JarCastingJsonSurfer - Let's surf on Json!
Why JsonSurfer
-
Streaming
No need to deserialize entire json into memory.
-
JsonPath
Selectively extract json data by the power of JsonPath.
-
Stoppable
JsonSurfer is built on stoppable SAX-like interface that allows the processor to stop itself if necessary.
-
Non-Blocking
JsonSurfer is event-driven and offers non-blocking parser interface.
-
Binary format
Support multiple binary data formats including Avro, CBOR, Protobuf, Smile and Ion.
Getting started
What is JsonPath?
- Supported JsonPath operator in JsonSurfer:
| Operator | Description |
|---|---|
$ |
root |
@ |
current node |
* |
wildcard |
.. |
recursive descent |
.<name> |
child |
['<name>' (, '<name>')] |
child/children |
[<number> (, <number>)] |
index/indices |
[start:end] |
array slice |
[?(<expression>)] |
filter expression |
- JsonSurfer is available in cetral maven repository.
JsonSurfer has drivers for most of popular json libraries including: Gson, Jackson, FastJson and JsonSimple. Choose one and add to your POM.
<dependency>
<groupId>com.github.jsurfer</groupId>
<artifactId>jsurfer-gson</artifactId>
<version>1.6.0</version>
</dependency>
<dependency>
<groupId>com.github.jsurfer</groupId>
<artifactId>jsurfer-jackson</artifactId>
<version>1.6.0</version>
</dependency>
<dependency>
<groupId>com.github.jsurfer</groupId>
<artifactId>jsurfer-fastjson</artifactId>
<version>1.6.0</version>
</dependency>
<dependency>
<groupId>com.github.jsurfer</groupId>
<artifactId>jsurfer-jsonsimple</artifactId>
<version>1.6.0</version>
</dependency>
Usage:
Create your JsonSurfer:
- JsonSurfer has flexible constructor. You can create yourself or pick a prebuilt one according the json library you used:
- Gson
// use gson parser and use gson provider use to deserialize json into gson model i.e.com.google.gson.JsonElement
JsonSurfer surfer = new JsonSurfer(GsonParser.INSTANCE, GsonProvider.INSTANCE);
or
JsonSurfer surfer = JsonSurferGson.INSTANCE;
- Jackson
JsonSurfer surfer = new JsonSurfer(JacksonParser.INSTANCE, JacksonProvider.INSTANCE);
or
JsonSurfer surfer = JsonSurferJackson.INSTANCE;
- JsonSimple
// use json-simple parser and json-simple provider to deserialize json into json-simple model i.e.org.json.simple.JSONObject or org.json.simple.JSONArray
JsonSurfer surfer = new JsonSurfer(JsonSimpleParser.INSTANCE, JsonSimpleProvider.INSTANCE);
or
JsonSurfer surfer = JsonSurferJsonSimple.INSTANCE;
- Fastjson
JsonSurfer surfer = new JsonSurfer(FastJsonParser.INSTANCE, FastJsonProvider.INSTANCE);
or
JsonSurfer surfer = JsonSurferFastJson.INSTANCE;
Collect value by JsonPath
Collector collector = surfer.collector(sample);
ValueBox<String> box1 = collector.collectOne("$.store.book[1].category", String.class);
ValueBox<Object> box2 = collector.collectOne("$.store.book[2].isbn");
ValueBox<Collection<Object>> box3 = collector.collectAll("$.store.book[*]");
collector.exec(); // make sure exec() invoked before getting value from boxes
box1.get();
box2.get();
box3.get();
【DEPRECATED】 Collect the first matched value and stop immediately
JsonSurfer jsonSurfer = JsonSurferGson.INSTANCE;
Object singleResult = jsonSurfer.collectOne(sample, "$.store.book[0]");
【DEPRECATED】 Colllect every matched value into a collection
JsonSurfer jsonSurfer = JsonSurferGson.INSTANCE;
Collection<Object> multipleResults = jsonSurfer.collectAll(sample, "$.store.book[*]");
"Surfing" in Json and collecting matched value in the listeners
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.book[*]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Reuse listener binding.
SurfingConfiguration is thread-safe as long as your listeners are stateless.
JsonSurfer surfer = JsonSurferGson.INSTANCE;
SurfingConfiguration config = surfer.configBuilder()
.bind("$.store.book[*]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.build();
surfer.surf(sample1, config);
surfer.surf(sample2, config);
Compiled JsonPath
JsonPath object is immutable and can be reused safely.
Tips: Most of JsonSurfer API have two version: accepting raw JsonPath string or JsonPath object. The latter is always faster than the former without compiling JsonPath.
JsonPath compiledPath = JsonPathCompiler.compile("$..book[1,3]['author','title']");
String value = surfer.collectOne(read("sample.json"), String.class, compiledPath);
JsonPath Filters
- Filter operators
| Operator | Description |
|---|---|
| == | equal |
| < | less than |
| > | greater than |
You can use logical operators '&&' and '||' to create more complex filter expression. For example:
$.store.book[?(@.price < 10 || @.category && @.isbn && @.price>10)].volumes[?(@.chapter == 1)]
Resolver API:
- Limitation: Wildcard and Recursive Descent are NOT supported.
- As of 1.2.6, JsonSurfer provides another way of processing json. You can directly resolve value with JsonPath from a well-built DOM like HashMap or even POJO:
Book book = new Book();
book.setAuthor("Leo");
book.setCategory("Fiction");
book.setPrice(100.0d);
book.setTitle("JsonSurfer is great!");
System.out.print(compile("$.author").resolve(book, new PoJoResolver()));
which prints "Leo".
List<String> list = Arrays.asList("foo", "bar");
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("list", list);
System.out.println(compile("$.list[1]").resolve(map, JavaCollectionProvider.INSTANCE));
which prints "bar".
- If you want to process POJO with full JsonPath feature, you can convert the POJO into binary format and then surfer on it.
Binaray format (Jackson only)
By importing Jackson binary format backend, JsonSurfer is capable to surfer with multiple binary object representation formats such as Avro, CBOR, Protobuf(A known bug to be fixed in Jackson 2.9.6), Smile and Ion.
For example, if you want to surfer with CBOR data, firstly, CBOR format backend need to be imported as dependency.
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-cbor</artifactId>
<version>${jackson.version}</version>
</dependency>
Then create a JsonSurfer with CBOR-backed JacksonParser and surfer as usual
surfer = new JsonSurfer(new JacksonParser(new CBORFactory()), provider);
Find more examples here: https://github.com/jsurfer/JsonSurfer/blob/master/jsurfer-all/src/test/java/org/jsfr/json/JacksonParserTest.java
Share data among processors
Since JsonSurfer emit data in the way of callback, it would be difficult if one of your processing depends one another. Therefore a simple transient map is added for sharing data among your processors. Following unit test shows how to use it:
surfer.configBuilder().bind("$.store.book[1]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
context.save("foo", "bar");
}
}).bind("$.store.book[2]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
assertEquals("bar", context.load("foo", String.class));
}
}).bind("$.store.book[0]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
assertNull(context.load("foo", String.class));
}
}).buildAndSurf(read("sample.json"));
Control parsing
- How to pause and resume parsing.
SurfingConfiguration config = surfer.configBuilder()
.bind("$.store.book[0]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
LOGGER.info("The first pause");
context.pause();
}
})
.bind("$.store.book[1]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
LOGGER.info("The second pause");
context.pause();
}
}).build();
ResumableParser parser = surfer.getResumableParser(read("sample.json"), config);
assertFalse(parser.resume());
LOGGER.info("Start parsing");
parser.parse();
LOGGER.info("Resume from the first pause");
assertTrue(parser.resume());
LOGGER.info("Resume from the second pause");
assertTrue(parser.resume());
LOGGER.info("Parsing stopped");
assertFalse(parser.resume());
- Completely stop parsing. Refer to Stoppable parsing
Java 8 Streams API support
As of 1.4, JsonSurfer can create an iterator from Json and JsonPath. Matched value can be pulled from the iterator one by one without loading entire json into memory.
Iterator iterator = surfer.iterator(read("sample.json"), JsonPathCompiler.compile("$.store.book[*]"));
Java8 user can also convert the iterator into a Stream
Stream<Object> targetStream = StreamSupport.stream(
Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED),
false);
Functions implmented by Streams API
public static Stream<Object> toStream(String json, String path) {
Iterator<Object> iterator = JsonSurferJackson.INSTANCE.iterator(json, JsonPathCompiler.compile(path));
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false);
}
public static void main(String[] s) throws Exception {
String json = "[1,3,5,7,11]";
// Count
System.out.println(toStream(json, "$[*]").count());
// Max
toStream(json, "$[*]").mapToInt(o -> ((LongNode) o).asInt()).max().ifPresent(System.out::println);
// Min
toStream(json, "$[*]").mapToInt(o -> ((LongNode) o).asInt()).min().ifPresent(System.out::println);
// Average
toStream(json, "$[*]").mapToDouble(o -> ((LongNode) o).asDouble()).average().ifPresent(System.out::println);
}
Non-Blocking parsing
As of 1.4, JsonSurfer support non-blocking parsing for JacksonParser. You can achieve 100% non-blocking JSON processing with JsonSurfer in a NIO application. Let's take a Vertx request handler as an example:
Vertx vertx = Vertx.vertx();
HttpServer server = vertx.createHttpServer(new HttpServerOptions());
JsonSurfer surfer = JsonSurferJackson.INSTANCE;
SurfingConfiguration config = surfer.configBuilder()
.bind("$[*]", (JsonPathListener) (value, context) -> {
// Handle json
System.out.println(value);
}).build();
server.requestHandler(request -> {
NonBlockingParser parser = surfer.createNonBlockingParser(config);
request.handler(buffer -> {
byte[] bytes = buffer.getBytes();
System.out.println("Received " + bytes.length + " bytes");
parser.feed(bytes, 0, bytes.length);
});
request.endHandler(aVoid -> {
parser.endOfInput();
System.out.println("End of request");
request.response().end();
});
}).listen(8080);
Examples
Sample Json:
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
},
"expensive": 10
}
| JsonPath | Result |
|---|---|
$.store.book[*].author |
Find the authors of all books |
$..author |
All authors |
$.store.* |
All things in store |
$.store..price |
The price of everything in the store |
$..book[2] |
The third book |
$..book[0,1] |
The first two books |
$.store.book[?(@.price==8.95)] |
Filter all books whose price equals to 8.95 |
$.store.book[?(@.category=='fiction')] |
Filter all books which belong to fiction category |
$.store.book[?(@.author=~/tolkien/i)] |
All books matching regex |
Find the authors of all books:
$.store.book[*].author
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.book[*].author", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
"Nigel Rees"
"Evelyn Waugh"
"Herman Melville"
"J. R. R. Tolkien"
All authors
$..author
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$..author", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
"Nigel Rees"
"Evelyn Waugh"
"Herman Melville"
"J. R. R. Tolkien"
All things in store
$.store.*
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.*", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]
{"color":"red","price":19.95}
The price of everything in the store
$.store..price
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store..price", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
8.95
12.99
8.99
22.99
19.95
The third book
$..book[2]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$..book[2]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99}
The first two books
$..book[0,1]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$..book[0,1]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95}
{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99}
Filter all books whose price equals to 8.95
$.store.book[?(@.price==8.95)]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.book[?(@.price==8.95)]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95}
Filter all books which belong to fiction category
$.store.book[?(@.category=='fiction')]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.book[?(@.category=='fiction')]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99}
{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99}
{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}
All books matching regex
$.store.book[?(@.author=~/tolkien/i)]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$.store.book[?(@.author=~/tolkien/i)]')]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
}
})
.buildAndSurf(sample);
Output
{"author":"J. R. R. Tolkien","price":22.99,"isbn":"0-395-19395-8","category":"fiction","title":"The Lord of the Rings"}
Stoppable parsing
The parsing is stopped when the first book found and printed.
$..book[0,1]
JsonSurfer surfer = JsonSurferGson.INSTANCE;
surfer.configBuilder()
.bind("$..book[0,1]", new JsonPathListener() {
@Override
public void onValue(Object value, ParsingContext context) {
System.out.println(value);
context.stop();
}
})
.buildAndSurf(sample);
Output
{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95}
Benchmark
- JsonSurfer is fast !!! The benchmark is powered by JMH
Benchmark Mode Cnt Score Error Units
BenchmarkCollectSingleValue.benchmarkFastjson thrpt 10 139772.275 8854.369 ops/s
BenchmarkCollectSingleValue.benchmarkFastjsonWithJsonSurfer thrpt 10 699176.961 23396.619 ops/s
BenchmarkCollectSingleValue.benchmarkGson thrpt 10 139394.358 6019.764 ops/s
BenchmarkCollectSingleValue.benchmarkGsonWithJsonSurfer thrpt 10 632155.657 15484.499 ops/s
BenchmarkCollectSingleValue.benchmarkJackson thrpt 10 160545.079 7006.525 ops/s
BenchmarkCollectSingleValue.benchmarkJacksonWithJsonSurfer thrpt 10 451870.586 13132.576 ops/s
BenchmarkCollectSingleValue.benchmarkJsonSimpleWithJsonSurfer thrpt 10 155094.948 4457.502 ops/s