Android中获取系统的一些信息以及一些小功能

一.获取手机内存的使用情况（VM heap）

     // 程序总共的内存     int maxMemory = (int) Runtime.getRuntime().maxMemory();     // 已经从系统拿出来的内存，但是没用     int freeMemory = (int) Runtime.getRuntime().freeMemory();     // 已经使用的总内存     int totalMemory = (int) Runtime.getRuntime().totalMemory();

二.从相册中获取一张图片并且进行裁剪

public void click(View view){Intent intent = new Intent(Intent.ACTION_GET_CONTENT,null);intent.setType("image/*");//获取任意的图片类型intent.putExtra("crop", "true");//滑动选中图片区域intent.putExtra("aspectX", 3);//表示剪切框的比例1:1的效果intent.putExtra("aspectY",5);intent.putExtra("outputX", 300);//制定输出图片的大小intent.putExtra("outputY",500);intent.putExtra("return-data",true);startActivityForResult(intent, 0);}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {// TODO Auto-generated method stubsuper.onActivityResult(requestCode, resultCode, data);if(requestCode==0){Bitmap bitmap = data.getParcelableExtra("data");img.setImageBitmap(bitmap);}}

三. 2次back退出

private long currentTime;@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if (keyCode == KeyEvent.KEYCODE_BACK) {if (System.currentTimeMillis() - currentTime < 2000) {finish();}currentTime = System.currentTimeMillis();return true;}return false;}

四、通过HttpPost请求网络数据

  //第一步创建HttpPost对象  HttpPost post = new HttpPost("url");  // 设置连接超时  post.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 5 * 1000);  // 获取数据超时  post.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT,5 * 1000);  //设置post请求参数  List<NameValuePair> params = new ArrayList<NameValuePair>();  params.add(new BasicNameValuePair("",""));  //设置发送数据的编码格式  post.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));  //实例化一个默认的请求客户端  HttpClient client = new DefaultHttpClient();  //执行请求  HttpResponse response = client.execute(post);  //请求返回码  int statusCode = response.getStatusLine().getStatusCode();  //请求返回的结果  if (statusCode == 200) {  String result = EntityUtils.toString(response.getEntity(),"UTF-8");  }

五、通过HttpURLConnection请求网络数据

URL url = new URL("URL");HttpURLConnection conn = (HttpURLConnection) url.openConnection();//通过url打开连接conn.setRequestMethod("POST");//设置请求方式conn.setDoInput(true);// 允许下载数据conn.setDoOutput(true);// 允许上传数据conn.setRequestProperty("Connection", "Keep-Alive");//是否需要持久连接 conn.setRequestProperty("Charset", "UTF-8");//设置编码格式conn.getOutputStream().write("".getBytes());//设置要传输的数据if (conn.getResponseCode() == 200) {//获取收到的数据InputStream is = conn.getInputStream();ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len;if ((len = is.read(buffer)) != -1) {baos.write(buffer, 0, len);}//得到的数据byte[] result = baos.toByteArray();is.close();baos.close();}

六、自定义文本的字体

//设置字体public void setFont(ViewGroup group, Typeface font) {int count = group.getChildCount();View v;for (int i = 0; i < count; i++) {v = group.getChildAt(i);if (v instanceof TextView || v instanceof EditText|| v instanceof Button) {((TextView) v).setTypeface(font);} else if (v instanceof ViewGroup)setFont((ViewGroup) v, font);}}

//从Asset文件夹中读取字体Typeface mFont = Typeface.createFromAsset(getAssets(), "STCAIYUN.TTF");//获取ViewGroupViewGroup root = (ViewGroup) findViewById(R.id.rl);//给ViewGroup设置字体setFont(root, mFont);

七、MarginLayoutParams

    //获取View原始的参数    MarginLayoutParams mlp = (MarginLayoutParams) view.getLayoutParams();    //重新设置参数    view.setMargins(-mlp.leftMargin, mlp.topMargin, mlp.rightMargin, mlp.bottomMargin);

八、截屏

public void click(View view){//设置为1秒钟后执行截屏操作，避免截下按钮点击的动作new Handler().postDelayed(new Runnable() {        @Override    public void run() {//获取窗口图像View v = getWindow().getDecorView();v.setDrawingCacheEnabled(true);v.buildDrawingCache();Bitmap bitmap = v.getDrawingCache();//获取状态栏的高度Rect fram = new Rect();getWindow().getDecorView().getWindowVisibleDisplayFrame(fram);int statusBarHeight = fram.top;//获取屏幕图像的高度DisplayMetrics outMetrics = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(outMetrics);int width = outMetrics.widthPixels;int height = outMetrics.heightPixels;//创建新的图像（去掉状态栏的高度）Bitmap bitmap2 = Bitmap.createBitmap(bitmap, 0, statusBarHeight, width, height-statusBarHeight);//保存图片到SDcard下try {    FileOutputStream fos = new FileOutputStream(File.createTempFile("capture", ".jpg", new File("mnt/sdcard")));    bitmap2.compress(Bitmap.CompressFormat.PNG, 90, fos);    fos.flush();    fos.close();} catch (Exception e) {    // TODO Auto-generated catch block    e.printStackTrace();}    }}, 1000);    }

九、TextView中插入表情

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), resouceId);//实例化一个ImageSpanImageSpan span = new ImageSpan(this, bitmap);SpannableString spannableString = new SpannableString("face");spannableString.setSpan(span, 0, 4, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);//添加editText.append(spannableString);