ImageView的使用，实现本地图片的适屏显示和裁剪功能。

调用系统的Intent的action 来实现图片的选取在imageview中根据屏幕进行适屏显示和图片裁剪后显示，并且可以实现裁剪功能。

布局文件：

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.imageview.MainActivity" >    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world" />    <Button        android:id="@+id/button1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView1"        android:layout_below="@+id/textView1"        android:text="选择图片" />    <Button        android:id="@+id/button2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignBaseline="@+id/button1"        android:layout_alignBottom="@+id/button1"        android:layout_centerHorizontal="true"        android:text="裁剪图片" />    <ImageView        android:id="@+id/imageView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/button1"        android:layout_below="@+id/button1"        android:layout_marginTop="82dp"        android:src="@drawable/ic_launcher" /></RelativeLayout>

activity中的代码如下，注释很详细，大家一看就能懂。

package com.example.imageview;import java.io.IOError;import android.R.anim;import android.R.integer;import android.app.Activity;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends Activity implements OnClickListener {private Button button1, button2;private ImageView imageView;// 声明两个静态的整型变量，主要是用于意图的返回的标志。private static final int IMAGE_SELECT = 1;// 选择图片private static final int IMAGE_CUT = 2;// 裁剪图片。@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button1 = (Button) this.findViewById(R.id.button1);button2 = (Button) this.findViewById(R.id.button2);imageView = (ImageView) this.findViewById(R.id.imageView1);button1.setOnClickListener(this);button2.setOnClickListener(this);}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {// TODO Auto-generated method stubsuper.onActivityResult(requestCode, resultCode, data);if (resultCode == RESULT_OK) {if (requestCode == IMAGE_SELECT) {Uri uri = data.getData();//获得图片路径。int dw = getWindowManager().getDefaultDisplay().getWidth();int dh = getWindowManager().getDefaultDisplay().getHeight() / 2;try {//实现对图片裁剪的类，是一个匿名内部类。BitmapFactory.Options options = new BitmapFactory.Options();options.inJustDecodeBounds = true;// 设置为真，允许查询图片不是按照像素分配给内存。Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null,options);// 对图片的宽度和高度对应手机的屏幕进行匹配。int hRatio = (int) Math.ceil(options.outHeight / (float) dh);// 如果大于1表示图片的高度大于手机屏幕的高度。ceil向下取整。int wRatio = (int) Math.ceil(options.outWidth / (float) dw);// 如果大于1 表示图片的宽度大于手机屏幕的宽度。// 缩放到1/radio的尺寸和1/radio^2像素。if (hRatio > 1 || wRatio > 1) {if (hRatio > wRatio) {// 如果高度大于宽度，以高度为准。options.inSampleSize = hRatio;} else {options.inSampleSize = wRatio;}}options.inJustDecodeBounds = false;bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);imageView.setImageBitmap(bitmap);} catch (Exception e) {// TODO: handle exception}} else if (requestCode == IMAGE_CUT) {Bitmap bitmap = data.getParcelableExtra("data");imageView.setImageBitmap(bitmap);}}}@Overridepublic void onClick(View v) {// TODO Auto-generated method stubswitch (v.getId()) {case R.id.button1:// 获取图片.Intent it = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);startActivityForResult(it, IMAGE_SELECT);break;case R.id.button2:// 图片裁剪.Intent intent = getImageClipIntent();startActivityForResult(intent, IMAGE_CUT);break;}}private Intent getImageClipIntent() {// TODO Auto-generated method stubIntent intent = new Intent(Intent.ACTION_GET_CONTENT, null);// 实现图片裁剪,比粗要设置图片的属性和大小。intent.setType("image/*");// 选取任意图片类型。intent.putExtra("crop", "true");// 滑动选中图片区域intent.putExtra("aspectX", 1);// 表示裁剪切框的比例1:1的效果intent.putExtra("aspectY", 1);intent.putExtra("outputX", 80);// 指定输出图片的大小intent.putExtra("outputX", 80);intent.putExtra("return-data", true);return intent;}}

这个代码可以下载，点击打开链接；http://download.csdn.net/detail/fengzy1990/7797219

下面是Bitmap与Imageview的显示的应用，

打开的是本地文件

imageView = (ImageView)findViewById(R.id.imageView);String path = "sdcard/test.jpg";File file = new File(path);if (file.exists()) {        Bitmap bmp = BitmapFactory.decodeFile(path);        imageView.setImageBitmap(bmp);}

Android用ImageView显示本地和网上的图片

ImageView是Android程序中经常用到的组件，它将一个图片显示到屏幕上。

在UI xml定义一个ImageView如下：

public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.myimage);     ImageView image1 = (ImageView) findViewById(R.myImage.image);     //Bitmap bitmap = getLoacalBitmap("/aa/aa.jpg"); //从本地取图片     Bitmap bitmap =getHttpBitmap("http://blog.3gstdy.com/wp-content/themes/twentyten/images/headers/path.jpg");//从网上取图片     image1 .setImageBitmap(bitmap);//设置Bitmap}/*** 加载本地图片* http://bbs.3gstdy.com* @param url* @return*/public static Bitmap getLoacalBitmap(String url) {     try {          FileInputStream fis = new FileInputStream(url);          return BitmapFactory.decodeStream(fis);     } catch (FileNotFoundException e) {          e.printStackTrace();          return null;     }}/*** 从服务器取图片*http://bbs.3gstdy.com* @param url* @return*/public static Bitmap getHttpBitmap(String url) {     URL myFileUrl = null;     Bitmap bitmap = null;     try {          Log.d(TAG, url);          myFileUrl = new URL(url);     } catch (MalformedURLException e) {          e.printStackTrace();     }     try {          HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();          conn.setConnectTimeout(0);          conn.setDoInput(true);          conn.connect();          InputStream is = conn.getInputStream();          bitmap = BitmapFactory.decodeStream(is);          is.close();     } catch (IOException e) {          e.printStackTrace();     }     return bitmap;}