Android官方Guide回顾补漏

来源：互联网发布：乔丹和詹姆斯数据对比编辑：程序博客网时间：2024/05/21 09:08

记录

1.设置启动Activity

            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="ANDROID.INTENT.CATEGORY.LAUNCHER" />            </intent-filter>

2.针对不同版本采用不同处理办法

private void setUpActionBar() {    // Make sure we're running on Honeycomb or higher to use ActionBar APIs    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {        ActionBar actionBar = getActionBar();        actionBar.setDisplayHomeAsUpEnabled(true);   //左上角图标是否显示    }}

3.默认安装位置

<manifest xmlns:android="http://schemas.android.com/apk/res/android"          package="com.example"          android:installLocation="auto">

4.文件相关知识

getFilesDir() //返回应用内部目录的File

getCacheDir()//返回应用临时缓存文件的内部目录的File

File file = File.createTempFile(filename.null,getCacheDir());//创建临时文件

getExternalStoragePublicDirectory(Environment.DIRECTORY_XXXX)//得到外部存储的公共文件夹

getExternalFilesDir() //得到外部存储的私有文件夹·

getFreeSpace() //获取可用空间

myFile.delete()//删除文件

myContext.deleteFile(filename)//删除内部文件

检测外部存储是否可写

public boolean isExternalStorageWritable() {    String state = Environment.getExternalStorageState();    if (Environment.MEDIA_MOUNTED.equals(state)) {        return true;    }    return false;}

5.Intent

使用Uri来携带数据，通过Intent的第一个参数Action确定需要调用的Activity。

Uri webpage = Uri.parse("http://www.android.com");Intent webIntent = new Intent(Intent.ACTION_VIEW, webpage);

检测是否存在可响应的Activity

PackageManager packageManager = getPackageManager();List activities = packageManager.queryIntentActivities(intent,        PackageManager.MATCH_DEFAULT_ONLY);boolean isIntentSafe = activities.size() > 0;

创建选择器，而不是选择默认程序

Intent chooser = Intent.createChooser(intent, title);// Verify the intent will resolve to at least one activityif (intent.resolveActivity(getPackageManager()) != null) {    startActivity(chooser);}

获取联系人数据后读取

@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {    // Check which request it is that we're responding to    if (requestCode == PICK_CONTACT_REQUEST) {        // Make sure the request was successful        if (resultCode == RESULT_OK) {            // Get the URI that points to the selected contact            Uri contactUri = data.getData();            // We only need the NUMBER column, because there will be only one row in the result            String[] projection = {Phone.NUMBER};            // Perform the query on the contact to get the NUMBER column            // We don't need a selection or sort order (there's only one result for the given URI)            // CAUTION: The query() method should be called from a separate thread to avoid blocking            // your app's UI thread. (For simplicity of the sample, this code doesn't do that.)            // Consider using CursorLoader to perform the query.            Cursor cursor = getContentResolver()                    .query(contactUri, projection, null, null, null);            cursor.moveToFirst();            // Retrieve the phone number from the NUMBER column            int column = cursor.getColumnIndex(Phone.NUMBER);            String number = cursor.getString(column);            // Do something with the phone number...        }    }}

6.系统权限

从6.0（api23）开始，安卓程序在运行时请求权限，而不是再程序安装时请求权限。

检查权限的方式

int permissionCheck = ContextCompat.checkSelfPermission(thisActivity,        Manifest.permission.WRITE_CALENDAR);         //有权限时返回 PackageManager.PERMISSION_GRANTED  无权限时返回PERMISSION_DENIED

        ActivityCompat.requestPermissions(thisActivity,//无权限时请求权限                new String[]{Manifest.permission.READ_CONTACTS},                MY_PERMISSIONS_REQUEST_READ_CONTACTS);

处理权限请求响应

public void onRequestPermissionsResult(int requestCode,        String permissions[], int[] grantResults) {    switch (requestCode) {        case MY_PERMISSIONS_REQUEST_READ_CONTACTS: {            // If request is cancelled, the result arrays are empty.            if (grantResults.length > 0                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {                // permission was granted, yay! Do the                // contacts-related task you need to do.            } else {                // permission denied, boo! Disable the                // functionality that depends on this permission.            }            return;        }        // other 'case' lines to check for other        // permissions this app might request    }}

7.应用间数据分享

首先定义Intent 设置Intent需要传递的数据

                Intent sendIntent = new Intent();                sendIntent.setAction(Intent.ACTION_SEND);                sendIntent.putExtra(Intent.EXTRA_STREAM,imageUri);                sendIntent.setType("image/jpeg");                startActivity(Intent.createChooser(sendIntent, getResources().getText(R.string.send_to)));

在需要获取信息的Activity的配置文件里设置过滤器

            <intent-filter>                <action android:name="ANDROID.INTENT.ACTION.SEND" />                <category android:name="ANDROID.INTENT.CATEGORY.DEFAULT" />                <data android:mimeType="image/*" />            </intent-filter>

在Activity中获取Intent并获取内容

    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_intent);        Intent intent = getIntent();        String action = intent.getAction();        String type = intent.getType();        if(Intent.ACTION_SEND.equals(action) && type != null){            if(type.startsWith("image/")){                handleSendImage(intent);            }        }    }    private void handleSendImage(Intent intent) {        Uri imageUri = intent.getParcelableExtra(Intent.EXTRA_STREAM);        if(imageUri != null){                    }    }

0 0