安卓开发——笔记（1）

Android

记录安卓开发时，所遇到的问题及方法

调试输出

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import android.util.Log;

Log.v("a", "Haha , this is a Verbose of MyAndroid. ");
Log.d("a", "Haha , this is a Debug of MyAndroid. ");
Log.i("a", "Haha , this is a Info of MyAndroid. ");
Log.w("a", "Haha , this is a Warning of MyAndroid. ");
Log.e("a", "Haha , this is a Error of MyAndroid. ");

点击事件获取文本内容

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final TextView value = (TextView) findViewById(R.id.textView);

Button btn = new Button(this);
//绑定点击事件
btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        String text = ((Button) v).getText().toString();
        value.setText(value.getText()+text);
    }
});

在xml里绑定事件并传参数

xml部分代码

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<Button 
        android:onClick="click"
        android:tag="params"/>

java部分代码

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public void click(View view){
    String param = view.getTag().toString();
}

引用res里的资源，类型变为 View

通过加载器 LayoutInflater

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LayoutInflater tableItem = LayoutInflater.from(this);
View viewItem = tableItem.inflate(R.layout.fbutton_item, null);

handler发送消息(线程间通讯)

子线程里无法调用ui，通过handler发送消息至ui线程

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private static final int SHOW_TOAST = 1;
private Handler mHandler = null;    

@Override
public void onCreate(){
    Message msg = new Message();
    msg.what = SHOW_TOAST;
    msg.obj = "信息";
    mHandler.sendMessage(msg);
}

// 发送消息
private class MsgHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what){
            case SHOW_TOAST:
                String text = msg.obj.toString();
                Toast toast = Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG);
                toast.setGravity(Gravity.CENTER, 0, 0);
                toast.show();
                break;
            default:
                throw new IllegalStateException("Unexpected value: " + msg.what);
        }
    }
}

广播事件

Tip:

  • 可一个接收器 对应多个 action ( 用 intent-filter 包裹) 或 多个接收器
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<receiver
    android:name=".MyBroadcastReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />
    </intent-filter>
    <intent-filter>
        <action android:name="android.intent.action.DOWNLOAD_COMPLETE" />
    </intent-filter>
</receiver>

将数据写入本地缓存

用 SharedPreferences

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private SharedPreferences sf;
private SharedPreferences.Editor edit;

public void onCreate() {
    // 链接库
    sf = getSharedPreferences(getResources().getString(R.string.app_name), Context.MODE_PRIVATE);
    // 编辑器
    edit = sf.edit();
    // set 值
    edit.putString("key","value");
    edit.commit();
    // get 值
    sf.getString("key","");
}

播放mp3音频

  • 在main目录下 新建个 assets目录 存放mp3音频
  • 用 MediaPlayer 播放音频
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private MediaPlayer musicPlay = null;
private AssetManager assetManager = null;
private List<AssetFileDescriptor> musicQueue = new ArrayList<AssetFileDescriptor>();
// 初始化播放器
private void initPlayer(Context context) {
    // 获取asset文件管理器
    assetManager = context.getAssets();
    // new 播放器
    musicPlay = new MediaPlayer();
    // 播放结束监听
    musicPlay.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mp) {
            // 存在播放队列
            if (musicQueue.size() != 0) {
                play(musicQueue.get(0));
                musicQueue.remove(0);
            }
            return;
        }
    });
}

// 开始播放
private void play(AssetFileDescriptor music) {
    try {
        // 存在播放任务,追加队列中
        if (musicPlay.isPlaying()) {
            musicQueue.add(music);
            return;
        }
        // 重置播放器
        musicPlay.reset();
        // 设置播放资源
        musicPlay.setDataSource(music.getFileDescriptor(), music.getStartOffset(), music.getLength());
        // 预加载
        musicPlay.prepare();
        // 开始
        musicPlay.start();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

// 选择播放音频
private void selectMusic() {
    try {
        // 播放 test.mp3
        this.play(assetManager.openFd("test.mp3"));
    } catch (IOException e) {
        e.printStackTrace();
    }
}

解析JSON

  • 用 阿里的 fastjson

app 配置文件

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dependencies {
	implementation 'com.alibaba:fastjson:1.2.62'
}

简单dome

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// 引
import com.alibaba.fastjson.JSONObject;

// 反序列化
JSONObject data = JSONObject.parseObject(res);
String type = data.getString("type");

socket

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// 连接 socket
socket = new Socket(SOCKET_IP, SOCKET_PORT);

//构建IO
InputStream is = socket.getInputStream();
OutputStream os = socket.getOutputStream();
bw = new BufferedWriter(new OutputStreamWriter(os));

//读取服务器返回的消息
br = new BufferedReader(new InputStreamReader(is));

//向服务器端发送一条消息
try {
    bw.write("msg" + "\n");
    bw.flush();
} catch (IOException e) {
    e.printStackTrace();
}

// 持续读消息
String res;
while ((res = br.readLine()) != null) {
        // 当读到消息 do something              
}

弹窗AlertDialog

基本用法

  • setTitle ：为对话框设置标题
  • setIcon ：为对话框设置图标
  • setMessage：为对话框设置内容
  • setView ： 给对话框设置自定义样式
  • setItems ：设置对话框要显示的一个list，一般用于显示几个命令时
  • setMultiChoiceItems ：用来设置对话框显示一系列的复选框
  • setSingleChoiceItems ：用来设置对话框显示一系列的单选框
  • setNeutralButton ：普通按钮
  • setPositiveButton ：给对话框添加”Yes”按钮
  • setNegativeButton ：对话框添加”No”按钮
  • create ： 创建对话框
  • show ：显示对话框

dome

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AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setTitle("这是标题")
    .setMessage("这是内容")
    .setNegativeButton("取消", null)
    .create();

builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int which) {
        // do something
    }
});
builder.show();

打开跳转至无障碍设置页面

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Intent intent = new Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
this.getApplicationContext().startActivity(intent);

通过shell静默开启无障碍模式

  • root权限

开启

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// 包名/程序名
String myAs = this.getPackageName() + "/" + MainAccessibilityService.class.getName();
// 获取目前设置无障碍模式的app
String nowAs = shellExec("settings get secure enabled_accessibility_services");
nowAs.replace("\n", "");
// 目前存在其它时,追加 : 隔开
if (nowAs.length() > 1 && !nowAs.contains(myAs)) {
    nowAs = ":" + nowAs;
}
// 不存在时,即设置.存在直接启动
if(!nowAs.contains(myAs)){
    String cmd = "settings put secure enabled_accessibility_services " + myAs + nowAs;
    shellExec(cmd);
}
// 启动
shellExec("settings put secure accessibility_enabled 1");

关闭

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// 包名/程序名
String myAs = this.getPackageName() + "/" + MainAccessibilityService.class.getName();
// 获取目前的配置
String nowAs = shellExec("settings get secure enabled_accessibility_services");
nowAs.replace("\n", "");
// 找到需关闭的程序对应下标
int index = nowAs.indexOf(myAs);
// 找到后
if (index >= 0) {
    // 前面的 : 下标
    int beforeIndex = nowAs.lastIndexOf(":", index);
    // 后面的 : 下标
    int afterIndex = nowAs.indexOf(":", index);
    // 判断下,得到 需关闭程序+: 的头尾 下标
    if (beforeIndex < 0) beforeIndex = 0;
    if (afterIndex < 0) afterIndex = nowAs.length();
    else afterIndex++;
    // 截取
    String As = nowAs.substring(0, beforeIndex) + nowAs.substring(afterIndex, nowAs.length());
    // 判断是否为空
    if (As.length() > 0) {
        shellExec("settings put secure enabled_accessibility_services " + As);
        shellExec("settings put secure accessibility_enabled 1");
    } else {
        shellExec("settings put secure enabled_accessibility_services ''");
        shellExec("settings put secure accessibility_enabled 0");
    }
}

执行shell 命令

简易版

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private String shellExec(String cmd) {
        StringBuilder result = new StringBuilder();
        try {
//            Log.i(Tag, "start shell command");

            Runtime runtime = Runtime.getRuntime();
            Process process = runtime.exec("su");

            DataOutputStream os = new DataOutputStream(process.getOutputStream());

            os.write(cmd.getBytes());
            os.writeBytes("\n");
            os.flush();
            os.writeBytes("exit\n");
            os.flush();

            BufferedReader successResult = new BufferedReader(new InputStreamReader(process.getInputStream()));
            BufferedReader errorResult = new BufferedReader(new InputStreamReader(process.getErrorStream()));

            String str;
            while ((str = errorResult.readLine()) != null) {
                result.append(str + "\n");
            }
            while ((str = successResult.readLine()) != null) {
                result.append(str + "\n");
            }


//            Log.i(Tag, result.toString());

//            Log.i(Tag, "end shell");
            os.close();
            successResult.close();
            errorResult.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result.toString();
    }

静默安装apk

  • root 权限
  • su 下执行
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// shell 运行命令
shellExec("pm install xxx/xxx.apk");
// 覆盖安装
shellExec("pm install -r xxx/xxx.apk");

调用系统安装apk (需手动点击安装)

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// 安装路径
String path = "xxx/xxx.apk";
File file = new File(path);
// 是否存在
if(file.exists()){
    Uri fileUri = Uri.fromFile(file);
    // 执行安装
    Intent installIntent = new Intent(Intent.ACTION_VIEW);
    installIntent.setDataAndType(fileUri, "application/vnd.android.package-archive");
    installIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    this.startActivity(installIntent);
}

Tip

  • 字体单位 用 sp

  • 常用单位dp