有时候json的key值顺序对于业务来说是有意义的，而且java-json的类型判断使用起来很困难。
根据定义json的key是无序集合，但是hash code顺序处理的感觉有点随意。如果你注意浏览器的实现，chrome浏览器是可以记录key顺序的。原生的opt**方法是试图转换成某种类型，但是几乎任何事物都可以转换成string，所以判断JOSNObject中键值的类型需要一些技巧，例如注意顺序，其实增加类似typeof的方法就可以有更加精确的值类型信息。
我给官方的实现提了request,但是没有被接受。
- 以下是我的简单实现 :
JSONObjectKeyOrder
package org.json;
import java.util.ArrayList;
import java.util.List;
/**
* sometimes we need key order in input,hashmap`s keyset is chaos.
* @author wangq
*
*/
public class JSONObjectKeyOrder extends JSONObject {
// store the name in order
private List<String> names;
public JSONObjectKeyOrder(String source) throws JSONException {
this(new JSONTokenerKeyOrder(source));
}
public JSONObjectKeyOrder(JSONTokenerKeyOrder jsonTokenerKeyOrder) {
super(jsonTokenerKeyOrder);
}
public JSONObjectKeyOrder putOnce(String key, Object value) throws JSONException {
super.putOnce(key, value);
if (names == null) {
names = new ArrayList<>();
}
names.add(key);
return this;
}
/**
* null is ugly,and evil
* @param jo
* @return
*/
public static String[] getNames(JSONObjectKeyOrder jo) {
if (jo.names == null) {
return new String[0];
}
return jo.names.toArray(new String[0]);
}
/**
* i do`t like the opt** methods,it`s hard to get type,such the everything can be cast to String
*
* @param key
* @return
*/
public boolean isInt(String key) {
try {
Integer.parseInt(optString(key));
return true;
} catch (Exception e) {
return false;
}
}
}
JSONTokenerKeyOrder
package org.json;
public class JSONTokenerKeyOrder extends JSONTokener{
public JSONTokenerKeyOrder(String s) {
super(s);
}
/**
*
*/
public Object nextValue() throws JSONException {
char c = this.nextClean();
String string;
switch (c) {
case '"':
case '\'':
return this.nextString(c);
case '{':
this.back();
return new JSONObjectKeyOrder(this);
case '[':
this.back();
return new JSONArray(this);
}
/*
* Handle unquoted text. This could be the values true, false, or
* null, or it can be a number. An implementation (such as this one)
* is allowed to also accept non-standard forms.
*
* Accumulate characters until we reach the end of the text or a
* formatting character.
*/
StringBuilder sb = new StringBuilder();
while (c >= ' ' && ",:]}/\\\"[{;=#".indexOf(c) < 0) {
sb.append(c);
c = this.next();
}
this.back();
string = sb.toString().trim();
if ("".equals(string)) {
throw this.syntaxError("Missing value");
}
return JSONObject.stringToValue(string);
}
}
TestMain
package org.json;
/**
* test JSONObjectKeyOrder
* @author wangq
*
*/
public class TestMain {
public static void main(String[] args) {
JSONObject jsonObject = new JSONObject("{a:1,d:{z:2,a:2},b:3}");
System.out.println(jsonObject);
JSONObjectKeyOrder jsonObject1 = new JSONObjectKeyOrder("{a:1,d:{z:2,a:2},b:3}");
print(jsonObject1,"");
}
/**
*a
*d
* z
* a
*b
* @param jsonObject
* @param index
*/
static void print(JSONObjectKeyOrder jsonObject,String index){
String[] names = JSONObjectKeyOrder.getNames(jsonObject);
for (String string : names) {
System.out.println(index+string);
if(jsonObject.optJSONObject(string)!=null){
print((JSONObjectKeyOrder) jsonObject.optJSONObject(string),index+" ");
}
}
}
}
