【android】仿照长按home键 恢复后台运行程序

permission <uses-permission android:name="android.permission.GET_TASKS"/>

package yanbin.recent;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import android.app.Activity;

import android.app.ActivityManager;

import android.app.Dialog;

import android.content.ActivityNotFoundException;

import android.content.Context;

import android.content.Intent;

import android.content.pm.ActivityInfo;

import android.content.pm.PackageManager;

import android.content.pm.ResolveInfo;

import android.database.DataSetObserver;

import android.graphics.drawable.Drawable;

import android.os.Bundle;

import android.util.Log;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.GridView;

import android.widget.ImageView;

import android.widget.ListAdapter;

import android.widget.TextView;

/**

* 弹出最近任务测试

* @author yanbin

*

*/

public class MainActivity extends Activity {

private Dialog mDialog;

private static int MAX_RECENT_TASKS = 12; // allow for some discards

private static int repeatCount = 12;//保证上面两个值相等

//用来存放每一个recentApplication的信息，我们这里存放应用程序名，应用程序图标和intent。

private List<HashMap<String,Object>> appInfos = new ArrayList<HashMap<String, Object>>();

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

reloadButtons();//程序加载的时候就加载出最近任务

}

public void click(View view){

int id = view.getId();

switch (id) {

case R.id.btn:

generateDialog();

break;

}

}

/**

* 弹出最近任务对话框

*/

public void generateDialog(){

mDialog = new Dialog(this,R.style.dialog);

LayoutInflater mInflater = LayoutInflater.from(this);

View dialogView = mInflater.inflate(R.layout.choose_dialog, null);

final GridView mGridView = (GridView) dialogView.findViewById(R.id.choose_dialog_gridview);

mGridView.setAdapter(new MyAppAdapter());

mDialog.setContentView(dialogView);

mDialog.setCanceledOnTouchOutside(true);

mDialog.show();

}

/**

* 核心方法，加载最近启动的应用程序

* 注意：这里我们取出的最近任务为 MAX_RECENT_TASKS + 1个，因为有可能最近任务中包好Launcher2。

* 这样可以保证我们展示出来的 最近任务 为 MAX_RECENT_TASKS 个

*/

private void reloadButtons() {

//得到包管理器和activity管理器

final Context context = this;

final PackageManager pm = context.getPackageManager();

final ActivityManager am = (ActivityManager)

context.getSystemService(Context.ACTIVITY_SERVICE);

//从ActivityManager中取出用户最近launch过的 MAX_RECENT_TASKS + 1 个，以从早到晚的时间排序，

//注意这个 0x0002,它的值在launcher中是用ActivityManager.RECENT_IGNORE_UNAVAILABLE

//但是这是一个隐藏域，因此我把它的值直接拷贝到这里

final List<ActivityManager.RecentTaskInfo> recentTasks =

am.getRecentTasks(MAX_RECENT_TASKS + 1, 0x0002);

//这个activity的信息是我们的launcher

ActivityInfo homeInfo =

new Intent(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_HOME)

.resolveActivityInfo(pm, 0);

int numTasks = recentTasks.size();

for (int i = 0; i < numTasks && (i < MAX_RECENT_TASKS); i++) {

HashMap<String, Object> singleAppInfo = new HashMap<String, Object>();//当个启动过的应用程序的信息

final ActivityManager.RecentTaskInfo info = recentTasks.get(i);

Intent intent = new Intent(info.baseIntent);

if (info.origActivity != null) {

intent.setComponent(info.origActivity);

}

//TODO 测试用，无意义代码

String currentInfo = "PackageName==" + intent.getComponent().getPackageName() + ",ClassName==" + intent.getComponent().getClassName();

/**

* 如果找到是launcher，直接continue，后面的appInfos.add操作就不会发生了

*/

if (homeInfo != null) {

if (homeInfo.packageName.equals(

intent.getComponent().getPackageName())

&& homeInfo.name.equals(

intent.getComponent().getClassName())) {

MAX_RECENT_TASKS = MAX_RECENT_TASKS + 1;

continue;

}

}

//设置intent的启动方式为 创建新task()【并不一定会创建】

intent.setFlags((intent.getFlags()&~Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED)

| Intent.FLAG_ACTIVITY_NEW_TASK);

//获取指定应用程序activity的信息(按我的理解是：某一个应用程序的最后一个在前台出现过的activity。)

final ResolveInfo resolveInfo = pm.resolveActivity(intent, 0);

if (resolveInfo != null) {

final ActivityInfo activityInfo = resolveInfo.activityInfo;

final String title = activityInfo.loadLabel(pm).toString();

Drawable icon = activityInfo.loadIcon(pm);

if (title != null && title.length() > 0 && icon != null) {

singleAppInfo.put("title", title);

singleAppInfo.put("icon", icon);

singleAppInfo.put("tag", intent);

}

}

appInfos.add(singleAppInfo);

}

MAX_RECENT_TASKS = repeatCount;

}

/**

* gridview的适配器

* @author yanbin

*

*/

private class MyAppAdapter implements ListAdapter{

@Override

public void registerDataSetObserver(DataSetObserver observer) {

}

@Override

public void unregisterDataSetObserver(DataSetObserver observer) {

}

@Override

public int getCount() {

return appInfos.size();

}

@Override

public Object getItem(int position) {

return appInfos.get(position);

}

@Override

public long getItemId(int position) {

return position;

}

@Override

public boolean hasStableIds() {

return false;

}

/**

* 自定义view

*/

@Override

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

LayoutInflater mInflater = LayoutInflater.from(MainActivity.this);

View infoView = mInflater.inflate(R.layout.choose_dialog_detail_info, null);

ImageView mImageView = (ImageView) infoView.findViewById(R.id.app_icon);

TextView mTextView = (TextView) infoView.findViewById(R.id.choose_dialog_detail_tv);

String title = (String) appInfos.get(position).get("title");

Drawable icon = (Drawable) appInfos.get(position).get("icon");

Intent singleIntent = (Intent) appInfos.get(position).get("tag");

infoView.setTag(singleIntent);

mImageView.setImageDrawable(icon);

mTextView.setText(title);

infoView.setOnClickListener(new SingleAppClickListener());

return infoView;

}

@Override

public int getItemViewType(int position) {

return 0;

}

@Override

public int getViewTypeCount() {

return 1;

}

@Override

public boolean isEmpty() {

return false;

}

@Override

public boolean areAllItemsEnabled() {

return false;

}

@Override

public boolean isEnabled(int position) {

return false;

}

}

/**

* 点击应用图标即可启动程序

* @author yanbin

*

*/

private class SingleAppClickListener implements View.OnClickListener{

@Override

public void onClick(View v) {

Intent intent = (Intent)v.getTag();

if (intent != null) {

intent.addFlags(Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY);

try {

MainActivity.this.startActivity(intent);

if(mDialog != null)

mDialog.dismiss();

} catch (ActivityNotFoundException e) {

Log.w("Recent", "Unable to launch recent task", e);

}

}

}

}

}