Android对话框与相册一体

package com.mycompany.myapp;
import android.*;
import android.annotation.*;
import android.content.*;
import android.content.pm.*;
import android.database.*;
import android.graphics.*;
import android.net.*;
import android.os.*;
import android.provider.*;
import android.support.v4.app.*;
import android.support.v4.content.*;
import android.support.v7.app.*;
import android.view.*;
import android.widget.*;
import com.mycompany.myapp.*;
import android.util.*;
import java.io.*;
import android.support.annotation.*;
public class Grzxmain extends AppCompatActivity
{
    ImageView toux;
    protected void onCreate(Bundle savedInstanceState)
	{
        super.onCreate(savedInstanceState);
        setContentView(R.layout.grzx);
		toux = findViewById(R.id.imageview_toux);
        toux.setOnClickListener(new View.OnClickListener() {
				@Override
				public void onClick(View view)
				{
					AlertDialog.Builder builder = new AlertDialog.Builder(Grzxmain.this);
					builder.setTitle("选择头像方式");
					builder.setMessage("请选择。");
					builder.setPositiveButton("相机", new DialogInterface.OnClickListener() {
							@Override
							public void onClick(DialogInterface dialog, int which)
							{
								xiangji();
							}
						});
					builder.setNegativeButton("相册", new DialogInterface.OnClickListener() {
							@Override
							public void onClick(DialogInterface dialog, int which)
							{
								if (ContextCompat.checkSelfPermission(Grzxmain.this, Manifest.permission
																	  .WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
								{
									ActivityCompat.requestPermissions(Grzxmain.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
								}
								else
								{
									//执行启动相册的方法
									openAlbum();
								}
							}
						});
					builder.show();
				}
			});
    }
	//相机
	static final int REQUEST_IMAGE_CAPTURE = 1;
	private void xiangji()
	{
		Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        if (takePictureIntent.resolveActivity(getPackageManager()) != null)
		{
            startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
		}
	}
//获取权限的结果
	@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
	{
        if (requestCode == 1)
		{
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) openAlbum();
            else Toast.makeText(Grzxmain.this, "你拒绝了", Toast.LENGTH_SHORT).show();
        }
    }
//启动相册的方法
	private void openAlbum()
	{
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent, 2);
    }
	@Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data)
	{
		if (requestCode == 2)
		{
			//判断安卓版本
 			if (resultCode == RESULT_OK && data != null)
			{
                if (Build.VERSION.SDK_INT >= 19)
					handImage(data);
                else handImageLow(data);
            }
        }
		if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK)
		{
            Bundle extras = data.getExtras();
            Bitmap imageBitmap = (Bitmap) extras.get("data");
            toux.setImageBitmap(imageBitmap);
        }
    }
//安卓版本大于4.4的处理方法
	@RequiresApi(api = Build.VERSION_CODES.KITKAT)
    private void handImage(Intent data)
	{
        String path =null;
        Uri uri = data.getData();
        //根据不同的uri进行不同的解析
        if (DocumentsContract.isDocumentUri(this, uri))
		{
            String docId = DocumentsContract.getDocumentId(uri);
            if ("com.android.providers.media.documents".equals(uri.getAuthority()))
			{
                String id = docId.split(":")[1];
                String selection = MediaStore.Images.Media._ID + "=" + id;
                path = 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));
                path = getImagePath(contentUri, null);
            }
        }
		else if ("content".equalsIgnoreCase(uri.getScheme()))
		{
            path = getImagePath(uri, null);
        }
		else if ("file".equalsIgnoreCase(uri.getScheme()))
		{
            path = uri.getPath();
        }
        //展示图片
        displayImage(path);
    }
//安卓小于4.4的处理方法
	private void handImageLow(Intent data)
	{
        Uri uri = data.getData();
        String path = getImagePath(uri, null);
        displayImage(path);
    }
//content类型的uri获取图片路径的方法
	private String getImagePath(Uri uri, String selection)
	{
        String path = null;
        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;
    }
//根据路径展示图片的方法
	private void displayImage(String imagePath)
	{
        if (imagePath != null)
		{
            Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
            toux.setImageBitmap(bitmap);
        }
		else
		{
            Toast.makeText(this, "fail to set image", Toast.LENGTH_SHORT).show();
        }
    }
}