21--JDK new features 5-apache developed introspection API

1. The way of introspection developed by Apache

Sun's introspection API is too cumbersome, so the Apache organization has developed a set of simple, Easy-to-use API action Bean properties, combined with a lot of actual development scenarios--beanutils

L Beanutils Tool Kit Common classes:

beanutils

propertyutils

Convertutils.regsiter (Converter convert, Class clazz)

• Custom Converters

Specific case Analysis:

Javabean:person

packageCom.java.Bean;

import java.util.Date;

Publicclass person {

Private String name;

Privateintage;

Private Date birthday;

Public String GetName () {

return name;

}

publicvoid setname (String name) {

this. Name = name;

}

publicint getage () {

return age;

}

publicvoid setage (int age) {

this. Age = age;

}

Public Date Getbirthday () {

return birthday;

}

publicvoid setbirthday (Date birthday) {

this. Birthday = Birthday;

}

Public String Getabc () {

Returnnull;

}

}

Main code:

Package Com.java.Bean;

Import java.lang.reflect.InvocationTargetException;

Import java.text.ParseException;

Import Java.text.SimpleDateFormat;

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;

Importorg.apache.commons.beanutils.locale.converters.DateLocaleConverter;

Import Org.junit.Test;

public class Beanutil {

@Test//Direct test method to debug a program

Public Voidtest1 () throws Illegalaccessexception, InvocationTargetException {

Person P =new person ();

Beanutils.setproperty (P, "name", "John");

System.out.println (P.getname ());

}

@Test

Beanutils tools can automatically convert types to basic data types, but special types such as data cannot be converted

Public Voidtest2 () throws Illegalaccessexception, InvocationTargetException {

Person P =new person ();

An anonymous class is used in a custom converter, and invoking convert is an excuse not to instantiate it directly, but to use its instantiated object, you can only anonymously class the method, or create a class and implement the interface as before

Convertutils.register (Newconverter () {

@Override

Publicobject convert (Class type, Object value) {

if (value==null) {

Returnnull;

}

if (!) ( Valueinstanceof String)) {

Thrownew conversionexception ("Convert only String type ... ");

}

String s= (string) value;

/*if (S.trim (). Equals ("")) {

Returnnull;

}*/

SIMPLEDATEFORMATSDF = new SimpleDateFormat ("Yyyy-mm-dd hh:mm:ss");

try {

Dated = Sdf.parse (s);

Returnd;

catch (ParseException e) {

Thrownew conversionexception ("Conversion error ...) ");

}

}

},date.class);

String name = "Dick";

String age = "21";

Stringbirthday = "1992-01-01 02:01:28";

Beanutils.setproperty (P, "name", name);

Beanutils.setproperty (P, ' age ', age);

Beanutils.setproperty (P, "Birthday", birthday);

System.out.println (P.getname () + "..." +p.getage () + "..." +p.getbirthday (). toLocaleString ());

There will be an error: Org.apache.commons.beanutils.ConversionException:DateConverter does not support default String to ' Date ' Conversion.

Then you need to customize a converter

}

Beanutils to the provided conversion class

@Test

Public Voidtest3 () throws Illegalaccessexception, InvocationTargetException {

Convertutils.register (Newdatelocaleconverter (), date.class);

Person P =new person ();

Stringbirthday = "1992-01-10"; Beanutils's own converter has bugs, and when you enter a null value of the date will be wrong, so the actual development of the use of their own definition of the converter.

Beanutils.setproperty (P, "Birthday", birthday);

System.out.println (P.getbirthday ());

In actual development, a string string like the one used above is a form that is filled out by Web server client users

}

}