Android-对相册中的图片进行上传或下载

目标效果：

   

打开相册选择一张图片，会显示到上方的ImageView中并存储到Bmob中，存储后进入Bmob后台，复制刚才添加的数据的objectId，粘贴到代码指定出，然后运行，点击下载会在下方的ImageView显示刚才上传的图片，这里的下载是指定objectId，可以进行动态获取objectId进行下载。

1.activity_main.xml页面设置布局。

activity_main.xml页面：

<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"
    tools:context=".MainActivity" >

	<ImageView 
	    android:id="@+id/ivHead"
	    android:layout_marginTop="20dp"
	    android:layout_centerHorizontal="true"
	    android:layout_width="150dp"
	    android:layout_height="150dp"/>

	<Button
	    android:id="@+id/btnSelectImage"
	    android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:layout_alignParentLeft="true"
	    android:layout_below="@+id/ivHead"
	    android:layout_marginTop="16dp"
	    android:text="打开相册" />

	<Button
	    android:id="@+id/btnDownloadImage"
	    android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:layout_alignParentLeft="true"
	    android:layout_below="@+id/btnSelectImage"
	    android:text="下载图片" />

	<ImageView
	    android:id="@+id/ivDownload"
	    android:layout_width="150dp"
	    android:layout_height="150dp"
	    android:layout_marginTop="20dp"
	    android:layout_centerHorizontal="true"
	    android:layout_below="@+id/btnDownloadImage" />
	
</RelativeLayout>

2.MainActivity.java页面定义上传与下载方法。

MainActivity.java页面：

package com.example.text;

import java.io.File;

import cn.bmob.v3.Bmob;
import cn.bmob.v3.BmobQuery;
import cn.bmob.v3.datatype.BmobFile;
import cn.bmob.v3.listener.DownloadFileListener;
import cn.bmob.v3.listener.GetListener;
import cn.bmob.v3.listener.UploadBatchListener;
import cn.bmob.v3.listener.UploadFileListener;

import com.android.volley.toolbox.ImageLoader;
import com.example.text.MainActivity;

import entity.Person;

import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

	private ImageView ivHead, ivDownload;
	private Button btnSelectImage, btnDownloadImage;

	private static final int IMAGE_CODE = 0;// 打开相册
	private static final int RESIZE_CODE = 2;// 调整大小

	private static final String IMAGE_NAME = " ";// 图片字符串

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		Bmob.initialize(this, "8ef8a4752f48682eadb32d3c8c8e398f");// 初始化Bmob

		// 初始化控件
		init();

		// 绑定点击事件
		bindClick();
	}

	// 初始化控件
	private void init() {
		ivHead = (ImageView) findViewById(R.id.ivHead);
		ivDownload = (ImageView) findViewById(R.id.ivDownload);
		btnSelectImage = (Button) findViewById(R.id.btnSelectImage);
		btnDownloadImage = (Button) findViewById(R.id.btnDownloadImage);
	}

	// 绑定点击事件
	private void bindClick() {
		btnSelectImage.setOnClickListener(this);
		btnDownloadImage.setOnClickListener(this);
	}

	@Override
	public void onClick(View view) {
		switch (view.getId()) {
		case R.id.btnSelectImage:
			Intent galleryIntent = new Intent(Intent.ACTION_GET_CONTENT);
			galleryIntent.addCategory(Intent.CATEGORY_OPENABLE);
			galleryIntent.setType("image/*");//图片
			startActivityForResult(galleryIntent, IMAGE_CODE);   //跳转，传递打开相册请求码
			break;
		case R.id.btnDownloadImage:
			BmobQuery<Person> query=new BmobQuery<Person>();
			query.getObject(this,"ef292ff6ef",new GetListener<Person>() {  //第二个参数为想要下载的BmobFile数据的objectId
				
				@Override
				public void onSuccess(Person person) {
					Toast.makeText(MainActivity.this,"获取成功",Toast.LENGTH_SHORT).show();
					
					//下载图片
					downloadImage(person);
				}
				
				@Override
				public void onFailure(int arg0, String arg1) {
					Toast.makeText(MainActivity.this,"获取失败",Toast.LENGTH_SHORT).show();
				}
			});
			break;
		default:
			break;
		}

	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		if (resultCode != RESULT_OK) {
			return;
		} else {
			switch (requestCode) {
			case IMAGE_CODE:
				Uri uri = data.getData();
				resizeImage(uri);
				// 将获取到的uri转换为String型
				String[] images = { MediaStore.Images.Media.DATA };// 将图片URI转换成存储路径
				Cursor cursor = this
						.managedQuery(uri, images, null, null, null);
				int index = cursor
						.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
				cursor.moveToFirst();
				String img_url = cursor.getString(index);
				upload(img_url);
				break;

			case RESIZE_CODE:
				if (data != null) {
					showResizeImage(data);
				}
				break;
			}
		}
		super.onActivityResult(requestCode, resultCode, data);
	}

	// 判断SD卡是否存在
	private boolean isSdcardExisting() {
		final String state = Environment.getExternalStorageState();
		if (state.equals(Environment.MEDIA_MOUNTED)) {
			return true;
		} else {
			return false;
		}
	}

	// 重塑图片大小
	public void resizeImage(Uri uri) {
		Intent intent = new Intent("com.android.camera.action.CROP");
		intent.setDataAndType(uri, "image/*");
		intent.putExtra("crop", "true");// 可以裁剪
		intent.putExtra("aspectX", 1);
		intent.putExtra("aspectY", 1);
		intent.putExtra("outputX", 150);
		intent.putExtra("outputY", 150);
		intent.putExtra("return-data", true);
		startActivityForResult(intent, RESIZE_CODE);// 跳转，传递调整大小请求码
	}

	// 获取路径
	private Uri getImageUri() {
		return Uri.fromFile(new File(Environment.getExternalStorageDirectory(),
				IMAGE_NAME));
	}

	// 显示图片
	private void showResizeImage(Intent data) {
		Bundle extras = data.getExtras();
		if (extras != null) {
			Bitmap photo = extras.getParcelable("data");
			Drawable drawable = new BitmapDrawable(photo);
			ivHead.setImageDrawable(drawable);
		}
	}

	// 图片上传
	private void upload(String imgpath) {
		final BmobFile icon = new BmobFile(new File(imgpath));
		icon.upload(this, new UploadFileListener() {

			@Override
			public void onSuccess() {
				Person person = new Person();
				person.setIcon(icon);
				person.save(MainActivity.this);
				Toast.makeText(MainActivity.this,"图片上传成功",Toast.LENGTH_SHORT).show();
			}

			@Override
			public void onFailure(int arg0, String arg1) {
				Toast.makeText(MainActivity.this,"图片上传失败",Toast.LENGTH_SHORT).show();
			}
		});
	}

	//下载图片
	private void downloadImage(Person person) {
		BmobFile icon=person.getIcon();
		icon.download(MainActivity.this,new DownloadFileListener() {
			
			@Override
			public void onSuccess(String url) {
				ivDownload.setImageBitmap(BitmapFactory.decodeFile(url));   //根据地址解码并显示图片
				
			}
			
			@Override
			public void onFailure(int arg0, String arg1) {
				Toast.makeText(MainActivity.this,"下载失败",Toast.LENGTH_SHORT).show();
			}
		});
		
	}
}

3.Person.java页面为实体类，运行自动生成一个Person表，这个表只有一个字段存储图片。

Person.java页面：

package entity;

import cn.bmob.v3.BmobObject;
import cn.bmob.v3.datatype.BmobFile;

public class Person extends BmobObject{

	private BmobFile icon;

	public BmobFile getIcon() {
		return icon;
	}

	public void setIcon(BmobFile icon) {
		this.icon = icon;
	}
	
}

4.因为使用了Bmob，所以需要添加权限。

AndroidManifest.xml页面：

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />
    <uses-permission android:name="android.permission.WRITE_CONTACTS"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET"/>
    
    <!-- 允许联网 -->
    <uses-permission android:name="android.permission.INTERNET" />
    <!-- 获取GSM（2g）、WCDMA（联通3g）等网络状态的信息 -->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <!-- 获取wifi网络状态的信息 -->
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <!-- 保持CPU 运转，屏幕和键盘灯有可能是关闭的,用于文件上传和下载 -->
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <!-- 获取sd卡写的权限，用于文件上传和下载 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <!-- 允许读取手机状态 用于创建BmobInstallation -->
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.text.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>

5.注意之前讲过使用Bmob需要下载第三方SDK，将libs文件夹中的所有内容都复制到项目libs目录下，然后Properties->Java Build Path->Libraries->Add JARs...添加刚复制的四个jar包