<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="com.example.useimage.MainActivity" >    <Button        android:onClick="selectImage"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="选择一个图片" />         <ImageView          android:id="@+id/iv"         android:layout_width="fill_parent"        android:layout_height="fill_parent"         /></LinearLayout>

package com.example.useimage;import android.content.Intent;import android.net.Uri;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.View;import android.widget.ImageView;public class MainActivity extends ActionBarActivity {    private ImageView iv;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                iv = (ImageView)findViewById(R.id.iv);            }            public void selectImage(View view)    {                Intent intent = new Intent();        intent.setAction(Intent.ACTION_PICK);        intent.setType("image/*");        startActivityForResult(intent, 0);            }    @Override    protected void onActivityResult(int arg0, int arg1, Intent data) {                if(data!=null)        {                        Uri uri = data.getData();            iv.setImageURI(uri);        }        super.onActivityResult(arg0, arg1, data);    }}