implements Grid SD Load Services in Java

java/src/main/java/com/genexus/GXDataGridProcedure.java

@@ -0,0 +1,80 @@
+package com.genexus;
+
+import com.genexus.diagnostics.core.ILogger;
+import com.genexus.diagnostics.core.LogManager;
+import com.genexus.webpanels.HttpContextWeb;
+
+public abstract class GXDataGridProcedure extends GXProcedure{
+
+	private static final ILogger logger = LogManager.getLogger(GXDataGridProcedure.class);
+
+	private static final String HAS_NEXT_PAGE = "HasNextPage";
+	private static final String RECORD_COUNT = "RecordCount";
+	private static final String RECORD_COUNT_SUPPORTED = "RecordCountSupported";
+	private long totalRecordCount = -1;
+
+	public GXDataGridProcedure(int remoteHandle, ModelContext context, String location) {
+		super(false, remoteHandle, context, location);
+	}
+
+	protected long recordCount(){
+		return -1;
+	}
+
+	protected boolean recordCountSupported(){
+		return true;
+	}
+
+	protected void setPaginationHeaders(boolean hasNextPage) {
+		try {
+			setHasNextPageHeader(hasNextPage);
+			setRecordCountSupportedHeader();
+		}
+		catch (Exception ex) {
+			logger.warn("A processing error occurred while setting pagination headers", ex);
+		}
+	}
+
+	private void setRecordCountSupportedHeader() {
+		if (!recordCountSupported()) {
+			logger.debug("Adding '{RECORD_COUNT_SUPPORTED}' header");
+			((HttpContextWeb) context.getHttpContext()).setHeader(RECORD_COUNT_SUPPORTED, String.valueOf(false));
+		}
+	}
+
+	private void setHasNextPageHeader(boolean hasNextPage) {
+		((HttpContextWeb) context.getHttpContext()).setHeader(HAS_NEXT_PAGE, String.valueOf(hasNextPage));
+	}
+
+	private void setRecordCountHeader() {
+		boolean recordCountHeaderRequired = false;
+		boolean setHeader = false;
+		if (context.getHttpContext() != null) {
+			recordCountHeaderRequired = !context.getHttpContext().getHeader(RECORD_COUNT).isEmpty();
+		}
+		if (totalRecordCount != -1) {
+			setHeader = true;
+		}
+		else if (recordCountHeaderRequired) {
+			totalRecordCount = recordCount();
+			setHeader = true;
+		}
+		if (setHeader) {
+			logger.debug("Adding '{RECORD_COUNT}' header: " + totalRecordCount);
+			((HttpContextWeb) context.getHttpContext()).setHeader(RECORD_COUNT, String.valueOf(totalRecordCount));
+		}
+	}
+
+	protected long getPaginationStart(long start, long count) {
+		if (start < 0) { //last page
+			totalRecordCount = recordCount();
+			long lastPageRecords = totalRecordCount % count;
+			if (lastPageRecords == 0)
+				start = totalRecordCount - count;
+			else
+				start = totalRecordCount - lastPageRecords;
+		}
+		setRecordCountHeader();
+		return start;
+	}
+}