关于SpannableString的使用

如果需要对TextView的样式进行具体修改，例如改变背景色或者粗体效果，靠多个TextView的拼接显然是十分麻烦的。因此需要用到SpannableString类。它可以对TextView中各个部分的文本来设置字体，大小，颜色，样式，以及超级链接等属性。

先上效果图：

非常简单，还是看代码吧：

import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.text.SpannableString;import android.text.Spanned;import android.text.method.LinkMovementMethod;import android.text.style.ForegroundColorSpan;import android.text.style.StrikethroughSpan;import android.text.style.TypefaceSpan;import android.text.style.URLSpan;import android.widget.TextView;public class MainActivity extends Activity {protected static final String TAG = "MainActivity";protected static final String str = "I am a SpannableString";private TextView tv1;private TextView tv2;private TextView tv3;private TextView tv4;private SpannableString ss;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);findViews();setSpan();}/** * 取4种做示范。其他还包括： * 设置字体（例如宋体） * 设置字体大小 * 设置字体前/后景色 * 设置字体样式（正常，粗体，斜体，粗斜体） * 设置下划线  * 设置删除线 * 设置上下标 */private void setSpan() {for (int i = 1; i <= 4; i++) {switch (i) {case 1://设置字体前景颜色ss = new SpannableString(str);ss.setSpan(new ForegroundColorSpan(Color.RED), 7, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);tv1.setText(ss);break;case 2://设置超链接ss = new SpannableString(str);ss.setSpan(new URLSpan("http://www.baidu.com"), 7, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);tv2.setMovementMethod(LinkMovementMethod.getInstance());tv2.setText(ss);break;case 3://设置字体为monospacess = new SpannableString(str);ss.setSpan(new TypefaceSpan("monospace"), 7, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);tv3.setText(ss);break;case 4://设置删除线ss = new SpannableString(str);ss.setSpan(new StrikethroughSpan(), 7, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);tv4.setText(ss);break;}}}private void findViews() {tv1 = (TextView) findViewById(R.id.tv1);tv2 = (TextView) findViewById(R.id.tv2);tv3 = (TextView) findViewById(R.id.tv3);tv4 = (TextView) findViewById(R.id.tv4);}}

除此之外，关于Spanned.SPAN_EXCLUSIVE_EXCLUSIVE属性，网上找到的，这是在 setSpan 时需要指定的 flag，它是用来标识在 Span 范围内的文本前后输入新的字符时是否把它们也应用这个效果。

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自定义TouchableSpan，继承自ClickableSpan，是超链接Span的父类，用来实现点击变色效果，可以自定义点击前、点击后的颜色，并取消跳转。

同时也要自定义LinkTouchMovementMethod，用来触发setPressed。下见代码

TouchableSpan.java

public abstract class TouchableSpan extends ClickableSpan {    private boolean mIsPressed;    private int mPressedBackgroundColor;    private int mNormalTextColor;    private int mPressedTextColor;    public TouchableSpan(int normalTextColor, int pressedTextColor, int pressedBackgroundColor) {        mNormalTextColor = normalTextColor;        mPressedTextColor = pressedTextColor;        mPressedBackgroundColor = pressedBackgroundColor;    }    public void setPressed(boolean isSelected) {        mIsPressed = isSelected;    }    @Override    public void updateDrawState(TextPaint ds) {        super.updateDrawState(ds);        ds.setColor(mIsPressed ? mPressedTextColor : mNormalTextColor);        ds.bgColor = mIsPressed ? mPressedBackgroundColor : 0xffeeeeee;        ds.setUnderlineText(false);    }    }

LinkTouchMovementMethod.java

public class LinkTouchMovementMethod extends LinkMovementMethod {    private TouchableSpan mPressedSpan;    @Override    public boolean onTouchEvent(TextView textView, Spannable spannable, MotionEvent event) {        if (event.getAction() == MotionEvent.ACTION_DOWN) {            mPressedSpan = getPressedSpan(textView, spannable, event);            if (mPressedSpan != null) {                mPressedSpan.setPressed(true);//设置后才会变色                Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan),                        spannable.getSpanEnd(mPressedSpan));            }        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {            TouchableSpan touchedSpan = getPressedSpan(textView, spannable, event);            if (mPressedSpan != null && touchedSpan != mPressedSpan) {                mPressedSpan.setPressed(false);                mPressedSpan = null;                Selection.removeSelection(spannable);            }        } else {            if (mPressedSpan != null) {                mPressedSpan.setPressed(false);                super.onTouchEvent(textView, spannable, event);            }            mPressedSpan = null;            Selection.removeSelection(spannable);        }        return true;    }    private TouchableSpan getPressedSpan(TextView textView, Spannable spannable, MotionEvent event) {        int x = (int) event.getX();        int y = (int) event.getY();        x -= textView.getTotalPaddingLeft();        y -= textView.getTotalPaddingTop();        x += textView.getScrollX();        y += textView.getScrollY();        Layout layout = textView.getLayout();        int line = layout.getLineForVertical(y);        int off = layout.getOffsetForHorizontal(line, x);        TouchableSpan[] link = spannable.getSpans(off, off, TouchableSpan.class);        TouchableSpan touchedSpan = null;        if (link.length > 0) {            touchedSpan = link[0];        }        return touchedSpan;    }}

使用

//设置自定义TouchableSpanTouchableSpan touchableSpan = new TouchableSpan(Color.BLACK, Color.RED, Color.GRAY) {@Overridepublic void onClick(View widget) {//TODO 点击后的动作}};ss.setSpan(touchableSpan, 7, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);ss = new SpannableString(str);tv4.setMovementMethod(new LinkTouchMovementMethod());tv4.setText(ss);