I'm using GSON on my Java EE server to provide some json to views.
In some object, I have long text, that can contains anything (like 'What a "great" news!').
I'm supprised that by default GSON doesn't escape the double quote, so it doesn't generate a valid JSON.
Is there a good way of doing this ?
Maybe I'm not understanding your question, but I was able to get GSON to handle Strings with quotes without any settings or changes.
import com.google.gson.Gson;
public class GSONTest {
public String value;
public static void main(String[] args) {
Gson g = new Gson();
GSONTest gt = new GSONTest();
gt.value = "This is a \"test\" of quoted strings";
System.out.println("String: " + gt.value);
System.out.println("JSON: " + g.toJson(gt));
}
}
Output:
String: This is a "test" of quoted strings
JSON: {"value":"This is a \"test\" of quoted strings"}
Maybe I don't understand what you're asking?
Try using setPrettyPrinting with DisableHtml escaping.
import com.google.gson.Gson;
Gson gson = new GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create();
JsonParser jp = new JsonParser();
JsonElement je = jp.parse(jsonArray.toString());
System.out.println( gson.toJson(je));
Here's some sample GSON code:
final JsonObject obj = new JsonObject();
obj.addProperty("foo", "b\"a\"r");
System.out.println(obj.toString());
The Output is:
{"foo":"b\"a\"r"}
(as it should be)
So either you are doing something wrong, or you are using an ancient version of GSON. Perhaps you should show some of your code?
That is what I did to solve that
private final Gson mGson;
{
GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(String.class, new EscapeStringSerializer());
mGson = builder.create();
}
private static class EscapeStringSerializer implements JsonSerializer<String> {
#Override
public JsonElement serialize(String s, Type type, JsonSerializationContext jsonSerializationContext) {
return new JsonPrimitive(escapeJS(s));
}
public static String escapeJS(String string) {
String escapes[][] = new String[][]{
{"\\", "\\\\"},
{"\"", "\\\""},
{"\n", "\\n"},
{"\r", "\\r"},
{"\b", "\\b"},
{"\f", "\\f"},
{"\t", "\\t"}
};
for (String[] esc : escapes) {
string = string.replace(esc[0], esc[1]);
}
return string;
}
}
Related
I have below json, i want to update each and every value of that json but sometimes only one value
{
"msgType": "NEW",
"code": "205",
"plid": "PLB52145",
}
I've already tried to update using below code
FileReader reader = new FileReader(filePath);
JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = (JSONObject) jsonParser.parse(reader);
System.out.println(jsonObject);
long id =Long.valueOf((String) idNewObj.get("plid"));
System.out.println(plid);
idNewObj.put("plid",PL809809809);
System.out.println(jsonObject);
To make transformation/filtering of JSON files, I'd suggest to use stream/event-oriented parsing and generating rather than any object mapping. Just an example, which uses simple and lightweight JSON parser https://github.com/anatolygudkov/green-jelly :
import org.green.jelly.AppendableWriter;
import org.green.jelly.JsonEventPump;
import org.green.jelly.JsonParser;
import java.io.StringWriter;
import java.io.Writer;
public class UpdateMyJson {
private static final String jsonToUpdate = "{\n" +
"\"msgType\": \"NEW\",\n" +
"\"code\": \"205\",\n" +
"\"plid\": \"PLB52145\",\n" +
"}";
public static void main(String[] args) {
final StringWriter result = new StringWriter();
final JsonParser parser = new JsonParser();
parser.setListener(new MyJsonUpdater(result));
parser.parse(jsonToUpdate); // if you read a file with a buffer,
// call parse() several times part by part in a loop until EOF
parser.eoj(); // and then call .eoj()
System.out.println(result);
}
static class MyJsonUpdater extends JsonEventPump {
private boolean isPlid;
MyJsonUpdater(final Writer output) {
super(new AppendableWriter<>(output));
}
#Override
public boolean onObjectMember(final CharSequence name) {
isPlid = "plid".contentEquals(name);
return super.onObjectMember(name);
}
#Override
public boolean onStringValue(final CharSequence data) {
if (isPlid) {
if ("PLB52145".contentEquals(data)) {
return super.onStringValue("PL809809809");
}
}
return super.onStringValue(data);
}
}
}
Props:
the file/data doesn't require to be loaded entirely into memory, you can process megs/gigs with no problems
it works much more faster, especially for large files
it's easy to implement any custom type/rule of transformation with this pattern
Both of standard Gson and Jackson libs also provide tokenizers to work with JSON in streaming manner.
UPDATED: JsonEventPump used
You need to write the updated JSON into the file from where JSON was read. Also, I did not understand your variable assignment so I have updated that as well. Use below code:
FileReader reader = new FileReader(filePath);
JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = (JSONObject) jsonParser.parse(reader);
System.out.println(jsonObject);
long id =Long.valueOf((String) idNewObj.get("plid"));
System.out.println(id);
jsonObject.put("plid",PL809809809);
System.out.println(jsonObject);
FileWriter writer = new FileWriter(filePath, false); //overwrites the content of file
writer.write(jsonObject.toString());
writer.close();
I have an Object array which is a list of argument values a function could take. This could be any complex object.
I am trying to build a json out of the Object array using gson as below:
private JsonArray createArgsJsonArray(Object... argVals) {
JsonArray argsArray = new JsonArray();
Arrays.stream(argVals).forEach(arg -> argsArray.add(gson.toJson(arg)));
return argsArray;
}
This treats all the arg values as String.
It escapes the String args
"args":["\"STRING\"","1251996697","85"]
I prefer the following output:
"args":["STRING",1251996697,85]
Is there a way to achieve this using gson?
I used org.json, I was able to achieve the desired result, but it does not work for complex objects.
EDIT:
I applied the solution provided by #Michał Ziober, but now how do I get back the object.
Gson gson = new Gson();
Object strObj = "'";
JsonObject fnObj = new JsonObject();
JsonObject fnObj2 = new JsonObject();
fnObj.add("response", gson.toJsonTree(strObj));
fnObj2.addProperty("response", gson.toJson(strObj));
System.out.println(gson.fromJson(fnObj.toString(),
Object.class)); --> prints {response='} //Not what I want!
System.out.println(gson.fromJson(fnObj2.toString(),
Object.class)); --> prints {response="\u0027"}
Use toJsonTree method:
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import java.util.Date;
public class GsonApp {
public static void main(String[] args) {
GsonApp app = new GsonApp();
System.out.println(app.createArgsJsonArray("text", 1, 12.2D));
System.out.println(app.createArgsJsonArray(new Date(), new A(), new String[] {"A", "B"}));
}
private Gson gson = new GsonBuilder().create();
private JsonArray createArgsJsonArray(Object... argVals) {
JsonArray argsArray = new JsonArray();
for (Object arg : argVals) {
argsArray.add(gson.toJsonTree(arg));
}
return argsArray;
}
}
class A {
private int id = 12;
}
Above code prints:
["text",1,12.2]
["Sep 19, 2019 3:25:20 PM",{"id":12},["A","B"]]
If you want to end up with a String, just do:
private String createArgsJsonArray(Object... argVals) {
Gson gson = new Gson();
return gson.toJson(argVals);
}
If you wish to collect it back and alter just do:
Object[] o = new Gson().fromJson(argValsStr, Object[].class);
Try using setPrettyPrinting with DisableHtml escaping.
Gson gson = new GsonBuilder().setPrettyPrinting().disableHtmlEscaping().create();
JsonParser jp = new JsonParser();
JsonElement je = jp.parse(jsonArray.toString());
System.out.println( gson.toJson(je));
I have a JSON Data which is a collection of objects like the one given below. I have to deserialize the below given data into a list of objects
[{\"Name\": \"Initialize\", \"Library\": \"BKS\", \"Type\": \"setup\", \"Status\": \"PASS\", \"StartTime\": \"20190429 15:06:36.020\", \"EndTime\": \"20190429 15:06:39.476\", \"Environment\": \"CLC-ER\", \"ScenarioName\": \"BKS-DISVAS\", \"ElapsedTime\": 456.0},{\"Name\": \"Initialize\", \"Library\": \"BKS\", \"Type\": \"setup\", \"Status\": \"PASS\", \"StartTime\": \"20190429 15:06:36.020\", \"EndTime\": \"20190429 15:06:39.476\", \"Environment\": \"CLC-ER\", \"ScenarioName\": \"BKS-DISVAS\", \"ElapsedTime\": 456.0}]
I have tried the following code snippet, but I am getting the following error.
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING
at com.google.gson.Gson.fromJson(Gson.java:822) ~[gson-2.3.1.jar:na]
at com.google.gson.Gson.fromJson(Gson.java:875) ~[gson-2.3.1.jar:na]
My Model class is given below
public class KeywordDetails {
public KeywordDetails() {
}
#JsonProperty("Name")
public String Name;
#JsonProperty("Type")
public String Type;
#JsonProperty("Library")
public String Library;
#JsonProperty("StartTime")
public String StartTime;
#JsonProperty("EndTime")
public String EndTime;
#JsonProperty("Status")
public String Status;
#JsonProperty("ScenarioName")
public String ScenarioName;
#JsonProperty("Environment")
public String Environment;
#JsonProperty("ElapsedTime")
public double ElapsedTime;
}
The deserialization code is given below,
Gson serializer = new Gson();
Type listType = new TypeToken<ArrayList<KeywordDetails>>() {
}.getType();
JsonParser parser = new JsonParser();
JsonElement kwJson = parser.parse(ser.getKeywordStats());
System.out.println(kwJson);
List<KeywordDetails> keywordDetails = serializer.fromJson(kwJson, listType);
The ser.getKeywordStats() method is giving the above JSON.
I should be able to deserialize the JSON into the list or array of objects.
As I am new to Java, I am not able to find the root cause or fix for this issue, can anyone help me with this issue?
Why JsonProperty instead of SerializableName? Are you mixing Jackson and Gson?
What is the output of ser.getKeywordStats()?
Because I have tested your code by hardcoding that json-string instead of ser.getKeywordStats(), and it worked without any issue.
Here is a working snippet,
private static final String ESCAPED_STRING =
"[{\"Name\": \"Initialize\", \"Library\": \"BKS\", \"Type\": \"setup\", \"Status\": \"PASS\", \"StartTime\": \"20190429 15:06:36.020\", \"EndTime\": \"20190429 15:06:39.476\", \"Environment\": \"CLC-ER\", \"ScenarioName\": \"BKS-DISVAS\", \"ElapsedTime\": 456.0},{\"Name\": \"Initialize\", \"Library\": \"BKS\", \"Type\": \"setup\", \"Status\": \"PASS\", \"StartTime\": \"20190429 15:06:36.020\", \"EndTime\": \"20190429 15:06:39.476\", \"Environment\": \"CLC-ER\", \"ScenarioName\": \"BKS-DISVAS\", \"ElapsedTime\": 456.0}]";
public static void main(String[] args) throws JsonProcessingException {
Gson gson = new Gson();
Type t= new TypeToken<List<KeywordDetails>>(){}.getType();
JsonParser parser = new JsonParser();
JsonElement jsonElements = parser.parse(ESCAPED_STRING);
System.out.println(jsonElements);
List<KeywordDetails> kd = gson.fromJson(jsonElements, t);
System.out.println(kd);
}
This has to do something with your String, the string must be void of the \ slashes to make it a valid JSON. So, I have used JsonParser to construct a valid JSON from the escaped String.
Use Gson or JsonParser not both.
Try with this code:
Gson serializer = new Gson();
Type listType = new TypeToken<ArrayList<KeywordDetails>>() {}.getType();
List<KeywordDetails> keywordDetails = serializer.fromJson(ser.getKeywordStats(), listType);
I don't know #JsonProperty annotation. You can use (or not) #SerializedName instead.
Then you can simply deserialize your json like this.
String json = ...
Gson gson = new Gson();
List< KeywordDetails > keywords = gson.fromJson(json, new TypeToken<List< KeywordDetails >>(){}.getType());
So I have an object with some fields...
protected String name;
protected String relativePathAndFileName;
protected DateTime next_Run;
protected ArrayList<String> hosts;
Which gets serialized to JSON like this:
public void serialize(){
Gson gson = Converters.registerDateTime(new GsonBuilder()).setPrettyPrinting().create();
String json = gson.toJson(this);
try {
FileWriter writer = new FileWriter(this.relativePathAndFileName);
writer.write (json);
writer.close();
} catch (IOException e) {
logger.error("Error while trying to write myAlert to json: ", e);
}
}
Later when I need to read in this json file, I try to do so like this:
try {
for (File f : alertConfigFiles) {
Gson gson = new Gson();
JsonReader reader = new JsonReader(new FileReader(f));
Type type = new TypeToken<Map<String, String>>(){}.getType();
Map<String, String> myMap = gson.fromJson(reader, type);
Alert tempAlert = new Alert(myMap);
myAlerts.add(tempAlert);
logger.debug("Imported: " + f.toString());
}
The error that I'm getting is:
Unhandled exception when trying to import config files:
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_ARRAY at line 28 column 13 path $.
The JSON inside the file is something to the effect of:
{
"name": "Logs Per Host - past 24 hours",
"relativePathAndFileName": "./Elk-Reporting/Alerts/logs_per_host24h.json",
"next_Run": "2017-06-07T22:24:56.682-04:00",
"hosts": [
"app-12c",
"app1-18",
"wp-01",
"app-02",
"wp-02",
"cent-04",
"app-06",
"app-05"
]
}
It seems to be choking when it tries to import the ArrayList of hosts, but it was able to write them out without issues.
Can anyone offer some advice on how to get my import working without issues?
try to keep it simple. Using maps and so on, is a way to have issues.
Here is a working code to deserialise / serialise :
package com.rizze.beans.labs.sof;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
import com.google.gson.Gson;
public class SOFGson {
public String json = "{ \"name\": \"Logs Per Host - past 24 hours\", \"relativePathAndFileName\": \"./Elk-Reporting/Alerts/logs_per_host24h.json\", \"next_Run\": \"2017-06-07T22:24:56.682-04:00\", \"hosts\": [ \"bos-qa-app-12c\", \"bos-qa-app1-18\", \"bos-qa-wp-01\", \"bos-lt-app-02\", \"bos-qa-wp-02\", \"bos-dev-cent-04.americanwell.com\", \"bos-qa-app-06\", \"bos-qa-app-05\" ]}";
public class MyObj{
protected String name;
protected String relativePathAndFileName;
protected String next_Run;
protected String[] hosts;
}
#Test
public void test() {
Gson gson = new Gson();
MyObj obj = gson.fromJson(json, MyObj.class);
assertTrue(obj!=null);
assertTrue(obj.hosts.length==8);
System.out.println(gson.toJson(obj));
}
}
here is the class in gist : https://gist.github.com/jeorfevre/7b32a96d4ddc4af68e40bf95f63f2c26
Those two lines seem to be the problem:
Type type = new TypeToken<Map<String, String>>(){}.getType();
Map<String, String> myMap = gson.fromJson(reader, type);
You serialize your object of some specific class. You then deserialize it to type. But your JSON does not fit into a Map. Better do it like this, so you can use your own class.
YourClass myMap = gson.fromJson(reader, YourClass.class);
If you want to use this approach, you might want to change your Java class to hold an array of strings instead of an ArrayList of strings.
Maybe this page helps you a bit. Especially the first case fits your situation.
Another option is a custom Deserialzer as described here.
In my Android project I'm trying to create a list of MyType using gson. For this I use the following code:
String result = "[{\"text\": \"lala\", \"created\": \"123456\"}, {\"text\": \"lele\", \"created\": \"123456\"}]";
class ReceivedMessage {
String text;
String created;
}
List<ReceivedMessage> receivedMessages = new Gson().fromJson(result, new TypeToken<List<ReceivedMessage>>(){}.getType());
for (ReceivedMessage mess : receivedMessages) {
Log.wtf("This is it", mess.created);
}
Unfortunately I get a nullpointerexception. Does anybody know what I'm doing wrong here?
Defining the class "outside" worked pretty well:
public class ReceivedMessage {
String text;
String created;
}
public static void main(String[] args) {
String result = "[{\"text\": \"lala\", \"created\": \"123456\"}, "
+"{\"text\": \"lele\", \"created\": \"123456\"}]";
List<ReceivedMessage> receivedMessages = new Gson().fromJson(result,
new TypeToken<List<ReceivedMessage>>() {}.getType());
for (ReceivedMessage mess : receivedMessages) {
System.out.println("This is it " + mess.created);
}
....
}
Note: Gson uses reflection and so it needs access to the class.
Please try this :
Type listType = new TypeToken<ArrayList<ReceivedMessage>>() {}.getType();
List<ReceivedMessage> receivedMessages= new Gson().fromJson(result, listType);
Google Gson - deserialize list<class> object? (generic type)