利用反射机制 实现 javabean 转化为 map（效率低，仅限学习）

package com.test.entity;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class ConvertUtil {

public static Map fromBean(Object object) throws IllegalArgumentException, IllegalAccessException, InstantiationException, InvocationTargetException, ClassNotFoundException
{

Map<String, Object> map=new HashMap<String, Object>();
Class class1=object.getClass();
Field[] fields=class1.getDeclaredFields();
Method[] methods=class1.getMethods();

for(Field eachField:fields)
{

String key=eachField.getName();//字段名称

String methodName="get"+key.substring(0, 1).toUpperCase()+key.substring(1);//方法名称

Method method=getMethodByName(methods, methodName);//得到方法

if(eachField.getType().isPrimitive())
{
System.out.println(methodName);
map.put(key, method.invoke(object, null));
continue;
}

Class theClass=Class.forName(eachField.getType().getName());

if(!Collection.class.isAssignableFrom(theClass)){//不是集合

if(method==null)//get方法存在
continue;
try {
Object result=method.invoke(object, null);//执行方法
map.put(key, result);//放入map

} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else {

Collection result=(Collection) method.invoke(object, null);
Iterator it=result.iterator();

Object object2=theClass.newInstance();
Collection collection=(Collection<Map>) object2;

while (it.hasNext()) {
Object object3=it.next();

Map map2=ConvertUtil.fromBean(object3);
collection.add(map2);

}

map.put(key, collection);

}

}

return map;

}

private static Method getMethodByName(Method[] methods,String name) {

for(Method each:methods)
{
if(each.getName().equals(name))
return each;
}

return null;

}

}

package com.test.entity;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Random;

public class ConvertUtilTest {

public static void main(String[] args) {

Demo demo=new Demo();
demo.setStr("abcdefg");
ArrayList list=new ArrayList<demoitem>();

String randomsString="abcdefghijklmnopqrstuvwxyz";
for(int i=0;i<5;i++)
{
DemoItem demoItem=new DemoItem();
demoItem.setStrr(randomsString.substring(i, i+3));
list.add(demoItem);
}
demo.setDemoList(list);

try {
Map map=ConvertUtil.fromBean(demo);
System.out.println(map.toString());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
}
</demoitem>

package com.test.entity;

import java.util.ArrayList;
import java.util.List;

public class Demo {

private String str;
private ArrayList demoList;
public String getStr() {
return str;
}
public void setStr(String str) {
this.str = str;
}
public ArrayList getDemoList() {
return demoList;
}
public void setDemoList(ArrayList demoList) {
this.demoList = demoList;
}
@Override
public String toString() {
return "Demo [demoList=" + demoList + ", str=" + str + "]";
}

}

package com.test.entity;

public class DemoItem {

private String strr;

public String getStrr() {
return strr;
}

public void setStrr(String strr) {
this.strr = strr;
}

@Override
public String toString() {
return "DemoItem [strr=" + strr + "]";
}

}