Android studio将Bitmap图像保存到真机

Android studio 将Bitmap图像保存到真机实现代码入下：

package com.example.jlzt.opencvgray;

import android.content.ContentResolver;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.File;
import java.io.FileOutputStream;



public class MainActivity extends AppCompatActivity {

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

        Button GiveFaceButton = (Button)findViewById(R.id.GiveFaceButton);
        GiveFaceButton.setOnClickListener(new Button.OnClickListener()
        {
            public void onClick(View v)
            {
                Intent myIntent = new Intent();

                //开启picture画面Type设置为image*
                myIntent.setType("image/*");

                //使用Intent.ACTION_GET_CONTENT这个Action
                myIntent.setAction(Intent.ACTION_GET_CONTENT);

                /*取得相片后返回本画面*/
                startActivityForResult(myIntent,1);
            }
        });

        Button GetFaceButton = (Button)findViewById(R.id.GetFaceButton);
        GetFaceButton.setOnClickListener(new Button.OnClickListener()
        {
            public void onClick(View v)
            {
                Intent myIntent = new Intent();

                //开启picture画面Type设置为image*
                myIntent.setType("image/*");

                //使用Intent.ACTION_GET_CONTENT这个Action
                myIntent.setAction(Intent.ACTION_GET_CONTENT);

                /*取得相片后返回本画面*/
                startActivityForResult(myIntent,2);
            }
        });
    }

    protected void onActivityResult(int requestCode,int resultCode,Intent data)
    {
        switch (requestCode)
        {
            case 1 :
                Uri uri = data.getData();
                Log.e("uri",uri.toString());
                ContentResolver cr = this.getContentResolver();

                try
                {
                    InputStream input = cr.openInputStream(uri);
                    BitmapFactory.Options options = new BitmapFactory.Options();
                    options.inJustDecodeBounds = true;
                    BitmapFactory.decodeStream(input, null, options);
                    if (options.outWidth > 1024 || options.outHeight > 1024){
                        options.inSampleSize = Math.max(options.outWidth / 1024, options.outHeight/1024);
                    }
                    options.inJustDecodeBounds = false;
                    Bitmap bitmap = BitmapFactory.decodeStream(cr.openInputStream(uri), null, options);

                    /*以下进行灰度化处理*/
                    int w = bitmap.getWidth();
                    int h = bitmap.getHeight();
                    int[] pix = new int[w * h];
                    bitmap.getPixels(pix, 0, w, 0, 0, w, h);
                    int[] resultPixels = OpenCVHelper.gray(pix, w, h);
                    Bitmap result = Bitmap.createBitmap(w, h, Bitmap.Config.RGB_565);
                    result.setPixels(resultPixels,0,w,0,0,w,h);

                    ImageView imageView = (ImageView)findViewById(R.id.IV01);
                    /*将处理好的灰度图设定到ImageView*/
                    imageView.setImageBitmap(result);

                    /*将result保存到指定路径*/
                    File file = new File(Environment.getExternalStorageDirectory()+"/ColorOS/Browser/gray.jpg");
                    if(file.exists() || file.isDirectory()){
                        file.delete();
                    }
                    //file.createNewFile();
                    FileOutputStream outputStream = new FileOutputStream(file);
                    result.compress(Bitmap.CompressFormat.JPEG,0,outputStream);
                }
                catch(FileNotFoundException e)
                {
                    Log.e("Exception",e.getMessage(),e);
                }
                break;
            case 2:
                Uri uri2 = data.getData();
                Log.e("uri2",uri2.toString());
                ContentResolver cr2 = this.getContentResolver();

                try
                {
                    InputStream input = cr2.openInputStream(uri2);
                    BitmapFactory.Options options = new BitmapFactory.Options();
                    options.inJustDecodeBounds = true;
                    BitmapFactory.decodeStream(input, null, options);
                    if (options.outWidth > 1024 || options.outHeight > 1024){
                        options.inSampleSize = Math.max(options.outWidth / 1024, options.outHeight/1024);
                    }
                    options.inJustDecodeBounds = false;
                    Bitmap bitmap = BitmapFactory.decodeStream(cr2.openInputStream(uri2), null, options);
                    ImageView imageView = (ImageView)findViewById(R.id.IV02);

                    /*将Bitmap设定到ImageView*/
                    imageView.setImageBitmap(bitmap);
                }
                catch(FileNotFoundException e)
                {
                    Log.e("Exception",e.getMessage(),e);
                }
                break;
            default:
                break;
        }
        super.onActivityResult(requestCode, resultCode,data);
    }
}

上述代码可能会有bug: open failed: EACCES (Permission denied)

解决方案：在app->src->res->AndroidManifest.xml中添加

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

修改完成后的AndroidManifest.xml文件如下：

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

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

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
    application>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
manifest>