本篇文章代码实现的功能是调用手机自带的相机进行拍照、录像和读取相册的功能，并将照片或者视频在指定的页面展示的功能。
我的效果是*页的布局会有拍照、录像、读取相册以及展示视频的选项。选择拍照或读取相册后，跳转到新的Intent进行操作并展示在ImageView中；选择录像会打开摄像头开始录像并保存在手机sd卡某一确定的缓存路径下;选择展示视频会展示这一确定的缓存路径下的视频文件。
下面是代码部分：
首先要对AndroidMainifest.xml进行设置，主要是存储权限的获得
<?xml version=”1.0″ encoding=”utf-8″?>
<manifest xmlns:android=”http://schemas.android.com/apk/res/android”
package=”com.mapscanner.mapscanner”>
<uses-feature
android:name=”android.hardware.camera2″
android:required=”true” />
<uses-permission android:name=”android.permission.CAMERA” />
<uses-feature android:name=”android.hardware.camera” />
<uses-feature android:name=”android.hardware.camera.autofocus” />
<uses-permission android:name=”android.permission.FLASHLIGHT” />
<uses-permission android:name=”android.permission.WRITE_EXTERNAL_STORAGE” />
<uses-permission android:name=”android.permission.READ_EXTERNAL_STORAGE” />
<uses-permission android:name=”android.permission.INTERNET” />
<application
android:allowBackup=”true”
android:icon=”@mipmap/ic_launcher”
android:label=”@string/app_name”
android:roundIcon=”@mipmap/ic_launcher_round”
android:supportsRtl=”true”
android:theme=”@style/AppTheme”>
<activity android:name=”.MainActivity”>
<intent-filter>
<action android:name=”android.intent.action.MAIN” />
<action android:name=”android.media.action.IMAGE_CAPTURE” />
<category android:name=”android.intent.category.LAUNCHER” />
</intent-filter>
</activity>
<provider
android:name=”android.support.v4.content.FileProvider”
android:authorities=”com.MapScanner.MapScanner”
android:exported=”false”
android:grantUriPermissions=”true”>
<meta-data
android:name=”android.support.FILE_PROVIDER_PATHS”
android:resource=”@xml/file_paths” />
</provider>
<activity android:name=”.Second_Activity” />
<activity android:name=”.Image_album_showActivity” />
</application>
因为上面有一句android:resource=”@xml/file_paths”，是说在xml文件夹下定义了file_paths的值，所以我们 右键Resource new一个category取名为xml，会看到Resource下面出现了一个名为xml的文件夹，再右键文件夹选择new-> XML resource file,创建一个资源文件，并输入下面代码。
<?xml version=”1.0″ encoding=”utf-8″?>
<paths xmlns:android=”http://schemas.android.com/apk/res/android”>
<external-path name=”my_images” path=”” />
</paths>
下面首先看一下布局文件MainActivity.xml
<?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 Photos” />
<Button
android:id=”@+id/take_video”
android:layout_width=”match_parent”
android:layout_height=”wrap_content”
android:text=”Take videos” />
<Button
android:id=”@+id/choose_from_album”
android:layout_width=”match_parent”
android:layout_height=”wrap_content”
android:text=”Choose From Album” />
<Button
android:id=”@+id/show_videos”
android:layout_width=”match_parent”
android:layout_height=”wrap_content”
android:text=”Show previous video” />
</LinearLayout>
下面是MainActivity内的内容，主要实现摁键的跳转以及参数传递的功能
package com.mapscanner.mapscanner;
import android.Manifest;
import android.annotation.TargetApi;
import android.app.Activity;
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.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.support.annotation.NonNull;
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.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.MediaController;
import android.widget.Toast;
import android.widget.VideoView;
import java.io.File;
import java.io.IOException;
public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO = 1;
public static final int CHOOSE_PHOTO = 2;
/*用来记录录像存储路径*/
File file = new File(Environment.getExternalStorageDirectory().getPath() + “/video.mp4”);//设置录像存储路径
Uri uri = Uri.fromFile(file);//文件转成Uri格式
@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);
Button takeVideo = (Button) findViewById(R.id.take_video);
Button showVideo = (Button) findViewById(R.id.show_videos);
//对照相功能的响应
takePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// 在新的Intent里面打开，并且传递TAKE_PHOTO选项
Intent intent = new Intent();
intent.setClass(MainActivity.this, Image_album_showActivity.class);//也可以这样写intent.setClass(MainActivity.this, OtherActivity.class);
Bundle bundle = new Bundle();
bundle.putInt(“id”, TAKE_PHOTO);//使用显式Intent传递参数，用以区分功能
intent.putExtras(bundle);
MainActivity.this.startActivity(intent);//启动新的Intent
}
});
//设置相册选择的响应
chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// 在新的Intent里面打开，并且传递CHOOSE_PHOTO选项
Intent intent = new Intent();
intent.setClass(MainActivity.this, Image_album_showActivity.class);//也可以这样写intent.setClass(MainActivity.this, OtherActivity.class);
Bundle bundle = new Bundle();
bundle.putInt(“id”, CHOOSE_PHOTO);
intent.putExtras(bundle);
MainActivity.this.startActivity(intent);
}
});
//设置录像选择的响应
takeVideo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// 保存录像到指定的路径
// File file = new File(“storage/sdcard1/video.mp4” );//设置录像存储路径
try {
if (file.exists()) {
file.delete();
}
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
// 激活系统的照相机进行录像，通过Intent激活相机并实现录像功能
Intent intent = new Intent();
intent.setAction(“android.media.action.VIDEO_CAPTURE”);
intent.addCategory(“android.intent.category.DEFAULT”);
intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
startActivityForResult(intent, 0);
}
});
showVideo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//initVideoPath();
Intent intent = new Intent();
intent.setClass(MainActivity.this, Second_Activity.class);//也可以这样写intent.setClass(MainActivity.this, OtherActivity.class);
MainActivity.this.startActivity(intent);
setContentView(R.layout.activity_second_);
}
});
}
}
接着点击包名new一下，选择Activity->Empty Activity生成一组配套的布局和类的文件，取名为image_album_show实现对拍照和读取相册的响应。
下面是对拍照和读取相册进行响应的布局文件Activity_image_album_show.xml
<?xml version=”1.0″ encoding=”utf-8″?>
<LinearLayout xmlns:android=”http://schemas.android.com/apk/res/android”
xmlns:app=”http://schemas.android.com/apk/res-auto”
android:orientation=”vertical”
xmlns:tools=”http://schemas.android.com/tools”
android:layout_width=”match_parent”
android:layout_height=”match_parent”
tools:context=”.Image_album_showActivity”>
<Button
android:id=”@+id/Return_Back_to_page1″
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:text=”Return to previous page” />
<ImageView
android:id=”@+id/V_Image”
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:layout_gravity=”center_horizontal”
/>
</LinearLayout>
下面是与Activity_image_album_show.xml配套的image_album_showActivity文件
package com.mapscanner.mapscanner;
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.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.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
public class Image_album_showActivity extends AppCompatActivity {
private ImageView picture;
private Uri imageUri;
private Button Return_page;
public static final int TAKE_PHOTO = 1;
public static final int CHOOSE_PHOTO = 2;
//接受前一个Intent传入的id
private Bundle bundle;
private int Show_Choice;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_album_show);
picture = (ImageView) findViewById(R.id.V_Image);
Return_page=(Button)findViewById(R.id.Return_Back_to_page1);
bundle = this.getIntent().getExtras();
Show_Choice=bundle.getInt(“id”);
Return_page.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent= new Intent();
intent.setClass(Image_album_showActivity.this, MainActivity.class);//也可以这样写intent.setClass(MainActivity.this, OtherActivity.class);
startActivity(intent);
}
});
//接收Intent传递的id值，并判断，照相功能为1，打开相册功能为2
switch (Show_Choice)
{
//如果传递为TAKE_PHOTO
case TAKE_PHOTO:{
File outputImage = new File(getExternalCacheDir(), “output_image.jpg”);
try {
if (outputImage.exists()) {
outputImage.delete();
}
outputImage.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
//判断版本号
if (Build.VERSION.SDK_INT < 24) {
imageUri = Uri.fromFile(outputImage);
} else {
imageUri = FileProvider.getUriForFile(Image_album_showActivity.this, “com.MapScanner.MapScanner”, outputImage);
}
// 启动相机程序
Intent intent = new Intent(“android.media.action.IMAGE_CAPTURE”);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, 1);
try {// 将拍摄的照片显示出来
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (Exception e) {
e.printStackTrace();
}
}
break;
//如果传递为CHOOSE_PHOTO
case CHOOSE_PHOTO:
{
//如果没有权限则申请权限
if (ContextCompat.checkSelfPermission(Image_album_showActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(Image_album_showActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
//调用打开相册
openAlbum();
}
default:
break;
}
}
private void openAlbum() {
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) {
openAlbum();
}
else {
Toast.makeText(this, “You denied the permission”, Toast.LENGTH_SHORT).show();
}
break;
default:
break;
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (Show_Choice) {
case 1:
try {// 将拍摄的照片显示出来
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (Exception e) {
e.printStackTrace();
}
break;
case 2:
// 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
handleImageBeforeKitKat(data);
}
break;
default:
break;
}
}
@TargetApi(19)
private void handleImageOnKitKat(Intent data) {
String imagePath = null;
Uri uri = data.getData();
Log.d(“TAG”, “handleImageOnKitKat: uri is ” + uri);
if (DocumentsContract.isDocumentUri(this, uri)) {
// 如果是document类型的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，直接获取图片路径即可
imagePath = uri.getPath();
}
displayImage(imagePath); // 根据图片路径显示图片
}
private void handleImageBeforeKitKat(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();
}
}
}
下面再新建一个Activity->EmptyActivity用于对视频的展示，我取名为Second_Activity,设置了一个button用于返回前一个activity以及用于视频展示的videoview控件。
还是先看一下布局文件activit_second_.xml
<?xml version=”1.0″ encoding=”utf-8″?>
<LinearLayout xmlns:android=”http://schemas.android.com/apk/res/android”
xmlns:app=”http://schemas.android.com/apk/res-auto”
android:orientation=”vertical”
xmlns:tools=”http://schemas.android.com/tools”
android:layout_width=”match_parent”
android:layout_height=”match_parent”
tools:context=”.Second_Activity”>
<Button
android:id=”@+id/Return_Back”
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:text=”Return to previous page” />
<VideoView
android:id=”@+id/V_video”
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:layout_gravity=”center_horizontal”
/>
</LinearLayout>
下面是Second_Activity中的内容
package com.mapscanner.mapscanner;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.MediaController;
import android.widget.Toast;
import android.widget.VideoView;
import java.io.File;
public class Second_Activity extends AppCompatActivity {
private VideoView mVideo;
private Button Turn_back;
File file = new File(Environment.getExternalStorageDirectory().getPath()+”/video.mp4″ );//设置录像存储路径
Uri uri = Uri.fromFile(file);//文件转成Uri格式
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second_);
Turn_back=(Button)findViewById(R.id.Return_Back);
mVideo=(VideoView)findViewById(R.id.V_video);
initVideoPath();
Turn_back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent= new Intent();
intent.setClass(Second_Activity.this, MainActivity.class);//也可以这样写intent.setClass(MainActivity.this, OtherActivity.class);
startActivity(intent);
}
});
}
private void initVideoPath() {
if (ContextCompat.checkSelfPermission(Second_Activity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(Second_Activity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
Toast.makeText(this, “have found video”, Toast.LENGTH_SHORT).show();
mVideo.setVideoURI(uri);
mVideo.setVideoPath(file.getAbsolutePath());
MediaController mediaController=new MediaController(this);
mVideo.setMediaController(mediaController);
mediaController.setMediaPlayer(mVideo);
mVideo.requestFocus();
mVideo.start();
}
}
以上代码主要借鉴与《*行代码》以及网上的一些实例，在理解后进行了综合的应用，解决了我需要的功能，值得一提的是，本实例调用的相机是利用Intent对本机的相机进行了捕获从而实现媒体设备的使用功能，还有一种实现方法是调用camera库实现此功能。我在其它文章会介绍camera的使用以及如何通过Socket实现实时视频的传输。
*后附上自己总结的一些经验，因为我都是用真机测试程序，有时会出现程序打不开闪退的现象，总结后主要有：
1、可能未获得权限，比如使用媒体设备，比如读取内存都需要获得权限，如果未获得权限就会闪退。
2、当跳转到一个新的页面时，都会有setContentView(R.layout.xxxxx_);
而对于button等的响应需要用到xxx=(Button)findViewById(R.id.xxx); findViewById必须放在setContentView后面，否则会找不到此按钮而闪退。
