Android 从相册中选取图片

package com.example.thinkpad.camera;

import android.Manifest;
import android.annotation.TargetApi;
import android.content.ContentUris;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.ImageWriter;
import android.net.Uri;
import android.os.Build;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;


public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO=1;
    public static final int CHOOSE_PHOTO=2;
    private ImageView picture;
    private Uri imageUri;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button takePhoto =(Button) findViewById(R.id.take_photo);
        Button chooseFromAlbum=(Button) findViewById(R.id.choose_from_album);
        picture =(ImageView) findViewById(R.id.pictrue);
        chooseFromAlbum.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED){
                    ActivityCompat.requestPermissions(MainActivity.this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
                }else {
                    openAblum();
                }
            }
        });

        takePhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //创建File对象，用于存储拍照后的图片
                File outputImage =new File(getExternalCacheDir(),"output_image.jpg");
                try{
                    if(outputImage.exists()){
                        outputImage.delete();
                    }
                    outputImage.createNewFile();
                }catch (IOException e){
                    e.printStackTrace();
                }
                if(Build.VERSION.SDK_INT>=24){
                    imageUri= FileProvider.getUriForFile(MainActivity.this,"com.example.cameraalbumtest.fileprovider",outputImage);
                }else{
                    imageUri=Uri.fromFile(outputImage);
                }
//启动相机程序
                Intent intent=new Intent("android.media.action.IMAGE_CAPTURE");
                intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
                startActivityForResult(intent,TAKE_PHOTO);
            }
        });
    }
    private void openAblum(){
Intent intent =new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent,CHOOSE_PHOTO);//打开相册
    }
    @Override
    public void onRequestPermissionsResult(int requestCode,String[] permissions,int[] grantResults){
        switch (requestCode){
            case 1:
                if(grantResults.length>0&&grantResults[0]==PackageManager.PERMISSION_GRANTED){
                    openAblum();
                }else{
                    Toast.makeText(this,"You denied the permission",Toast.LENGTH_SHORT).show();
                }
                break;
            default:
        }
    }

    protected void onActivityResult(int requestCode,int resultCode,Intent data){
        switch(requestCode){
            case TAKE_PHOTO:
                if(resultCode==RESULT_OK){
                    try{
                        //将拍摄的照片显示出来
                        Bitmap bitmap= BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
                        picture.setImageBitmap(bitmap);
                    }catch (FileNotFoundException e){
                        e.printStackTrace();
                    }
                }
            break;
            case CHOOSE_PHOTO:
                if(resultCode==RESULT_OK){
                    //判断手机系统版本号
                    if(Build.VERSION.SDK_INT>=19){
                        //4.4及以上系统使用这个方法处理图片
                        handleImageOnKitkat(data);
                    }else{
                        //4.4以下系统使用这个方法处理图片
                        handleImageBeforeKitKathy(data);
                    }
                }
                break;
            default:
                break;
        }
    }
@TargetApi(19)
    private void handleImageOnKitkat(Intent data){
    String imagePath=null;
    Uri uri=data.getData();
    if(DocumentsContract.isDocumentUri(this,uri)){
        //如果是document 类型Uri，则通过document id 处理
        String docId=DocumentsContract.getDocumentId(uri);
        if("com.android.providers.media.documents".equals(uri.getAuthority())){
            String id =docId.split(";")[1];//解析出数字格式的id
            String selection =MediaStore.Images.Media._ID+"="+id;
            imagePath=getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,selection);
        }else if("com.android.providers.downloads.documents".equals(uri.getAuthority())){
            Uri contentUri= ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),Long.valueOf(docId));
            imagePath=getImagePath(contentUri,null);
        }
    }else if("content".equalsIgnoreCase(uri.getScheme())){
        //如果是content类型的Uri ，则使用普通方式处理
        imagePath=getImagePath(uri,null);
    }else if("file".equalsIgnoreCase(uri.getScheme())){
        //如果是file类型的Uri，直接使用普通的方式处理
        imagePath=uri.getPath();
    }
    displayImage(imagePath);//根据图片路径显示图片
}
private void handleImageBeforeKitKathy(Intent data){
    Uri uri=data.getData();
    String imagePath=getImagePath(uri,null);
    displayImage(imagePath);
}
private String getImagePath(Uri uri,String selection){
    String path=null;
    //通过Uri和selection来获取真实的图片路径
    Cursor cursor =getContentResolver().query(uri,null,selection,null,null);
    if(cursor !=null){
        if(cursor.moveToFirst()){
            path=cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
        }
        cursor.close();
    }
    return path;
}
private  void displayImage(String imagePath){
    if(imagePath!=null){
        Bitmap bitmap=BitmapFactory.decodeFile(imagePath);
        picture.setImageBitmap(bitmap);
    }else {
        Toast.makeText(this,"failed to get image",Toast.LENGTH_SHORT).show();
    }
}
}

在上一次拍照的基础上增加一个选取照片按钮

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
<Button
    android:id="@+id/take_photo"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Take Photo"/>
    <Button
        android:id="@+id/choose_from_album"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Choose From Album"/>
<ImageView
    android:id="@+id/pictrue"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"/>

</LinearLayout>

其他的文件代码和上次拍照的相同概不赘述。

Android 从相册中选取图片

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