java对象转换成json 字符串的方法

package com.test.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class JsonData {

@SuppressWarnings("unchecked")
public static String toJsonObj(Object obj) {

StringBuffer sb = new StringBuffer();
if (obj instanceof Object[]) {
sb.append("[");
Object[] values = (Object[]) obj;
for (int i = 0; i < values.length; i++) {
sb.append(toJsonObj(values[i]) + ",");
}
sb.append("]");
} else if (obj instanceof ArrayList) {
ArrayList list = (ArrayList) obj;
sb.append("[");
for (int i = 0; i < list.size(); i++) {
sb.append(toJsonObj(list.get(i)) + ",");
}
sb.append("]");
} else if (obj instanceof Set) {
Set vset=(Set)obj;
sb.append("[");
Iterator it1 = vset.iterator();
while(it1.hasNext()){
sb.append(toJsonObj(it1.next())+",");
}
sb.append("]");
} else if (obj instanceof Map) {
Map map =(HashMap)obj;
Set set =map.keySet();
Iterator it = set.iterator();
sb.append("{");
while(it.hasNext()){
Object keyObj=it.next();
try{
String key=keyObj.toString().replace("/"", "/////"");
sb.append("/""+key+"/":");
sb.append(toJsonObj(map.get(keyObj)));
sb.append(",");
}catch(Exception e){
sb.append("/""+keyObj+"/":");
sb.append(toJsonObj(map.get(keyObj)));
sb.append(",");
}
}
sb.append("}");
} else {
if (obj instanceof String||obj instanceof Integer
|| obj instanceof Double || obj instanceof Float
|| obj instanceof Long || obj instanceof Character
|| obj instanceof Byte || obj instanceof BigDecimal) {
sb.append("/"");
sb.append(obj.toString().replaceAll("/"", "/////""));
sb.append("/"");
} else {
if(obj==null){
return"/"null/"";
}else if("".equals(obj)){
return "/" /"";
}
StringBuffer objSB = new StringBuffer();
StringBuffer objSB2 = new StringBuffer();
String getMethod = "";
Class c = obj.getClass();
try {
objSB.append("{");
Method[] method=c.getMethods();
for(int i=0;i<method.length;i++){
String methodName=method[i].getName();
if(methodName.startsWith("get")
&&method[i].getParameterTypes().length==0
&&!"getClass".equals(methodName)
&&methodName.length()>3){
String field=methodName.substring(3);
field=field.replaceFirst(field.substring(0, 1), field.substring(0, 1).toLowerCase());
try{
Object objValue=c.getMethod(methodName, new Class[]{}).invoke(obj, new Object[]{});
objSB.append("/""+field+"/":");
objSB.append(toJsonObj(objValue));
objSB.append(",");
}catch(Exception nme){
System.out.println("[warn] no method of "+ getMethod + " in "+c.getName());
}
}
}
objSB.append("}");
sb.append(objSB.toString());

} catch (Exception e) {
objSB2.append("/"");
objSB2.append(obj.toString().replaceAll("/"", "/////""));
objSB2.append("/"");
sb.append(objSB2.toString());
}
}
}

return sb.toString().replaceAll(",}", "}").replaceAll(",]", "]");

}

}