将不同数据类型转为json格式写的java类

package com.stone.util;

import java.lang.reflect.Array;

import java.lang.reflect.Field;

import java.lang.reflect.Modifier;

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

/*

将各种对象转换为json对象

*/

public class JsonUtil {
public static String toJSONString(Object value) {
if (value == null) {
return "null";
}

if (value instanceof Number) {
return value.toString();
}

if (value instanceof Boolean) {
return value.toString();
}

if (value instanceof String) {
return "\"" + escape((String) value) + "\"";
}

if (value instanceof Double) {
if (((Double) value).isInfinite() || ((Double) value).isNaN()) {
return "null";
} else {
return value.toString();
}
}

if (value instanceof Float) {
if (((Float) value).isInfinite() || ((Float) value).isNaN()) {
return "null";
} else {
return value.toString();
}
}

if (value instanceof Map) {
return map2Json((Map) value);
}
if (value instanceof Collection) {
return coll2Json((Collection) value);
}
if (value.getClass().isArray()) {
return array2Json(value);
}
return pojo2Json(value);

}

private static String array2Json(Object array) {
if (null == array){
return "null";
}
StringBuffer sb = new StringBuffer();
sb.append('[');
// 此处减1是为了下面的 逗号 追加
int len = Array.getLength(array) - 1;
if (len > -1) {
int i;
for (i = 0; i < len; i++) {
sb.append(toJSONString(Array.get(array, i))).append(", ");
}
sb.append(toJSONString(Array.get(array, i)));
}
sb.append(']');
return sb.toString();
}

private static String coll2Json(Collection coll) {
if (null == coll){
return "null";
}
StringBuffer sb = new StringBuffer();
sb.append('[');
for (Iterator it = coll.iterator(); it.hasNext();) {
sb.append(toJSONString(it.next()));
if (it.hasNext()){
sb.append(", ");
}
}
sb.append(']');
return sb.toString();
}

private static String pojo2Json(Object obj) {
Class type = obj.getClass();
Field[] fields = type.getDeclaredFields();
Map map = new HashMap();
for (Field f : fields) {
if (Modifier.isStatic(f.getModifiers())){
continue;
}
String name = f.getName();
f.setAccessible(true);
Object value = null;
try {
value = f.get(obj);
} catch (Exception e) {
value = null;
}
map.put(name, value);
}
type = null;
fields = null;
return map2Json(map);
}

private static String map2Json(Map map) {
if (null == map){
return "null";
}
StringBuffer sb = new StringBuffer();
sb.append('{');
for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
Map.Entry entry = (Map.Entry) it.next();
String key = (String) entry.getKey();
if (null == key){
continue;
}
sb.append('\"');
escape(key, sb);
sb.append('\"').append(':').append(toJSONString(entry.getValue()));
if (it.hasNext()){
sb.append(", ");
}
}
sb.append('}');
return sb.toString();

};

public static String escape(String s) {
if (s == null){
return null;
}
StringBuffer sb = new StringBuffer();
escape(s, sb);
return sb.toString();
}

private static void escape(String s, Strin
919d
gBuffer sb) {
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')|| (ch >= '\u007F' && ch <= '\u009F')|| (ch >= '\u2000' && ch <= '\u20FF')) {
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);
}
}
}
}

}