Textview加入Intent、表情，点击跳转Activity

      （ 第二届 Google 暑期大学生博客分享大赛 - 2011 Android 成长篇 ）

      做过web开发的人应该都知道，在HTML里支持<a>标签在文本里插入一个链接，点击后跳转；并且有<img>标签可以插入图片。Android开发是否也支持呢？带着这个疑问，我们去APIDemos探索一下。OK，在com.example.android.apis.text.link这个类里，官方演示了TextView支持的一些链接，上个图：

 

      看来TextView是支持链接跳转的，不过做Android开发的应该都知道，android的View载体是Activity，能不能支持activity跳转呢，很遗憾，不支持。

      不过无所谓，Android很有爱，开源的，理解了原理后我们自己去做，这也是我写本篇文章的主要目的，"授之以鱼，不如授之以渔"，希望大家在遇到相似问题时能像我这样去分析源码，然后找出解决办法（或者大家可以提出更好的方法），另外，文中如有不妥的地方，也欢迎大家批评指正。先上效果图：点击左边的链接后跳转到右边。

  

 

    现在我们开始开发吧！第一步，研究相关的源代码吧。通过跟踪TextView的源码，我们发现TextView支持的链接是由 android.text.style.URLSpan 这个类实现的，它重写了一个onClick方法：

 

    public void onClick(View widget) {
        Uri uri = Uri.parse(getURL());
        Context context = widget.getContext();
        Intent intent = new Intent(Intent.ACTION_VIEW, uri);
        intent.putExtra(Browser.EXTRA_APPLICATION_ID, context.getPackageName());
        context.startActivity(intent);
    }
  

      大家看到了吧startActivity，多么熟悉的方法。既然它能实现，为什么我们不能呢，答案是可以的。我们接着跟踪代码，可以看到URLSpan其实继承的是android.text.style.ClickableSpan，我们来看一下他的源码：

 

    public abstract class ClickableSpan extends CharacterStyle implements UpdateAppearance {

    /**
     * Performs the click action associated with this span.
     */
    public abstract void onClick(View widget);
   
    /**
     * Makes the text underlined and in the link color.
     */
    @Override
    public void updateDrawState(TextPaint ds) {
        ds.setColor(ds.linkColor);
        ds.setUnderlineText(true);
    }
}
  

 是不是有点眉目了，我们直接继承这个类，重写他的方法不就可以了吗？大胆假设，小心求证，我们新建一个类：

 

    import android.content.Context;
import android.content.Intent;
import android.text.TextPaint;
import android.text.style.ClickableSpan;
import android.view.View;

/**
 * If an object of this type is attached to the text of a TextView with a
 * movement method of LinkMovementMethod, the affected spans of text can be
 * selected. If clicked, the {@link #onClick} method will be called.
 * 
 * @author 张宁
 */
public class MyClickableSpan extends ClickableSpan {

	int color = -1;
	private Context context;
	private Intent intent;

	public MyClickableSpan(Context context, Intent intent) {
		this(-1, context, intent);
	}

	/**
	 * constructor
	 * @param color the link color
	 * @param context
	 * @param intent
	 */
	public MyClickableSpan(int color, Context context, Intent intent) {
		if (color!=-1) {
			this.color = color;
		}
		this.context = context;
		this.intent = intent;
	}

	/**
	 * Performs the click action associated with this span.
	 */
	public void onClick(View widget){
		context.startActivity(intent);
	};

	/**
	 * Makes the text without underline.
	 */
	@Override
	public void updateDrawState(TextPaint ds) {
		if (color == -1) {
			ds.setColor(ds.linkColor);
		} else {
			ds.setColor(color);
		}
		ds.setUnderlineText(false);
	}
}
  

 

      在这个类里，我们重写了onClick事件，实现了Activity的跳转,并且去掉了下划线。Ok，第一个目的就达到了，下面我们来看一下如何在TextView里加入表情。

      这个就比较复杂了，因为TextView只能在其上下左右方向加入图片，是由Drawables这个类实现的，而我们想要的效果是在中间也可以插入，看来这次TextView插入图片源码帮不了我们了。不过我们可以去android.text这个包里去找别的类，大家可以看到在这个包里有一个Html类，做过web开发的应该可以想到什么吧？在文章开头已经提到了Html的<img>标签可以插入图片，那这个类是否提供这个功能呢？带着这个疑问我们可以进去看看，其中有个接口：

 

     /**
     * Retrieves images for HTML <img> tags.
     */
    public static interface ImageGetter {
        /**
         * This methos is called when the HTML parser encounters an
         * &lt;img&gt; tag.  The <code>source</code> argument is the
         * string from the "src" attribute; the return value should be
         * a Drawable representation of the image or <code>null</code>
         * for a generic replacement image.  Make sure you call
         * setBounds() on your Drawable if it doesn't already have
         * its bounds set.
         */
        public Drawable getDrawable(String source);
    }
  

 

     看到 <code>source</code>这个没，熟悉吧，结合URLSpan的用法，我们是否可以配合Spanned实现一个

ImageSpan呢？OK，上代码：

 

    import java.util.Map;
import java.util.Set;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.text.Html;
import android.text.Spanned;
import android.text.Html.ImageGetter;

/**
 * this is a class which defining a spanned with image
 * @author 张宁
 *
 */
public class ImageSpan {
	
	/**
	 * the map of face.
	 */
	private Map<String, String> faceMap;
	private Context context;
	
	public ImageSpan(Context context, Map<String, String> faceMap){
		this.context = context;
		this.faceMap = faceMap;
	} 

	/**
	 * get the image by the given key
	 */
	private ImageGetter imageGetter = new Html.ImageGetter() {
		@Override
		public Drawable getDrawable(String source) {
			Drawable drawable = null;
			String sourceName = context.getPackageName() + ":drawable/"
					+ source;
			int id = context.getResources().getIdentifier(sourceName, null, null);
			if (id != 0) {
				drawable = context.getResources().getDrawable(id);
				if (drawable != null) {
					drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
							drawable.getIntrinsicHeight());
				}
			}
			return drawable;
		}
	};
	
	/**
	 * return a {@link Spanned} with image
	 * @param text
	 * @return
	 */
	public Spanned getImageSpan(CharSequence text){
		String cs = text.toString();
		if (faceMap != null) {
			Set<String> keys = faceMap.keySet();
			for (String key : keys) {
				if (cs.contains(key)) {
					cs = cs.replace(key, "<img src='" + faceMap.get(key) + "'>");
				}
			}
		}
		return Html.fromHtml(cs, imageGetter, null);
	}

}
  

 

      到目前为止可以说关键代码都已经实现了，但是会有人问，我该如何使用这两个类呢？下面，我们在实现一个工具类来封装这两个类的方法，以方便调用：

 

    import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.content.Intent;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.method.LinkMovementMethod;
import android.widget.EditText;
import android.widget.TextView;

/**
 * TextView with intent that can redirect to a new activity
 * 
 * @author 张宁
 * 
 */
public class CustomTextView {

	private static Map<String, String> faceMap;

	static {
		faceMap = new HashMap<String, String>();
		faceMap.put("[哭]", "face_1");
		faceMap.put("[怒]", "face_2");
	}

	/**
	 * make textview a clickable textview<br>
	 * Note: make true the order of textList and intentList are mapped
	 * 
	 * @param context
	 * @param textView
	 * @param textList
	 *            the text should be set to this textview,not null
	 * @param intentList
	 *            the intent map to the text, if the text have no intent mapped
	 *            to, please set a null value.Or it will happen some unknown
	 *            error.<br>
	 *            not null
	 */
	public static void setClickableTextView(Context context, TextView textView,
			List<String> textList, List<Intent> intentList) {
		if (textList == null || intentList == null) {
			return;
		}
		SpannableStringBuilder builder = new SpannableStringBuilder();
		int end = -1, length = -1;
		int size = textList.size();
		Intent intent;
		for (int i = 0; i < size; i++) {
			String text = textList.get(i);
			if (TextUtils.isEmpty(text)) {
				continue;
			}
			builder.append(textList.get(i));
			if ((intent = intentList.get(i)) != null) {
				end = builder.length();
				length = textList.get(i).length();
				builder.setSpan(getClickableSpan(context, intent),
						end - length, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
			}
			builder.append(" ");
		}
		textView.setText(builder);
		textView.setFocusable(true);
		textView.setMovementMethod(LinkMovementMethod.getInstance());
	}
	
	/**
	 *  make textview a clickable textview<br>
	 *  Note: make true the order of textList and intentList are mapped
	 * @param context
	 * @param textView
	 * @param text
	 * @param intent
	 */
	public static void setClickableTextView(Context context, TextView textView,
			String text, Intent intent) {
		SpannableStringBuilder builder = new SpannableStringBuilder(text);
		builder.setSpan(getClickableSpan(context, intent), 0, text.length(), 
				Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
		textView.setText(builder);
		textView.setMovementMethod(LinkMovementMethod.getInstance());
	}

	/**
	 * make TextView a View with image at any index  
	 * @param context
	 * @param textView
	 * @param textList
	 */
	public static void setImgTextView(Context context, TextView textView,
			List<String> textList) {
		StringBuilder builder = new StringBuilder();
		for (int i = 0; i < textList.size(); i++) {
			builder.append(textList.get(i)).append(" ");
		}
		setImgTextView(context, textView, builder.toString());

	}

	/**
	 * make TextView a View with image at any index  
	 * @param context
	 * @param textView
	 * @param text
	 */
	public static void setImgTextView(Context context, TextView textView,
			String text) {
		ImageSpan imageSpan = new ImageSpan(context, faceMap);
		Spanned spanned = imageSpan.getImageSpan(text);
		textView.setText(spanned);
	}
	
	/**
	 * make EditText a View with image at any index  
	 * @param context
	 * @param EditText
	 * @param text
	 */
	public static void setImgTextView(Context context, EditText editText,
			String text) {
		ImageSpan imageSpan = new ImageSpan(context, faceMap);
		Spanned spanned = imageSpan.getImageSpan(text);
		editText.setText(spanned);
	}

	/**
	 * return a custom ClickableSpan
	 * 
	 * @param context
	 * @param intent
	 * @return
	 */
	public static MyClickableSpan getClickableSpan(Context context,
			Intent intent) {
		return new MyClickableSpan(context, intent);
	}

	/**
	 * make textview a clickable textview with image<br>
	 * Note: make true the order of textList and intentList are mapped
	 * 
	 * @param context
	 *            not null
	 * @param haveImg
	 *            whether this is image in the text,not null
	 * @param textView
	 *            not null
	 * @param textList
	 *            the text should be set to this textview,not null
	 * @param intentList
	 *            the intent map to the text, if the text have no intent mapped
	 *            to, please set a null value.Or it will happen some unknown
	 *            error.<br>
	 *            allow null
	 */
	public static void setCustomText(Context context, Boolean haveImg,
			TextView textView, List<String> textList, List<Intent> intentList) {
		SpannableStringBuilder builder = new SpannableStringBuilder();
		int end = -1, length = -1;
		if (intentList != null) {
			int size = textList.size();
			Intent intent;
			for (int i = 0; i < size; i++) {
				String text = textList.get(i);
				if (TextUtils.isEmpty(text)) {
					continue;
				}
				builder.append(textList.get(i));
				if ((intent = intentList.get(i)) != null) {
					end = builder.length();
					length = textList.get(i).length();
					builder.setSpan(getClickableSpan(context, intent), end
							- length, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
				}
				builder.append(" ");
			}
		} else {
			for (String text : textList) {
				builder.append(text).append(" ");
			}
		}
		if (haveImg) {
			ImageSpan imageSpan = new ImageSpan(context, faceMap);
			Spanned spanned = imageSpan.getImageSpan(builder);
			textView.setText(spanned);
		} else {
			textView.setText(builder);
		}
		textView.setMovementMethod(LinkMovementMethod.getInstance());

	}

}
  

 

    有了这个类，我们就可以方便的实现在TextView中插入Intent和表情了，甚至不用管底层是怎样实现的，也降低了代码的耦合度。但是又回到我写这篇文章的目的：希望大家能得到“渔”而不仅仅是“鱼”。

    Ok，任务完成。源码奉上。

注：原创作品，转载请标明出处：

 

  http://zhangning290.iteye.com/blog/1134286

 

 

Textview加入Intent、表情，点击跳转Activity