ANDROID笔记:通过ContentProvider得到SD卡的图片

activity:

package com.example.android_contentprovider;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.provider.MediaStore.Audio.Media;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    // 图片数据集
    List<ImagePro> list = new ArrayList<ImagePro>();
    LayoutInflater inflater;

    @Override
    protected void onCreate(Bundle savedInstancetate) {
        super.onCreate(savedInstancetate);
        setContentView(R.layout.activity_main);
        inflater = LayoutInflater.from(MainActivity.this);
        // 重新扫描图片,添加新图片
        allScan();
        initData();
        GridView gridView = (GridView) findViewById(R.id.grid);
        gridView.setAdapter(adapter);
        gridView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
                View view = getLayoutInflater().inflate(R.layout.grid_item,
                        null);

                ImageView imageView = (ImageView) view
                        .findViewById(R.id.imageView1);
                TextView textView = (TextView) view.findViewById(R.id.text);

                imageView.setImageBitmap(BitmapFactory.decodeFile(list
                        .get(arg2).getData()));
                textView.setText(list.get(arg2).getName());
                // 弹出对话框
                new AlertDialog.Builder(MainActivity.this).setView(view)
                        .setPositiveButton("ok", null).show();
            }
        });
    }

    private void initData() {
        // 判断SD卡是否存在
        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            // 获得存储卡的路径
            String sdpath = Environment.getExternalStorageDirectory() + "/";
            Toast.makeText(MainActivity.this, sdpath, Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(MainActivity.this, "null=========",
                    Toast.LENGTH_LONG).show();
        }
        // 使用MediaStore.Images.Media.EXTERNAL_CONTENT_URI,疯狂android讲义463页的Media.EXTERNAL_CONTENT_URI查找不到图片
        Cursor cursor = getContentResolver().query(
                MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null,
                null);
        while (cursor.moveToNext()) {
            ImagePro imagePro = new ImagePro();
            // 得到图片名称
            imagePro.setName(cursor.getString(cursor
                    .getColumnIndex(Media.DISPLAY_NAME)));
            // 得到图片尺寸
            imagePro.setDesc(cursor.getString(cursor.getColumnIndex(Media.SIZE)));
            // 得到图片路径
            byte[] path = cursor.getBlob(cursor.getColumnIndex(Media.DATA));
            imagePro.setData(new String(path, 0, path.length - 1));
            list.add(imagePro);
        }
    }

    /**
     * 扫描SD卡,添加新图片
     */
    public void allScan() {
        sendBroadcast(new Intent(
                Intent.ACTION_MEDIA_MOUNTED,
                Uri.parse("file://" + Environment.getExternalStorageDirectory())));
    }

    private BaseAdapter adapter = new BaseAdapter() {

        @Override
        public View getView(int arg0, View arg1, ViewGroup arg2) {
            // 不能直接显示全部图片,会内存溢出(OOM)
            View view = inflater.inflate(R.layout.grid_item, null);
            TextView textView = (TextView) view.findViewById(R.id.text);
            textView.setText(list.get(arg0).getName());
            return view;
        }

        @Override
        public long getItemId(int arg0) {
            // TODO Auto-generated method stub
            return arg0;
        }

        @Override
        public Object getItem(int arg0) {
            // TODO Auto-generated method stub
            return list.get(arg0);
        }

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return list.size();
        }
    };

}

pojo类

package com.example.android_contentprovider;

public class ImagePro {
    private String name;
    private String desc;
    private String data;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public String getData() {
        return data;
    }

    public void setData(String data) {
        this.data = data;
    }

    public ImagePro() {
    }

    public ImagePro(String name, String desc, String data) {
        super();
        this.name = name;
        this.desc = desc;
        this.data = data;
    }

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <GridView
        android:id="@+id/grid"
        android:numColumns="2"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >
    </GridView>

</RelativeLayout>

grid_item.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:orientation="vertical" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:text="0000"/>

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android_contentprovider"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <uses-permission android:name="android.permission.RESTART_PACKAGES" />

    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.android_contentprovider.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

PS:权限需要写在activity前

android系统为其他的应用程序访问多媒体资源提供了ContentProvider

MediaStore.Audio.Media.EXTERNAL_CONTENT_URI:存储在SD卡上的音频文件ContentProvider的URI

MediaStore.Audio.Media.INTERNAL_CONTENT_URI:存储在手机内部存储器卡上的音频文件ContentProvider的URI

MediaStore.Images.Media.EXTERNAL_CONTENT_URI：存储在SD卡上的图像文件文件ContentProvider的URI

MediaStore.Images.Media.INTERNAL_CONTENT_URI:存储在手机内部存储器上图像文件ContentProvider的URI

MediaStore.Video.Media.INTERNAL_CONTENT_URI:存储在手机内部存储器上的视频文件ContentProvider的URI

MediaStore.Video.Media.EXTERNAL_CONTENT_URI：存储在SD卡上的视频文件ContentProvider的URI