Android实战简易教程-第十枪（画廊组件Gallery有用研究）

时间：2023-03-08 19:28:52

Gallery组件用于拖拽浏览图片，以下我们就来看一下怎样实现。

一、实现Gallery

1.布局文件非常easy：

<?xml version="1.0" encoding="utf-8"?

>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/MyLayout"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:background="#FFFFFF"

    android:orientation="vertical" >

    <Gallery

        android:id="@+id/myGallery"

        android:gravity="center_vertical"

        android:layout_width="match_parent"

        android:layout_height="wrap_content" />

</LinearLayout>

2.自己定义适配器类，能够直接覆写BaseAdapter类中的几个方法。

package org.yayun.demo;

import android.content.Context;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.Gallery;

import android.widget.ImageView;

import android.widget.Gallery.LayoutParams;

public class ImageGalleryAdapter extends BaseAdapter {

	private Context context;

	private int imgRes[] = new int[] { R.drawable.ispic_a, R.drawable.ispic_b,

			R.drawable.ispic_c, R.drawable.ispic_d, R.drawable.ispic_e, };

	public ImageGalleryAdapter(Context c) {//构造方法，用于获取上下文对象

		this.context = c;

	}

	public int getCount() {

		return imgRes.length;

	}

	public Object getItem(int position) {

		return imgRes[position];

	}

	public long getItemId(int position) {

		return imgRes[position];

	}

	public View getView(int position, View convertView, ViewGroup parent) {

		ImageView img = new ImageView(this.context);

		img.setBackgroundColor(0xFFFFFFFF);

		img.setImageResource(this.imgRes[position]);//设置资源

		img.setScaleType(ImageView.ScaleType.CENTER);//居中显示

		img.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,

				LayoutParams.WRAP_CONTENT));

		return img;

	}

}

3.MainActivity.java:

package org.yayun.demo;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.AdapterView;

import android.widget.Toast;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.Gallery;

public class MainActivity extends Activity {

	private Gallery gallery;

	public void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState); // 生命周期方法

		super.setContentView(R.layout.main); // 设置要使用的布局管理器

		gallery = (Gallery) findViewById(R.id.myGallery);

		gallery.setAdapter(new ImageGalleryAdapter(this));

		gallery.setOnItemClickListener(new OnItemClickListener() {

			public void onItemClick(AdapterView<?> parent, View view,

					int position, long id) {

				Toast.makeText(MainActivity.this,

						"您选择了第" + String.valueOf(position + 1) + "张图片",

						Toast.LENGTH_SHORT).show();

			}

		});

	}

}

4.执行实比例如以下：

Android实战简易教程-第十枪（画廊组件Gallery有用研究）

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二、Gallery和ImageSwitcher结合

这时的Gallery我们用SimpleAdapter类完毕。

1.布局文件：

<?

xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/MyLayout"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:background="#FFFFFF"

    android:gravity="bottom"

    android:orientation="vertical" >

    <ImageSwitcher

        android:id="@+id/imageSwitcher"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content" >

    </ImageSwitcher>

    <Gallery

        android:id="@+id/gallery"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:gravity="center_vertical"

        android:spacing="5dp" />

</LinearLayout>

2.定义显示模板：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:background="#FFFFFF"

    android:orientation="horizontal" >

    <ImageView

        android:id="@+id/img"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:scaleType="center" />

</LinearLayout>

3.MainActivity.java程序：

package org.yayun.demo;

import java.lang.reflect.Field;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.AdapterView;

import android.widget.ImageSwitcher;

import android.widget.ImageView;

import android.widget.SimpleAdapter;

import android.widget.Toast;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.Gallery.LayoutParams;

import android.widget.Gallery;

import android.widget.ViewSwitcher.ViewFactory;

public class MainActivity extends Activity {

	private Gallery gallery;

	private List<Map<String, Integer>> list = new ArrayList<Map<String, Integer>>();

	private SimpleAdapter simpleAdapter;

	private ImageSwitcher imageSwitcher;

	public void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState); // 生命周期方法

		super.setContentView(R.layout.main); // 设置要使用的布局管理器

		initAdapter();

		gallery = (Gallery) findViewById(R.id.gallery);

		imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher);

		imageSwitcher.setFactory(new ViewFactory() {

			public View makeView() {

				ImageView imageView = new ImageView(MainActivity.this);

				imageView.setBackgroundColor(0xFFFFFFFF);

				imageView.setScaleType(ImageView.ScaleType.CENTER);

				imageView.setLayoutParams(new ImageSwitcher.LayoutParams(

						LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

				return imageView;

			}

		});

		gallery.setAdapter(simpleAdapter);

		gallery.setOnItemClickListener(new OnItemClickListener() {

			public void onItemClick(AdapterView<?> parent, View view,

					int position, long id) {

				Map<String, Integer> map = (Map<String, Integer>) MainActivity.this.simpleAdapter

						.getItem(position);// 取出map

				MainActivity.this.imageSwitcher.setImageResource(map.get("img"));// 设置显示图片

			}

		});

	}

	private void initAdapter() {

		Field[] fields = R.drawable.class.getDeclaredFields();// Java反射机制获取全部资源图片

		for (int i = 0; i < fields.length; i++) {

			if (fields[i].getName().startsWith("ispic_")) {// 推断开头

				Map<String, Integer> map = new HashMap<String, Integer>();

				try {

					map.put("img", fields[i].getInt(R.drawable.class));

				} catch (IllegalArgumentException e) {

					// TODO Auto-generated catch block

					e.printStackTrace();

				} catch (IllegalAccessException e) {

					// TODO Auto-generated catch block

					e.printStackTrace();

				}

				this.list.add(map);

			}

		}

		simpleAdapter = new SimpleAdapter(this, this.list,

				R.layout.grid_layout, new String[] { "img" },

				new int[] { R.id.img });

	}

}

4.执行实例：

Android实战简易教程-第十枪（画廊组件Gallery有用研究）