串返回
            try {
        
                String name = BeanUtils.getProperty(dog, "name");
                System.out.println(name); // 小狗
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 12、获得属性值作为字符串返回
            // TODO 暂未发现与 getProperty 的区别
            try {
        
                String age = BeanUtils.getSimpleProperty(dog, "age");
                System.out.println(age); // 2
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 13、将Map转换成对象
            try {
        
                Dog dog3 = new Dog();
                BeanUtils.populate(dog3, PropertyUtils.describe(dog));
                System.out.println(dog3);
                // Dog(name=小狗, age=2, color=黄色, son=Dog(name=小狗的儿子dog1, age=1, color=黑色, son=null, hobbies=null, habits=null),
                // hobbies=[swimming, running, sleeping], habits={drinking=beer, smoking=tobacco})
            } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
        
                throw new RuntimeException(e);
            }
    
            // 14、设置属性值
            try {
        
                BeanUtils.setProperty(dog, "name", "大狗子");
                System.out.println(dog.getName()); // 大狗子
            } catch (IllegalAccessException | InvocationTargetException e) {
        
                throw new RuntimeException(e);
            }
    
            // 15、对异常进行包装 - TODO 不知何用
            NullPointerException nullPointerException = new NullPointerException("情况一");
            NullPointerException nullPointerException1 = new NullPointerException("情况二");
            boolean initCause = BeanUtils.initCause(nullPointerException, nullPointerException1);
            System.out.println(initCause); // true
    
            // 16、创建缓存 - TODO 不知何用
            Map<Object, Object> cache = BeanUtils.createCache();
            System.out.println(cache); // {}
    
            // 17、getCacheFast - TODO 不知何用
            boolean fast = BeanUtils.getCacheFast(cache);
            System.out.println(fast); // false
    
            // 18、setCacheFast - TODO 不知何用
            BeanUtils.setCacheFast(cache, true);
    
        }
    
    }