Java反射通过Getter方法获取对象VO的属性值过程解析

这篇⽂章主要介绍了Java反射通过Getter⽅法获取对象VO的属性值过程解析,⽂中通过⽰例代码介绍的⾮常详细，对⼤家的学习或者⼯作具有⼀定的参考学习价值,需要的朋友可以参考下有时候，需要动态获取对象的属性值。

⽐如，给你⼀个List，要你遍历这个List的对象的属性，⽽这个List⾥的对象并不固定。⽐如，这次User，下次可能是Company。

e.g. 这次我需要做⼀个Excel导出的⼯具类，导出的批量数据是以List类型传⼊的，List⾥的对象⾃然每次都不同，这取决于需要导出什么信息。

为了使⽤⽅便，将对象的属性名与属性值存于Map当中，使⽤时就可以直接遍历Map了。此次的思路是通过反射和Getter⽅法取得值，然后记录在⼀个Map当中。Kick start...

将对象的属性名与属性值存于Map当中，以key，value的形式存在，⽽value并不希望以单⼀类型（如String）存在（因为涉及多种类型），所以⽤⼀个FieldEntity的⾃定义类（此类包含属性名，属性值，属性值类型 等属性）FieldEntity

package com.nicchagil.util.fields;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.HashMap;import java.util.Map;public class FieldsCollector {

public static Map getFileds(Object object)

throws SecurityException, IllegalArgumentException, NoSuchMethodException, IllegalAccessException, InvocationTargetException { Class clazz = object.getClass();

Field[] fields = clazz.getDeclaredFields();

Map map = new HashMap ();

for (int i = 0; i < fields.length; i++) {

Object resultObject = invokeMethod(object, fields[i].getName(), null);

map.put(fields[i].getName(), new FieldEntity(fields[i].getName(), resultObject, fields[i].getType())); }

return map; }

public static Object invokeMethod(Object owner, String fieldname,

Object[] args) throws SecurityException, NoSuchMethodException,

IllegalArgumentException, IllegalAccessException, InvocationTargetException { Class ownerClass = owner.getClass();

Method method = null;

method = ownerClass.getMethod(GetterUtil.toGetter(fieldname)); Object object = null;

object = method.invoke(owner); return object; }}

主类，通过这个类的静态⽅法获取结果MapFieldsCollector

package com.nicchagil.util.fields;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.HashMap;import java.util.Map;public class FieldsCollector {

public static Map getFileds(Object object)

throws SecurityException, IllegalArgumentException, NoSuchMethodException, IllegalAccessException, InvocationTargetException { Class clazz = object.getClass();

Field[] fields = clazz.getDeclaredFields();

Map map = new HashMap ();

for (int i = 0; i < fields.length; i++) {

Object resultObject = invokeMethod(object, fields[i].getName(), null);

map.put(fields[i].getName(), new FieldEntity(fields[i].getName(), resultObject, fields[i].getType())); }

return map; }

public static Object invokeMethod(Object owner, String fieldname,

Object[] args) throws SecurityException, NoSuchMethodException,

IllegalArgumentException, IllegalAccessException, InvocationTargetException { Class ownerClass = owner.getClass();

Method method = null;

method = ownerClass.getMethod(GetterUtil.toGetter(fieldname)); Object object = null;

object = method.invoke(owner); return object; }}

为了代码清楚些，将⼀些⼯具⽅法独⽴⼀下，如field name到getter name的转换⽅法GetterUtil

package com.nicchagil.util.fields;

public class GetterUtil { /**

* Get getter method name by field name * @param fieldname * @return */

public static String toGetter(String fieldname) {

if (fieldname == null || fieldname.length() == 0) { return null; }

/* If the second char is upper, make 'get' + field name as getter name. For example, eBlog -> geteBlog */ if (fieldname.length() > 2) {

String second = fieldname.substring(1, 2); if (second.equals(second.toUpperCase())) {

return new StringBuffer(\"get\").append(fieldname).toString(); } }

/* Common situation */

fieldname = new StringBuffer(\"get\").append(fieldname.substring(0, 1).toUpperCase()) .append(fieldname.substring(1)).toString();

return fieldname; }

}

⼤功告成

现在，写个VO作为模拟数据User

import java.util.Date;public class User {

private String username; private String password; private String eBlog;

private Date registrationDate;

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; }

public String geteBlog() { return eBlog; }

public void seteBlog(String eBlog) { this.eBlog = eBlog; }

public Date getRegistrationDate() { return registrationDate; }

public void setRegistrationDate(Date registrationDate) { this.registrationDate = registrationDate; }}

最后，测试类，此类将直接调⽤FieldsCollector~~Call

import java.util.Date;import java.util.Map;

import com.nicchagil.util.fields.FieldEntity;import com.nicchagil.util.fields.FieldsCollector;

public class Call {

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

User user = new User();

user.setUsername(\"user109\"); user.setPassword(\"pwd109\");

user.seteBlog(\"http://www.cnblogs.com/nick-huang/\"); user.setRegistrationDate(new Date());

Map map = FieldsCollector.getFileds(user); System.out.println(map);

}}

Oh year， 成功了~~~

以上就是本⽂的全部内容，希望对⼤家的学习有所帮助，也希望⼤家多多⽀持。