对象转换成JSON字符串

package com.sy.test;      

 import java.lang.reflect.Field;

 import java.util.ArrayList;

 import java.util.HashMap;

 public class JSONUtil {

 public static String toJSON(Object obj) {

 HashMap<String, String> map = new HashMap<String, String>();

 Class c = obj.getClass();

 Field[] fields = c.getDeclaredFields();

 for (int i = 0; i < fields.length; i++) {

 String name = fields[i].getName();

 try {

 fields[i].setAccessible(true);

 Object o = fields[i].get(obj);

 if (o instanceof Number) {

 map.put("\"" + name + "\"", o.toString());

 } else if (o instanceof String) {

 map.put("\"" + name + "\"", "\"" + o.toString() + "\"");

 }

 } catch (IllegalArgumentException e) {

 } catch (IllegalAccessException e) {

 }

 }

 String s = map.toString();

 String str = s.replaceAll("\"=", "\":");

 return str;

 }

 public static String toJSON(Object[] objs) {

 String[] strs = new String[objs.length];

 for (int i = 0; i < objs.length; i++) {

 strs[i] = toJSON(objs[i]);

 }

 return toJSONArray(strs);

 }

 public static String toJSONArray(String[] strs) {

 StringBuffer sb = new StringBuffer();

 sb.append("{");

 for (int i = 0; i < strs.length; i++) {

 sb.append("\"");

 sb.append(i);

 sb.append("\":");

 sb.append(strs[i]);

 sb.append(",");

 }

 sb.append("\"length\":");

 sb.append(strs.length);

 sb.append("}");

 return sb.toString();

 }

 @SuppressWarnings("unchecked")

 public static void main(String[] args) {

 User user = new User();

 user.setId("1234");

 user.setName("hahaha");

 user.setAge(21);

 User user1 = new User();

 user1.setId("5767");

 user1.setName("hehehe");

 user1.setAge(18);

 User[] users={user1,user};

 System.out.println(JSONUtil.toJSON(users));

 ArrayList list = new ArrayList();

 list.add(user);

 list.add(user1);

 // System.out.println(JSON.toJSON(user));

 System.out.println(JSONUtil.toJSON(list.toArray()));

 }

 }

 class User {

 private String name;

 private String id;

 private int age;

 public int getAge() {

 return age;

 }

 public void setAge(int age) {

 this.age = age;

 }

 public String getId() {

 return id;

 }

 public void setId(String id) {

 this.id = id;

 }

 public String getName() {

 return name;

 }

 public void setName(String name) {

 this.name = name;

 }

 }