dbhelper.java

简单的java代码实现手机地图功能

package lordhong.apps;

import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

public class DBHelper {
	
	static String LOGGER = "mini.gmap.DBHelper";
    class AddressRow extends Object {
        public long rowId;
        public String address;
        public long latitude;
        public long longitude;
    }

    private static final String DATABASE_CREATE =
        "create table addresses (rowid integer primary key autoincrement, "
            + "address text not null, latitude integer, longitude integer);";

    private static final String DATABASE_NAME = "minigmap091";

    private static final String DATABASE_TABLE = "addresses";

    private static final int DATABASE_VERSION = 1;

    private SQLiteDatabase db;

    public DBHelper(Context ctx) {
        try {
            db = ctx.openDatabase(DATABASE_NAME, null);
        } catch (FileNotFoundException e) {
            try {
                db =
                    ctx.createDatabase(DATABASE_NAME, DATABASE_VERSION, 0,
                        null);
                db.execSQL(DATABASE_CREATE);
                
                // empire state building
                createRow("350 5th Ave, New York, NY 10118", 40748356, -73984621);
                // grand central station
                createRow("15 Vanderbilt Ave, New York, NY 10017", 40752831, -73977864);
                // the white house
                createRow("1600 Pennsylvania Avenue NW,  Washington, DC 20500", 38898590, -77036473);
            } catch (FileNotFoundException e1) {
            	Log.e(LOGGER, e1.toString());
                db = null;
            }
        }
    }

    public void close() {
        db.close();
    }

    public void createRow(String address, long latitude, long longitude) {
        ContentValues initialValues = new ContentValues();
        initialValues.put("address", address);
        initialValues.put("latitude", latitude);
        initialValues.put("longitude", longitude);
        db.insert(DATABASE_TABLE, null, initialValues);
    }

    public void deleteRow(long rowId) {
        db.delete(DATABASE_TABLE, "rowid=" + rowId, null);
    }

    public List<AddressRow> fetchAllRows() {
        ArrayList<AddressRow> ret = new ArrayList<AddressRow>();
        try {
            Cursor c =
                db.query(DATABASE_TABLE, new String[] {
                    "rowid", "address", "latitude", "longitude"}, null, null, null, null, null);
            int numRows = c.count();
            c.first();
            for (int i = 0; i < numRows; ++i) {
                AddressRow row = new AddressRow();
                row.rowId = c.getLong(0);
                row.address = c.getString(1);
                row.latitude = c.getLong(2);
                row.longitude = c.getLong(3);
                ret.add(row);
                c.next();
            }
        } catch (SQLException e) {
            Log.e(LOGGER, e.toString());
        }
        return ret;
    }

    public AddressRow fetchRow(long rowId) {
        AddressRow row = new AddressRow();
        Cursor c =
            db.query(true, DATABASE_TABLE, new String[] {
                "rowid", "address", "latitude", "longitude"}, "rowid=" + rowId, null, null,
                null, null);
        if (c.count() > 0) {
            c.first();
            row.rowId = c.getLong(0);
            row.address = c.getString(1);
            row.latitude = c.getLong(2);
            row.longitude = c.getLong(3);
            return row;
        } else {
            row.rowId = -1;
            row.address = null;
            row.latitude = 0;
            row.longitude = 0;
        }
        return row;
    }
    
    public AddressRow fetchRow(String address) {
    	Log.e(LOGGER, "fetch row: " + address);
        AddressRow row = new AddressRow();
        Cursor c =
            db.query(false, DATABASE_TABLE, new String[] {
                "rowid", "address", "latitude", "longitude"}, "address='" + address+"'", null, null,
                null, null);
        if (c.count() > 0) {
        	Log.e(LOGGER, "count > 0 ");
            c.first();
            row.rowId = c.getLong(0);
            row.address = c.getString(1);
            row.latitude = c.getLong(2);
            row.longitude = c.getLong(3);
            return row;
        } else {
        	Log.e(LOGGER, "count == 0 ");
            row.rowId = -1;
            row.address = null;
            row.latitude = 0;
            row.longitude = 0;
        }
        return row;
    }

    public void updateRow(long rowId, String address, long latitude, long longitude) {
        ContentValues args = new ContentValues();
        args.put("address", address);
        args.put("latitude", latitude);
        args.put("longitude", longitude);
        db.update(DATABASE_TABLE, args, "rowid=" + rowId, null);
    }
       
}