Yeah, I kinda sorta did with my new proposed JSON library.
But you can go even faster.
Create a java class which mimics essentially exactly the structure of
your JSON - with getter methods for everything relevant.
Give this class NO fields whatsoever, just getters. Then let it extend
JavaScriptObject.
Make each getter native and grab the data straight from the JSON
structure. e.g. if you have:
{'name' = "foobar", 'age'=10}
you could make:
public final class Name extends JavaScriptObject {
public native String getName() /*-{ return this.name; }-*/;
public native int getAge() /*-{ return this.age; }-*/;
}
This is exactly as fast as it can possibly be in javascript, as this
whole hullabaloo gets eliminated entirely by the compiler. A call to
name.getName() will be translated directly to 'name.name' in the
javascript.
You can get arbitrarily funky with your JSON, but you'll need to write
all your accessors in javascript, so you'll need to know a thing or
two about javascript to build yoru accessor class. Good luck.
Make extends JavaScriptObject.
On Nov 19, 6:51 pm, "Jose Santa Elena" <[EMAIL PROTECTED]> wrote:
> Hi all...
> Has someone addressed the performance problem on parsing large JSON files?
>
> I created one Wrapper to do a "latter bind"...
>
> public class JSONMap implements Map {
> private JSONObject wrappedJSONObject;
> public JSONMap(JSONObject jsonObject) {
> if (jsonObject == null) {
> throw new WrongUseException("Invalid JSONObject");}
>
> this.wrappedJSONObject = jsonObject;}
>
> public void clear() {
> throw new UnsupportedOperationException();}
>
> public boolean containsKey(Object key) {
> throw new UnsupportedOperationException();
>
> }
>
> public boolean containsValue(Object value) {
> throw new UnsupportedOperationException();
>
> }
>
> public Set entrySet() {
> throw new UnsupportedOperationException();}
>
> protected String getKey(Object key) {
> String keyValue;
> if (key instanceof String) {
> keyValue = (String)key;} else {
>
> keyValue = key.toString();
>
> }
> return keyValue;
> }
>
> public Object get(Object key) {
> JSONArray jsonArray;
> JSONBoolean jsonbBoolean;
> JSONNumber jsonNumber;
> JSONObject jsonObject;
> JSONString jsonString;
> JSONValue jsonValue = wrappedJSONObject.get(getKey(key));
> if ((jsonArray = jsonValue.isArray()) != null) {
> return new JSONList(jsonArray);} else if ((jsonbBoolean =
> jsonValue.isBoolean()) != null) {
>
> return new Boolean(jsonbBoolean.booleanValue());} else if ((jsonNumber =
> jsonValue.isNumber()) != null) {
>
> return new Double(jsonNumber.doubleValue());} else if ((jsonObject =
> jsonValue.isObject()) != null) {
>
> return new JSONMap(jsonObject);} else if ((jsonString = jsonValue.isString())
> != null) {
>
> return jsonString.stringValue();} else {
> return null;
> }
> }
>
> public JSONMap getMap(String key) {
> return new JSONMap(wrappedJSONObject.get(key).isObject());}
>
> public String getString(String key) {
> return wrappedJSONObject.get(key).isString().stringValue();}
>
> public Double getDouble(String key) {
> return new Double(wrappedJSONObject.get(key).isNumber().doubleValue());}
>
> public JSONList getList(String key) {
> return new JSONList(wrappedJSONObject.get(key).isArray());
>
> }
>
> public boolean isEmpty() {
> return wrappedJSONObject.size() == 0;
>
> }
>
> public Set keySet() {
> return wrappedJSONObject.keySet();
>
> }
>
> public Object put(Object arg0, Object arg1) {
> throw new UnsupportedOperationException();
>
> }
>
> public void putAll(Map arg0) {
> throw new UnsupportedOperationException();
>
> }
>
> public Object remove(Object key) {
> throw new UnsupportedOperationException();
>
> }
>
> public int size() {
> return wrappedJSONObject.size();
>
> }
>
> public Collection values() {
> throw new UnsupportedOperationException();
>
> }
> }
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