Java 实现将其他类型数据转换成 JSON 字符串工具类

这是网上一个大神实现的，具体出处已找不到，在这做个记录，方便以后使用。

 package com.wb.test;
 import java.beans.IntrospectionException;
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 /**
  * 将其他数据类型转换成json字符串格式
  */
 public class JsonUtil {  

     /**
      * 入口方法
      * @param obj
      * @return
      */
     public static String object2json(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(string2json(obj.toString())).append("\"");
         } else if (obj instanceof Object[]) {
             json.append(array2json((Object[]) obj));
         } else if (obj instanceof List) {
             json.append(list2json((List<?>) obj));
         } else if (obj instanceof Map) {
             json.append(map2json((Map<?, ?>) obj));
         } else if (obj instanceof Set) {
             json.append(set2json((Set<?>) obj));
         } else {
             json.append(bean2json(obj));
         }
         return json.toString();
     }

     public static String string2json(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();
     }

     public static String array2json(Object[] array) {
         StringBuilder json = new StringBuilder();
         json.append("[");
         if (array != null && array.length > 0) {
             for (Object obj : array) {
                 json.append(object2json(obj));
                 json.append(",");
             }
             json.setCharAt(json.length() - 1, ']');
         } else {
             json.append("]");
         }
         return json.toString();
     }

     public static String list2json(List<?> list) {
         StringBuilder json = new StringBuilder();
         json.append("[");
         if (list != null && list.size() > 0) {
             for (Object obj : list) {
                 json.append(object2json(obj));
                 json.append(",");
             }
             json.setCharAt(json.length() - 1, ']');
         } else {
             json.append("]");
         }
         return json.toString();
     }

     public static String map2json(Map<?, ?> map) {
         StringBuilder json = new StringBuilder();
         json.append("{");
         if (map != null && map.size() > 0) {
             for (Object key : map.keySet()) {
                 json.append(object2json(key));
                 json.append(":");
                 json.append(object2json(map.get(key)));
                 json.append(",");
             }
             json.setCharAt(json.length() - 1, '}');
         } else {
             json.append("}");
         }
         return json.toString();
     }

     public static String set2json(Set<?> set) {
         StringBuilder json = new StringBuilder();
         json.append("[");
         if (set != null && set.size() > 0) {
             for (Object obj : set) {
                 json.append(object2json(obj));
                 json.append(",");
             }
             json.setCharAt(json.length() - 1, ']');
         } else {
             json.append("]");
         }
         return json.toString();
     }

     public static String bean2json(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 = object2json(props[i].getName());
                     String value = object2json(props[i].getReadMethod().invoke(bean));
                     json.append(name);
                     json.append(":");
                     json.append(value);
                     json.append(",");
                 } catch (Exception e) {}
             }
             json.setCharAt(json.length() - 1, '}');
          } else {
              json.append("}");
         }
          return json.toString();
     }

 }