【我的Android进阶之旅】Android使用getIdentifier()方法根据资源名来获取资源id

来源：互联网发布：王凯歆私生活知乎编辑：程序博客网时间：2024/05/16 16:56

有时候我们想动态的根据一个资源名获得到对应的资源id，就可以使用getResources().getIdentifier()方法来获取该id。然后再使用该id进行相关的操作。

1、Demo示例

下面用一个小Demo来讲解如何使用getResources().getIdentifier()方法来获取该id。

例如，新建一个Android项目，项目结构部分截图如下所示：
这里写图片描述

MainActivity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());        Log.d(TAG, "----> 获取到的图片资源 drawableId= " + layoutId);        //获取图片资源的ID        mImageView = (ImageView) findViewById(R.id.imageView);        int drawableId = getResources().getIdentifier("oyp", "drawable", getPackageName());        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());        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());        mTextView.setText(stringId);        Log.d(TAG, "----> 获取到的字符串资源 stringId=" + stringId);    }}

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>

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>

运行该程序，运行效果如下所示：
这里写图片描述

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= 213096860111-24 22:15:02.476 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 drawableId=213083757911-24 22:15:02.477 12023-12023/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 mipmapId=213090304011-24 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
这里写图片描述

这里写图片描述

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
这里写图片描述

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() {        }    }

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() {        }    }

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() {        }    }

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() {        }    }

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);    }

这里写图片描述

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);    }}

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= 213096860111-24 23:44:16.916 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 drawableId=213083757911-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的图片资源 mipmapId=213090304011-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的字符串资源 stringId=213109966911-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的颜色资源 colorId=213142734711-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的颜色资源 dimenId=213123073011-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的integer资源 integerId=213136179311-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的bool资源 boolId=213116518411-24 23:44:16.918 8543-8543/com.oyp.demo D/MainActivity: ----> 获取到的attr资源 attrId=2130772027

作者：欧阳鹏欢迎转载，与人分享是进步的源泉！
转载请保留原文地址：
http://blog.csdn.net/ouyang_peng/article/details/53328000

这里写图片描述

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