org.xerial.util.bean
Class BeanUtil

java.lang.Object
  org.xerial.util.bean.BeanUtil

public class BeanUtil
extends Object

BeanUtil class supports data binding between JSON data and a bean class. A bean class must have the followings: - A public default (no argument) constructor - To bind data object to a class, there must be public getter/seter methods in the target class, prefixd with get/set. -- Allowable data classes are: ---- primitive types: int/Integer, double/Double, float/Float, boolean/Boolean, String ---- bean classes ---- Collection of allowable data classes. e.g. List, Set, etc. ---- Map with key and value classes. key and value also must be allowable classes. ------ to bind JSON data to map object, putSomething() method is requried. See the following description. For example, a Person class with integer id and string name values must have public int getId() and public String getName(), and public void setId(int id) and public void setName(String name) methods. Usage Example. class Person { int id; String name; public Person(); public Person(int id, String name) { this.id = id; this.name = name; } public int getId() { return id; } public String getName() { return name; } public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } } Person p1 = new Person(1, "leo"); String json = BeanUtil.toJSON(p1); // it will give a json string { "id" : 1, "name" : "leo"} Person p2 = new Person() // empty data BeanUtil.populate(p2, json); // fill p2 with a give json data // p2.id = 1, p2.name = "leo" In the GWT (Google Web Toolkit) of the current version (1.3.3, Mar 2007), the generics feature of Jave (since JDK1.5) cannot be used within the client Java codes. This is a problematic since GWT cannot compile the following method: void setPersonList(List personList) { this.personList = personList; } So you have to change the argument of the avobe method as: void setPersonList(List personList) { ... } But, with this setter method, we have no information about the element type contained in the List class. So given a JSON data, e.g.,{ "personList" : [ {"id":1, "name":"leo"}, {"id":2, "name":"taro"}] }, BeanUtil class cannot instantiate any Person classes. To resolve this problem, BeanUtil supports data binding via adder methods. For example, instead of using setters, by using the follwing adder, you can load several Person class data as a collection: void addPersonList(Person person) { personList.add(person); } Note that, in order to use adders correctly, the target of an adder, that is, a collection class, must be initialized before the invocation of the adder. For example, public PersonList { Vector personList = new Vector(); // it must be initialized. public PersonList() {} void addPersonList(Person p) { personList.add(p); } public getPersonList() { return personList; } } Otherwise, BeanUtil.populate method cuases NullPointerException or some other undisired effects. In BeanUtil, a setter method, whose argument has no generic type parameter, e.g., public void setList(List l) never be used to bind JSON data to a class instance. In order to use a Bean class with Map objects, you must define public Map getSomething() and public void putSomething(KeyType key, ValueType value) methods, since BeanUtil learns class types K, V from the putSomething(K key, V value) methods. If a method public void setSomething(Map map) exists, BeanUtil simply ignores it. The following is an example of a bean class with Map object. public MapBean { Map entry = new TreeMap(); public MapBean(){} public void putEntry(Key key, Value v) { entry.put(key, value); } public Map getEntry() { return entry; } }

Author:

leo

Method Summary

static Object	createBeanFromJSON(Class beanType, Reader jsonReader)
static Object	createBeanFromJSON(Class beanType, String json)
static Object	createInstance(Class c)
static <E> E	createXMLBean(Class<E> valueType, Reader xmlReader)
static Object	createXMLBean(Class valueType, String xmlData)
static BeanBinderSet	getBeanLoadRule(Class c)
static BeanBinderSet	getBeanOutputRule(Class c)
static Pair<Class,Class>	getGenericMapTypesOfMethodArgument(Method method, int argIndex)
static ParameterizedType	getParameterizedType(Type t)
static ParameterizedType	getParentParameterizedType(Type t, Class target)
static JSONValue	getValue(Object bean, String propertyName)
static org.xerial.util.bean.BinderSet	inspectSetter(Class beanClass)
static <T> void	loadJSON(Reader jsonReader, Class<T> beanClass, BeanHandler<T> beanHandler)
protected static void	populateBean(Object bean, JSONArray jsonArray)
static void	populateBean(Object bean, JSONObject json) fill a bean class with a given JSONObject data
protected static void	populateBeanWithJSON(Object bean, Object jsonValue)
static void	populateBeanWithJSON(Object bean, Reader jsonReader)
static void	populateBeanWithJSON(Object bean, String jsonData) fill a bean class with a given JSON data
static void	populateBeanWithMap(Object bean, Map<?,?> map)
static void	populateBeanWithXML(Object bean, Element xmlElement)
static void	populateBeanWithXML(Object bean, Reader xmlReader)
static void	populateBeanWithXML(Object bean, String xmlData)
static String	toJSON(Object bean)
static String	toJSONFromResultSet(ResultSet resultSet)
static JSONObject	toJSONObject(Collection collection)
static JSONObject	toJSONObject(Object bean)
static String	toXML(String tagName, Object bean)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getBeanOutputRule

public static BeanBinderSet getBeanOutputRule(Class c)
                                       throws BeanException

Throws:

BeanException

getBeanLoadRule

public static BeanBinderSet getBeanLoadRule(Class c)
                                     throws BeanException

Throws:

BeanException

inspectSetter

public static org.xerial.util.bean.BinderSet inspectSetter(Class beanClass)
                                                    throws BeanException

Throws:

BeanException

getGenericMapTypesOfMethodArgument

public static Pair<Class,Class> getGenericMapTypesOfMethodArgument(Method method,
                                                                   int argIndex)

getParameterizedType

public static ParameterizedType getParameterizedType(Type t)

getParentParameterizedType

public static ParameterizedType getParentParameterizedType(Type t,
                                                           Class target)

toXML

public static String toXML(String tagName,
                           Object bean)
                    throws BeanException

Throws:

BeanException

toJSONFromResultSet

public static String toJSONFromResultSet(ResultSet resultSet)
                                  throws SQLException

Throws:

SQLException

toJSON

public static String toJSON(Object bean)
                     throws BeanException

Throws:

BeanException

toJSONObject

public static JSONObject toJSONObject(Object bean)
                               throws BeanException

Throws:

BeanException

toJSONObject

public static JSONObject toJSONObject(Collection collection)
                               throws BeanException

Throws:

BeanException

getValue

public static JSONValue getValue(Object bean,
                                 String propertyName)
                          throws BeanException

Throws:

BeanException

populateBeanWithMap

public static void populateBeanWithMap(Object bean,
                                       Map<?,?> map)
                                throws XerialException

Throws:

XerialException

populateBeanWithXML

public static void populateBeanWithXML(Object bean,
                                       Reader xmlReader)
                                throws BeanException

Throws:

BeanException

populateBeanWithXML

public static void populateBeanWithXML(Object bean,
                                       String xmlData)
                                throws BeanException

Throws:

BeanException

populateBeanWithXML

public static void populateBeanWithXML(Object bean,
                                       Element xmlElement)
                                throws BeanException

Throws:

BeanException

populateBeanWithJSON

public static void populateBeanWithJSON(Object bean,
                                        Reader jsonReader)
                                 throws BeanException,
                                        IOException

Throws:

BeanException

IOException

populateBeanWithJSON

public static void populateBeanWithJSON(Object bean,
                                        String jsonData)
                                 throws BeanException

fill a bean class with a given JSON data

Parameters:

bean - a bean class

jsonData - a string representation of a JSON data

Throws:

InvalidJSONDataException - when the input json data is invalid (cannot interpret as a JSON object)

InvalidBeanException - when a bean class has invalid structure

BeanException

populateBean

public static void populateBean(Object bean,
                                JSONObject json)
                         throws BeanException

fill a bean class with a given JSONObject data

Parameters:

bean - a bean class

json - a JSONOBject

Throws:

InvalidBeanException

InvalidJSONDataException

IllegalAccessException

InstantiationException

BeanException

populateBean

protected static void populateBean(Object bean,
                                   JSONArray jsonArray)
                            throws BeanException

Throws:

BeanException

populateBeanWithJSON

protected static void populateBeanWithJSON(Object bean,
                                           Object jsonValue)
                                    throws BeanException

Throws:

BeanException

createBeanFromJSON

public static Object createBeanFromJSON(Class beanType,
                                        Reader jsonReader)
                                 throws IOException,
                                        BeanException

Throws:

IOException

BeanException

createBeanFromJSON

public static Object createBeanFromJSON(Class beanType,
                                        String json)
                                 throws BeanException

Throws:

BeanException

createInstance

public static Object createInstance(Class c)
                             throws BeanException

Throws:

BeanException

createXMLBean

public static <E> E createXMLBean(Class<E> valueType,
                                  Reader xmlReader)
                       throws BeanException,
                              IOException,
                              BeanException

Throws:

BeanException

IOException

createXMLBean

public static Object createXMLBean(Class valueType,
                                   String xmlData)
                            throws BeanException

Throws:

BeanException

loadJSON

public static <T> void loadJSON(Reader jsonReader,
                                Class<T> beanClass,
                                BeanHandler<T> beanHandler)
                     throws IOException,
                            BeanException

Throws:

IOException

BeanException