Android读取系统相册图片并获得绝对地址

public class MainActivity extends Activity {
private Button btn;
private ImageView img;
Bitmap bitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn=(Button)findViewById(R.id.select);
img=(ImageView)findViewById(R.id.pic);
//设置监听
setlistener();
}

private void setlistener() {
// TODO Auto-generated method stub
btn.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent();
intent.setType("image/*");//set intent type
intent.setAction(Intent.ACTION_GET_CONTENT);
//取得图片信息返回MainActivity
startActivityForResult(intent,1);
}
});
}
protected void onActivityResult(int requestCode,int resultCode,Intent data)
{
if(resultCode==RESULT_OK)
{
Uri uri = data.getData();
//通过URI获取图片绝对地址
String[] proj = { MediaStore.Images.Media.DATA };
Cursor cursor = managedQuery(uri,proj,null,null,null);
int actual_image_column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
//游标跳到首位，防止越界
cursor.moveToFirst();
String img_path = cursor.getString(actual_image_column_index);
//通过地址获得位图信息
bitmap =BitmapFactory.decodeFile(img_path);
//设置ImageView资源
img.setImageBitmap(bitmap);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

}