java反射實現物件轉JSON(貼上可用)
package test;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import java.lang.reflect.Field;
import java.util.Map;
public class JsonUtils {
/**
* @param obj
* @return
* @throws InstantiationException
* @throws IllegalAccessException
*/
public static String getJsonString(Object obj) throws InstantiationException, IllegalAccessException {
//如果傳入的物件為集合
if (obj instanceof Collection) {
//執行collectionTojson方法將集合型別轉為json格式
return collectionTojson(obj);
}
//如果獲取的物件型別為一個Map集合
else if (obj instanceof Map) {
//執行mapTojson方法將Map型別轉為json格式
return mapTojson(obj);
}
//如果獲取的物件型別為普通物件
else{
//執行classTojson方法將普通型別轉為json格式
return classTojson(obj);
}
}
/**
* @描述 將集合轉為json格式的字串
* @param obj
* @return
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
private static String collectionTojson(Object obj) throws IllegalArgumentException, IllegalAccessException{
//定義一個StringBuffer型別的字串
StringBuffer buffer = new StringBuffer();
buffer.append("[");
Class<? extends Object> clazz = obj.getClass();
//獲取類中所有的欄位
Field[] declaredFields = clazz.getDeclaredFields();
//設定可以獲得私有欄位的value
Field.setAccessible(declaredFields, true);
//定義全域性變數
boolean listf = false;
boolean setf = false;
Set<Object> set = null;
List<Object> list = null;
//遍歷獲取到的所有欄位
for (Field field : declaredFields) {
//getDeclaringClass()同getClasses()，但不侷限於public修飾，只要是目標類中宣告的內部類和介面均可
String simpleName = clazz.getSimpleName();
//判斷獲取到的型別
if(simpleName.equals("ArrayList")||simpleName.equals("LinkedList")){
list = (List<Object>) obj;
listf=true;
}
if(simpleName.equals("HashSet")||simpleName.equals("TreeSet")){
set = (Set<Object>) obj;
setf=true;
}
}
//如果獲取的物件型別為一個List集合
if(listf == true){
return listTojson(buffer, list).toString();
}
//如果獲取的物件型別為一個Set集合
if(setf == true){
buffer = setTojson(set, buffer);
}
buffer.append("]");
return buffer.toString();
}
/**
* 描述 將基本類轉為json格式
* @param obj
* @return
*/
private static String classTojson(Object obj){
//通過反射獲取到類
Class<? extends Object> clazz = obj.getClass();
//獲取類中所有的欄位
Field[] fields = clazz.getDeclaredFields();
StringBuffer buffer = new StringBuffer();
buffer.append("[{");
//設定setAccessible方法能獲取到類中的私有屬性和方法
Field.setAccessible(fields, true);
//遍歷所有的方法和屬性
for (Field field : fields) {
try {
Object object = field.get(obj);
//獲取到該屬性對應型別名稱
String fieldName = field.getType().getSimpleName();
//如果該屬性的值為空
if(object == null){
//根據型別判斷追加的值
if(fieldName.equals("String"))
{
buffer.append("\""+field.getName()+"\":\"\",");
}
else if(fieldName.equals("Boolean")||fieldName.equals("Integer")||fieldName.equals("Double")||fieldName.equals("Float")||fieldName.equals("Long")){
buffer.append("\""+field.getName()+"\":0,");
}
else{
buffer.append("\""+field.getName()+"\":null,");
}
}
else{
//獲取到該屬性的值對應的類
Class<? extends Object> fieldclass = object.getClass();
String simpleName = fieldclass.getSimpleName();
if(simpleName.equals("String")){
buffer.append("\""+field.getName()+"\":\""+field.get(obj)+"\",");
}
else if(simpleName.equals("Boolean")||simpleName.equals("Integer")||simpleName.equals("Double")||simpleName.equals("Float")||simpleName.equals("Long")){
buffer.append("\""+field.getName()+"\":"+field.get(obj)+",");
}
else if(simpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+field.getName()+"\":\""+simdate+"\",");
}
else if(simpleName.equals("ArrayList")||simpleName.equals("LinkedList"))
{
//將獲取到的值強轉為list集合
List<Object> list = (List<Object>) object;
buffer.append("\""+field.getName()+"\":[");
//執行listTojson方法將獲取到的list轉為json格式
buffer = listTojson(buffer, list).append("]");
}
else if(simpleName.equals("HashSet")||simpleName.equals("TreeSet"))
{
//將獲取到的值強轉為set集合
buffer.append("\""+field.getName()+"\":[");
Set<Object> set = (Set<Object>) object;
//執行setTojson方法將獲取到的set轉為json格式
buffer = setTojson(set, buffer).append("]");
}
else if(simpleName.equals("HashMap")||simpleName.equals("HashTable"))
{
buffer.append("\""+field.getName()+"\":");
//執行mapTojson方法將獲取到的map物件轉為json格式
StringBuffer mapbuffer = new StringBuffer(mapTojson(object));
mapbuffer.deleteCharAt(0);
buffer.append(mapbuffer);
}
else{
buffer = beanTojson(object,buffer).append(",");
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
buffer = new StringBuffer(buffer.substring(0,buffer.length()-1));
buffer.append("}]");
return buffer.toString();
}
/**
* 描述 將map集合轉為json格式
* @param obj
* @return
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
private static String mapTojson(Object obj) throws IllegalArgumentException, IllegalAccessException{
StringBuffer buffer = new StringBuffer();
Class<? extends Object> clazz = obj.getClass();
Field[] declaredFields = clazz.getDeclaredFields();
Field.setAccessible(declaredFields, true);
buffer.append("[");
Map<Object,Object> map = (Map<Object, Object>) obj;
//通過Map.entrySet使用iterator(迭代器)遍歷key和value
Set<Entry<Object, Object>> set = map.entrySet();
Iterator iterator = set.iterator();
buffer.append("{");
while (iterator.hasNext()){
//使用Map.Entry接到通過迭代器迴圈出的set的值
Map.Entry mapentry = (Map.Entry) iterator.next();
Object value = mapentry.getValue();
//使用getKey()獲取map的鍵，getValue()獲取鍵對應的值
String valuename = value.getClass().getSimpleName();
if(valuename.equals("String")){
buffer.append("\""+mapentry.getKey()+"\":\""+mapentry.getValue()+"\",");
}
else if(valuename.equals("Boolean")||valuename.equals("Integer")||valuename.equals("Double")||valuename.equals("Float")||valuename.equals("Long")){
buffer.append("\""+mapentry.getKey()+"\":"+mapentry.getValue()+",");
}
else if(valuename.equals("Date")){
Date date = (Date) value;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+mapentry.getKey()+"\":\""+simdate+"\",");
}else if(valuename.equals("ArrayList")||valuename.equals("LinkedList"))
{
List<Object> list = (List<Object>) value;
buffer.append("\""+mapentry.getKey()+"\":[");
buffer = listTojson(buffer, list).append("]");
}
else if(valuename.equals("HashSet")||valuename.equals("TreeSet"))
{
buffer.append("\""+mapentry.getKey()+"\":[");
Set<Object> sets = (Set<Object>) value;
buffer = setTojson(sets, buffer).append("]");
}
else if(valuename.equals("HashMap")||valuename.equals("HashTable"))
{
buffer.append("\""+mapentry.getKey()+"\":");
StringBuffer mapbuffer = new StringBuffer(mapTojson(value));
mapbuffer.deleteCharAt(0);
buffer.append(mapbuffer);
}
else{
buffer.append("\""+mapentry.getKey()+"\":");
buffer.append("{");
Class<? extends Object> class1 = value.getClass();
Field[] fields = class1.getDeclaredFields();
Field.setAccessible(fields, true);
for (Field field : fields) {
Object object = field.get(value);
String fieldName = field.getType().getSimpleName();
if(object == null){
if(fieldName.equals("String"))
{
buffer.append("\""+field.getName()+"\":\"\",");
}
else{
buffer.append("\""+field.getName()+"\":null,");
}
}
else{
Class<? extends Object> fieldclass = field.get(value).getClass();
String simpleName = fieldclass.getSimpleName();
if(simpleName.equals("String")){
buffer.append("\""+field.getName()+"\":\""+field.get(value)+"\",");
}
else if(simpleName.equals("Boolean")||simpleName.equals("Integer")||simpleName.equals("Double")||simpleName.equals("Float")||simpleName.equals("Long")){
buffer.append("\""+field.getName()+"\":"+field.get(value)+",");
}
else if(simpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+field.getName()+"\":\""+simdate+"\",");
}
else if(simpleName.equals("ArrayList")||simpleName.equals("LinkedList")){
List<Object> list = (List<Object>) object;
buffer.append("\""+field.getName()+"\":[");
StringBuffer append = listTojson(buffer, list).append("]");
buffer.append(append);
}
else if(simpleName.equals("HashSet")||simpleName.equals("TreeSet")){
buffer.append("\""+field.getName()+"\":[");
Set<Object> sets = (Set<Object>) object;
buffer = setTojson(sets, buffer).append("]");
}
else if(simpleName.equals("HashMap")||simpleName.equals("HashTable")){
buffer.append("\""+field.getName()+"\":");
StringBuffer mapbuffer = new StringBuffer(mapTojson(object));
mapbuffer.deleteCharAt(0);
buffer.append(mapbuffer);
}
else{
buffer = beanTojson(object,buffer).append(",");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
buffer.append("},");
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
return buffer.toString()+"}]";
}
/**
* @描述 將不是基本型別的欄位轉為json格式
* @param obj
* @param buffer
* @return
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
private static StringBuffer beanTojson(Object obj,StringBuffer buffer) throws IllegalArgumentException, IllegalAccessException{
Class<? extends Object> clazz = obj.getClass();
Field[] declaredFields = clazz.getDeclaredFields();
Field.setAccessible(declaredFields, true);
buffer.append("\""+clazz.getSimpleName()+"\":{");
for (Field field : declaredFields) {
Object object = field.get(obj);
String fieldName = field.getType().getSimpleName();
if(object == null){
if(fieldName.equals("String"))
{
buffer.append("\""+field.getName()+"\":\"\",");
}
else{
buffer.append("\""+field.getName()+"\":null,");
}
}
else{
Class<? extends Object> fieldclass = object.getClass();
String simpleName = fieldclass.getSimpleName();
if(simpleName.equals("String")){
buffer.append("\""+field.getName()+"\":\""+field.get(obj)+"\",");
}
else if(simpleName.equals("Boolean")||simpleName.equals("Integer")||simpleName.equals("Double")||simpleName.equals("Float")||simpleName.equals("Long")){
buffer.append("\""+field.getName()+"\":"+field.get(obj)+",");
}
else if(simpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+field.getName()+"\":\""+simdate+"\",");
}
else if(simpleName.equals("ArrayList")||simpleName.equals("LinkedList")){
List<Object> list = (List<Object>) object;
buffer = listTojson(buffer, list);
}
else if(simpleName.equals("HashSet")||simpleName.equals("TreeSet")){
Set<Object> set = (Set<Object>) object;
buffer = setTojson(set, buffer);
}
else if(simpleName.equals("HashMap")||simpleName.equals("HashTable")){
buffer.append("\""+field.getName()+"\":");
StringBuffer mapbuffer = new StringBuffer(mapTojson(object));
mapbuffer.deleteCharAt(0);
buffer.append(mapbuffer);
}
else{
buffer = beanTojson(object,buffer).append("}");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
buffer.append("}");
return buffer;
}
/**
* @描述 將list陣列轉為json格式
* @param buffer
* @param list
* @return
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
private static StringBuffer listTojson(StringBuffer buffer,List list) throws IllegalArgumentException, IllegalAccessException{
//遍歷傳過來的list陣列
for (Object object : list) {
//判斷遍歷出的值是否為空
if (object == null) {
buffer.append(",");
}
else{
Class<? extends Object> class1 = object.getClass();
String simpleName = class1.getSimpleName();
if(simpleName.equals("String")){
buffer.append("\""+object.toString()+"\",");
}
else if(simpleName.equals("Boolean")||simpleName.equals("Integer")||simpleName.equals("Double")||simpleName.equals("Float")||simpleName.equals("Long")){
buffer.append(""+object.toString()+",");
}
else if(simpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append(""+simdate+",");
}
else{
Class<? extends Object> class2 = object.getClass();
Field[] fields = class2.getDeclaredFields();
Field.setAccessible(fields, true);
buffer.append("{");
//遍歷物件中的所有欄位獲取欄位值和欄位名稱拼成json字串
for (Field field : fields) {
Object fieldobj = field.get(object);
String fieldName = field.getType().getSimpleName();
if(fieldobj == null){
if(fieldName.equals("String"))
{
buffer.append("\""+field.getName()+"\":\"\",");
}
else{
buffer.append("\""+field.getName()+"\":null,");
}
}
else{
String fsimpleName = fieldobj.getClass().getSimpleName();
if(fsimpleName.equals("String")){
buffer.append("\""+field.getName()+"\":\""+field.get(object)+"\",");
}
else if(fsimpleName.equals("Boolean")||fsimpleName.equals("Integer")||fsimpleName.equals("Double")||fsimpleName.equals("Float")||fsimpleName.equals("Long")){
buffer.append("\""+field.getName()+"\":"+field.get(object)+",");
}
else if(fsimpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+field.getName()+"\":"+simdate+",");
}
else{
buffer = beanTojson(fieldobj, buffer).append(",");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
buffer.append("},");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
buffer.append("]");
return buffer;
}
/**
* @描述 將set陣列轉為json格式
* @param set
* @param buffer
* @return
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
private static StringBuffer setTojson(Set set,StringBuffer buffer) throws IllegalArgumentException, IllegalAccessException{
for (Object object : set) {
if (object == null) {
buffer.append(""+"null"+",");
}
else{
Class<? extends Object> class1 = object.getClass();
//判斷集合中的值是否為java基本型別
String simpleName = class1.getSimpleName();
if(simpleName.equals("String")){
buffer.append("\""+object.toString()+"\",");
}
else if(simpleName.equals("Boolean")||simpleName.equals("Integer")||simpleName.equals("Double")||simpleName.equals("Float")||simpleName.equals("Long")){
buffer.append(""+object.toString()+",");
}
else if(simpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append(""+simdate+",");
}
else{
Class<? extends Object> class2 = object.getClass();
Field[] fields = class2.getDeclaredFields();
Field.setAccessible(fields, true);
buffer.append("{");
//遍歷物件中的所有欄位獲取欄位值和欄位名稱拼成json字串
for (Field field : fields) {
Object fieldobj = field.get(object);
String fieldName = field.getType().getSimpleName();
if(object == null){
if(fieldName.equals("String"))
{
buffer.append("\""+field.getName()+"\":\"\",");
}
else{
buffer.append("\""+field.getName()+"\":null,");
}
}
else{
String fsimpleName = fieldobj.getClass().getSimpleName();
if(fsimpleName.equals("String")){
buffer.append("\""+field.getName()+"\":\""+field.get(object)+"\",");
}
else if(fsimpleName.equals("Boolean")||fsimpleName.equals("Integer")||fsimpleName.equals("Double")||fsimpleName.equals("Float")||fsimpleName.equals("Long")){
buffer.append("\""+field.getName()+"\":"+field.get(object)+",");
}
else if(fsimpleName.equals("Date")){
Date date = (Date) object;
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String simdate = simpleDateFormat.format(date);
buffer.append("\""+field.getName()+"\":"+simdate+",");
}
else{
buffer = beanTojson(fieldobj, buffer).append(",");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
buffer.append("},");
}
}
}
buffer = new StringBuffer(""+buffer.substring(0,buffer.length()-1)+"");
return buffer;
}
}