概述

BeanUtils 是 Apache commons组件的成员之一,主要用于简化JavaBean封装数据的操作
它可以给JavaBean封装一个字符串数据
将一个表单提交的所有数据封装到JavaBean中

JavaBean类

实现序列化接口
属性私有
提供set/get方法
提供无参构造

工具类的使用

导入第三方jar包
- commons-beanutils-1.8.3.jar
- commons-logging-1.1.1.jar

常用方法

BeanUtils类的方法
方法	作用
public static String getProperty(Object obj,String name)	获取obj对象的name变量的值
public static void setProperty(Object obj,String name,Object value)	将value的值,赋值给obj对象的name变量
public static void populate(Object obj, Map<String,String[]> properties)	将Map集合的值,赋值给obj对象（键为变量的名字，值为变量的值）

案例

案例1:测试getProperty方法

User.java

/**
 * @Title: User
 * @Description:标准的JavaBean类
 * @date 2018年7月21日
 */
public class User {

	private String id;

	private String username;

	private String password;

	public User() {
		super();
	}

	public User(String id, String username, String password) {
		super();
		this.id = id;
		this.username = username;
		this.password = password;
	}

	get/set方法...(必须有)

	@Override
	public String toString() {
		return "User [id=" + id + ", username=" + username + ", password=" + password + "]";
	}

}

TestBeanUtilsGetProperty.java

import org.apache.commons.beanutils.BeanUtils;

public class TestBeanUtilsGetProperty {

	public static void main(String[] args) throws Exception {

		User user = new User("it001","liuliu","123456");
		
		String id = BeanUtils.getProperty(user, "id");
		String username = BeanUtils.getProperty(user, "username");
		String password = BeanUtils.getProperty(user, "password");
		
		System.out.println(id+"\t"+username+"\t"+password);
		
	}
}

案例2:测试setProperty方法

import org.apache.commons.beanutils.BeanUtils;

public class TestBeanUtilsSetProperty {

	public static void main(String[] args) throws Exception {

		User user = new User();
		
		BeanUtils.setProperty(user, "id", "it001");
		BeanUtils.setProperty(user, "username", "lf");
		BeanUtils.setProperty(user, "password", "123456");
		
		System.out.println(user);
	}
}

案例3:测试

User.java

public class User {

	private String name;
	
	private String age;
	
	private String [] hobbies;

	public User() {
		super();
	}

	public User(String name, String age, String[] hobbies) {
		super();
		this.name = name;
		this.age = age;
		this.hobbies = hobbies;
	}

	public String getName() {
		return name;
	}

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

	public String getAge() {
		return age;
	}

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

	public String[] getHobbies() {
		return hobbies;
	}

	public void setHobbies(String[] hobbies) {
		this.hobbies = hobbies;
	}

	@Override
	public String toString() {
		return "User [name=" + name + ", age=" + age + ", hobbies=" + Arrays.toString(hobbies) + "]";
	}
	
}

TestBeanUtilsPopulate.java

import java.util.HashMap;

import org.apache.commons.beanutils.BeanUtils;

public class TestBeanUtilsPopulate {

	public static void main(String[] args) throws Exception {
		// 1.创建User对象
		User user = new User();
		// 2.创建集合
		HashMap<String, String[]> hm = new HashMap<String, String[]>();
		// 3.向集合中添加元素
		hm.put("name", new String[] { "张三" });
		hm.put("age", new String[] { "35" });
		hm.put("hobbies", new String[] { "抽烟", "喝酒", "烫头" });
		// 4.调用方法给对象赋值
		BeanUtils.populate(user, hm);
		// 5.打印
		System.out.println(user);

	}
}

案例3:自己封装一个工具类

MyBeanUtils.java

import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;

public class MyBeanUtils {

	public static Object populate(Class<?> clazz, Map<String, String[]> properties) {
		Object obj = null;
		try {
			// 创建类对象
			obj = clazz.newInstance();
			// 调用方法给对象赋值
			BeanUtils.populate(obj, properties);

		} catch (Exception e) {
			// 发生异常,直接挂掉
			// 把编译时异常转换成运行时异常
			throw new RuntimeException();
		}
		// 将赋值之后的对象返回
		return obj;
	}
}

TestMyBeanUtilsPopulate.java

import java.util.HashMap;

public class TestMyBeanUtilsPopulate {

	public static void main(String[] args) {
		// 1.创建集合
		HashMap<String, String[]> hm = new HashMap<String, String[]>();
		// 2.向集合中添加元素
		hm.put("name", new String[] { "张三" });
		hm.put("age", new String[] { "35" });
		hm.put("hobbies", new String[] { "抽烟", "喝酒", "烫头" });
		// 3.调用方法给对象赋值
		User user = (User) MyBeanUtils.populate(User.class, hm);
		// 4.打印
		System.out.println(user);

	}
}

案例4:将XML文件中的数据读取到对象中,并在控制台打印

data.xml

<?xml version="1.0" encoding="UTF-8"?>
 <beans>
    <bean className="pack1.User">
    	<property name="username" value="rose"></property>
    	<property name="password" value="123"></property>
    </bean>
    
    <bean className="pack2.Person">
       <property name="name" value="jack"></property>
       <property name="age" value="22"></property>
    </bean>
 </beans>

创建类
解析XML文件
将数据保存到对象中
打印结果

User.java

package pack1;

public class User {

	private String username;
	private String password;

	public User() {
		super();
	}

	public User(String username, String password) {
		super();
		this.username = username;
		this.password = password;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return "User [username=" + username + ", password=" + password + "]";
	}

}

Person.java

package pack2;

public class Person {

	private String name;
	private String age;

	public Person() {
		super();
	}

	public Person(String name, String age) {
		super();
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

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

	public String getAge() {
		return age;
	}

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

	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + "]";
	}

}

TestDemo.java

import java.util.List;

import org.apache.commons.beanutils.BeanUtils;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class TestDemo {

	public static void main(String[] args) throws Exception {
		// 1.解析XML文件
		// 1.1创建SAXReader对象
		SAXReader sr = new SAXReader();
		// 1.2将XML文件读取到内存
		Document document = sr.read("data.xml");
		// 1.3获取根元素(beans)
		Element rootElement = document.getRootElement();
		// 1.4获取beans子元素
		List<Element> elements = rootElement.elements();
		for (Element element : elements) {
			// 1.5获取bean的属性值
			String className = element.attributeValue("className");
			// 2.创建相关类的对象
			Class<?> clazz = Class.forName(className);
			Object obj = clazz.newInstance();
			// 3.给对象的变量赋值
			// 3.1获取bean的子元素property
			List<Element> property = element.elements();
			for (Element e : property) {
				// 3.2获取property属性name的值
				String name = e.attributeValue("name");
				// 3.3获取property属性value的值
				String value = e.attributeValue("value");
				// 3.3给name变量赋值成value
				BeanUtils.setProperty(obj, name, value);
			}
			// 4.打印对象
			System.out.println(obj);
		}
	}
}

输出结果:

BeanUtils工具类

概述

JavaBean类

工具类的使用

常用方法

案例

案例1:测试getProperty方法

案例2:测试setProperty方法

案例3:测试

案例3:自己封装一个工具类

案例4:将XML文件中的数据读取到对象中,并在控制台打印

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