Java的反射体制,是指在JVM运行环境下,对类进行动态讲解的一种方式。和我们常规的new对象不同;new Object属于硬编码,而反射更像是一种在运行时动态编写的代码块。
可参考:通过Java反射机制,动态给对象属性赋值,并获取属性值
- package com.matol;
-
- import java.lang.reflect.Field;
- import java.lang.reflect.Method;
- import java.text.SimpleDateFormat;
- import java.util.Date;
- import java.util.HashMap;
- import java.util.Locale;
- import java.util.Map;
- import java.util.Map.Entry;
-
- /*
- * 通过Java反射机制,动态给对象属性赋值,并获取属性值
- */
- public class ClassRefUtil {
-
- /**
- * @param args
- */
- public static void main(String[] args) {
- Map<String, String> valMap = new HashMap<String, String>();
- valMap.put("userName", "michael");
- valMap.put("age", "27");
- valMap.put("height", "173.5");
- valMap.put("date", "2010-10-24");
- valMap.put("times", "1287932898276");
- valMap.put("flag", "false");
-
- ChildInfo rl = new ChildInfo();
- System.out.println("通过反射赋值.");
- PublicUtil.setFieldValue(rl, valMap);
-
- System.out.println("通过反射取值:");
- int i = 0;
- Map<String, String> fieldValMap = PublicUtil.getFieldValueMap(rl);
- for (Entry<String, String> entry : fieldValMap.entrySet()) {
- i++;
- System.out.println("[字段 "+i+"] ["+entry.getKey()+"] --- [" + entry.getValue()+"]");
- }
- }
-
-
- /**
- * 取Bean的属性和值对应关系的MAP
- * @param bean
- * @return Map
- */
- public static Map<String, String> getFieldValueMap(Object bean) {
- Class<?> cls = bean.getClass();
- Map<String, String> valueMap = new HashMap<String, String>();
- // 取出bean里的所有方法
- Method[] methods = cls.getDeclaredMethods();
- Field[] fields = cls.getDeclaredFields();
-
- for (Field field : fields) {
- try {
- String fieldType = field.getType().getSimpleName();
- String fieldGetName = parGetName(field.getName());
- if (!checkGetMet(methods, fieldGetName)) {
- continue;
- }
- Method fieldGetMet = cls.getMethod(fieldGetName, new Class[] {});
- Object fieldVal = fieldGetMet.invoke(bean, new Object[] {});
- String result = null;
- if ("Date".equals(fieldType)) {
- result = fmtDate((Date) fieldVal);
- } else {
- if (null != fieldVal) {
- result = String.valueOf(fieldVal);
- }
- }
- valueMap.put(field.getName(), result);
- } catch (Exception e) {
- continue;
- }
- }
- return valueMap;
-
- }
-
- /**
- * set属性的值到Bean
- * @param bean
- * @param valMap
- */
- public static void setFieldValue(Object bean, Map<String, String> valMap) {
- Class<?> cls = bean.getClass();
- // 取出bean里的所有方法
- Method[] methods = cls.getDeclaredMethods();
- Field[] fields = cls.getDeclaredFields();
-
- for (Field field : fields) {
- try {
- String fieldSetName = parSetName(field.getName());
- if (!checkSetMet(methods, fieldSetName)) {
- continue;
- }
- Method fieldSetMet = cls.getMethod(fieldSetName, field.getType());
- String value = valMap.get(field.getName());
- if (null != value && !"".equals(value)) {
- String fieldType = field.getType().getSimpleName();
- if ("String".equals(fieldType)) {
- fieldSetMet.invoke(bean, value);
- } else if ("Date".equals(fieldType)) {
- Date temp = parseDate(value);
- fieldSetMet.invoke(bean, temp);
- } else if ("Integer".equals(fieldType) || "int".equals(fieldType)) {
- Integer intval = Integer.parseInt(value);
- fieldSetMet.invoke(bean, intval);
- } else if ("Long".equalsIgnoreCase(fieldType)) {
- Long temp = Long.parseLong(value);
- fieldSetMet.invoke(bean, temp);
- } else if ("Double".equalsIgnoreCase(fieldType)) {
- Double temp = Double.parseDouble(value);
- fieldSetMet.invoke(bean, temp);
- } else if ("Boolean".equalsIgnoreCase(fieldType)) {
- Boolean temp = Boolean.parseBoolean(value);
- fieldSetMet.invoke(bean, temp);
- } else {
- System.out.println("not supper type" + fieldType);
- }
- }
- } catch (Exception e) {
- continue;
- }
- }
-
- }
-
- /**
- * 格式化string为Date
- * @param datestr
- * @return date
- */
- private static Date parseDate(String datestr) {
- if (null == datestr || "".equals(datestr)) {
- return null;
- }
- try {
- String fmtstr = null;
- if (datestr.indexOf(':') > 0) {
- fmtstr = "yyyy-MM-dd HH:mm:ss";
- } else {
- fmtstr = "yyyy-MM-dd";
- }
- SimpleDateFormat sdf = new SimpleDateFormat(fmtstr, Locale.UK);
- return sdf.parse(datestr);
- } catch (Exception e) {
- return null;
- }
- }
- /**
- * 日期转化为String
- * @param date
- * @return date string
- */
- private static String fmtDate(Date date) {
- if (null == date) {
- return null;
- }
- try {
- SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US);
- return sdf.format(date);
- } catch (Exception e) {
- return null;
- }
- }
-
- /**
- * 判断是否存在某属性的 set方法
- * @param methods
- * @param fieldSetMet
- * @return boolean
- */
- private static boolean checkSetMet(Method[] methods, String fieldSetMet) {
- for (Method met : methods) {
- if (fieldSetMet.equals(met.getName())) {
- return true;
- }
- }
- return false;
- }
- /**
- * 判断是否存在某属性的 get方法
- * @param methods
- * @param fieldGetMet
- * @return boolean
- */
- private static boolean checkGetMet(Method[] methods, String fieldGetMet) {
- for (Method met : methods) {
- if (fieldGetMet.equals(met.getName())) {
- return true;
- }
- }
- return false;
- }
-
- /**
- * 拼接某属性的 get方法
- * @param fieldName
- * @return String
- */
- private static String parGetName(String fieldName) {
- if (null == fieldName || "".equals(fieldName)) {
- return null;
- }
- return "get" + fieldName.substring(0, 1).toUpperCase()
- + fieldName.substring(1);
- }
- /**
- * 拼接在某属性的 set方法
- * @param fieldName
- * @return String
- */
- private static String parSetName(String fieldName) {
- if (null == fieldName || "".equals(fieldName)) {
- return null;
- }
- return "set" + fieldName.substring(0, 1).toUpperCase()
- + fieldName.substring(1);
- }
-
- }
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