android上文本框输入限制最大字节数

public class MaxByteLengthEditText extends EditText {
	
	private int maxByteLength = 100;
	
	private String encoding = "GBK";

	public MaxByteLengthEditText(Context context) {
		super(context);
		init();
	}
	
	public MaxByteLengthEditText(Context context,AttributeSet attrs) {  
		super(context,attrs);
		init();
	}
	
	private void init() {
		setFilters(new InputFilter[] {inputFilter});
	}
	
	public int getMaxByteLength() {
		return maxByteLength;
	}

	public void setMaxByteLength(int maxByteLength) {
		this.maxByteLength = maxByteLength;
	}

	public String getEncoding() {
		return encoding;
	}

	public void setEncoding(String encoding) {
		this.encoding = encoding;
	}

	/**
	 * input输入过滤
	 */
	private InputFilter inputFilter = new InputFilter() {
		@Override
		public CharSequence filter(CharSequence source, int start, int end,
				Spanned dest, int dstart, int dend) {
            try {
            	int len = 0;
            	boolean more = false;
            	do {
            		SpannableStringBuilder builder = 
            			new SpannableStringBuilder(dest).replace(dstart, dend, source.subSequence(start, end));
                    len = builder.toString().getBytes(encoding).length;
                    more = len > maxByteLength;
                    if (more) {
                    	end--;
                    	source = source.subSequence(start, end);
                    }
            	} while (more);
                return source;
            } catch (UnsupportedEncodingException e) {
            	return "Exception";
            }
		}
    };
}