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Android入门之Gallery用法实例解析

时间:2021-03-06 23:04     来源/作者:Android开发网

本文实例介绍的android的gallery控件是个很不错的看图控件,可以大大减轻开发者对于看图功能的开发,并且效果也很美观。本文实例中的gallery的用法,主要实现用反射机制来动态读取资源中的图片。

该实例代码运行的效果图如下:

Android入门之Gallery用法实例解析

main.xml源码如下:

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<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
<gallery android:id="@+id/gallery" android:layout_height="fill_parent" android:layout_width="fill_parent"></gallery>
</linearlayout>

java程序源码如下:

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package com.testimageview;
 
import java.lang.reflect.field;
import java.util.arraylist;
 
import android.app.activity;
import android.content.context;
import android.graphics.bitmap;
import android.graphics.bitmapfactory;
import android.os.bundle;
import android.view.view;
import android.view.viewgroup;
import android.widget.adapterview;
import android.widget.baseadapter;
import android.widget.gallery;
import android.widget.imageview;
import android.widget.adapterview.onitemclicklistener;
 
public class testimageview extends activity {
  private gallery mgallery;
  @override
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.main);
     
    mgallery = (gallery)findviewbyid(r.id.gallery);
    try {
      mgallery.setadapter(new imageadapter(this));
    } catch (illegalargumentexception e) {
      // todo auto-generated catch block
      e.printstacktrace();
    } catch (illegalaccessexception e) {
      // todo auto-generated catch block
      e.printstacktrace();
    }
    mgallery.setonitemclicklistener(new onitemclicklistener() {
      public void onitemclick(adapterview parent, view v, int position, long id) {
        testimageview.this.settitle(string.valueof(position));
      }
    });
  }
   
  /*
   * class imageadapter is used to control gallery source and operation.
   */
  private class imageadapter extends baseadapter{
    private context mcontext;
    private arraylist<integer> imglist=new arraylist<integer>();
    private arraylist<object> imgsizes=new arraylist<object>();
    public imageadapter(context c) throws illegalargumentexception, illegalaccessexception{
      mcontext = c;
       
      //用反射机制来获取资源中的图片id和尺寸
      field[] fields = r.drawable.class.getdeclaredfields();
      for (field field : fields)
      {
        if (!"icon".equals(field.getname()))//除了icon之外的图片
        {  
          int index=field.getint(r.drawable.class);
          //保存图片id
          imglist.add(index);
          //保存图片大小
          int size[]=new int[2];
          bitmap bmimg=bitmapfactory.decoderesource(getresources(),index);
          size[0]=bmimg.getwidth();size[1]=bmimg.getheight();
          imgsizes.add(size);
        }
      }
    }
    @override
    public int getcount() {
      // todo auto-generated method stub
 
      return imglist.size();
    }
 
    @override
    public object getitem(int position) {
      // todo auto-generated method stub
 
      return position;
    }
 
    @override
    public long getitemid(int position) {
      // todo auto-generated method stub
 
      return position;
    }
 
    @override
    public view getview(int position, view convertview, viewgroup parent) {
      // todo auto-generated method stub
 
      imageview i = new imageview (mcontext);
      //从imglist取得图片id
      i.setimageresource(imglist.get(position).intvalue());
      i.setscaletype(imageview.scaletype.fit_xy);
      //从imgsizes取得图片大小
      int size[]= new int[2];
      size=(int[]) imgsizes.get(position);
      i.setlayoutparams(new gallery.layoutparams(size[0], size[1]));
      return i;
    }
     
  };
}

 

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