Android得到系统已安装应用程序包列表方法 自定义ListView显示 PackageManager的使用

得到系统安装的程序包，可以通过PackageManager对象getInstalledPackages方法，该方法直接返回一个包含程序包信息PackageInfo的List。今天学习PackageManager的同时，顺便记一下ListView使用自定义适配器以及自定义视图的方法，前面写得不够详细。先看效果图：
[img][/img]
每一项分成三部分，左边是应用图标，右边分上下两部分，上面是应用名，下面是包名。顺便说一下，ListView的自定义布局，定义的是一项的布局，然后根据项的数量叠加。
下面是这个布局的xml代码 piitem.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ImageView android:id="@+id/icon" android:layout_width="48dip"
android:layout_height="48dip" />
<LinearLayout android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="wrap_content">
<TextView android:id="@+id/appName" android:layout_width="fill_parent" android:layout_height="wrap_content"/>
<TextView android:id="@+id/packageName" android:layout_width="fill_parent" android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>

main.xml的布局就不贴了吧，就一个ListView,id为lv
写个自定义的适配器：
package com.pocketdigi;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class Adapter extends SimpleAdapter {
private int[] mTo;
    private String[] mFrom;
    private ViewBinder mViewBinder;
    private List<? extends Map<String, ?>> mData;
    private int mResource;
    private LayoutInflater mInflater;
public Adapter(Context context,List<? extends Map<String, ?>> data, int resource, String[] from,int[] to) {
super(context, data, resource, from, to);
mData = data;
        mResource = resource;
        mFrom = from;
        mTo = to;
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

    public View getView(int position, View convertView, ViewGroup parent) {
        return createViewFromResource(position, convertView, parent, mResource);
    }
    private View createViewFromResource(int position, View convertView,
            ViewGroup parent, int resource) {
        View v;
        if (convertView == null) {
            v = mInflater.inflate(resource, parent, false);

            final int[] to = mTo;
            final int count = to.length;
            final View[] holder = new View[count];

            for (int i = 0; i < count; i++) {
                holder[i] = v.findViewById(to[i]);
            }
            v.setTag(holder);
        } else {
            v = convertView;
        }
        bindView(position, v);
        return v;
    }

    private void bindView(int position, View view) {
        final Map dataSet = mData.get(position);
        if (dataSet == null) {
            return;
        }

        final ViewBinder binder = mViewBinder;
        final View[] holder = (View[]) view.getTag();
        final String[] from = mFrom;
        final int[] to = mTo;
        final int count = to.length;

        for (int i = 0; i < count; i++) {
            final View v = holder[i];
            if (v != null) {
                final Object data = dataSet.get(from[i]);
                String text = data == null ? "" : data.toString();
                if (text == null) {
                    text = "";
                }

                boolean bound = false;
                if (binder != null) {
                    bound = binder.setViewValue(v, data, text);
                }

                if (!bound) {
                //自定义适配器，关键在这里，根据传过来的控件类型以及值的数据类型，执行相应的方法
                //可以根据自己需要自行添加if语句。另CheckBox等继承自TextView的控件也会被识别成TextView， 这就需要判断值的类型了
                  if (v instanceof TextView) {
                  //如果是TextView控件
                        setViewText((TextView) v, text);
                        //调用SimpleAdapter自带的方法，设置文本
                    } else if (v instanceof ImageView) {//如果是ImageView控件
                        setViewImage((ImageView) v, (Drawable) data);
                        //调用下面自己写的方法，设置图片
                    } else {
                        throw new IllegalStateException(v.getClass().getName() + " is not a " +
                                " view that can be bounds by this SimpleAdapter");
                    }
                }
            }
        }
    }

    public void setViewImage(ImageView v, Drawable value) {
    v.setImageDrawable(value);

    }

};

关键部分已注释，如果用到其他控件，只要修改注释的地方增加判断就可以了。
下面是主程序代码 Main.java:
package com.pocketdigi;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import android.app.Activity;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.widget.ListView;

public class Main extends Activity {
/** Called when the activity is first created. */
ListView lv;
Adapter adapter;
ArrayList<HashMap<String, Object>> items=new ArrayList<HashMap<String, Object>>();

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
lv = (ListView) findViewById(R.id.lv);
PackageManager  pm= getPackageManager();
//得到PackageManager对象
List<PackageInfo> packs = pm.getInstalledPackages(0);
//得到系统 安装的所有程序包的PackageInfo对象

for (PackageInfo pi : packs) {
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("icon", pi.applicationInfo.loadIcon(pm));
//图标
map.put("appName", pi.applicationInfo.loadLabel(pm));
//应用名
map.put("packageName", pi.packageName);
//包名
items.add(map);
//循环读取存到HashMap,再增加到ArrayList.一个HashMap就是一项
}

adapter = new Adapter(this, items, R.layout.piitem, new String[] {
"icon", "appName", "packageName" }, new int[] { R.id.icon,
R.id.appName, R.id.packageName });
//参数:Context,ArrayList(item的集合),item的layout,包含ArrayList中Hashmap的key的数组,key所对应的值相对应的控件id
lv.setAdapter(adapter);

}
}

原文地址：http://www.pocketdigi.com/20110728/425.html