最近对Java的反射很是困惑，求解惑！ - 黑马程序员技术交流社区

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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