嗨，我是Android数据库的新手。我想在按钮单击时向表中插入值。这是我使用的代码。但是数据库未打开时会显示错误。我该怎么办？请帮忙
以下是代码：
package com.istyle;
import java.io.File;
import java.io.IOException;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class Profile_Page extends Activity {
protected SQLiteDatabase sampleDB;
private static final String DATABASE_NAME = "istyle.sqlite";
private static final int SELECT_PICTURE = 1;
private String selectedImagePath;
private ImageView img;
String readName;
String readMail;
EditText Name;
EditText Email;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.profile_page);
Name=(EditText)findViewById(R.id.editText1);
Email=(EditText)findViewById(R.id.editText2);
final DataBaseHelper dbAdapter = DataBaseHelper.getInstance(this, DATABASE_NAME);
try {
if (getFirstRun()) {
sampleDB = dbAdapter.getDatabase();
setRunned();
} else {
sampleDB = dbAdapter.getWritableDatabase();
}
Cursor c1 = sampleDB.rawQuery("SELECT * FROM USER_PROFILE WHERE user_id='1'", null);
if (c1.moveToFirst()) {
do{
System.out.println(c1.getString(c1.getColumnIndex("user_id")));
System.out.println(c1.getString(c1.getColumnIndex("user_name")));
System.out.println(c1.getString(c1.getColumnIndex("user_email")));
} while (c1.moveToNext());
}
Button ok=(Button)findViewById(R.id.button1);
ok.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
readName=Name.getText().toString();
readMail=Email.getText().toString();
String Query="UPDATE TABLE user_profile SET user_name="+readName+" user_email="+readMail+" WHERE user_id='1'";
sampleDB.execSQL(Query);
}
});
c1.close();
sampleDB.close();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
img = (ImageView)findViewById(R.id.imageView1);
((Button) findViewById(R.id.button3))
.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent,"Select Picture"), SELECT_PICTURE);
}
});
}
private void setRunned() {
// TODO Auto-generated method stub
}
private boolean getFirstRun() {
// TODO Auto-generated method stub
return false;
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
Uri selectedImageUri = data.getData();
selectedImagePath = getPath(selectedImageUri);
System.out.println("Image Path : " + selectedImagePath);
img.setImageURI(selectedImageUri);
}
}
}
public String getPath(Uri uri) {
String[] projection = { MediaStore.Images.Media.DATA };
Cursor cursor = managedQuery(uri, projection, null, null, null);
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}
}
我使用的数据库助手类如下
package com.istyle;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;
// Modify by me 24/6/2010
public class DataBaseHelper extends SQLiteOpenHelper {
private static SQLiteDatabase sqliteDb;
private static DataBaseHelper instance;
//private static final int DATABASE_VERSION = 1;
private static final int DATABASE_VERSION = 4;
// the default database path is :
// /data/data/pkgNameOfYourApplication/databases/
private static String DB_PATH_PREFIX = "/data/data/";
private static String DB_PATH_SUFFIX = "/databases/";
private static final String TAG = "DataBaseHelper";
private Context context;
/***
* Contructor
*
* @param context
* : app context
* @param name
* : database name
* @param factory
* : cursor Factory
* @param version
* : DB version
*/
private DataBaseHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, name, factory, version);
this.context = context;
Log.i(TAG, "Create or Open database : " + name);
}
/***
* Initialize method
*
* @param context
* : application context
* @param databaseName
* : database name
*/
private static void initialize(Context context, String databaseName) {
if (instance == null) {
/**
* Try to check if there is an Original copy of DB in asset
* Directory
*/
if (!checkDatabase(context, databaseName)) {
// if not exists, I try to copy from asset dir
try {
copyDataBase(context, databaseName);
} catch (IOException e) {
Log.e(TAG,"Database "+ databaseName + " does not exists and there is no Original Version in Asset dir");
}
}
Log.i(TAG, "Try to create instance of database (" + databaseName + ")");
instance = new DataBaseHelper(context, databaseName,
null, DATABASE_VERSION);
sqliteDb = instance.getWritableDatabase();
Log.i(TAG, "instance of database (" + databaseName + ") created !");
}
}
/***
* Static method for getting singleton instance
*
* @param context
* : application context
* @param databaseName
* : database name
* @return : singleton instance
*/
public static final DataBaseHelper getInstance(
Context context, String databaseName) {
initialize(context, databaseName);
return instance;
}
/***
* Method to get database instance
*
* @return database instance
*/
public SQLiteDatabase getDatabase() {
return sqliteDb;
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG, "onCreate : nothing to do");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.d(TAG, "onUpGrade : add column Cache_Id3 to table BUI_BUILDINGS in adcensusdb.sql. This is an upgrade");
}
/***
* Method for Copy the database from asset directory to application's data
* directory
*
* @param databaseName
* : database name
* @throws IOException
* : exception if file does not exists
*/
private void copyDataBase(String databaseName) throws IOException {
copyDataBase(context, databaseName);
}
/***
* Static method for copy the database from asset directory to application's
* data directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @throws IOException
* : exception if file does not exists
*/
private static void copyDataBase(Context aContext, String databaseName)
throws IOException {
// Open your local db as the input stream
InputStream myInput = aContext.getAssets().open(databaseName);
// Path to the just created empty db
String outFileName = getDatabasePath(aContext, databaseName);
Log.i(TAG, "Check if create dir : " + DB_PATH_PREFIX
+ aContext.getPackageName() + DB_PATH_SUFFIX);
// if the path doesn't exist first, create it
File f = new File(DB_PATH_PREFIX + aContext.getPackageName()
+ DB_PATH_SUFFIX);
if (!f.exists())
f.mkdir();
Log.i(TAG, "Trying to copy local DB to : " + outFileName);
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the 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();
Log.i(TAG, "DB (" + databaseName + ") copied!");
}
/***
* Method to check if database exists in application's data directory
*
* @param databaseName
* : database name
* @return : boolean (true if exists)
*/
public boolean checkDatabase(String databaseName) {
return checkDatabase(context, databaseName);
}
/***
* Static Method to check if database exists in application's data directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @return : boolean (true if exists)
*/
public static boolean checkDatabase(Context aContext, String databaseName) {
SQLiteDatabase checkDB = null;
try {
String myPath = getDatabasePath(aContext, databaseName);
Log.i(TAG, "Trying to conntect to : " + myPath);
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
Log.i(TAG, "Database " + databaseName + " found!");
checkDB.close();
} catch (SQLiteException e) {
Log.i(TAG, "Database " + databaseName + " does not exists!");
}
return checkDB != null ? true : false;
}
/***
* Method that returns database path in the application's data directory
*
* @param databaseName
* : database name
* @return : complete path
*/
private String getDatabasePath(String databaseName) {
return getDatabasePath(context, databaseName);
}
/***
* Static Method that returns database path in the application's data
* directory
*
* @param aContext
* : application context
* @param databaseName
* : database name
* @return : complete path
*/
private static String getDatabasePath(Context aContext, String databaseName) {
return DB_PATH_PREFIX + aContext.getPackageName() + DB_PATH_SUFFIX
+ databaseName;
}
}
答案 0 :(得分：0)
此处：Android SQLite Database。 （并在下次询问之前确实使用Google进行查询）
答案 1 :(得分：0)
您可以将Sqlite数据库检查为Android sqlite和SQLite 供进一步参考。
答案 2 :(得分：0)
您没有在表上创建表USER_PROFILE并触发查询。从Android database tutorial或this获取Android数据库概述。
答案 3 :(得分：0)
我真的不明白为什么你需要在这里使用dbAdapter.getDatabase（）。但是如果它在数据库设计和流程中不那么重要，你可以使用这行代码
final DataBaseHelper dbAdapter = DataBaseHelper.getInstance(this, DATABASE_NAME);
try {
sampleDB = dbAdapter.getWritableDatabase();
...
而不是一个：
final DataBaseHelper dbAdapter = DataBaseHelper.getInstance(this, DATABASE_NAME);
try {
if (getFirstRun()) {
sampleDB = dbAdapter.getDatabase();
setRunned();
}
else {
sampleDB = dbAdapter.getWritableDatabase();
}
...
答案 4 :(得分：0)