设置字间距

来源：http://stackoverflow.com/questions/1640659/how-to-adjust-text-kerning-in-android-textview/16429758#16429758

1、直接设置

public static Spannable applyKerning(CharSequence src, float kerning, int start, int end){
    if (src == null) 
        return null; 
    final int srcLength = src.length();   
    if (srcLength < 2) 
        return src instanceof Spannable ? (Spannable)src: new SpannableString(src); 
    if (start < 0) 
        start = 0; 
    if (end > srcLength) 
        end = srcLength;
     
    final String nonBreakingSpace = "\u00A0"; 
    final SpannableStringBuilder builder = src instanceof SpannableStringBuilder ? (SpannableStringBuilder)src: new SpannableStringBuilder(src); 
    for (int i = src.length(); i >= 1; i--) {       
        builder.insert(i, nonBreakingSpace);       
        builder.setSpan(new ScaleXSpan(kerning), i, i + 1, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    }  
    return builder;
}

2、自定义控件

/**
 * Text view that allows changing the letter spacing of the text.
 * 
 * @author Pedro Barros (pedrobarros.dev at gmail.com)
 * @since May 7, 2013
 */
import android.content.Context;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ScaleXSpan;
import android.util.AttributeSet;
import android.widget.TextView;
public class LetterSpacingTextView extends TextView {
    private float letterSpacing = LetterSpacing.NORMAL;
    private CharSequence originalText = "";
    public LetterSpacingTextView(Context context) {
        super(context);
    }
    public LetterSpacingTextView(Context context, AttributeSet attrs){
        super(context, attrs);
    }
    public LetterSpacingTextView(Context context, AttributeSet attrs, int defStyle){
        super(context, attrs, defStyle);
    }
    public float getLetterSpacing() {
        return letterSpacing;
    }
    public void setLetterSpacing(float letterSpacing) {
        this.letterSpacing = letterSpacing;
        applyLetterSpacing();
    }
    @Override
    public void setText(CharSequence text, BufferType type) {
        originalText = text;
        applyLetterSpacing();
    }
    @Override
    public CharSequence getText() {
        return originalText;
    }
    private void applyLetterSpacing() {
        StringBuilder builder = new StringBuilder();
        for(int i = 0; i < originalText.length(); i++) {
            builder.append(originalText.charAt(i));
            if(i+1 < originalText.length()) {
                builder.append("\u00A0");
            }
        }
        SpannableString finalText = new SpannableString(builder.toString());
        if(builder.toString().length() > 1) {
            for(int i = 1; i < builder.toString().length(); i+=2) {
                finalText.setSpan(new ScaleXSpan((letterSpacing+1)/10), i, i+1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            }
        }
        super.setText(finalText, BufferType.SPANNABLE);
    }
    public class LetterSpacing {
        public final static float NORMAL = 0;
    }
}

调用方法：

LetterSpacingTextView textView = new LetterSpacingTextView(context);
textView.setLetterSpacing(10); //Or any float. To reset to normal, use 0 or LetterSpacingTextView.LetterSpacing.NORMAL
textView.setText("My text");
//Add the textView in a layout, for instance:
((LinearLayout) findViewById(R.id.myLinearLayout)).addView(textView);

来自为知笔记(Wiz)