如何获得pojo中嵌套属性的类型

写一个helper,注意map类，其它可以beanutils，也可用反射
象这样，几处关键代码：
Field[] flds =class.getFields();
..
for(Field f : flds){
设f可访问;
f.getName()等于想匹配的;
...
}

你这个不行吧，没有实现嵌套属性的访问。

一直听说“反射很耗性能的”，也一直听说要缓存起来
但是一直都没发现除了method能放进map还有什么能缓存的
而且把method放进map和反射的性能又没什么关系啊~

写这个东西还是有点耗时间的，LZ要感谢我哦。

package test;

import java.lang.reflect.Field;
import java.util.Date;

/**
 * 
 * @author YDSoft-15
 *
 */
public class ObjectFields {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		ObjectFields of = new ObjectFields();
		System.out.println(of.ObjectFields2String(new A()));
	}

	/**
	 * 
	 * @param obj
	 * @return 对象存在的属性值
	 */
	public String ObjectFields2String(Object obj) {
		return ObjectFields2String(new StringBuffer(), obj, 0);
	}

	/**
	 * 
	 * @param sb
	 * @param obj
	 * @param index
	 * @return 对象存在的属性值
	 */
	private String ObjectFields2String(StringBuffer sb, Object obj, int index) {
		Class<?> clas = obj.getClass();// 加载类
		sb.append(clas.getName());
		Field[] fields = clas.getDeclaredFields();// 获得对象属性集合
		sb.append(" {");
		printBlankSpace(sb, index + 1);
		for (int i = 0; i < fields.length; i++) {
			Field field = fields[i];
			String fieldName = field.getName();// 得到字段名

			sb.append(fieldName);
			sb.append("(");

			Class<?> fieldType = field.getType();// 得到字段类别
			sb.append(fieldType.getSimpleName());
			sb.append(") = ");

			try {
				field.setAccessible(true); // 设置强制访问
				Object fieldValue = field.get(obj);// 得到属性值
				if (fieldType.getClassLoader() != null) {// 如果ClassLoader为ExtClassLoader、AppClassLoader
					ObjectFields2String(sb, fieldValue, index + 1);// 递归
				} else {
					sb.append(fieldValue);
				}
			} catch (IllegalArgumentException e) {
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				e.printStackTrace();
			} finally {
				field.setAccessible(false);
			}
			if (i != fields.length - 1) {
				printBlankSpace(sb, index + 1);
			}
		}
		printBlankSpace(sb, index);
		sb.append("}");
		return sb.toString();
	}

	private void printBlankSpace(StringBuffer sb, int index) {
		sb.append("\n");
		for (int i = 0; i < index; i++) {
			sb.append("    ");
		}
	}

}

class A {
	String a = "A String of class A";
	B b = new B();
	long l = 123456l;
	Date d = new Date();
	StringBuffer sb = new StringBuffer();
	java.awt.Image img = null;

	public A() {
		sb.append("StringBuffer");
	}
}

class B {
	String b = "A String of class B";
	C c = new C();
}

class C {
	String b = "A String of class C";
}

test.A {
    a(String) = A String of class A
    b(B) = test.B {
        b(String) = A String of class B
        c(C) = test.C {
            b(String) = A String of class C
        }
    }
    l(long) = 123456
    d(Date) = Thu May 03 18:10:51 CST 2012
    sb(StringBuffer) = StringBuffer
    img(Image) = null
}

怎么不能嵌套呢？
具体的就是map和普通class,你再好好想想。：）

你是说把所有的类和嵌套类放到Map中？ 那如果map中的类有相同的属性怎么办？

还有就是事先就不知道我的嵌套类有哪些。

class B {  
    String b = "A String of class B";  
    C c;  
}


已经报错了，不是真正的pojo类

报错你Debug了吗？问题出在哪儿？要不你给我个“真正的”“POJO类”，让我测……

java.util.GregorianCalendar {
    BC(int) = 0
    BCE(int) = 0
    AD(int) = 1
    CE(int) = 1
    EPOCH_OFFSET(int) = 719163
    EPOCH_YEAR(int) = 1970
    MONTH_LENGTH(int[]) = [I@79616c7
    LEAP_MONTH_LENGTH(int[]) = [I@eb166b5
    ONE_SECOND(int) = 1000
    ONE_MINUTE(int) = 60000
    ONE_HOUR(int) = 3600000
    ONE_DAY(long) = 86400000
    ONE_WEEK(long) = 604800000
    MIN_VALUES(int[]) = [I@33837697
    LEAST_MAX_VALUES(int[]) = [I@7bdecdec
    MAX_VALUES(int[]) = [I@60a1807c
    serialVersionUID(long) = -8125100834729963327
    gcal(Gregorian) = sun.util.calendar.Gregorian@afa7e74
    jcal(JulianCalendar) = null
    jeras(Era[]) = null
    DEFAULT_GREGORIAN_CUTOVER(long) = -12219292800000
    gregorianCutover(long) = -12219292800000
    gregorianCutoverDate(long) = 577736
    gregorianCutoverYear(int) = 1582
    gregorianCutoverYearJulian(int) = 1582
    gdate(Date) = 2012-05-04T00:00:00.000Z
    cdate(Date) = 2012-05-04T00:00:00.000Z
    calsys(BaseCalendar) = sun.util.calendar.Gregorian@afa7e74
    zoneOffsets(int[]) = [I@2da679b7
    originalFields(int[]) = null
    cachedFixedDate(long) = 734627
    $assertionsDisabled(boolean) = true
}
java.util.HashMap {
    DEFAULT_INITIAL_CAPACITY(int) = 16
    MAXIMUM_CAPACITY(int) = 1073741824
    DEFAULT_LOAD_FACTOR(float) = 0.75
    table(Entry[]) = [Ljava.util.HashMap$Entry;@24a20892
    size(int) = 0
    threshold(int) = 12
    loadFactor(float) = 0.75
    modCount(int) = 0
    entrySet(Set) = null
    serialVersionUID(long) = 362498820763181265
}

有错，已经改了，加了两个判断条件，但决定不贴出来了，Debug时很容易发现。

cn.ydsoft.xcsqfwpt.foreground.level2.action.Level2NewsListPageAction {
    logger(Logger) = org.apache.log4j.Logger {
        FQCN(String) = org.apache.log4j.Level
        class$org$apache$log4j$Level(Class) = class org.apache.log4j.Level
    }
    serialVersionUID(long) = 1
    administrativeAreaService(AdministrativeAreaService) = null
    level2NewsListService(Level2NewsListService) = null
    state(String) = null
    message(String) = null
    l0(String) = null
    l1(String) = null
    l2(String) = null
    l3(String) = null
    l4(String) = null
    l5(String) = null
    l6(String) = null
    lm0(List) = null
    pageInfo(PageInfo) = cn.ydsoft.xcsqfwpt.bean.PageInfo {
        pageSize(int) = 10
        pageNumber(int) = 1
        DEFAULT_PAGE_SIZE(int) = 10
        DEFAULT_PAGE_NUMBER(int) = 1
        totalRow(int) = 0
        totalPage(int) = 0
        previousPage(int) = 0
        nextPage(int) = 0
        startRow(int) = 0
        endRow(int) = 0
        date(List) = null
        visiblePages(List) = null
        startPage(int) = 0
        endPage(int) = 0
        MAX_VISIBLE_PAGES(int) = 10
        previousPages(int) = 0
        followingPages(int) = 0
    }
    pageNumber(int) = 0
    xw01(Xw01) = null
    nr01(Nr01) = null
    zh01(Zh01) = null
    zx01(Zx01) = null
    dw02(Dw02) = null
    rx01(Rx01) = null
    zq01(Zq01) = null
    zq02(Zq02) = null
    fw01(Fw01) = null
    fw02(Fw02) = null
    es01(Es01) = null
    fj01(Fj01) = null
    bbs(String) = null
    sslb(String) = null
    ssnr(String) = null
}