Java内省之第三方包BeanUtils

Java自带了一个内省的API，但是在实际项目中经常使用一个更为强大的第三方包：

Apache的BeanUtils组件。下面先给出官方的下载链接。

https://commons.apache.org/proper/commons-beanutils/download_beanutils.cgi（2016-05-22:commons-beanutils-1.9.2-bin.zip）

同时，beanutils依赖于另外一个第三方包：commons-logging，下面是链接地址.

https://commons.apache.org/proper/commons-logging/download_logging.cgi  (2016-05-22:commons-logging-1.2-bin.zip)

关于两个日志的比较与说明，参链接：http://blog.csdn.net/courage89/article/details/29649801

以下给出简单的使用Demo:测试前首先下载好BeanUtils的jar和logging的jar并引入到项目中。

JavaBean:

package com.rt.gwq.introspector;

public class Person {
    
    private String name ;
    private String password ;
    private int age ;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
}

 BeanUtils Demo:

package com.rt.gwq.introspector;

import java.lang.reflect.InvocationTargetException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.util.Date;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConversionException;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;
import org.junit.Test;

public class Demo_BeanUtils {
    
    /**
     * BeanUtils 使用Deom 存取基本数据类型的属性
     * @throws Exception
     */
    @Test
    public void test1() throws Exception{
        
        Person p = new Person();
        BeanUtils.setProperty(p, "age",23);
        
        String age = BeanUtils.getProperty(p, "age");
        
        System.out.println(age);
    }
    
    /**
     * 转换器：BeanUtils String转换时间示例
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     * @throws NoSuchMethodException
     * @throws ParseException 
     */
    @Test
    public void test2() throws IllegalAccessException, InvocationTargetException, NoSuchMethodException, ParseException{
        
        Person p = new Person();
        String date = "1999-01-01";
        
        //注册转换器
        ConvertUtils.register(new Converter() {
            
            @Override
            public Object convert(Class type, Object value) {
                String str = (String) value;
                //为null
                if(value==null){
                    return null;
                }
                //空字符串
                if(str.toString().trim()==""){
                    return null;
                }
                //飞字符串对象
                if(!(value instanceof String)){
                    throw new ConversionException("只支持String类型");
                }
                //装换为时间格式
                SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd");
                try {
                    return sf.parse(str);
                } catch (ParseException e) {
                    throw new RuntimeException(e);
                }
                
            }
        }, Date.class);
        
        //存取值
        BeanUtils.setProperty(p, "birthday", date);
        Date d = p.getBirthday();
        //验证
        System.out.println(d.toLocaleString());
        
    }

}