布局文件代码如下：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.oyp.demo.MainActivity">
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:text="@string/title" />
<ImageView
android:id="@+id/mipmapImageView"
android:layout_below="@id/title"
android:layout_marginTop="40dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"/>
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/imageView"
android:layout_centerHorizontal="true"
android:layout_marginTop="50dip" />
</RelativeLayout>
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用到的strings.xml字符串资源代码如下：
<resources>
<string name="app_name">Demo</string>
<string name="title">利用getIdentifier()方法获取资源ID</string>
<string name="author">欧阳鹏 http://blog.csdn.net/ouyang_peng</string>
</resources>
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运行该程序，运行效果如下所示：
打印出来的log为：
11-24 22:15:02.471 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 drawableId= 2130968601
11-24 22:15:02.476 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 drawableId=2130837579
11-24 22:15:02.477 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 mipmapId=2130903040
11-24 22:15:02.477 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的字符串资源 stringId=2131099669
我们打开编译好后的 com.oyp.demo.R文件
首先来看看activity_main这个layout的id是不是和我们打印出来的一样是2130968601，如下图所示，在 com.oyp.demo.R文件中，activity_main的值确实是2130968601
部分代码如下所示：
public static final class layout {
......
public static final int abc_screen_simple = 2130968595
public static final int abc_screen_simple_overlay_action_mode = 2130968596
public static final int abc_screen_toolbar = 2130968597
public static final int abc_search_dropdown_item_icons_2line = 2130968598
public static final int abc_search_view = 2130968599
public static final int abc_select_dialog_material = 2130968600
public static final int activity_main = 2130968601
public static final int notification_media_action = 2130968602
public static final int notification_media_cancel_action = 2130968603
public static final int notification_template_big_media = 2130968604
public static final int notification_template_big_media_narrow = 2130968605
......
public layout() {
}
}
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drawable类型的图片 ic_launcher 的资源id 为 2130903040
public static final class mipmap {
public static final int ic_launcher = 2130903040
public mipmap() {
}
}
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drawable类型的图片 oyp 资源id为 2130837579
public static final class drawable {
......
public static final int abc_textfield_search_material = 2130837578
public static final int notification_template_icon_bg = 2130837580
public static final int oyp = 2130837579
public drawable() {
}
}
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String类型的资源author id为 2131099669
public static final class string {
......
public static final int app_name = 2131099668
public static final int author = 2131099669
public static final int status_bar_notification_info_overflow = 2131099667
public static final int title = 2131099670
public string() {
}
}
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可以发现打印出来的资源id和com.oyp.demo.R文件生成的资源id是一致的，因此使用getResources().getIdentifier(）方法完全可以正确地获取资源的id。
2、getIdentifier(）方法封装
点击查看getIdentifier(）方法源代码如下所示：
/**
* Return a resource identifier for the given resource name. A fully
* qualified resource name is of the form "package:type/entry". The first
* two components (package and type) are optional if defType and
* defPackage, respectively, are specified here.
*
* <p>Note: use of this function is discouraged. It is much more
* efficient to retrieve resources by identifier than by name.
*
* @param name The name of the desired resource.
* @param defType Optional default resource type to find, if "type/" is
* not included in the name. Can be null to require an
* explicit type.
* @param defPackage Optional default package to find, if "package:" is
* not included in the name. Can be null to require an
* explicit package.
*
* @return int The associated resource identifier. Returns 0 if no such
* resource was found. (0 is not a valid resource ID.)
*/
public int getIdentifier(String name, String defType, String defPackage) {
if (name == null) {
throw new NullPointerException("name is null")
}
try {
return Integer.parseInt(name)
} catch (Exception e) {
// Ignore
}
return mAssets.getResourceIdentifier(name, defType, defPackage)
}
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第一个参数为资源ID名，第二个为资源属性的类型，第三个为包名。
下面是一个封装好的工具栏，可以直接用来获取资源id。
package com.oyp.demo
import android.content.Context
/**
* 工具类，可以通过资源名来获取资源id
* </p><br/><br/><br/>
* <a href = " http://blog.csdn.net/ouyang_peng "> 欧阳鹏博客</a>
*/
public class ResourceUtil {
public static int getId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "id")
}
public static int getLayoutId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "layout")
}
public static int getStringId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "string")
}
public static int getDrawableId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "drawable")
}
public static int getMipmapId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "mipmap")
}
public static int getColorId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "color")
}
public static int getDimenId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "dimen")
}
public static int getAttrId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "attr")
}
public static int getStyleId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "style")
}
public static int getAnimId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "anim")
}
public static int getArrayId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "array")
}
public static int getIntegerId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "integer")
}
public static int getBoolId(Context context, String resourceName) {
return getIdentifierByType(context, resourceName, "bool")
}
private static int getIdentifierByType(Context context, String resourceName, String defType) {
return context.getResources().getIdentifier(resourceName,
defType,
context.getPackageName())
}
}
将封装好的com.oyp.demo.ResourceUtil类应用到刚才的MainActivity中，代码如下：
package com.oyp.demo
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.util.Log
import android.widget.ImageView
import android.widget.TextView
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName()
private ImageView mImageView
private ImageView mipmapImageView
private TextView mTextView
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//获取布局文件资源的ID
// int layoutId = getResources().getIdentifier("activity_main", "layout", getPackageName())
int layoutId = ResourceUtil.getLayoutId(this, "activity_main")
Log.d(TAG, "----> 获取到的布局文件资源 drawableId= " + layoutId);
//获取图片资源的ID
mImageView = (ImageView) findViewById(R.id.imageView);
// int drawableId = getResources().getIdentifier("oyp", "drawable", getPackageName());
int drawableId = ResourceUtil.getDrawableId(this, "oyp");
mImageView.setImageResource(drawableId);
Log.d(TAG, "----> 获取到的图片资源 drawableId=" + drawableId);
mipmapImageView = (ImageView) findViewById(R.id.mipmapImageView);
// int mipmapId = getResources().getIdentifier("ic_launcher", "mipmap", getPackageName());
int mipmapId = ResourceUtil.getMipmapId(this, "ic_launcher");
mipmapImageView.setImageResource(mipmapId);
Log.d(TAG, "----> 获取到的图片资源 mipmapId=" + mipmapId);
//获取字符串资源
mTextView = (TextView) findViewById(R.id.textView);
// int stringId = getResources().getIdentifier("author", "string", getPackageName());
int stringId = ResourceUtil.getStringId(this, "author");
mTextView.setText(stringId);
Log.d(TAG, "----> 获取到的字符串资源 stringId=" + stringId);
int colorId = ResourceUtil.getColorId(this , "colorPrimary");
Log.d(TAG, "----> 获取到的颜色资源 colorId=" + colorId);
int dimenId = ResourceUtil.getDimenId(this , "abc_dialog_min_width_major");
Log.d(TAG, "----> 获取到的颜色资源 dimenId=" + dimenId);
int integerId = ResourceUtil.getIntegerId(this , "abc_config_activityDefaultDur");
Log.d(TAG, "----> 获取到的integer资源 integerId=" + integerId);
int boolId = ResourceUtil.getBoolId(this , "abc_allow_stacked_button_bar");
Log.d(TAG, "----> 获取到的bool资源 boolId=" + boolId);
int attrId = ResourceUtil.getAttrId(this , "actionBarDivider");
Log.d(TAG, "----> 获取到的attr资源 attrId=" + attrId);
}
}
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打印出来的Log日志为：
11-24 23:44:16.911 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的布局文件资源 drawableId= 2130968601
11-24 23:44:16.916 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 drawableId=2130837579
