2、我发现手机前置摄像头拍出来的照片只有几百KB，直接用imageView.setImageURI(uri);没有很大问题，但是后置摄像头拍出来的照片比较大，这个时候使用imageView.setImageURI(uri);就容易出现 out of memory（oom）错误，我们需要先把URI转换为Bitmap,再压缩bitmap，然后通过imageView.setImageBitmap(bitmap);来显示图片。
3、将照片存放到SD卡中后，照片不能立即出现在系统相册中，因此我们需要发送广播去提醒相册更新照片。
4、这里用到了sharepreference，要注意用完之后移除缓存。
代码：
MainActivity:
package com.sctu.edu.test;
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.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import com.sctu.edu.test.tools.ImageTools;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class MainActivity extends AppCompatActivity {
private static final int PHOTO_FROM_GALLERY = 1;
private static final int PHOTO_FROM_CAMERA = 2;
private ImageView imageView;
private File appDir;
private Uri uriForCamera;
private Date date;
private String str = "";
private SharePreference sharePreference;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Android不推荐使用全局变量，我在这里使用了sharePreference
sharePreference = SharePreference.getInstance(this);
imageView = (ImageView) findViewById(R.id.imageView);
}
//从相册取图片
public void gallery(View view) {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(intent, PHOTO_FROM_GALLERY);
}
//拍照取图片
public void camera(View view) {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
uriForCamera = Uri.fromFile(createImageStoragePath());
sharePreference.setCache("uri", String.valueOf(uriForCamera));
/**
* 指定了uri路径，startActivityForResult不返回intent，
* 所以在onActivityResult()中不能通过data.getData()获取到uri;
*/
intent.putExtra(MediaStore.EXTRA_OUTPUT, uriForCamera);
startActivityForResult(intent, PHOTO_FROM_CAMERA);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
//第一层switch
switch (requestCode) {
case PHOTO_FROM_GALLERY:
//第二层switch
switch (resultCode) {
case RESULT_OK:
if (data != null) {
Uri uri = data.getData();
imageView.setImageURI(uri);
}
break;
case RESULT_CANCELED:
break;
}
break;
case PHOTO_FROM_CAMERA:
if (resultCode == RESULT_OK) {
Uri uri = Uri.parse(sharePreference.getString("uri"));
updateDCIM(uri);
try {
//把URI转换为Bitmap，并将bitmap压缩，防止OOM(out of memory)
Bitmap bitmap = ImageTools.getBitmapFromUri(uri, this);
imageView.setImageBitmap(bitmap);
} catch (IOException e) {
e.printStackTrace();
}
removeCache("uri");
} else {
Log.e("result", "is not ok" + resultCode);
}
break;
default:
break;
}
}
/**
* 设置相片存放路径，先将照片存放到SD卡中，再操作
*
* @return
*/
private File createImageStoragePath() {
if (hasSdcard()) {
appDir = new File("/sdcard/testImage/");
if (!appDir.exists()) {
appDir.mkdirs();
}
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
date = new Date();
str = simpleDateFormat.format(date);
String fileName = str + ".jpg";
File file = new File(appDir, fileName);
return file;
} else {
Log.e("sd", "is not load");
return null;
}
}
/**
* 将照片插入系统相册，提醒相册更新
*
* @param uri
*/
private void updateDCIM(Uri uri) {
Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
intent.setData(uri);
this.sendBroadcast(intent);
Bitmap bitmap = BitmapFactory.decodeFile(uri.getPath());
MediaStore.Images.Media.insertImage(getContentResolver(), bitmap, "", "");
}
/**
* 判断SD卡是否可用
*
* @return
*/
private boolean hasSdcard() {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
return true;
} else {
return false;
}
}
/**
* 移除缓存
*
* @param cache
*/
private void removeCache(String cache) {
if (sharePreference.ifHaveShare(cache)) {
sharePreference.removeOneCache(cache);
} else {
Log.e("this cache", "is not exist.");
}
}
}
