android - SimpleCursorAdapter 中的图像

Question

我正在尝试使用带有 ViewBinder 的 SimpleCursorAdapter 从数据库中获取图像并将其放入我的 ListView 项目 View .这是我的代码:

private void setUpViews() {
    mNewsView = (ListView) findViewById(R.id.news_list);

    Cursor cursor = getNews();
    SimpleCursorAdapter curAdapter = new SimpleCursorAdapter(
            getApplicationContext(), R.layout.cursor_item, cursor,
            new String[] { "title", "content", "image" },
            new int[] { R.id.cursor_title, R.id.cursor_content,
                    R.id.news_image });
    
    ViewBinder viewBinder = new ViewBinder() {
        
        public boolean setViewValue(View view, Cursor cursor,
                int columnIndex) {
            ImageView image = (ImageView) view;
            byte[] byteArr = cursor.getBlob(columnIndex);
            image.setImageBitmap(BitmapFactory.decodeByteArray(byteArr, 0, byteArr.length));
            return true;
        }
    };
    ImageView image = (ImageView) findViewById(R.id.news_image);
    viewBinder.setViewValue(image, cursor, cursor.getColumnIndex("image"));
    curAdapter.setViewBinder(viewBinder);
    mNewsView.setAdapter(curAdapter);
}

我得到:

android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 60

在执行 byte[] byteArr = cursor.getBlob(columnIndex); 时。有谁知道我做错了什么？

Answer 1

我扩展了 SimpleCursorAdapter，虽然我没有使用 ViewBinder，但这里是我的代码，用于在 ListView 中使用作为 blob 存储在 sqlite 数据库中的图像。这是改编 self 读过的一篇文章 here .

我的一行布局文件是:

row_layout_two_line.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/select_item">

<ImageView 
    android:id="@+id/pic"
    android:layout_width="40dp"
    android:layout_height="40dp"
    android:layout_marginLeft="10dp"
    android:contentDescription="@string/imagedesc"
    android:src="@drawable/icon"
    android:layout_gravity="center_vertical">
</ImageView>

<LinearLayout
    android:id="@+id/linearLayout0"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_vertical" 
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <TextView
            android:id="@+id/label"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:text="@+id/label"
            android:textStyle="bold"
            android:textColor="#000"
            android:textSize="20sp" >
        </TextView>

        <TextView
            android:id="@+id/label1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:text="@+id/label1"
            android:textStyle="bold"
            android:textColor="#000"
            android:textSize="20sp" >
        </TextView>

    </LinearLayout>

    <TextView
        android:id="@+id/label2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="35dp"
        android:text="@+id/label2"
        android:textColor="#000"
        android:textSize="15sp" >
    </TextView>
</LinearLayout>

调用代码

...
    adapter = null;
    mCursor = search();

    startManagingCursor(mCursor);
    // Now create a new list adapter bound to the cursor.
    BaseAdapter adapter = new ImageCursorAdapter(this, // Context.
            R.layout.row_layout_two_line, // Specify the row template
                                                    // to use (here, two
                                                    // columns bound to the
                                                    // two retrieved cursor
                                                    // rows).
            mCursor, // Pass in the cursor to bind to.
            // Array of cursor columns to bind to.
            new String [] {"personImage", "firstName", "lastName", "title"},
            // Parallel array of which template objects to bind to those
            // columns.
            new int[] { R.id.pic, R.id.label, R.id.label1, R.id.label2 });


    // Bind to our new adapter.
    setListAdapter(adapter);
...

ImageCursorAdapter.java

import android.content.Context;
import android.database.Cursor;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;

public class ImageCursorAdapter extends SimpleCursorAdapter {

    private Cursor c;
    private Context context;

public ImageCursorAdapter(Context context, int layout, Cursor c, String[] from, int[] to) {
    super(context, layout, c, from, to);
    this.c = c;
    this.context = context;
}

public View getView(int pos, View inView, ViewGroup parent) {
       View v = inView;
       if (v == null) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = inflater.inflate(R.layout.row_layout_two_line, null);
       }
       this.c.moveToPosition(pos);      
       String firstName = this.c.getString(this.c.getColumnIndex("firstName"));
       String lastName = this.c.getString(this.c.getColumnIndex("lastName"));
       String titleStr = this.c.getString(this.c.getColumnIndex("title"));
       byte[] image = this.c.getBlob(this.c.getColumnIndex("personImage"));
       ImageView iv = (ImageView) v.findViewById(R.id.pic);
       if (image != null) {
           // If there is no image in the database "NA" is stored instead of a blob 
           // test if there more than 3 chars "NA" + a terminating char if more than
           // there is an image otherwise load the default
           if(image.length > 3)
           {
               iv.setImageBitmap(BitmapFactory.decodeByteArray(image, 0, image.length));
           }
           else
           {
               iv.setImageResource(R.drawable.icon);
           }
       }
           TextView fname = (TextView) v.findViewById(R.id.label);
           fname.setText(firstName);

           TextView lname = (TextView) v.findViewById(R.id.label1);
           lname.setText(lastName);

           TextView title = (TextView) v.findViewById(R.id.label2);
           title.setText(titleStr);
       return(v);
}

最后是这样的