android - 数据库代码在每个 android API 上崩溃，但 4.1

Question

我有一些代码是关于将填充的数据库复制到 android 中的 sqlite 数据库中。

我已经使用 android API 4.1 版测试了我的所有代码。但是现在当我尝试从 db 获取查询时，所有其他版本都会崩溃。这是 dbHelper 的代码：

package com.rasta.ghavanin;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

    public class DatabaseHelper extends SQLiteOpenHelper{

    //The Androids default system path of your application database.
    private static String DB_PATH = "/data/data/com.rasta.ghavanin/databases/";

    private static String DB_NAME;
    private static String COLUMN_ID_NAME = "_id";
    private static String COLUMN_DESC_NAME = "Description";

    private SQLiteDatabase DataBase; 

    private final Context myContext;

    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */
    public DatabaseHelper(Context context , String DBName) {

        super(context, DBName, null, 1);
        DB_NAME = DBName;
        this.myContext = context;
    }   

    /**
     * Creates a empty database on the system and rewrites it with your own database.
     * */
    public void createDataBase() throws IOException{

        //By calling this method and empty database will be created into the default system path
        //of your application so we are gonna be able to overwrite that database with our database.
        this.getReadableDatabase();

        try 
        {
            copyDataBase();
        }
        catch (IOException e) 
        {
            throw new Error("Error copying database");
        }
    }

    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * This is done by transfering bytestream.
     * */
    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(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();

    }

    // this method simply open the database
    public void openDataBase() throws SQLException{

        //Open the database
        String myPath = DB_PATH + DB_NAME;
        DataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
    }

    @Override
    public synchronized void close() {

            if(DataBase != null)
                DataBase.close();

            super.close();

    }

    public String getLaw(int lawID)
    {
        String[] columnNames = { COLUMN_ID_NAME, COLUMN_DESC_NAME};
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query("Laws", columnNames, COLUMN_ID_NAME + "=?",
                new String[] { String.valueOf(lawID) }, null, null, null, null);

        if (cursor != null)
        {
            cursor.moveToFirst();
            return cursor.getString(1);
        }
        else
        {
            return "salam :D";
        }
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    // Add your public helper methods to access and get content from the database.
    // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
    // to you to create adapters for your views.

}

这是logcat，全部都是：D

01-06 15:10:39.554: D/dalvikvm(562): Not late-enabling CheckJNI (already on)
01-06 15:10:40.254: I/dalvikvm(562): Turning on JNI app bug workarounds for target SDK version 8...
01-06 15:10:42.214: D/gralloc_goldfish(562): Emulator without GPU emulation detected.
01-06 15:10:46.974: D/dalvikvm(562): GC_CONCURRENT freed 160K, 3% free 10163K/10439K, paused 7ms+8ms
01-06 15:10:47.304: I/SqliteDatabaseCpp(562): sqlite returned: error code = 1, msg = no such table: Laws, db=/data/data/com.rasta.ghavanin/databases/Constitution
01-06 15:10:47.316: D/AndroidRuntime(562): Shutting down VM
01-06 15:10:47.324: W/dalvikvm(562): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
01-06 15:10:47.384: E/AndroidRuntime(562): FATAL EXCEPTION: main
01-06 15:10:47.384: E/AndroidRuntime(562): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rasta.ghavanin/com.rasta.ghavanin.ViewActivity}: android.database.sqlite.SQLiteException: no such table: Laws: , while compiling: SELECT _id, Description FROM Laws WHERE _id=?
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread.access$600(ActivityThread.java:122)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.os.Handler.dispatchMessage(Handler.java:99)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.os.Looper.loop(Looper.java:137)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread.main(ActivityThread.java:4340)
01-06 15:10:47.384: E/AndroidRuntime(562):  at java.lang.reflect.Method.invokeNative(Native Method)
01-06 15:10:47.384: E/AndroidRuntime(562):  at java.lang.reflect.Method.invoke(Method.java:511)
01-06 15:10:47.384: E/AndroidRuntime(562):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-06 15:10:47.384: E/AndroidRuntime(562):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-06 15:10:47.384: E/AndroidRuntime(562):  at dalvik.system.NativeStart.main(Native Method)
01-06 15:10:47.384: E/AndroidRuntime(562): Caused by: android.database.sqlite.SQLiteException: no such table: Laws: , while compiling: SELECT _id, Description FROM Laws WHERE _id=?
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:64)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1564)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1449)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1405)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1523)
01-06 15:10:47.384: E/AndroidRuntime(562):  at com.rasta.ghavanin.DatabaseHelper.getLaw(DatabaseHelper.java:111)
01-06 15:10:47.384: E/AndroidRuntime(562):  at com.rasta.ghavanin.ViewActivity.updateDescription(ViewActivity.java:110)
01-06 15:10:47.384: E/AndroidRuntime(562):  at com.rasta.ghavanin.ViewActivity.onCreate(ViewActivity.java:82)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.Activity.performCreate(Activity.java:4465)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
01-06 15:10:47.384: E/AndroidRuntime(562):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
01-06 15:10:47.384: E/AndroidRuntime(562):  ... 11 more
01-06 15:10:50.554: I/Process(562): Sending signal. PID: 562 SIG: 9

score 0 · Accepted Answer

终于解决了。

当您在 android 中创建数据库时，它会自动将名为 android_metadata 的表添加到数据库中。现在，因为我正在使用流复制我的外部数据库，所以我正在重写整个文件，因此 4.1 之前的 API 所需的 android_metadata 必须手动添加到外部数据库中。

score 0 · Accepted Answer

在没有表定义的情况下诊断这个有点棘手，但我可以告诉你。关键错误在此语句中：

java.lang.RuntimeException：无法启动活动 ComponentInfo{com.rasta.ghavanin/com.rasta.ghavanin.ViewActivity}：android.database.sqlite.SQLiteException：没有这样的表：法律：，编译时：SELECT _id，描述 FROM法律 WHERE _id=?

请注意，它说没有TABLE Laws. 不知何故，这并没有在您正在测试的每个模拟器上导入。一些提示。

应该只有一个位置来获取数据库路径，所有其他功能都应该引用它。这将避免任何混淆，并在以后需要时更容易更改。
正如 Doomsknight 建议的那样，您最好使用 absolutePath 作为此参考。
我会尝试通过 adb 使用 sqlite来查看数据库是否正确。我怀疑当你这样做时，问题就会显现出来。

score 0 · Accepted Answer

要获取数据库路径，您应该真正使用类似的东西

String myPath = myContext.getDatabasePath(DB_NAME).getAbsolutePath();

而不是你所做的方式DB_PATH + DB_NAME

有几个地方你已经这样做了。不确定它会解决问题，但值得一试。并且无论哪种方式都是更好的做法。

（您已硬编码 DB_PATH 不/data/data/com.rasta.ghavanin/databases/理想）

android - 数据库代码在每个 android API 上崩溃，但 4.1

3 回答 3

Related

Reference