【Android】安卓中常用的图片加载方法

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" android:gravity="center_horizontal">


<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="使用系统照相机拍照" android:onClick="click"/>


<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</LinearLayout>

package uk.ac.essex.camerademo1;

import java.io.File;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.Display;
import android.view.View;
import android.widget.ImageView;

public class Camerademo1Activity extends Activity {
    private static final int CAPTURE_PIC = 0;

    private ImageView imageView;

    private int width;
    private int height;
    private String imageFilePath;
    private Uri imageFileUri;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        imageView = (ImageView) findViewById(R.id.imageView);
        init();
    }

    private void init() {
        Display display = getWindowManager().getDefaultDisplay();
        width = display.getWidth();
        height = display.getHeight();

        imageFilePath = Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED) ? Environment
                .getExternalStorageDirectory() + "/1.jpg" : null;
        imageFileUri = Uri.fromFile(new File(imageFilePath));
    }

    public void click(View view) {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);// 相机捕捉图片的意图
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageFileUri);// 指定系统相机拍照保存在imageFileUri所指的位置
        startActivityForResult(intent, CAPTURE_PIC);// 启动系统相机,等待返回
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK && requestCode == CAPTURE_PIC) {
            Options options = new Options();
            options.inJustDecodeBounds = true;// 设置解码只是为了获取图片的width和height值,而不是真正获取图片
            Bitmap bitmap = BitmapFactory.decodeFile(imageFilePath, options);// 解码后可以options.outWidth和options.outHeight来获取图片的尺寸

            int widthRatio = (int) Math.ceil(options.outWidth / width);// 获取宽度的压缩比率
            int heightRatio = (int) Math.ceil(options.outHeight / height);// 获取高度的压缩比率

            if (widthRatio > 1 || heightRatio > 1) {// 只要其中一个的比率大于1,说明需要压缩
                if (widthRatio >= heightRatio) {// 取options.inSampleSize为宽高比率中的最大值
                    options.inSampleSize = widthRatio;
                } else {
                    options.inSampleSize = heightRatio;
                }
            }

            options.inJustDecodeBounds = false;// 设置为真正的解码图片
            bitmap = BitmapFactory.decodeFile(imageFilePath, options);// 解码图片

            imageView.setImageBitmap(bitmap);
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

}

public void Camera() {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);// 相机捕捉图片的意图
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageFileUri);// 指定系统相机拍照保存在imageFileUri所指的位置
startActivityForResult(intent, 1);// 启动系统相机,等待返回
}

public void OpenImage() {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(intent, 2);// 打开本地图库
}

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1 && resultCode == Activity.RESULT_OK) {
String sdStatus = Environment.getExternalStorageState();
if (!sdStatus.equals(Environment.MEDIA_MOUNTED)) { // 检测sd是否可用
Log.i("TestFile", "存储卡读取失败.");
return;
}
// Bundle bundle = data.getExtras();
// Bitmap bitmap = (Bitmap) bundle.get("data");//

Options options = new Options();
options.inJustDecodeBounds = true;// 设置解码只是为了获取图片的width和height值,而不是真正获取图片
Bitmap bitmap = BitmapFactory.decodeFile(imageFilePath, options);// 解码后可以options.outWidth和options.outHeight来获取图片的尺寸

int widthRatio = (int) Math.ceil(options.outWidth / width);// 获取宽度的压缩比率
int heightRatio = (int) Math.ceil(options.outHeight / height);// 获取高度的压缩比率

if (widthRatio > 1 || heightRatio > 1) {// 只要其中一个的比率大于1,说明需要压缩
if (widthRatio >= heightRatio) {// 取options.inSampleSize为宽高比率中的最大值
options.inSampleSize = widthRatio;
} else {
options.inSampleSize = heightRatio;
}
}

options.inJustDecodeBounds = false;// 设置为真正的解码图片
bitmap = BitmapFactory.decodeFile(imageFilePath, options);// 解码图片

}
if (requestCode == 2 && resultCode == RESULT_OK && null != data) {
Uri uri = data.getData();
if (!TextUtils.isEmpty(uri.getAuthority())) {
Cursor cursor = getContentResolver().query(uri,
new String[] { MediaStore.Images.Media.DATA }, null,
null, null);
if (null == cursor) {
Tools.ToastShort("打开失败，请重试！");
return;
}
cursor.moveToFirst();
String path = cursor.getString(cursor
.getColumnIndex(MediaStore.Images.Media.DATA));// 选择的本地图片的路径

BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inJustDecodeBounds = true;
;// 设置解码只是为了获取图片的width和height值,而不是真正获取图片
BitmapFactory.decodeFile(path, opts);// 解码后可以options.outWidth和options.outHeight来获取图片的尺寸
opts.inSampleSize = 10;
opts.inJustDecodeBounds = false;// 设置为真正的解码图片

try {
Bitmap bmp = BitmapFactory.decodeFile(path, opts);

} catch (OutOfMemoryError err) {

}