Question

我的Android设备中有一个包含多个.CSV文件的文件夹。

我想将所有这些导入我的SQLite数据库，但是每个文件必须是不同的表。

所有.CSV文件都很简单。他们只有一栏。

示例：

File.CSV

AnotherFile.CSV

XXXXX

ZZZZZZZZZZ

FFFF

这是我的方法，它不起作用。我不明白为什么：

@TargetApi(Build.VERSION_CODES.M)
public void importaTabelas() {

    //Check the read permission
    if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {

        try {

            //Check if the folder exists
            File importDir = new File (Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/ENEL/IMPORTADOS/");
            if (!importDir.exists())
            {
                importDir.mkdirs();
            }

            //Read all file names
            for (File f : importDir.listFiles()) {

                if (f.isFile()) {

                    //Put the files names into variable nomeArq
                    nomeArq = f.getName();

                    //Take off the file extension .csv
                    if (nomeArq.indexOf(".") > 0)
                        nomeArq = nomeArq.substring(0, nomeArq.lastIndexOf("."));

                    SQLiteDatabase db = this.banco.getWritableDatabase();

                    try {

                        //Create table with the name of the .csv file
                        String criaTab = "CREATE TABLE IF NOT EXISTS " + nomeArq +  " (id integer PRIMARY KEY AUTOINCREMENT, codigo varchar (50))";
                        db.execSQL(criaTab);
                        db.close();

                    } catch (SQLException e) {
                        e.printStackTrace();
                    }

                    //String for the file location
                    String fn = importDir + "/" + nomeArq + ".csv";

                    //Reads the file
                    FileReader fileReader = new FileReader(fn);

                    BufferedReader buffer = new BufferedReader(fileReader);

                    //ContentValues contentValues = new ContentValues();

                    String line = "";

                    //db.beginTransaction();

                    while ((line = buffer.readLine()) != null) {

                        //String[] colums = line.split("\t");

                        //String[] colums = line.split(";");

                        Toast.makeText(this, line, Toast.LENGTH_SHORT).show();

                        //contentValues.put("codigo", line);

                        //db.insert(nomeArq, null, contentValues);

                        db.execSQL("INSERT INTO " + nomeArq +  " (codigo) VALUES ('" + line + "')");

                    }

                    //db.setTransactionSuccessful();
                    //db.endTransaction();

                }

            }

        } catch (Exception e) {

            Toast.makeText(this, "Catch!", Toast.LENGTH_SHORT).show();
            e.printStackTrace();

        }

    }

    else {

        requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);

    }

}

您会帮助我使其成功吗？谢谢！

Answer 1

我将您的代码重构为许多较小的方法。每种方法都只负责一件事，这是一种好习惯，请尽可能尝试做到这一点。

我只做了几处更改：

创建FileReader的行现在使用该文件（容易出错）
通过创建单个插入查询来更改插入方式，以减少对数据库的访问（例如：INSERT INTO table(codigo) VALUES ('XXXX'), ('ZZZZ'), ('FFFF');）
更改了Toasts中的文本，以更好地确定错误的出处。

尝试一下，看看是否可以更好地发现错误。（我没有尝试编译代码，因此您可能需要对其进行一些调整，但总体而言应该没问题）

主要导入方法：

public void importaTabelas() {

    //Check the read permission
    if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
        try {
            makeDirs();

            //Read all file names
            for (File f : importDir.listFiles()) {
                if (f.isFile()) {
                    importFile(f);
                }
            }
        } catch (IOException e) {
            Toast.makeText(this, "Could not import tables! " + e.getMessage(), Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    } else {
        requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
    }

}

创建目录

private void makeDirs() {
    //Check if the folder exists
    File importDir = new File (Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/ENEL/IMPORTADOS/");
    if (!importDir.exists()) {
        importDir.mkdirs();
    }
}

导入单个文件

private void importFile(File f) {
    try {
        SQLiteDatabase db = this.banco.getWritableDatabase();

        //Put the files names into variable nomeArq
        String nomeArq = f.getName();

        //Take off the file extension .csv
        if (nomeArq.indexOf(".") > 0)
            nomeArq = nomeArq.substring(0, nomeArq.lastIndexOf("."));

        createTable(db, nomeArq);

        String insertQuery = buildImportQuery(f, nomeArq);
        db.execSQL(insertQuery);
    } catch (SQLException e) {
        Toast.makeText(this, "Could not import file. " + e.getMessage(), Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    }
}

为特定文件构建插入查询

private String buildImportQuery(File f, String nomeArq) {
    StringBuilder sb = new StringBuilder();
    try {
        //Reads the file
        FileReader fileReader = new FileReader(f);
        BufferedReader buffer = new BufferedReader(fileReader);
        String line;

        sb.append("INSERT INTO " + nomeArq +  " (codigo) VALUES ");
        boolean addComma = false;
        while ((line = buffer.readLine()) != null) {
            if(line.length() > 0) {
                if(addComma) {
                    sb.append(",");
                }
                sb.append("('" + line.trim() + "')");
                addComma = true;
            }
        }
        sb.append(";");
    } catch (IOException e) {
        Toast.makeText(this, "Could not write query. " + e.getMessage(), Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    }

    return sb.toString();

}

创建一个表

private void createTable(SQLiteDatabase db, String tableName) {
    try {
        //Create table with the name of the .csv file
        String criaTab = "CREATE TABLE IF NOT EXISTS " + tableName +  " (id integer PRIMARY KEY AUTOINCREMENT, codigo varchar (50))";
        db.execSQL(criaTab);
        db.close();

    } catch (Exception e) {
        Toast.makeText(this, "Could not create table " + tableName + "." +  e.getMessage(), Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    }
}

Android-将多个.CSV文件导入到SQLite数据库中的多个表

1 个答案: