一个简单的仿 Launcher 应用

时间：2021-12-08 23:47:44

本例实现两个功能：

  1. 系统桌面上的app图标能够排列在我们的页面上。
  2. 点击自定义桌面上的app图标,能够打开对应的app。

实现思路：

  1. 我们知道，一个应用的启动页 Activity 的 Intent 的 filter 中 包含 action 为 Intent.ACTION_MAIN和category为 Intent.CATEGORY_LAUNCHER 信息，我们构造一个这样的 Intent 来查询所有启动页 Activity 。
  2. 用一个 RecyclerView 来展示信息。
  3. 通过 Intent 跳转到对应 app 的主页面。

主要代码如下：

activity_main.xml

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

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context="com.example.sharpcj.launchertest.MainActivity">

    <android.support.v7.widget.RecyclerView

        android:padding="10dp"

        android:id="@+id/rv_test"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:text="Hello World!"

        app:layout_constraintBottom_toBottomOf="parent"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

recyclerview_item.xml

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

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

    android:orientation="vertical"

    android:layout_width="100dp"

    android:layout_height="100dp">

    <ImageView

        android:id="@+id/iv_icon"

        android:layout_width="70dp"

        android:layout_height="70dp"

        android:layout_marginLeft="15dp"

        android:layout_marginTop="10dp"/>

    <TextView

        android:id="@+id/tv_name"

        android:layout_width="wrap_content"

        android:layout_height="15dp"

        android:layout_marginTop="5dp"

        android:textSize="13sp"

        android:maxLines="1"

        android:ellipsize="end"

        android:layout_gravity="center_horizontal"

        />

</LinearLayout>

MainActivity.java

package com.example.sharpcj.launchertest;

import android.content.ComponentName;

import android.content.Intent;

import android.content.pm.ResolveInfo;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.support.v7.widget.GridLayoutManager;

import android.support.v7.widget.RecyclerView;

import android.view.View;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRvTest;

    private List<ResolveInfo> mlsResolveInfo;

    private RvTestAdapter mAdapter;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mRvTest = findViewById(R.id.rv_test);

        mlsResolveInfo = new ArrayList<>();

        mRvTest.setLayoutManager(new GridLayoutManager(this, 4));

        mAdapter = new RvTestAdapter(MainActivity.this, mlsResolveInfo, new RvTestAdapter.OnItemClickListener() {

            @Override

            public void onClick(View view, int position) {

                ResolveInfo resolveInfo = mlsResolveInfo.get(position);

                startAppByResolveInfo(resolveInfo);

                MainActivity.this.finish();

            }

        });

        mRvTest.setAdapter(mAdapter);

        List<ResolveInfo> resolveInfos = queryMainActivitiesInfo();

        mlsResolveInfo.addAll(resolveInfos);

        mAdapter.notifyDataSetChanged();

    }

    /**

     * 查询所有包含启动 intent 的 Activity 信息（去掉本应用）

     *

     * @return

     */

    private List<ResolveInfo> queryMainActivitiesInfo() {

        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);

        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

        List<ResolveInfo> resolveInfos = getPackageManager().queryIntentActivities(mainIntent, 0);

        // 去掉本应用

        Iterator<ResolveInfo> iterator = resolveInfos.iterator();

        while (iterator.hasNext()) {

            ResolveInfo resolveInfo = iterator.next();

            String packageName = resolveInfo.activityInfo.packageName;

            if (packageName.equals(getApplication().getPackageName())) {

                iterator.remove();

            }

        }

        return resolveInfos;

    }

    private void startAppByResolveInfo(ResolveInfo resolveInfo) {

        String pkg = resolveInfo.activityInfo.packageName;

        String cls = resolveInfo.activityInfo.name;

        ComponentName componet = new ComponentName(pkg, cls);

        //打开该应用的主activity

        Intent intent = new Intent();

        intent.setComponent(componet);

        startActivity(intent);

    }

}

RvTestAdapter.java

package com.example.sharpcj.launchertest;

import android.content.Context;

import android.content.pm.ResolveInfo;

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.TextView;

import java.util.List;

/**

 * Created by SharpCJ on 2018/7/26.

 */

public class RvTestAdapter extends RecyclerView.Adapter<RvTestAdapter.ViewHolder> {

    public interface OnItemClickListener {

        void onClick(View view, int position);

    }

    private Context mContext;

    private List<ResolveInfo> mlsResolveInfo;

    private OnItemClickListener mListener;

    public RvTestAdapter(Context context, List<ResolveInfo> resolveInfos, OnItemClickListener listener) {

        this.mContext = context;

        this.mlsResolveInfo = resolveInfos;

        this.mListener = listener;

    }

    public void setmListener(OnItemClickListener listener) {

        this.mListener = listener;

    }

    @Override

    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(mContext).inflate(R.layout.recyclerview_item, parent, false);

        RvTestAdapter.ViewHolder viewHolder = new RvTestAdapter.ViewHolder(view, mListener);

        return viewHolder;

    }

    @Override

    public void onBindViewHolder(ViewHolder holder, int position) {

        ResolveInfo resolveInfo = mlsResolveInfo.get(position);

        holder.imageView.setImageDrawable(resolveInfo.activityInfo.loadIcon(mContext.getPackageManager()));

        holder.textView.setText(resolveInfo.activityInfo.applicationInfo.loadLabel(mContext.getPackageManager()));![](https://images2018.cnblogs.com/blog/758949/201807/758949-20180727193233793-2028954389.gif)

    }

    @Override

    public int getItemCount() {

        return mlsResolveInfo.size();

    }

    class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        OnItemClickListener onItemClickListener;

        ImageView imageView;

        TextView textView;

        public ViewHolder(View itemView, OnItemClickListener onItemClickListener) {

            super(itemView);

            this.onItemClickListener = onItemClickListener;

            imageView = itemView.findViewById(R.id.iv_icon);

            textView = itemView.findViewById(R.id.tv_name);

            itemView.setOnClickListener(this);

        }

        @Override

        public void onClick(View v) {

            if (onItemClickListener != null) {

                onItemClickListener.onClick(v, getAdapterPosition());

            }

        }

    }

}

运行效果如图：

一个简单的仿 Launcher 应用

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