轉 android 搜尋圖片 @ pcwiki的部落格

package demo.camera;

import android.app.Activity;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.provider.MediaStore.Images.Media;
import android.util.Log;
import android.view.View;
import android.widget.ImageButton;
import android.widget.TextView;
/**
* 该类完成图片的检索，显示功能
* @author Administrator
*
*/
public class PhotoManager extends Activity {

public static final float DISPLAY_WIDTH = 200;
public static final float DISPLAY_HEIGHT = 200;

//这里采用ImageButton的原因是有Button的作用
private ImageButton photoView;
private TextView nameView;

private Cursor cursor;

private String photoPath; //存放某张图片对应的位置信息
private Bitmap currPhoto;

/*这三个变量主要用来保存Media.DATA,Media.TITLE,Media.DISPLAY_NAME的索引号，来获取每列的数据*/
private int photoIndex;
//private int titleIndex;
private int nameIndex;

public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.photo_view);

photoView = (ImageButton)this.findViewById(R.id.image_view);
photoView.setOnClickListener(clickListener);
nameView = (TextView)this.findViewById(R.id.view_name);

//指定获取的列
String columns[] = new String[]{
Media.DATA,Media._ID,Media.TITLE,Media.DISPLAY_NAME
};
//cursor = this.managedQuery(Media.EXTERNAL_CONTENT_URI, columns, null, null, null);
cursor = this.getContentResolver().query(Media.EXTERNAL_CONTENT_URI, columns, null, null, null);
photoIndex = cursor.getColumnIndexOrThrow(Media.DATA);
//titleIndex = cursor.getColumnIndexOrThrow(Media.TITLE);
nameIndex = cursor.getColumnIndexOrThrow(Media.DISPLAY_NAME);

Log.v("HERE First:", "First Debug");
//显示第一张图片，但是首先要判断一下，Cursor是否有值
if(cursor.moveToFirst()){
showImage();
}
}

private View.OnClickListener clickListener = new View.OnClickListener() {

@Override
public void onClick(View v) {

if(cursor.moveToNext()){
showImage();
}
}
};

/**
* 显示图像信息
*/
private void showImage(){
photoPath = cursor.getString(photoIndex); //这里获取到的就是图片存储的位置信息
//这里怎样获取图片呢？看decodeBitmap
Log.v("Photo Path:", photoPath);
currPhoto = decodeBitmap(photoPath);
photoView.setImageBitmap(currPhoto);
nameView.setText(cursor.getString(nameIndex));
}

/**
* 从path中获取图片信息
* @param path
* @return
*/
private Bitmap decodeBitmap(String path){
BitmapFactory.Options op = new BitmapFactory.Options();
op.inJustDecodeBounds = true;
Bitmap bmp = BitmapFactory.decodeFile(path, op); //获取尺寸信息
//获取比例大小
int wRatio = (int)Math.ceil(op.outWidth/DISPLAY_WIDTH);
int hRatio = (int)Math.ceil(op.outHeight/DISPLAY_HEIGHT);
//如果超出指定大小，则缩小相应的比例
if(wRatio > 1 && hRatio > 1){
if(wRatio > hRatio){
op.inSampleSize = wRatio;
}else{
op.inSampleSize = hRatio;
}
}
op.inJustDecodeBounds = false;
bmp = BitmapFactory.decodeFile(path, op);
return bmp;
}