APIDEMO GRIDVIEW

最新推荐文章于 2013-04-15 17:57:09 发布

最新推荐文章于 2013-04-15 17:57:09 发布 · 92 阅读

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本文介绍了一个简单的 Android GridView 示例，展示了如何加载应用图标并将其显示在 GridView 中。通过封装 Intent 查询所有可启动 Activity 的方式，获取应用程序列表，并使用自定义 Adapter 来填充 GridView。

/* * Copyright (C) 2007 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.android.apis.view; import android.app.Activity; import android.content.Intent; import android.content.pm.ResolveInfo; import android.os.Bundle; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.GridView; import android.widget.ImageView; import java.util.List; //Need the following import to get access to the app resources, since this //class is in a sub-package. import com.example.android.apis.R; public class Grid1 extends Activity { GridView mGrid; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); loadApps(); // do this in onresume? setContentView(R.layout.grid_1); mGrid = (GridView) findViewById(R.id.myGrid); mGrid.setAdapter(new AppsAdapter()); } //程序信息列表 private List<ResolveInfo> mApps; private void loadApps() { //封装查询用Intent, 查询所以Action=ACTION_MAIN且action=CATEGORY_LAUNCHER的程序Activity. //<action android:name="android.intent.action.MAIN" /> // <category android:name="android.intent.category.LAUNCHER" /> Intent mainIntent = new Intent(Intent.ACTION_MAIN, null); mainIntent.addCategory(Intent.CATEGORY_LAUNCHER); //PackageManage查询 mApps = getPackageManager().queryIntentActivities(mainIntent, 0); } public class AppsAdapter extends BaseAdapter { public AppsAdapter() { } //返回对应position位置的view public View getView(int position, View convertView, ViewGroup parent) { ImageView i; //优先使用convertView,可以节省每次的创建内存。 if (convertView == null) { i = new ImageView(Grid1.this); i.setScaleType(ImageView.ScaleType.FIT_CENTER); i.setLayoutParams(new GridView.LayoutParams(50, 50)); } else { i = (ImageView) convertView; } ResolveInfo info = mApps.get(position); //ResolveInfo.activityInfo 相关Activity的信息 i.setImageDrawable(info.activityInfo.loadIcon(getPackageManager())); return i; } //返回ListAdapter View数目 public final int getCount() { return mApps.size(); } //返回ListAdapter 对应View public final Object getItem(int position) { return mApps.get(position); } //返回ListAdapter 对应View的position public final long getItemId(int position) { return position; } } }

介绍一下里面的某些属性：

android:numColumns="auto_fit" ，GridView的列数设置为自动

android:columnWidth="90dp"，每列的宽度，也就是Item的宽度
android:stretchMode="columnWidth"，缩放与列宽大小同步
android:verticalSpacing="10dp"，两行之间的边距，如：行一(NO.0~NO.2)与行二(NO.3~NO.5)间距为10dp
android:horizontalSpacing="10dp"，两列之间的边距。