java如何从图库中选取图像，裁剪并保存在数据分区中

Question

我需要一些帮助 我想从gallery中选取一个图像，然后将其重新调整为自定义大小，例如480*800，然后将其放入数据分区的文件夹中（例如（/data/test_wall））。 我试了很多次谷歌搜索，但都没有

这是我到目前为止的代码，但我无法从图库中选择并保存图像给我强制关闭：

package com.example.walpaperpicker;

import java.io.FileOutputStream;
import 安卓.os.Bundle;
import 安卓.annotation.SuppressLint;
import 安卓.app.Activity;
import 安卓.content.Intent;
import 安卓.graphics.Bitmap;
import 安卓.view.View;
import 安卓.widget.Button;
import 安卓.widget.ImageView;

public class MainActivity extends Activity {

private static final int PICK_FRPM_GALLERY = 1;

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

    Button button1  = (Button) findViewById(R.id.button1);

    button1.setOnClickListener(new View.OnClickListener() { 
        @Override
        public void onClick(View v) {
            PickPic();
        }

        private void PickPic() {
            // this code working for pick a picture with camera
             Intent cameraIntent = new Intent(
                    安卓.provider.MediaStore.ACTION_IMAGE_CAPTURE);
            startActivityForResult(cameraIntent, PICK_FRPM_GALLERY);

            // this code not working give me fc after i select picture from gallery see my logcat
            /*Intent GallaryIntent = new Intent();
            GallaryIntent.setType("image/*");
            GallaryIntent.setAction(Intent.ACTION_GET_CONTENT);

            startActivityForResult(GallaryIntent, PICK_FRPM_GALLERY);*/


        }
    });
}
@SuppressLint("SdCardPath")
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == PICK_FRPM_GALLERY) {
                Bitmap photo = (Bitmap) data.getExtras().get("data");
                ImageView test = (ImageView) findViewById(R.id.imageView1);
                test.setImageBitmap(photo);
                try {
                    //I want put it in data partition but i dont know this is for sdcard
                    FileOutputStream out = new FileOutputStream("/sdcard/wallpaper.png");
                    photo.compress(Bitmap.CompressFormat.PNG, 90, out);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

/*i want crop output picture
 *to custom size for example 480*800
 *but i dont know.
 */
  }

舱单。xml

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

    <uses-sdk
        安卓:minSdkVersion="8"
        安卓:targetSdkVersion="18" />
    <uses-permission 安卓:name="安卓.permission.WRITE_INTERNAL_STORAGE"> </uses-permission>
    <uses-permission 安卓:name="安卓.permission.READ_INTERNAL_STORAGE"> </uses-permission>
    <uses-permission 安卓:name="安卓.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission 安卓:name="安卓.permission.READ_EXTERNAL_STORAGE"></uses-permission>


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

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

</manifest>

如果我从相机拍摄照片并将其保存在“/sdcard/wallpar.png”中，此代码将正常工作 但我不想从相机里拿出一张照片放在SD卡里。 我想先从图库中选取一张图片，将其裁剪为480*800 然后把它放在数据分区的文件夹中（我有根设备）。请参阅我的上述代码

这是我的原木猫

01-31 02:27:37.545: E/AndroidRuntime(5241): FATAL EXCEPTION: main
01-31 02:27:37.545: E/AndroidRuntime(5241): Process: com.example.walpaperpicker, PID: 5241
01-31 02:27:37.545: E/AndroidRuntime(5241): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://com.安卓.providers.media.documents/document/image:26274 flg=0x1 }} to activity {com.example.walpaperpicker/com.example.walpaperpicker.MainActivity}: java.lang.NullPointerException
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread.deliverResults(ActivityThread.java:3368)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread.handleSendResult(ActivityThread.java:3411)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread.access$1300(ActivityThread.java:138)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.os.Handler.dispatchMessage(Handler.java:102)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.os.Looper.loop(Looper.java:136)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread.main(ActivityThread.java:5050)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at java.lang.reflect.Method.invokeNative(Native Method)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at java.lang.reflect.Method.invoke(Method.java:515)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:595)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at dalvik.system.NativeStart.main(Native Method)
01-31 02:27:37.545: E/AndroidRuntime(5241): Caused by: java.lang.NullPointerException
01-31 02:27:37.545: E/AndroidRuntime(5241):     at com.example.walpaperpicker.MainActivity.onActivityResult(MainActivity.java:50)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.Activity.dispatchActivityResult(Activity.java:5433)
01-31 02:27:37.545: E/AndroidRuntime(5241):     at 安卓.app.ActivityThread.deliverResults(ActivityThread.java:3364)
01-31 02:27:37.545: E/AndroidRuntime(5241):     ... 11 more

谢谢你的帮助 我在等你

Answer 1

我已经写了几篇关于如何选择画廊图片或缩略图的文章，这将对你有所帮助

How to Pick Image from Gallery in Android

And

How to pick the Image thumb-nail from gallery in android

好的，让我试着解释一下它是如何工作的

1。我们需要创建从Gallary中挑选图像的意图

Intent i = new Intent(Intent.ACTION_PICK,android.provider.MediaStore  
                              .Images.Media.EXTERNAL_CONTENT_URI);  
startActivityForResult(i, RESULT_LOAD_IMAGE); 

2。在同一活动中，我们需要使用onActivityResult方法处理拾取的图像

@Override  
    protected void onActivityResult(int requestCode,   
                                     int resultCode, Intent data) {  
        super.onActivityResult(requestCode, resultCode, data);  

        if (requestCode == RESULT_LOAD_IMAGE &&   
                              resultCode == RESULT_OK && null != data) {  
            Uri selectedImage = data.getData();  
            String[] filePathColumn = { MediaStore.Images.Media.DATA };  

            Cursor cursor = getContentResolver().query(selectedImage,  
                    filePathColumn, null, null, null);  
            cursor.moveToFirst();  

            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);  
            String picturePath = cursor.getString(columnIndex);  
            cursor.close(); 

            imageView = (ImageView) findViewById(R.id.imageView);

            //here you can call createImageThumbnail method passing (picturePath,480,800) 
            //and set the received bitmap imageview directly instead of storing in bitmap.
            // eg. imageView.setImageBitmap(createImageThumbnail( picturePath, 480, 800));


            imageView.setImageBitmap(BitmapFactory  
                            .decodeFile(picturePath));  

        }  


    }  

3。根据需要调整图像大小（宽度*高度）

Bitmap createImageThumbnail(String imagePath, int width, int height) {  
  BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();  
  bmpFactoryOptions.inJustDecodeBounds = true;  
  int heightRatio = (int) Math.ceil(bmpFactoryOptions.outHeight  
    / (float) height);  
  int widthRatio = (int) Math.ceil(bmpFactoryOptions.outWidth  
    / (float) width);  

  if (heightRatio > 1 || widthRatio > 1) {  
   if (heightRatio > widthRatio) {  
    bmpFactoryOptions.inSampleSize = heightRatio;  
   } else {  
    bmpFactoryOptions.inSampleSize = widthRatio;  
   }  
  }  
  bmpFactoryOptions.inJustDecodeBounds = false;  

  if (bitmap != null) {  
   bitmap.recycle();  
   bitmap = null;  
  }  

  bitmap = BitmapFactory.decodeFile(imagePath, bmpFactoryOptions);  
  return bitmap;  
 } 

如果你在这方面有什么困难，请告诉我。很乐意帮忙