【转换】Bean、List、Map、Array、String与JSON字符串的相互转换

import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang3.StringUtils;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

/**
 * JSONUtil.java
 *
 * Date: 2013-7-19 下午3:30:55
 * Version: 1.0
 *
 * Copyright(c) 2013 by Highershine
 */
/**
 * <p>
 * 类/接口 定义
 * </p>
 *
 * 类/接口作用...
 *
 * @author starwing
 *
 */
public class JSONUtil {
 private static JSONParser parser;

 /**
  * 将Json字符串解析为Map
  * @param jsonString
  * @return
  * @throws ParseException
  */
 @SuppressWarnings("unchecked")
 public static Map<String,Object> parseJsonToMap(String jsonString)
  throws ParseException{
  Map<String,Object> result = null;
  if(parser == null){
   parser = new JSONParser();
  }
  if(!StringUtils.isEmpty(jsonString)){
   result = (Map<String,Object>)parser.parse(jsonString);
  }
  return result;
 }

 /**
  * 将json字符串解析为List
  * @param jsonString
  * @return
  * @throws ParseException
  */
 @SuppressWarnings("unchecked")
 public static List<Object> parseJsonToList(String jsonString)
  throws ParseException{
  List<Object> result = null;
  if(parser == null){
   parser = new JSONParser();
  }
  if(!StringUtils.isEmpty(jsonString)){
   try{
    result = (List<Object>)parser.parse(jsonString);
   }catch(ParseException e){
    System.out.println(e.getMessage());
    throw e;
   }
  }
  return result;
 }
 /**
  * 将Json字符串转换为Map
  * @param jsonString
  * @return
  * @throws ParseException
  */
 public static Map<String, String> JSONParser(String jsonString)
   throws ParseException {
  JSONParser parser = new JSONParser();
  JSONArray jsonArray = (JSONArray) parser.parse(jsonString);

  HashMap<String, String> map = new HashMap<String, String>();
  for (int i = 0; i < jsonArray.size(); i++) {
   JSONObject obj = (JSONObject) jsonArray.get(i);
   // if (!"".equals(obj.get("value").toString().trim())) {
   map.put(obj.get("name").toString(), obj.get("value").toString());

   // }
  }
  return map;
 }

 /**
  * 将对象转换为Json字符串
  * <br>主方法
  * @param obj
  * @return
  */
 @SuppressWarnings("unchecked")
 public static String objectTojson(Object obj) {
  StringBuilder json = new StringBuilder();
  if (obj == null) {
   json.append("\"\"");
  } else if (obj instanceof String || obj instanceof Integer
    || obj instanceof Float || obj instanceof Boolean
    || obj instanceof Short || obj instanceof Double
    || obj instanceof Long || obj instanceof BigDecimal
    || obj instanceof BigInteger || obj instanceof Byte) {
   json.append("\"").append(stringTojson(obj.toString())).append("\"");
  } else if (obj instanceof Object[]) {
   json.append(arrayTojson((Object[]) obj));
  } else if (obj instanceof List) {
   json.append(listTojson((List<?>) obj));
  } else if (obj instanceof Map) {
   json.append(mapTojson((Map<?, ?>) obj));
  } else if (obj instanceof Set) {
   json.append(setTojson((Set<?>) obj));
  } else {
   json.append(beanTojson(obj));
  }
  return json.toString();
 }

 /**
  * Map转换为Json字符串
  *<p> 注意：Value值会被转成String类型。
  * @param map
  * @return
  */
 public static String mapTojson(Map<?, ?> map) {
  StringBuilder json = new StringBuilder();
  json.append("{");
  if (map != null && map.size() > 0) {
   for (Object key : map.keySet()) {
    json.append(objectTojson(key));
    json.append(":");
    json.append(objectTojson(map.get(key)));
    json.append(",");
   }
   json.setCharAt(json.length() - 1, '}');
  } else {
   json.append("}");
  }
  return json.toString();
 }

 /**
  * 数组转换为Json字符串
  * @param array
  * @return
  */
 public static String arrayTojson(Object[] array) {
  StringBuilder json = new StringBuilder();
  json.append("[");
  if (array != null && array.length > 0) {
   for (Object obj : array) {
    json.append(objectTojson(obj));
    json.append(",");
   }
   json.setCharAt(json.length() - 1, ']');
  } else {
   json.append("]");
  }
  return json.toString();
 }

 /**
  * List转换为Json字符串
  * @param list
  * @return
  */
 public static String listTojson(List<?> list) {
  StringBuilder json = new StringBuilder();
  json.append("[");
  if (list != null && list.size() > 0) {
   for (Object obj : list) {
    json.append(objectTojson(obj));
    json.append(",");
   }
   json.setCharAt(json.length() - 1, ']');
  } else {
   json.append("]");
  }
  return json.toString();
 }

 /**
  * SET集合转换为json字符串
  * @param set
  * @return
  */
 public static String setTojson(Set<?> set) {
  StringBuilder json = new StringBuilder();
  json.append("[");
  if (set != null && set.size() > 0) {
   for (Object obj : set) {
    json.append(objectTojson(obj));
    json.append(",");
   }
   json.setCharAt(json.length() - 1, ']');
  } else {
   json.append("]");
  }
  return json.toString();
 }

 /**
  * Bean实体转换为Json字符串
  * @param bean
  * @return
  */
 public static String beanTojson(Object bean) {
  StringBuilder json = new StringBuilder();
  json.append("{");
  PropertyDescriptor[] props = null;
  try {
   props = Introspector.getBeanInfo(bean.getClass(), Object.class)
     .getPropertyDescriptors();
  } catch (IntrospectionException e) {
  }
  if (props != null) {
   for (int i = 0; i < props.length; i++) {
    try {
     String name = objectTojson(props[i].getName());
     String value = objectTojson(props[i].getReadMethod()
       .invoke(bean));
     json.append(name);
     json.append(":");
     json.append(value);
     json.append(",");
    } catch (Exception e) {
     System.err.println(e.getMessage());
    }
   }
   json.setCharAt(json.length() - 1, '}');
  } else {
   json.append("}");
  }
  return json.toString();
 }

 /**
  * 字符串转为Json字符串
  * @param s
  * @return
  */
 public static String stringTojson(String s) {
  if (s == null)
   return "";
  StringBuilder sb = new StringBuilder();
  for (int i = 0; i < s.length(); i++) {
   char ch = s.charAt(i);
   switch (ch) {
   case '"':
    sb.append("\\\"");
    break;
   case '\\':
    sb.append("\\\\");
    break;
   case '\b':
    sb.append("\\b");
    break;
   case '\f':
    sb.append("\\f");
    break;
   case '\n':
    sb.append("\\n");
    break;
   case '\r':
    sb.append("\\r");
    break;
   case '\t':
    sb.append("\\t");
    break;
   case '/':
    sb.append("\\/");
    break;
   default:
    if (ch >= '\u0000' && ch <= '\u001F') {
     String ss = Integer.toHexString(ch);
     sb.append("\\u");
     for (int k = 0; k < 4 - ss.length(); k++) {
      sb.append('0');
     }
     sb.append(ss.toUpperCase());
    } else {
     sb.append(ch);
    }
   }
  }
  return sb.toString();
 }

}