如何在 Android 中以编程方式设置背景可绘制对象

How set background drawable programmatically in Android(如何在 Android 中以编程方式设置背景可绘制对象)

问题描述

RelativeLayout layout =(RelativeLayout)findViewById(R.id.background);
layout.setBackgroundResource(R.drawable.ready);

这是最好的方法吗?

推荐答案

layout.setBackgroundResource(R.drawable.ready);是正确的.
实现它的另一种方法是使用以下方法:

layout.setBackgroundResource(R.drawable.ready); is correct.
Another way to achieve it is to use the following:

final int sdk = android.os.Build.VERSION.SDK_INT;
if(sdk < android.os.Build.VERSION_CODES.JELLY_BEAN) {
    layout.setBackgroundDrawable(ContextCompat.getDrawable(context, R.drawable.ready) );
} else {
    layout.setBackground(ContextCompat.getDrawable(context, R.drawable.ready));
}

但我认为出现问题是因为您尝试加载大图像.
这里是一个很好的教程如何加载大位图.

But I think the problem occur because you are trying to load big images.
Here is a good tutorial how to load large bitmaps.

更新:
API 级别 22 中不推荐使用 getDrawable(int)

getDrawable(int) 现在在 API 级别 22 中已弃用.您应该改用支持库中的以下代码:

UPDATE:
getDrawable(int ) deprecated in API level 22

getDrawable(int ) is now deprecated in API level 22. You should use the following code from the support library instead:

ContextCompat.getDrawable(context, R.drawable.ready)

如果参考ContextCompat.getDrawable，它会给你这样的东西:

If you refer to the source code of ContextCompat.getDrawable, it gives you something like this:

/**
 * Return a drawable object associated with a particular resource ID.
 * <p>
 * Starting in {@link android.os.Build.VERSION_CODES#LOLLIPOP}, the returned
 * drawable will be styled for the specified Context's theme.
 *
 * @param id The desired resource identifier, as generated by the aapt tool.
 *            This integer encodes the package, type, and resource entry.
 *            The value 0 is an invalid identifier.
 * @return Drawable An object that can be used to draw this resource.
 */
public static final Drawable getDrawable(Context context, int id) {
    final int version = Build.VERSION.SDK_INT;
    if (version >= 21) {
        return ContextCompatApi21.getDrawable(context, id);
    } else {
        return context.getResources().getDrawable(id);
    }
}

更多关于 ContextCompat

从 API 22 开始，您应该使用 getDrawable(int, Theme) 方法而不是 getDrawable(int).

As of API 22, you should use the getDrawable(int, Theme) method instead of getDrawable(int).

更新:
如果您使用的是 support v4 库，则以下内容对于所有版本都足够了.

UPDATE:
If you are using the support v4 library, the following will be enough for all versions.

ContextCompat.getDrawable(context, R.drawable.ready)

您需要在您的应用 build.gradle 中添加以下内容

You will need to add the following in your app build.gradle

compile 'com.android.support:support-v4:23.0.0' # or any version above

或者在任何 API 中使用 ResourceCompat，如下所示:

Or using ResourceCompat, in any API like below:

import android.support.v4.content.res.ResourcesCompat;
ResourcesCompat.getDrawable(getResources(), R.drawable.name_of_drawable, null);

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