Android 原始资源

Android允许除了任意XML文件之外的原始文件。这些资源放在 /res/raw 文件夹中。

原始文件可能是音频，视频或文本文件，需要通过资源ID进行本地化或引用。

这些文件不会编译，而是按原样移动到应用程序包。

每个文件都有一个在R.java中生成的标识符。

例子

如果你要在 /res/raw/test.txt 中放置一个文本文件，你将能够使用以下代码读取该文件。

String getStringFromRawFile(Activity activity)
throws IOException{
   Resources r = activity.getResources();
   InputStream is = r.openRawResource(R.raw.test);
   String myText = workOnInputStream(is);
   is.close();
   return myText;
}

具有重复基本名称的文件名会生成构建错误。

加载和解析原始xml文件

下面的代码显示了如何加载和解析原始xml文件。

布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent" 
  android:layout_height="fill_parent" >
  <TextView
    android:id="@+id/selection"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
  />
  <ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:drawSelectorOnTop="false"
  />
</LinearLayout>

res/raw/words.xml

<words>
  <word value="lorem" />
  <word value="ipsum" />
  <word value="dolor" />
  <word value="sit" />
  <word value="amet" />
  <word value="consectetuer" />
  <word value="adipiscing" />
  <word value="elit" />
  <word value="morbi" />
  <word value="vel" />
  <word value="ligula" />
  <word value="vitae" />
  <word value="arcu" />
  <word value="aliquet" />
  <word value="mollis" />
  <word value="etiam" />
  <word value="vel" />
  <word value="erat" />
  <word value="placerat" />
  <word value="ante" />
  <word value="porttitor" />
  <word value="sodales" />
  <word value="pellentesque" />
  <word value="augue" />
  <word value="purus" />
</words>

Java代码

import android.app.Activity;
import android.os.Bundle;
import android.app.ListActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.InputStream;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
/*from  www.w3cschool.cn*/
public class MainActivity extends ListActivity {
  TextView selection;
  ArrayList<String> items=new ArrayList<String>();
  
  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);
    selection=(TextView)findViewById(R.id.selection);
    
    try {
      InputStream in=getResources().openRawResource(R.raw.words);
      DocumentBuilder builder=DocumentBuilderFactory
                                .newInstance()
                                .newDocumentBuilder();
      Document doc=builder.parse(in, null);
      NodeList words=doc.getElementsByTagName("word");
      
      for (int i=0;i<words.getLength();i++) {
        items.add(((Element)words.item(i)).getAttribute("value"));
      }
      
      in.close();
    }
    catch (Throwable t) {
      Toast
        .makeText(this, "Exception: "+t.toString(), 2000)
        .show();
    }
    
    setListAdapter(new ArrayAdapter<String>(this,
                                  android.R.layout.simple_list_item_1,
                                  items));
  }
  
  public void onListItemClick(ListView parent, View v, int position,
                  long id) {
    selection.setText(items.get(position).toString());
  }
}
/***
  Copyright (c) 2008-2009 CommonsWare, LLC
  
  Licensed under the Apache License, Version 2.0 (the "License"); you may
  not use this file except in compliance with the License. You may obtain
  a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

静态资源

这里是使用静态资源的三个步骤:

• 将文件放入你的包的res/raw文件夹
• 使用Activity类中的getResources()方法返回一个Resources对象
• 使用其openRawResource()方法打开res/raw文件夹中包含的文件

package cn.w3cschool.myapplication3.app;
//from  www.w3cschool.cn
import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class MainActivity extends Activity {
    EditText textBox;
    static final int READ_BLOCK_SIZE = 100;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textBox = (EditText) findViewById(R.id.txtText1);

        InputStream is = this.getResources().openRawResource(R.raw.textfile);
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        String str = null;
        try {
            while ((str = br.readLine()) != null) {
                Toast.makeText(getBaseContext(),
                        str, Toast.LENGTH_SHORT).show();
            }
            is.close();
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

存储在 res/raw 文件夹中资源的ID以其没有扩展名的文件名命名。例如，如果文本文件是textfile.txt，则其资源ID为R.raw.textfile。