Question

我是Android开发的新手，想要使用Assets文件夹中的csv文件创建和预填充SQLite数据库。我正在使用数据库适配器类，并在创建数据库后的onCreate方法中，我想从assets文件夹中读取csv文件，并使用它来使用DatabaseUtils.InsertHelper插入行。

import android.database.DatabaseUtils.InsertHelper; 
//... 

public void onCreate(SQLiteDatabase db) {
    db.execSQL(DATABASE_CREATE);

    // need to read the path csv data here containing columns "_id" and "path"

    try {
        InputStream is = getAssets().open("pathcsv"); 

        int size = is.available();

        // Read the entire asset into a local byte buffer.
        byte[] buffer = new byte[size];
        is.read(buffer);
        is.close();

        // Convert the buffer into a string.
        String text = new String(buffer);

    } catch (IOException e) {
        // Should never happen!
        throw new RuntimeException(e);
    }


    // Create a single InsertHelper to handle this set of insertions. 
    InsertHelper ih = new InsertHelper(db, "path_table"); 

    // Get the numeric indexes for each of the columns that we're updating 
    final int id_Column = ih.getColumnIndex("_id"); 
    final int path_Column = ih.getColumnIndex("path"); 

    while (moreRowsToInsert) { 
        // ... Create the data for this row (not shown) ... 

        // Get the InsertHelper ready to insert a single row 
        ih.prepareForInsert(); 

        // Add the data for each column 
        ih.bind(id_Column, idData); 
        ih.bind(path_Column, pathData); 

        // Insert the row into the database. 
        ih.execute(); 
    } 
} 
//... 


}

我在getAssets（）行上遇到了一个日食错误：

-The method getAssets() is undefined for the type DatabaseHelper

我似乎无法让上下文工作，任何帮助都会受到赞赏。

更新

我应该包含所有代码，即：

private static class DatabaseHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);} 

    @Override
    public void onCreate(SQLiteDatabase db) {
           db.execSQL(PATH_TABLE_CREATE);
           try {
               InputStream is = getAssets().open("@string/path");  

    // the rest is as in my first post above....

如果我按如下方式添加上下文，则会收到错误：

private static class DatabaseHelper extends SQLiteOpenHelper {

    private Context myContext; 

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);} 

    @Override
    public void onCreate(SQLiteDatabase db, Context context) {
           db.execSQL(PATH_TABLE_CREATE);
           myContext = context; 
           try {
               InputStream is = myContext.getAssets().open("@string/path");  

    // the rest is as in my first post above....

我得到的错误是：

The method onCreate(SQLiteDatabase, Context) of type DQDbAdapter.DatabaseHelper must   override or implement a supertype method

请您帮我解决此错误。感谢

Answer 1

您是否需要在应用中填充数据库，还是可以提前准备？见这里：

Populate Android Database From CSV file?

如果您真的想要在您发布的代码中执行您要执行的操作，则可以执行以下操作：

public class DatabaseHelper extends SQLiteOpenHelper {
...
    private Context context;

    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        ...
        context.getAssets()...
    }

Android，使用InsertHelper和Assets创建和填充SQLite数据库

1 个答案: