Get API

Get Request

GetRequest is like:

GetRequest getRequest = new GetRequest(
        "posts", //Index
        "doc",  //Type
        "1");   //Document id

Optional arguments

The configurable parameters are as follows:

//Disable Source Retrieval and Open by Default
request.fetchSourceContext(FetchSourceContext.DO_NOT_FETCH_SOURCE); 

//Configure the source include field
String[] includes = new String[]{"message", "*Date"};
String[] excludes = Strings.EMPTY_ARRAY;
FetchSourceContext fetchSourceContext =
        new FetchSourceContext(true, includes, excludes);
request.fetchSourceContext(fetchSourceContext); 

To configure source exclude field
String[] includes = Strings.EMPTY_ARRAY;
String[] excludes = new String[]{"message"};
FetchSourceContext fetchSourceContext =
        new FetchSourceContext(true, includes, excludes);
request.fetchSourceContext(fetchSourceContext); 

//Configure retrieve storage fields (fields that need to be stored in the mapping)
request.storedFields("message"); 
GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
String message = getResponse.getField("message").getValue(); 

//Routing value
request.routing("routing"); 

//Parent value
request.parent("parent"); 

//Preference value
request.preference("preference"); 

//Set realtime flag to false (true by default)
request.realtime(false); 

//Set to refresh before retrieving documents (false by default)
request.refresh(true); 

//Setting Version
request.version(2); 

//Version type
request.versionType(VersionType.EXTERNAL); 

Synchronous Execution

GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);

Asynchronous Execution

Asynchronous execution of index requests requires passing the GetRequest instance and ActionListener instance to the asynchronous method:

client.getAsync(request/*GetRequest to be executed*/, RequestOptions.DEFAULT, listener/*Callback after completion of execution*/); 

Asynchronous execution does not block and returns immediately. Once completed, if the execution is successful, the onResponse method is used to call back the ActionListener, and if the execution fails, the onFailure method is used to call back the ActionListener.

Typical GetResponse:

ActionListener<GetResponse> listener = new ActionListener<GetResponse>() {
    //Callback when the call is successful and return information as a parameter
    @Override
    public void onResponse(GetResponse getResponse) {
        
    }
    //Callback when call fails, error message is passed in as parameter
    @Override
    public void onFailure(Exception e) {
        
    }
};

Get Response

The response information returned from GetResponse is as follows:

String index = getResponse.getIndex();
String type = getResponse.getType();
String id = getResponse.getId();
if (getResponse.isExists()) {
    long version = getResponse.getVersion();
    //Get string response
    String sourceAsString = getResponse.getSourceAsString();  
    //Get Map < String, Object > response     
    Map<String, Object> sourceAsMap = getResponse.getSourceAsMap(); 
    //Get byte [] response
    byte[] sourceAsBytes = getResponse.getSourceAsBytes();          
} else {
    
}

If the document is not found, it returns a normal GetResponse with a 404 response code instead of throwing an exception. Such a response does not contain a source, and its isExists method returns false.

When operating on a non-existent index, the 404 response code and the following Elastic search Exception are returned:

GetRequest request = new GetRequest("does_not_exist", "doc", "1");
try {
    GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
} catch (ElasticsearchException e) {
    //Document does not exist
    if (e.status() == RestStatus.NOT_FOUND) {
        
    }
}

If you access a specified version of a document, but the document has a different version, a version conflict exception occurs:

try {
    GetRequest request = new GetRequest("posts", "doc", "1").version(2);
    GetResponse getResponse = client.get(request, RequestOptions.DEFAULT);
} catch (ElasticsearchException exception) {
    //Version conflict
    if (exception.status() == RestStatus.CONFLICT) {
        
    }
}