1

其次，我真的是 android 的新手，还没有完全掌握它的工作方式（对于编写大部分教程的人来说，我可以在网上很遗憾地找到，所以一个好的快速和肮脏的教程也会很棒）。继续解决问题，我将尝试仅发布相关代码，如果我跳过某些内容，请告诉我。

清单条目：

<provider android:name="MyContentProvider" android:authorities="hua.it20910.android.provider"/>

主要活动调用：

Cursor c = getContentProvider().query(MyContentProvider.getTableUri(1), null, null, null, null);

内容提供商：

private static SQLiteDatabase db;
private static final String database_name = "contactlist.db";
private static final int database_version = 1;
private static final String table1="Contacts";
private static final String[] table1_row={"_id","Surname","Name","Phone","Email","Address","Group"};
private static final String table2="Groups";
private static final String[] table2_row={"_id","Name"};

public static final String PROVIDER_NAME = "hua.it20910.android.provider";
public static final Uri CONTACTS_URI = Uri.parse("content://"+ PROVIDER_NAME + "/"+table1);
public static final Uri GROUPS_URI = Uri.parse("Content://"+PROVIDER_NAME + "/"+table2);

private static final int CONTACTS = 1;
private static final int CONTACT_ID = 2;
private static final int GROUPS = 3;
private static final int GROUP_ID = 4;

private static final UriMatcher myMatcher;
static {
    myMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    myMatcher.addURI(PROVIDER_NAME, table1, CONTACTS);
    myMatcher.addURI(PROVIDER_NAME, table1+"/#", CONTACT_ID);
    myMatcher.addURI(PROVIDER_NAME, table2, GROUPS);
    myMatcher.addURI(PROVIDER_NAME, table1+"/#", GROUP_ID);
}
private static final String table1Sql = "CREATE TABLE "
            + table1 + "(" 
            + table1_row[0] + " INTEGER PRIMARY KEY AUTOINCREMENT, " 
            + table1_row[1] + " VARCHAR(25), "
            + table1_row[2] + " VARCHAR(25), " 
            + table1_row[3] + " INTEGER, " 
            + table1_row[4] + " VARCHAR(25), "
            + table1_row[5] + " VARCHAR(25)) ";

    private static final String table2Sql = "CREATE TABLE " 
            + table2 + "("
            + table2_row[0] + " INTEGER PRIMARY KEY AUTOINCREMENT, "
            + table2_row[1] + " VARCHAR(25))";


private class DatabaseHelper extends SQLiteOpenHelper{

    public DatabaseHelper(Context context) {
        super(context, database_name, null, database_version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(table1Sql);
        db.execSQL(table2Sql);
    }

    @Override
      public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
         db.execSQL("DROP TABLE IF EXISTS "+table1 );
         db.execSQL("DROP TABLE IF EXISTS "+table2 );
         onCreate(db);
      }     
}


public static Uri getTableUri(int i){
    if (i==1){
        return CONTACTS_URI;
    }
    if (i==2){
        return GROUPS_URI;
    }
    else{
        return null;
    }
}

@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
    SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();
    switch (myMatcher.match(uri)){
        case CONTACTS:
            sqlBuilder.setTables(table1);
            break;
        case CONTACT_ID:
            sqlBuilder.setTables(table1);
            sqlBuilder.appendWhere("_id=" + uri.getPathSegments().get(1));
            break;
        case GROUPS:
            sqlBuilder.setTables(table2);
            break;
        case GROUP_ID:
            sqlBuilder.setTables(table2);
            sqlBuilder.appendWhere("_id=" + uri.getPathSegments().get(1));
            break;
        default:
            throw new SQLException("Wrong uri " + uri);
    }
    if (sortOrder == null || sortOrder == "")
        sortOrder = "_id DESC";
    Cursor c = db.query(null, projection, selection, selectionArgs, null, null, sortOrder);
    c.setNotificationUri(getContext().getContentResolver(), uri);
    return null;
}

正如标题中提到的，我目前收到的错误消息是执行查询时的无效表，但我已经经历了一大堆其他错误才能到达这里，我不确定我是解决了它们还是只是走来走去他们只是为了将来再次找到它们，因此将不胜感激任何错误纠正。

日志猫：

01-11 05:43:08.385: E/Trace(930): error opening trace file: No such file or directory (2)
01-11 05:43:08.525: I/ActivityThread(930): Pub hua.it20910.android.provider: hua.it20910.android.MyContentProvider
01-11 05:43:09.515: D/dalvikvm(930): GC_FOR_ALLOC freed 57K, 7% free 2583K/2760K, paused 191ms, total 193ms
01-11 05:43:09.515: I/dalvikvm-heap(930): Grow heap (frag case) to 3.241MB for 635812-byte allocation
01-11 05:43:09.565: D/dalvikvm(930): GC_FOR_ALLOC freed 1K, 6% free 3202K/3384K, paused 43ms, total 43ms
01-11 05:43:09.616: D/dalvikvm(930): GC_CONCURRENT freed <1K, 6% free 3214K/3384K, paused 5ms+13ms, total 52ms
01-11 05:43:09.635: D/AndroidRuntime(930): Shutting down VM
01-11 05:43:09.645: W/dalvikvm(930): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
01-11 05:43:09.655: E/AndroidRuntime(930): FATAL EXCEPTION: main
01-11 05:43:09.655: E/AndroidRuntime(930): java.lang.RuntimeException: Unable to start activity ComponentInfo{hua.it20910.android/hua.it20910.android.MainActivity}: java.lang.IllegalStateException: Invalid tables
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.os.Handler.dispatchMessage(Handler.java:99)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.os.Looper.loop(Looper.java:137)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread.main(ActivityThread.java:5039)
01-11 05:43:09.655: E/AndroidRuntime(930):  at java.lang.reflect.Method.invokeNative(Native Method)
01-11 05:43:09.655: E/AndroidRuntime(930):  at java.lang.reflect.Method.invoke(Method.java:511)
01-11 05:43:09.655: E/AndroidRuntime(930):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-11 05:43:09.655: E/AndroidRuntime(930):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-11 05:43:09.655: E/AndroidRuntime(930):  at dalvik.system.NativeStart.main(Native Method)
01-11 05:43:09.655: E/AndroidRuntime(930): Caused by: java.lang.IllegalStateException: Invalid tables
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.database.sqlite.SQLiteDatabase.findEditTable(SQLiteDatabase.java:971)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1161)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1032)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1200)
01-11 05:43:09.655: E/AndroidRuntime(930):  at hua.it20910.android.MyContentProvider.query(MyContentProvider.java:178)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.content.ContentProvider.query(ContentProvider.java:652)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.content.ContentProvider$Transport.query(ContentProvider.java:189)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.content.ContentResolver.query(ContentResolver.java:372)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.content.ContentResolver.query(ContentResolver.java:315)
01-11 05:43:09.655: E/AndroidRuntime(930):  at hua.it20910.android.MainActivity.displayRecords(MainActivity.java:31)
01-11 05:43:09.655: E/AndroidRuntime(930):  at hua.it20910.android.MainActivity.onCreate(MainActivity.java:19)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.Activity.performCreate(Activity.java:5104)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
01-11 05:43:09.655: E/AndroidRuntime(930):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
01-11 05:43:09.655: E/AndroidRuntime(930):  ... 11 more
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1 回答 1

1

正如标题中提到的，我目前收到的错误消息是执行查询时的无效表，但我已经经历了围绕其他错误的地狱般的工作才能到达这里，我不确定我是否解决了它们[... ]

你得到这个异常是正常的，因为你在 的方法中null执行 sqlite 查询时作为表名传递，这一行：queryContentProvider

Cursor c = db.query(null, projection, selection, selectionArgs, null, null, sortOrder);

第一个参数是表名，您必须提供有效的表名才能使查询成功。因此，根据Uri您选择正确的表并分配一个有效的表名。另外，SQLiteQueryBuilder如果您要完全忽略它并简单地直接查询数据库，那么在同一查询方法中使用 a 的目的是什么？

关于教程，我想你错过了最重要的一个，官方指南ContentProviders，你甚至有一个在那里构建的例子。

于 2013-01-11T08:30:02.887 回答