? ? ? ?commons-beanutils是Apache提供的一個用于操作JAVA bean的工具包熙含。里面提供了各種各樣的工具類禀综，讓我們可以很方便的對bean對象的屬性進行各種操作。

一 commons-beanutils依賴

? ? ? ?pom方式的引入(maven項目)奠伪。

        <!-- https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils -->
        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.4</version>
        </dependency>

二 commons-beanutils的使用

? ? ? ?關于commons-beanutils的使用主要是熟悉commons-beanutils庫里面MethodUtils掂墓、ConstructorUtils、PropertyUtils打掘、BeanUtils华畏、ConvertUtils的使用鹏秋。

2.1 MethodUtils

? ? ? ?MethodUtils通過反射對對象的方法做各種各樣的操作。

? ? ? ?MethodUtils提供的一些靜態(tài)方法：

? ? ? ?因為MethodUtils里面的方法都比較簡單侣夷，所以我們就不給出例子了。

2.2 ConstructorUtils

? ? ? ?ConstructorUtils通過反射對對象的構造方法做各種操作仑乌。

? ? ? ?ConstructorUtils提供的靜態(tài)方法：

? ? ? ?因為ConstructorUtils里面的方法都比較簡單百拓，所以我們就不給出例子了。

2.3 PropertyUtils

? ? ? ?PropertyUtils通過反射對對象的屬性做各種操作晰甚。

? ? ? ?PropertyUtils提供的靜態(tài)方法：

? ? ? ?PropertyUtils的使用帝火，如下實例。

public class PropertyUtilsTest {

    public static class Address {
        private String email;

        public Address(String email) {
            this.email = email;
        }

        public String getEmail() {
            return email;
        }

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

    public static class UserInfo {
        private String userName;
        private int age;
        private Address address;
        private List<String> friendsNames;
        private Map<String, String> tag;

        UserInfo(String userName, int age, Address address, List<String> friendsNames, Map<String, String> tag) {
            this.userName = userName;
            this.age = age;
            this.address = address;
            this.friendsNames = friendsNames;
            this.tag = tag;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public List<String> getFriendsNames() {
            return friendsNames;
        }

        public void setFriendsNames(List<String> friendsNames) {
            this.friendsNames = friendsNames;
        }

        public Map<String, String> getTag() {
            return tag;
        }

        public void setTag(Map<String, String> tag) {
            this.tag = tag;
        }

        public Address getAddress() {
            return address;
        }

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

    @Test
    public void test() {
        List<String> friendList = Lists.newArrayList("張三", "李四");
        Map<String, String> tag = Maps.newHashMap();
        tag.put("key1", "value1");
        tag.put("key2", "value2");
        UserInfo userInfo = new UserInfo("tuacy", 18, new Address("1@qq.com"), friendList, tag);
        try {
            Map<String, Object> propertyMap = PropertyUtils.describe(userInfo);
            Object friend0 = PropertyUtils.getIndexedProperty(userInfo, "friendsNames[0]"); // 張三
            Object friend0Temp = PropertyUtils.getIndexedProperty(userInfo, "friendsNames", 0); // 張三
            Object mapperProperty = PropertyUtils.getMappedProperty(userInfo, "tag(key1)"); // value1
            Object mapperPropertyTemp = PropertyUtils.getMappedProperty(userInfo, "tag", "key1"); // value1
            Object nestedProperty = PropertyUtils.getNestedProperty(userInfo, "address.email"); // 1@qq.com
            Object name = PropertyUtils.getProperty(userInfo, "userName"); // tuacy
            PropertyDescriptor propertyDescriptor = PropertyUtils.getPropertyDescriptor(userInfo, "userName"); // PropertyDescriptor是對屬性的一個封裝
            PropertyDescriptor[] propertyDescriptors = PropertyUtils.getPropertyDescriptors(userInfo); // 獲取所有的屬性
            Class<?> classType = PropertyUtils.getPropertyType(userInfo, "address"); // 獲取屬性的類型Address
            Method getMethod = PropertyUtils.getReadMethod(PropertyUtils.getPropertyDescriptor(userInfo, "userName")); // getUserName()方法
            Object simpleProperty = PropertyUtils.getSimpleProperty(userInfo, "userName");
            Method setMethod = PropertyUtils.getWriteMethod(PropertyUtils.getPropertyDescriptor(userInfo, "userName")); // setUserName()方法
            boolean isReadable = PropertyUtils.isReadable(userInfo, "userName"); // true
            boolean isWriteable = PropertyUtils.isWriteable(userInfo, "userName"); // true
            PropertyUtils.setIndexedProperty(userInfo, "friendsNames[0]", "張三第一次修改"); // 修改friendsNames第一個元素
            PropertyUtils.setIndexedProperty(userInfo, "friendsNames", 0, "張三第二次修改"); // 修改friendsNames第一個元素
            PropertyUtils.setMappedProperty(userInfo, "tag(key1)", "value1第一次修改"); // 修改tag key為key1的值
            PropertyUtils.setMappedProperty(userInfo, "tag", "key1", "value1第二次修改"); // 修改tag key為key1的值
            PropertyUtils.setNestedProperty(userInfo, "address.email", "1007@qq.com"); // 修改address屬性對象對應的email屬性
            PropertyUtils.setProperty(userInfo, "userName", "tuacy0"); // 修改userName對應的屬性值
            PropertyUtils.setSimpleProperty(userInfo, "age", 19); // 修改age對應的屬性值
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

2.4 BeanUtils

? ? ? ?BeanUtils通過反射提供了Bean對象的一些便捷操作方法购公。

? ? ? ?BeanUtils提供的靜態(tài)方法：

? ? ? ?BeanUtils的使用：

public class BeanUtilsTest {

    public static class Address {
        private String email;

        public Address(String email) {
            this.email = email;
        }

        public String getEmail() {
            return email;
        }

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

    public static class UserInfo {
        private String userName;
        private int age;
        private Address address;
        private List<String> friendsNames;
        private Map<String, String> tag;

        public UserInfo() {

        }

        public UserInfo(String userName, int age, Address address, List<String> friendsNames, Map<String, String> tag) {
            this.userName = userName;
            this.age = age;
            this.address = address;
            this.friendsNames = friendsNames;
            this.tag = tag;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        public List<String> getFriendsNames() {
            return friendsNames;
        }

        public void setFriendsNames(List<String> friendsNames) {
            this.friendsNames = friendsNames;
        }

        public Map<String, String> getTag() {
            return tag;
        }

        public void setTag(Map<String, String> tag) {
            this.tag = tag;
        }

        public Address getAddress() {
            return address;
        }

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

    @Test
    public void test() {
        List<String> friendList = Lists.newArrayList("張三", "李四");
        Map<String, String> tag = Maps.newHashMap();
        tag.put("key1", "value1");
        tag.put("key2", "value2");
        UserInfo userInfo = new UserInfo("tuacy", 18, new Address("1@qq.com"), friendList, tag);
        try {
            Object voClone = BeanUtils.cloneBean(userInfo);
            UserInfo userInfo1 = new UserInfo();
            BeanUtils.copyProperties(userInfo1, userInfo);
            BeanUtils.copyProperty(userInfo1, "userName", "user1");
            Map<String, String> map = BeanUtils.describe(userInfo); // 獲取所有的屬性名字和屬性對應的值比庄，注意這里值都會轉換成String
            String[] arrays =  BeanUtils.getArrayProperty(userInfo, "friendsNames"); // friendsNames數(shù)組轉換成數(shù)組
            Object item = BeanUtils.getIndexedProperty(userInfo, "friendsNames[0]"); // 張三
            Object itemItem = BeanUtils.getIndexedProperty(userInfo, "friendsNames", 0); // 張三
            Object value = BeanUtils.getMappedProperty(userInfo, "tag(key1)"); // value1
            Object valueValue = BeanUtils.getMappedProperty(userInfo, "tag", "key1"); // value1
            Object email = BeanUtils.getNestedProperty(userInfo, "address.email"); // 1@qq.com
            String userName = BeanUtils.getProperty(userInfo, "userName"); // tuacy
            String userName0 = BeanUtils.getSimpleProperty(userInfo, "userName"); // tuacy
            UserInfo userInfo2 = new UserInfo();
            BeanUtils.populate(userInfo2, PropertyUtils.describe(userInfo)); // map轉換成對象
            BeanUtils.setProperty(userInfo2, "userName", "tuacy0"); // map轉換成對象
            NullPointerException nullPointerException = new NullPointerException("情況一");
            NullPointerException nullPointerException1 = new NullPointerException("情況二");
            BeanUtils.initCause(nullPointerException, nullPointerException1); // map轉換成對象
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

2.5 ConvertUtils

? ? ? ?ConvertUtils提供了數(shù)據(jù)類型相互轉換的一些方法。

? ? ? ?ConvertUtils靜態(tài)方法介紹：

? ? ? ?ConvertUtils的使用乏盐。

public class ConvertUtilsTest {


    @Test
    public void test() {
        try {
            // 注冊一個Date轉換器佳窑，把字符串轉換為Date
            ConvertUtils.register(new Converter() {
                @Override
                public <T> T convert(Class<T> type, Object value) {
                    try {
                        return (T) new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse((String) value);
                    } catch (ParseException e) {
                        return null;
                    }
                }
            }, Date.class);
            System.out.println(ConvertUtils.convert("2019-10-28 15:30:00", Date.class));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}