问题
Hi i am new to android and i am developing an app to display the top 10 travel destinations using achartengine. The problem is that i am using random values generated to plot the graph. What i need is to connect a database created using sqlite data browser to plot the graph. I am following the following tutorial to draw the graph http://www.youtube.com/watch?v=E9fozQ5NlSo. But i am not finding many tutorials on how to connect a database to plot a bar chart. Please post any links for the above.
package flu.solutions.travelsense;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.achartengine.ChartFactory;
import org.achartengine.chart.BarChart.Type;
import org.achartengine.model.CategorySeries;
import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.SimpleSeriesRenderer;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import org.achartengine.renderer.XYMultipleSeriesRenderer.Orientation;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
public class ChartActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
XYMultipleSeriesRenderer renderer = getBarDemoRenderer();
setChartSettings(renderer);
Intent intent = ChartFactory.getBarChartIntent(this, getBarDemoDataset(), renderer, Type.DEFAULT);
startActivity(intent);
}
public Intent createIntent()
{
String[] titles = new String[] { "Top 10 Destinations", " " };
List<double[]> values = new ArrayList<double[]>();
values.add(new double[] { 8, 6, 4, 6, 7, 7, 9, 5, 7, 8, 8 });
values.add(new double[] {});
int[] colors = new int[] { Color.RED, Color.BLACK};
XYMultipleSeriesRenderer renderer = buildBarRenderer(colors);
renderer.setOrientation(Orientation.HORIZONTAL);
setChartSettings(renderer);
renderer.setXLabels(1);
renderer.setYLabels(10);
renderer.addXTextLabel(1, "Bangalore");
renderer.addXTextLabel(2, "Mysore");
renderer.addXTextLabel(3, "Chennai");
renderer.addXTextLabel(4, "Delhi");
renderer.addXTextLabel(5, "Kolkatta");
renderer.addXTextLabel(6, "Kashmir");
renderer.addXTextLabel(7, "Hyderabad");
renderer.addXTextLabel(8, "Mumbai");
renderer.addXTextLabel(9, "Kerala");
renderer.addXTextLabel(10, "Gujarat");
int length = renderer.getSeriesRendererCount();
for (int i = 0; i < length; i++)
{
SimpleSeriesRenderer seriesRenderer = renderer.getSeriesRendererAt(i);
seriesRenderer.setDisplayChartValues(false);
}
return ChartFactory.getBarChartIntent(this, buildBarDataset(titles, values), renderer,Type.DEFAULT);
}
public XYMultipleSeriesRenderer getBarDemoRenderer() {
XYMultipleSeriesRenderer renderer = new XYMultipleSeriesRenderer();
renderer.setAxisTitleTextSize(16);
renderer.setChartTitleTextSize(20);
renderer.setLabelsTextSize(15);
renderer.setLegendTextSize(15);
renderer.setMargins(new int[] {20, 30, 15, 0});
SimpleSeriesRenderer r = new SimpleSeriesRenderer();
r.setColor(Color.BLUE);
renderer.addSeriesRenderer(r);
r = new SimpleSeriesRenderer();
r.setColor(Color.GREEN);
renderer.addSeriesRenderer(r);
return renderer;
}
private XYMultipleSeriesDataset getBarDemoDataset() {
XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
final int nr = 10;
Random r = new Random();
int SERIES_NR = 2;
for (int i = 0; i < SERIES_NR; i++) {
CategorySeries series = new CategorySeries("Demo series " + (i + 1));
for (int k = 0; k < nr; k++) {
series.add(100 + r.nextInt() % 100);
}
dataset.addSeries(series.toXYSeries());
}
return dataset;
}
private void setChartSettings(XYMultipleSeriesRenderer renderer) {
renderer.setChartTitle("Chart demo");
renderer.setXTitle("x values");
renderer.setYTitle("y values");
renderer.setXAxisMin(0);
renderer.setXAxisMax(5);
renderer.setYAxisMin(0);
renderer.setYAxisMax(250);
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_chart, menu);
return true;
}
}
Can you tell me what i am doing wrong here.
回答1:
Refer this link you may find it usefull
Generating graph by using remote data from database on achartengine
and get back to me for any doubts.
回答2:
First tell me where your database is 1> is it is local to your application 2> is it in server(there are various ways to access ex:you can send http request for getting datas from the server) 3>is the database is in anther application in your phone you can use content provider to access data.
try this code
public class DataBaseHelper extends SQLiteOpenHelper {
private Context mycontext;
//private String DB_PATH = mycontext.getApplicationContext().getPackageName()+"/databases/";
private static String DB_NAME = "(datbasename).sqlite";//the extension may be .sqlite or .db
public SQLiteDatabase myDataBase;
/*private String DB_PATH = "/data/data/"
+ mycontext.getApplicationContext().getPackageName()
+ "/databases/";*/
public DataBaseHelper(Context context) throws IOException {
super(context,DB_NAME,null,1);
this.mycontext=context;
boolean dbexist = checkdatabase();
if (dbexist) {
//System.out.println("Database exists");
opendatabase();
} else {
System.out.println("Database doesn't exist");
createdatabase();
}
}
public void createdatabase() throws IOException {
boolean dbexist = checkdatabase();
if(dbexist) {
//System.out.println(" Database exists.");
} else {
this.getReadableDatabase();
try {
copydatabase();
} catch(IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkdatabase() {
//SQLiteDatabase checkdb = null;
boolean checkdb = false;
try {
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
//checkdb = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE);
checkdb = dbfile.exists();
} catch(SQLiteException e) {
System.out.println("Database doesn't exist");
}
return checkdb;
}
private void copydatabase() throws IOException {
//Open your local db as the input stream
InputStream myinput = mycontext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outfilename = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myoutput = new FileOutputStream("/data/data/(packagename)/databases /(datbasename).sqlite");
// transfer byte to inputfile to outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myinput.read(buffer))>0) {
myoutput.write(buffer,0,length);
}
//Close the streams
myoutput.flush();
myoutput.close();
myinput.close();
}
public void opendatabase() throws SQLException {
//Open the database
String mypath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
}
public synchronized void close() {
if(myDataBase != null) {
myDataBase.close();
}
super.close();
}
}
for reading the database from asset folder..
来源：https://stackoverflow.com/questions/13814917/how-to-take-the-values-from-a-database-to-plot-a-bar-chart