Android——Carema的使用

相机可以自己编写，也可以调用系统的相机，此处我们是调用系统相机

使用camera要先加权限

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

实例

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" tools:context=".MainActivity">
<Button
android:id="@+id/btn_camera"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="调用系统相机"/>
<ImageView
android:id="@+id/imageview"
android:layout_width="match_parent"
android:layout_height="match_parent"

/>

</LinearLayout>

GetPathFromUri4kitkat ，4.4以上版本通过Uri获得文件路径的方法

package com.example.administrator.mycamera;

import android.annotation.SuppressLint;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;

/**
* Created by Administrator on 2015/9/16.
*/
public class GetPathFromUri4kitkat {

/**
* 专为Android4.4设计的从Uri获取文件绝对路径，以前的方法已不好使
* 若为4.4以下版本此方法忽略
*/
@SuppressLint("NewApi")
public static String getPath(final Context context, final Uri uri) {

final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];

if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}

// TODO handle non-primary volumes
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {

final String id = DocumentsContract.getDocumentId(uri);
final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];

Uri contentUri = null;
if ("image".equals(type)) {
contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
} else if ("video".equals(type)) {
contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
} else if ("audio".equals(type)) {
contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
}

final String selection = "_id=?";
final String[] selectionArgs = new String[] { split[1] };

return getDataColumn(context, contentUri, selection, selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}

return null;
}

/**
* Get the value of the data column for this Uri. This is useful for
* MediaStore Uris, and other file-based ContentProviders.
*
* @param context
*            The context.
* @param uri
*            The Uri to query.
* @param selection
*            (Optional) Filter used in the query.
* @param selectionArgs
*            (Optional) Selection arguments used in the query.
* @return The value of the _data column, which is typically a file path.
*/
public static String getDataColumn(Context context, Uri uri, String selection,
String[] selectionArgs) {

Cursor cursor = null;
final String column = "_data";
final String[] projection = { column };

try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
null);
if (cursor != null && cursor.moveToFirst()) {
final int column_index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(column_index);
}
} finally {
if (cursor != null)
cursor.close();
}
return null;
}

/**
* @param uri
*            The Uri to check.
* @return Whether the Uri authority is ExternalStorageProvider.
*/
public static boolean isExternalStorageDocument(Uri uri) {
return "com.android.externalstorage.documents".equals(uri.getAuthority());
}

/**
* @param uri
*            The Uri to check.
* @return Whether the Uri authority is DownloadsProvider.
*/
public static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

/**
* @param uri
*            The Uri to check.
* @return Whether the Uri authority is MediaProvider.
*/
public static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}
}

MainActivity

package com.example.administrator.mycamera;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button mBtnCamera;
private ImageView imageView;
private File file;
private Button mBtnGetGallery;
private static final int GET_GALLERY=0x24;
private static final int TAKE_PICTURE=0x23;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mBtnCamera= (Button) findViewById(R.id.btn_camera);
imageView= (ImageView) findViewById(R.id.imageview);
mBtnCamera.setOnClickListener(this);
mBtnGetGallery= (Button) findViewById(R.id.btn_get_gallery);
mBtnGetGallery.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btn_camera:
Intent intent=new Intent();
//隐式启动系统相机
intent.setAction(MediaStore.ACTION_IMAGE_CAPTURE);
//创建照片的存储位置及文件名
file=new File(Environment.getExternalStorageDirectory(),System.currentTimeMillis()+".jpg");
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
//告诉相机保存照片的位置
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
//开始启动
startActivityForResult(intent,TAKE_PICTURE);
break;
case R.id.btn_get_gallery:
Intent intentFromGallery = new Intent();
intentFromGallery.setAction(Intent.ACTION_GET_CONTENT);
intentFromGallery.setType("image/*");
startActivityForResult(intentFromGallery,GET_GALLERY);
break;
}
}

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

if(resultCode==RESULT_OK){
//得到图片
switch (requestCode){
case TAKE_PICTURE:
//某些手机不能显示大图片，故此处调用将图片压缩的方法
zipImage(file.getAbsolutePath());
imageView.setImageURI(Uri.fromFile(file));
break;
case GET_GALLERY:
Uri uri=data.getData();
//调用获得4.4版本以上由Uri获得文件路径的方法
File file1=new File(GetPathFromUri4kitkat.getPath(MainActivity.this,uri)) ;
//调用压缩图片的方法对文件进行压缩
zipImage(file1.getAbsolutePath());
//将图片设置到imageView上
imageView.setImageURI(Uri.fromFile(file1));
//                        imageView.setImageURI(uri);
break;
}}

}

/**
* 压缩图片的方法
* @param savePath
*/
private void zipImage(String savePath) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(savePath, options);
options.inSampleSize = computeInitialSampleSize(options, 480, 480 * 960);
options.inJustDecodeBounds = false;
Bitmap bitmap = BitmapFactory.decodeFile(savePath, options);
try {
FileOutputStream fos = new FileOutputStream(savePath);
bitmap.compress(Bitmap.CompressFormat.JPEG, 90, fos);
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
bitmap.recycle();
bitmap = null;
System.gc();
}
public int computeSampleSize(BitmapFactory.Options options,
int minSideLength, int maxNumOfPixels) {
int initialSize = computeInitialSampleSize(options, minSideLength,
maxNumOfPixels);
int roundedSize;
if (initialSize <= 8) {
roundedSize = 1;
while (roundedSize < initialSize) {
roundedSize <<= 1;
}
} else {
roundedSize = (initialSize + 7) / 8 * 8;
}
return roundedSize;
}

private int computeInitialSampleSize(BitmapFactory.Options options,
int minSideLength, int maxNumOfPixels) {
double w = options.outWidth;
double h = options.outHeight;
int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math
.sqrt(w * h / maxNumOfPixels));
int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(
Math.floor(w / minSideLength), Math.floor(h / minSideLength));
if (upperBound < lowerBound) {
// return the larger one when there is no overlapping zone.
return lowerBound;
}
if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
return 1;
} else if (minSideLength == -1) {
return lowerBound;
} else {
return upperBound;
}
}

}