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Android开发实用工具与方法汇总

1. 测量View的宽高

增加View测量宽高的方法：

public static void measureWidthAndHeight(View view) {
    int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    view.measure(widthMeasureSpec, heightMeasureSpec);
}

2. 压缩图片的方式

图片压缩需要谨慎处理：

public static Bitmap pressScaleCompress(Bitmap bitmap) {
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.PNG, 80, os);
    byte[] bt = os.toByteArray();
    Bitmap bitmap1 = BitmapFactory.decodeByteArray(bt, 0, bt.length);
    return bitmap1;
}

width和height压缩方法：

public static Bitmap pressScaleWidthHeightCompress(Bitmap bitmap) {
    Matrix matrix = new Matrix();
    matrix.postScale(0.6f, 0.6f);
    Bitmap bitmap1 = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
    return bitmap1;
}

3. 倒计时工具类

倒计时工具实现：

public class CountDownUtils extends BaseCountDownTimer {
    TextView tv;
    public CountDownUtils(long millisInFuture, long countDownInterval, TextView tv) {
        super(millisInFuture, countDownInterval);
        this.tv = tv;
    }
    @Override
    public void onTick(long millisUntilFinished) {
        tv.setEnabled(false);
        tv.setText("重新获取(" + millisUntilFinished / 1000 + "s)");
    }
    @Override
    public void onFinish() {
        tv.setText("重新验证");
        tv.setEnabled(true);
    }
}

4. 清除缓存工具类

彻底清除缓存：

public static void clearAllCache(Context context) {
    deleteDir(context.getCacheDir());
    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
        deleteDir(context.getExternalCacheDir());
    }
}

deleteDir方法实现：

private static boolean deleteDir(File dir) {
    if (dir != null && dir.isDirectory()) {
        String[] children = dir.list();
        for (int i = 0; i < children.length; i++) {
            boolean success = deleteDir(new File(dir, children[i]));
            if (!success) {
                return false;
            }
        }
    }
    return dir.delete();
}

5._DOUBLE精确计算工具类

避免Double精度问题：

public static double add(Double value1, Double value2) {
    BigDecimal b1 = new BigDecimal(Double.toString(value1));
    BigDecimal b2 = new BigDecimal(Double.toString(value2));
    return b1.add(b2).doubleValue();
}

6.图片保存到本地并返回路径

图片URI转File：

public static String getRealPathFromUri(Context context, Uri uri) {
    int sdkVersion = Build.VERSION.SDK_INT;
    if (sdkVersion >= 19) {
        return getRealPathFromUriAboveApi19(context, uri);
    } else {
        return getRealPathFromUriBelowAPI19(context, uri);
    }
}

getDataColumn方法：

private static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
    String path = null;
    String[] projection = {MediaStore.Images.Media.DATA};
    Cursor cursor = null;
    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
        if (cursor != null && cursor.moveToFirst()) {
            int columnIndex = cursor.getColumnIndexOrThrow(projection[0]);
            path = cursor.getString(columnIndex);
        }
    } catch (Exception e) {
        if (cursor != null) {
            cursor.close();
        }
    }
    return path;
}

7.网络请求Retrofit工具类

高效网络请求工具：

public class RetrofitManager {
    private static final String BASE_URL = "http://yb.dashuibei.com/index.php/Home/";
    private static RetrofitManager instance = null;
    private final Retrofit retrofit;
    private RetrofitManager(String baseUrl) {
        retrofit = new Retrofit.Builder()
                .baseUrl(baseUrl)
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(buildOkHttpClient())
                .build();
    }
    public static RetrofitManager getDefault() {
        if (instance == null) {
            instance = new RetrofitManager(BASE_URL);
        }
        return instance;
    }
    private OkHttpClient buildOkHttpClient() {
        return new OkHttpClient.Builder()
                .readTimeout(5000, TimeUnit.MILLISECONDS)
                .writeTimeout(5000, TimeUnit.MILLISECONDS)
                .connectTimeout(5000, TimeUnit.MILLISECONDS)
                .build();
    }
}

8.关于时间

时间工具类实现：

public static String getStandardDate(String timeStr) {
    long t = Long.parseLong(timeStr);
    long currentTime = System.currentTimeMillis() - t * 1000;
    StringBuilder sb = new StringBuilder();
    long seconds = currentTime / 1000;
    long minutes = (currentTime / 1000) / 60;
    long hours = (currentTime / 1000) / 3600;
    long days = (currentTime / 1000) / 86400;
    if (days > 1) {
        sb.append(String.format("%d天", days));
    } else if (hours > 24) {
        sb.append(String.format("1天"));
    } else if (hours > 0) {
        sb.append(String.format("%d小时", hours));
    } else if (minutes > 0) {
        sb.append(String.format("%d分钟", minutes));
    } else if (seconds > 0) {
        sb.append(String.format("%d秒", seconds));
    } else {
        sb.append("刚刚");
    }
    if (!sb.toString().equals("刚刚")) {
        sb.append("前");
    }
    return sb.toString();
}

9.ूष意工具类

关闭软键盘方法：

public static void closeKeyboard(Activity context) {
    ((InputMethodManager) context.getSystemService(context.INPUT_METHOD_SERVICE))
            .hideSoftInputFromWindow(context.getCurrentFocus().getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}

10.杂

Base64图片转字符串：

public static String Bitmap2StrByBase64(Bitmap bit) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    bit.compress(Bitmap.CompressFormat.JPEG, 40, bos);
    byte[] bytes = bos.toByteArray();
    return Base64.encodeToString(bytes, Base64.DEFAULT);
}

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