Android™

Retrieve Metadata from Gzip Data in Memory (BinData)

This example demonstrates how to use the GetGzipInfoBd method to retrieve metadata from Gzip data stored in memory within a BinData object.

The Gzip data is first loaded into the BinData instance. The GetGzipInfoBd method then extracts any available metadata from the Gzip header, including the embedded filename, comment, and optional extra data.

The metadata is returned in a JsonObject. Because these fields are optional, the example checks for the existence of each JSON member using HasMember before retrieving its value.

Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  This example demonstrates how to retrieve metadata from Gzip data
    //  stored in a BinData object.

    CkGzip gzip = new CkGzip();
    CkBinData bd = new CkBinData();
    CkJsonObject json = new CkJsonObject();

    //  Load a Gzip file into BinData:
    success = bd.LoadFile("example.txt.gz");
    if (success == false) {
        Log.i(TAG, bd.lastErrorText());
        return;
        }

    //  Get the metadata information from the in-memory Gzip data:
    success = gzip.GetGzipInfoBd(bd,json);
    if (success == false) {
        Log.i(TAG, gzip.lastErrorText());
        return;
        }

    //  Output the JSON containing metadata:
    Log.i(TAG, "Gzip metadata JSON:");
    Log.i(TAG, json.emit());

    //  Access individual fields only if they exist:

    if (json.HasMember("filename") == true) {
        String filename = json.stringOf("filename");
        Log.i(TAG, "Filename: " + filename);
        }

    if (json.HasMember("comment") == true) {
        String comment = json.stringOf("comment");
        Log.i(TAG, "Comment: " + comment);
        }

    if (json.HasMember("extraData") == true) {
        String extraData = json.stringOf("extraData");
        Log.i(TAG, "ExtraData (Base64): " + extraData);
        }


  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}