Android - Context中的getText(int resId)方法和getString(int resId)方法的区别

Android开发中，经常在Activity中使用getText(int resId)和getString(int resId)这两个方法，那么这两个方法有什么区别和联系呢？

这两个方法的参数都是资源ID，区别在于getText(int resId)返回的是一个CharSequence，而getString(int resId)返回的是一个String。源代码如下：

getText(int resId)：

 /**
  * Return a localized, styled CharSequence from the application‘s package‘s
  * default string table.
  *
  * @param resId Resource id for the CharSequence text
  */
 public final CharSequence getText(int resId) {
     return getResources().getText(resId);
 }

getString(int resId)：

/**
  * Return a localized string from the application‘s package‘s
  * default string table.
  *
  * @param resId Resource id for the string
  */
 public final String getString(int resId) {
     return getResources().getString(resId);
 }

可以看到，他们在各自的内部又调用了Resources类的getText(int id)和getString(int id)方法，那么我们就再看一下Resources类中的这两个方法是怎么写的:

Resources类中的getText(int id)：

 /**
   * Return the string value associated with a particular resource ID.  The
   * returned object will be a String if this is a plain string; it will be
   * some other type of CharSequence if it is styled.
   * {@more}
   *
   * @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.
   *
   * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
   *
   * @return CharSequence The string data associated with the resource, plus
   *         possibly styled text information.
   */
  public CharSequence getText(int id) throws NotFoundException {
      CharSequence res = mAssets.getResourceText(id);
      if (res != null) {
          return res;
      }
      throw new NotFoundException("String resource ID #0x"
                                  + Integer.toHexString(id));
  }

Resources类中的getString(int id)：

/**
   * Return the string value associated with a particular resource ID.  It
   * will be stripped of any styled text information.
   * {@more}
   *
   * @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.
   *
   * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
   *
   * @return String The string data associated with the resource,
   * stripped of styled text information.
   */
  public String getString(int id) throws NotFoundException {
      CharSequence res = getText(id);
      if (res != null) {
          return res.toString();
      }
      throw new NotFoundException("String resource ID #0x"
                                  + Integer.toHexString(id));
  }

看到这里我想大家就都明白了，Resources类的中getString(int id)方法其实就是调用了Resources类的getText(int id)方法后，多做了一个toString()处理，那么也就是说，我们要讨论的问题的结论就可以理解为：Context类中的getString(int resId)==getText(int resId).toString()。

更直观一点，我们来做个小demo：

首先，在Strings中定义两个string资源：

<string name="get_text"><b>getText</b></string>
<string name="get_string"><b>getString</b></string>

接着，在layout文件中定义两个TextView，分别是textView1和textView2（代码省略）。

最后，分别使用getText(int resId)和getString(int resId)获取上面两个资源，并在textView1和textView2中显示：

CharSequence charSequence = getText(R.string.get_text);
String str = getString(R.string.get_string);
((TextView)findViewById(R.id.textView1)).setText(charSequence);
((TextView)findViewById(R.id.textView2)).setText(str);

结果一目了然：