CursorLoader连接到错误的ContentProvider

Question

问题

CursorLoader实例化似乎使用以前的CursorLoader的URI,而不是作为参数传入的URI.

CursorLoader cursor = new CursorLoader(this, FLASHCARD_CONTENT_URI, 
FLASHCARD_FROM, null, null, null);

给出以下错误:

no such column: front (code 1): , while compiling: 
SELECT _ID, front, back, FROM deck

课程

1. DeckIndex.java - 负责查询数据库"deck"表并返回游标的Cursor数组.
2. DeckShow.java - 负责查询数据库"flashcard"表并返回一个Cursor数组的flashcards.
3. AuducardOpenHelper.java - 负责数据库的DDL和创建.
4. DecksProvider - 负责"甲板"表的CRUD
5. FlashcardsProvider - 负责"flashcard"表的CRUD

说明

传递的URI:

public static final Uri FLASHCARD_CONTENT_URI = 
Uri.parse("content://" + AUTHORITY + "/" + FLASHCARD_TABLE_NAME);

我知道这是由DecksProvider而不是FlashcardsProvider处理的事实.

和FlashcardsProvider中的UriMatcher:

@Override
public boolean onCreate(){
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    uriMatcher.addURI(AUTHORITY, "flashcard", FLASHCARDS);

    auducards = new AuducardOpenHelper(getContext());
    return true;
}

我认为重要的是要提到首先调用DecksIndex类,因此成功完成对DeckProvider的调用.直到我在调用DeckShow onCreate方法时单击其中一个甲板(启动DeckShow活动)时:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getLoaderManager().initLoader(1, null, this);
        setContentView(R.layout.activity_deck_show);
        mAdapter = new SimpleCursorAdapter(this, R.layout.flashcard_item, null, 
              FLASHCARD_FROM, FLASHCARD_TO, 0 );

        Intent intent = getIntent();
        String message = intent.getStringExtra(DeckIndex.EXTRA_MESSAGE);

    }

并发生错误.

LoaderManager初始化行:

DeckIndex.java

getLoaderManager().initLoader(0, null, this);

DeckShow.java

getLoaderManager().initLoader(1, null, this);

感谢您查看我的问题,如果有任何其他详细信息或代码有帮助,请告诉我们!

Answer 1

我遇到了这个问题,并了解到为了添加第二个内容提供商,我不得不:

• 在Androidmanifest.xml文件中定义第二个提供程序.将android:authority设置为包和类的全名.
• 使用权限作为URL

每个提供者的权限必须是唯一的,并且每个提供者的URL必须与权限相匹配.URL也必须全部小写.

这是一个假设的配置:

AndroidManifest.xml中

<application>
  <provider android:name="com.acme.ProviderOne"
    android:authorities="com.acme.providerone" />
  <provider android:name="com.acme.ProviderTwo"
    android:authorities="com.acme.providertwo" />
</application

SRC/COM/ACME/providerone.java

package com.acme

import android.content.ContentProvider;

public class ProviderOne extends ContentProvider {
  public static final Uri CONTENT_URI = Uri.parse("content://com.acme.providerone/objects");
  private static final int ALLROWS = 1;
  private static final int SINGLE_ROW = 2;

  static {
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    uriMatcher.addURI("com.acme.providerone", "objects", ALLROWS);
    uriMatcher.addURI("com.acme.providerone", "objects/#", SINGLE_ROW);
  }
}

SRC/COM/ACME/providertwo.java

package com.acme

import android.content.ContentProvider;

public class ProviderTwo extends ContentProvider {
  public static final Uri CONTENT_URI = Uri.parse("content://com.acme.providertwo/objects");
  private static final int ALLROWS = 1;
  private static final int SINGLE_ROW = 2;

  static {
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    uriMatcher.addURI("com.acme.providertwo", "objects", ALLROWS);
    uriMatcher.addURI("com.acme.providertwo", "objects/#", SINGLE_ROW);
  }
}