内省—beanutils工具包

Apache组织开发了一套用于操作JavaBean的API，这套API考虑到了很多实际开发中的应用场景，因此在实际开发中很多程序员使用这套API操作JavaBean，以简化程序代码的编写。

BeanUtils的作用：

1）支持String到8种基本数据类型的转换；

2）其他引用数据类型都需要注册转换器：ConvertUtils.register(Converter,Class);

public class Person {

    private String name;

    private String password;

    private Integer age;

    private Date birthday;

    getter/setter

}

 

采用beanutils设置属性

@Test

public void test1() throws Exception {

    Person person = new Person();

    BeanUtils.setProperty(person, "name", "zhangsan");

    System.out.println(person.getName());

}

 

采用beanutils拷贝对象的属性(基本类型)

@Test

public void test2() throws Exception {

    String name = "zhangsan";

    String password = "123";

    String age = "34";



    Person person = new Person();

    BeanUtils.setProperty(person, "name", name);

    BeanUtils.setProperty(person, "password", password);

    BeanUtils.setProperty(person, "age", age);// 自动类型转换，只支持8种基本数据类型



    System.out.println(person);

}

 

采用beanutils拷贝对象的属性(非基本类型)

@Test

public void test3() throws Exception {

    String name = "zhangsan";

    String password = "123";

    String age = "34";

    String birthday = "1980-09-05";



    Person person = new Person();

    BeanUtils.setProperty(person, "name", name);

    BeanUtils.setProperty(person, "password", password);

    BeanUtils.setProperty(person, "age", age);// 自动类型转换

    BeanUtils.setProperty(person, "birthday", birthday); // 类型转换失败

    System.out.println(person);

}

为让Date能够赋值到birthday属性上，我们给beanutils注册一个日期转换器。

改进代码如下：

@Test

public void test4() throws Exception {

    String name = "zhangsan";

    String password = "123";

    String age = "34";

    String birthday = "1980-09-05";



    ConvertUtils.register(new Converter() { @Override public Object convert(Class type, Object value) { if (value == null) { return null; } if (!(value instanceof String)) { throw new ConversionException("只支持String类型的转换!"); } String str = (String) value; if (null == str || "".equals(str.trim())) { return null; } SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); try { return format.parse(str); } catch (ParseException e) { throw new ConversionException(e); } } }, Date.class);



    Person person = new Person();

    BeanUtils.setProperty(person, "name", name);

    BeanUtils.setProperty(person, "password", password);

    BeanUtils.setProperty(person, "age", age);// 自动类型转换

    BeanUtils.setProperty(person, "birthday", birthday); 

    System.out.println(person);

}

 

采用beanutils自带的日期类型转换器

@Test

public void test5() throws Exception {

    String name = "zhangsan";

    String password = "123";

    String age = "34";

    String birthday = "1980-09-05";



    ConvertUtils.register(new DateLocaleConverter(), Date.class);



    Person person = new Person();

    BeanUtils.setProperty(person, "name", name);

    BeanUtils.setProperty(person, "password", password);

    BeanUtils.setProperty(person, "age", age);// 自动类型转换

    BeanUtils.setProperty(person, "birthday", birthday); 

    System.out.println(person);

}

 

收集数据到map中，并通过beanutils拷贝到指定的对象中去

@Test

public void test6() throws Exception {



    Person person = new Person();



    ConvertUtils.register(new DateLocaleConverter(), Date.class);



    Map<String, Object> map = new HashMap<String, Object>();

    map.put("name", "aa");

    map.put("password", "123");

    map.put("age", 23);

    map.put("birthday", "1980-09-05");



    // 用map集合中的值，填充bean的属性，

    // 注意：属性名称必须要一致

 BeanUtils.populate(person, map);



    System.out.println(person);

}