android索引

项目需要，今天学习了一下索引

涉及到的技术：

绘制右侧的索引条

点击某个字母，定位到ListView控件的指定位置

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
	<com.example.suoyin.IndexableListView
	    android:layout_width="fill_parent"
	    android:layout_height="fill_parent"
	    android:id="@+id/listview" />
</LinearLayout>

自定义索引条：

package com.example.suoyin;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.view.MotionEvent;
import android.widget.Adapter;
import android.widget.ListView;
import android.widget.SectionIndexer;

/**
 * 右侧的索引条
 *
 * @author by 佚名
 *
 */
public class IndexScroller {

	private float mIndexbarWidth; // 索引条宽度
	private float mIndexbarMargin; // 索引条外边距
	private float mPreviewPadding; //
	private float mDensity; // 密度
	private float mScaledDensity; // 缩放密度
	private float mAlphaRate; // 透明度
	private int mState = STATE_HIDDEN; // 状态
	private int mListViewWidth; // ListView宽度
	private int mListViewHeight; // ListView高度
	private int mCurrentSection = -1; // 当前部分
	private boolean mIsIndexing = false; // 是否正在索引
	private ListView mListView = null;
	private SectionIndexer mIndexer = null;
	private String[] mSections = null;
	private RectF mIndexbarRect;

	// 4种状态（已隐藏、正在显示、已显示、正在隐藏）
	private static final int STATE_HIDDEN = 0;
	private static final int STATE_SHOWING = 1;
	private static final int STATE_SHOWN = 2;
	private static final int STATE_HIDING = 3;

	public IndexScroller(Context context, ListView lv) {
		mDensity = context.getResources().getDisplayMetrics().density;
		mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;
		mListView = lv;
		setAdapter(mListView.getAdapter());

		mIndexbarWidth = 20 * mDensity; // 索引条宽度
		mIndexbarMargin = 10 * mDensity;// 索引条间距
		mPreviewPadding = 5 * mDensity; // 内边距
	}

	public void draw(Canvas canvas) {
		if (mState == STATE_HIDDEN)
			return;

		// mAlphaRate determines the rate of opacity
		Paint indexbarPaint = new Paint();
		indexbarPaint.setColor(Color.BLACK);
		indexbarPaint.setAlpha((int) (64 * mAlphaRate));
		indexbarPaint.setAntiAlias(true);
		// 画右侧字母索引的圆矩形
		canvas.drawRoundRect(mIndexbarRect, 5 * mDensity, 5 * mDensity,
				indexbarPaint);

		if (mSections != null && mSections.length > 0) {
			// Preview is shown when mCurrentSection is set
			if (mCurrentSection >= 0) {
				Paint previewPaint = new Paint(); // 用来绘画所以条背景的画笔
				previewPaint.setColor(Color.BLACK);// 设置画笔颜色为黑色
				previewPaint.setAlpha(96); // 设置透明度
				previewPaint.setAntiAlias(true);// 设置抗锯齿
				previewPaint.setShadowLayer(3, 0, 0, Color.argb(64, 0, 0, 0)); // 设置阴影层

				Paint previewTextPaint = new Paint(); // 用来绘画索引字母的画笔
				previewTextPaint.setColor(Color.WHITE); // 设置画笔为白色
				previewTextPaint.setAntiAlias(true); // 设置抗锯齿
				previewTextPaint.setTextSize(50 * mScaledDensity); // 设置字体大小

				// 文本的宽度
				float previewTextWidth = previewTextPaint
						.measureText(mSections[mCurrentSection]);

				float previewSize = 2 * mPreviewPadding
						+ previewTextPaint.descent()
						- previewTextPaint.ascent();
				RectF previewRect = new RectF(
						(mListViewWidth - previewSize) / 2,
						(mListViewHeight - previewSize) / 2,
						(mListViewWidth - previewSize) / 2 + previewSize,
						(mListViewHeight - previewSize) / 2 + previewSize);

				// 中间索引的那个框
				canvas.drawRoundRect(previewRect, 5 * mDensity, 5 * mDensity,
						previewPaint);
				// 绘画索引字母
				canvas.drawText(
						mSections[mCurrentSection],
						previewRect.left + (previewSize - previewTextWidth) / 2
								- 1,
						previewRect.top + mPreviewPadding
								- previewTextPaint.ascent() + 1,
						previewTextPaint);
			}

			// 绘画右侧索引条的字母
			Paint indexPaint = new Paint();
			indexPaint.setColor(Color.WHITE);
			indexPaint.setAlpha((int) (255 * mAlphaRate));
			indexPaint.setAntiAlias(true);
			indexPaint.setTextSize(12 * mScaledDensity);

			float sectionHeight = (mIndexbarRect.height() - 2 * mIndexbarMargin)
					/ mSections.length;
			float paddingTop = (sectionHeight - (indexPaint.descent() - indexPaint
					.ascent())) / 2;
			for (int i = 0; i < mSections.length; i++) {
				float paddingLeft = (mIndexbarWidth - indexPaint
						.measureText(mSections[i])) / 2;
				canvas.drawText(mSections[i], mIndexbarRect.left + paddingLeft,
						mIndexbarRect.top + mIndexbarMargin + sectionHeight * i
								+ paddingTop - indexPaint.ascent(), indexPaint);
			}
		}
	}

	public boolean onTouchEvent(MotionEvent ev) {
		switch (ev.getAction()) {
		case MotionEvent.ACTION_DOWN: // 按下，开始索引
			// If down event occurs inside index bar region, start indexing
			if (mState != STATE_HIDDEN && contains(ev.getX(), ev.getY())) {
				setState(STATE_SHOWN);

				// It demonstrates that the motion event started from index bar
				mIsIndexing = true;
				// Determine which section the point is in, and move the list to
				// that section
				mCurrentSection = getSectionByPoint(ev.getY());
				mListView.setSelection(mIndexer
						.getPositionForSection(mCurrentSection));
				return true;
			}
			break;
		case MotionEvent.ACTION_MOVE: // 移动
			if (mIsIndexing) {
				// If this event moves inside index bar
				if (contains(ev.getX(), ev.getY())) {
					// Determine which section the point is in, and move the
					// list to that section
					mCurrentSection = getSectionByPoint(ev.getY());
					mListView.setSelection(mIndexer
							.getPositionForSection(mCurrentSection));
				}
				return true;
			}
			break;
		case MotionEvent.ACTION_UP: // 抬起
			if (mIsIndexing) {
				mIsIndexing = false;
				mCurrentSection = -1;
			}
			if (mState == STATE_SHOWN)
				setState(STATE_HIDING);
			break;
		}
		return false;
	}

	public void onSizeChanged(int w, int h, int oldw, int oldh) {
		mListViewWidth = w;
		mListViewHeight = h;
		mIndexbarRect = new RectF(w - mIndexbarMargin - mIndexbarWidth,
				mIndexbarMargin, w - mIndexbarMargin, h - mIndexbarMargin);
	}

	// 显示
	public void show() {
		if (mState == STATE_HIDDEN)
			setState(STATE_SHOWING);
		else if (mState == STATE_HIDING)
			setState(STATE_HIDING);
	}

	// 隐藏
	public void hide() {
		if (mState == STATE_SHOWN)
			setState(STATE_HIDING);
	}

	public void setAdapter(Adapter adapter) {
		if (adapter instanceof SectionIndexer) {
			mIndexer = (SectionIndexer) adapter;
			mSections = (String[]) mIndexer.getSections();
		}
	}

	// 设置状态
	private void setState(int state) {
		if (state < STATE_HIDDEN || state > STATE_HIDING)
			return;

		mState = state;
		switch (mState) {
		case STATE_HIDDEN:
			// Cancel any fade effect
			// 取消渐退的效果
			mHandler.removeMessages(0);
			break;
		case STATE_SHOWING:
			// Start to fade in
			// 开始渐进效果
			mAlphaRate = 0;
			fade(0);
			break;
		case STATE_SHOWN:
			// Cancel any fade effect
			// 取消渐退的效果
			mHandler.removeMessages(0);
			break;
		case STATE_HIDING:
			// Start to fade out after three seconds
			// 隐藏3秒钟
			mAlphaRate = 1;
			fade(3000);
			break;
		}
	}

	private boolean contains(float x, float y) {
		// Determine if the point is in index bar region, which includes the
		// right margin of the bar
		return (x >= mIndexbarRect.left && y >= mIndexbarRect.top && y <= mIndexbarRect.top
				+ mIndexbarRect.height());
	}

	private int getSectionByPoint(float y) {
		if (mSections == null || mSections.length == 0)
			return 0;
		if (y < mIndexbarRect.top + mIndexbarMargin)
			return 0;
		if (y >= mIndexbarRect.top + mIndexbarRect.height() - mIndexbarMargin)
			return mSections.length - 1;
		return (int) ((y - mIndexbarRect.top - mIndexbarMargin) / ((mIndexbarRect
				.height() - 2 * mIndexbarMargin) / mSections.length));
	}

	private void fade(long delay) {
		mHandler.removeMessages(0);
		mHandler.sendEmptyMessageAtTime(0, SystemClock.uptimeMillis() + delay);
	}

	private Handler mHandler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);

			switch (mState) {
			case STATE_SHOWING:
				// Fade in effect
				// 淡进效果
				mAlphaRate += (1 - mAlphaRate) * 0.2;
				if (mAlphaRate > 0.9) {
					mAlphaRate = 1;
					setState(STATE_SHOWN);
				}

				mListView.invalidate();
				fade(10);
				break;
			case STATE_SHOWN:
				// If no action, hide automatically
				setState(STATE_HIDING);
				break;
			case STATE_HIDING:
				// Fade out effect
				// 淡出效果
				mAlphaRate -= mAlphaRate * 0.2;
				if (mAlphaRate < 0.1) {
					mAlphaRate = 0;
					setState(STATE_HIDDEN);
				}

				mListView.invalidate();
				fade(10);
				break;
			}
		}

	};
}

自定义索引列表：

package com.example.suoyin;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ListAdapter;
import android.widget.ListView;

/**
 * 自定义索引列表
 *
 * @author by 佚名
 *
 */
public class IndexableListView extends ListView {

	private boolean mIsFastScrollEnabled = false;
	private IndexScroller mScroller = null;//绘制索引条
	private GestureDetector mGestureDetector = null;//检查上下滑动的手势

	public IndexableListView(Context context) {
		super(context);
	}

	public IndexableListView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	public IndexableListView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
	}

	@Override
	public boolean isFastScrollEnabled() {
		return mIsFastScrollEnabled;
	}

	@Override
	public void setFastScrollEnabled(boolean enabled) {
		mIsFastScrollEnabled = enabled;
		if (mIsFastScrollEnabled) {
			if (mScroller == null)
				mScroller = new IndexScroller(getContext(), this);
		} else {
			if (mScroller != null) {
				mScroller.hide();
				mScroller = null;
			}
		}
	}

	@Override
	public void draw(Canvas canvas) {
		super.draw(canvas);

		// Overlay index bar
		if (mScroller != null)
			mScroller.draw(canvas);
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		// Intercept ListView's touch event
		if (mScroller != null && mScroller.onTouchEvent(ev))
			return true;

		if (mGestureDetector == null) {
			// 创建一个GestureDetector（手势探测器）
			mGestureDetector = new GestureDetector(getContext(),
					new GestureDetector.SimpleOnGestureListener() {

						@Override
						public boolean onFling(MotionEvent e1, MotionEvent e2,
								float velocityX, float velocityY) {
							// If fling happens, index bar shows
							// 显示索引条
							mScroller.show();
							return super.onFling(e1, e2, velocityX, velocityY);
						}

					});
		}
		mGestureDetector.onTouchEvent(ev);

		return super.onTouchEvent(ev);
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		return true;
	}

	@Override
	public void setAdapter(ListAdapter adapter) {
		super.setAdapter(adapter);
		if (mScroller != null)
			mScroller.setAdapter(adapter);
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);
		if (mScroller != null)
			mScroller.onSizeChanged(w, h, oldw, oldh);
	}

}

字符串匹配类：将索引条字母与索引列表项进行匹配判断

package com.example.suoyin;

public class StringMatcher {

	//
	private final static char KOREAN_UNICODE_START = '?'; // 韩文字符编码开始？
	private final static char KOREAN_UNICODE_END = '?';	  // 韩文字符编码结束？
	private final static char KOREAN_UNIT = '?' - '?';	  // 不知道是啥？
	// 韩文的一些字符初始化
	private final static char[] KOREAN_INITIAL = { '?', '?', '?', '?', '?',
			'?', '?', '?', '?', '?', '?', '?', '?', '?', '?', '?', '?', '?',
			'?' };

	/**
	 * 字符匹配
	 * @param value	需要keyword匹配的字符串 list中的文本
	 * @param keyword #ABCDEFGHIJKLMNOPQRSTUVWXYZ中的一个
	 * @return  只要value中包含keyword就返回真
	 */
	public static boolean match(String value, String keyword) {
		if (value == null || keyword == null)
			return false;
		if (keyword.length() > value.length())
			return false;//在一个小的字符串中查找一个大的字符串肯定找不到

		int i = 0, j = 0;
		do {
			// 如果是韩文字符并且在韩文初始数组里面
			if (isKorean(value.charAt(i)) && isInitialSound(keyword.charAt(j))) {
				if (keyword.charAt(j) == getInitialSound(value.charAt(i))) {
					i++;
					j++;
				} else if (j > 0)
					break;
				else
					i++;
			} else {
				// 逐个字符匹配
				if (keyword.charAt(j) == value.charAt(i)) {
					i++;
					j++;
				} else if (j > 0)
					break;
				else
					i++;
			}
		} while (i < value.length() && j < keyword.length());
		// 如果最后j等于keyword的长度说明匹配成功
		return (j == keyword.length()) ? true : false;
	}

	// 判断字符是否在韩文字符编码范围内
	private static boolean isKorean(char c) {
		if (c >= KOREAN_UNICODE_START && c <= KOREAN_UNICODE_END)
			return true;
		return false;
	}

	// 判断是否在韩文字符里面
	private static boolean isInitialSound(char c) {
		for (char i : KOREAN_INITIAL) {
			if (c == i)
				return true;
		}
		return false;
	}

	// 获得韩文初始化字符数组里面的一个字符
	private static char getInitialSound(char c) {
		return KOREAN_INITIAL[(c - KOREAN_UNICODE_START) / KOREAN_UNIT];
	}
}

在Activity中使用：

package com.example.suoyin;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.SectionIndexer;

public class IndexableListViewActivity extends Activity {
	private ArrayList<String> mItems;
	private IndexableListView mListView;  

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);  

		// 初始化一些数据
		mItems = new ArrayList<String>();
		mItems.add("Diary of a Wimpy Kid 6: Cabin Fever");
		mItems.add("Steve Jobs");
		mItems.add("Inheritance (The Inheritance Cycle)");
		mItems.add("11/22/63: A Novel");
		mItems.add("The Hunger Games");
		mItems.add("The LEGO Ideas Book");
		mItems.add("Explosive Eighteen: A Stephanie Plum Novel");
		mItems.add("Catching Fire (The Second Book of the Hunger Games)");
		mItems.add("Elder Scrolls V: Skyrim: Prima Official Game Guide");
		mItems.add("Death Comes to Pemberley");
		mItems.add("Diary of a Wimpy Kid 6: Cabin Fever");
		mItems.add("Steve Jobs");
		mItems.add("Inheritance (The Inheritance Cycle)");
		mItems.add("11/22/63: A Novel");
		mItems.add("The Hunger Games");
		mItems.add("The LEGO Ideas Book");
		mItems.add("Explosive Eighteen: A Stephanie Plum Novel");
		mItems.add("Catching Fire (The Second Book of the Hunger Games)");
		mItems.add("Elder Scrolls V: Skyrim: Prima Official Game Guide");
		mItems.add("做作");
		mItems.add("1");
		mItems.add("2");
		mItems.add("wokao");  

		Collections.sort(mItems); // 排序
		ContentAdapter adapter = new ContentAdapter(this,android.R.layout.simple_list_item_1,mItems);

		mListView = (IndexableListView) findViewById(R.id.listview);
		mListView.setAdapter(adapter);
		mListView.setFastScrollEnabled(true); // 设置快速滑动
	}  

	private class ContentAdapter extends ArrayAdapter<String> implements
	SectionIndexer {  

		private String mSections = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ";  

		public ContentAdapter(Context context, int textViewResourceId,
				List<String> objects) {
			super(context, textViewResourceId, objects);
		}  

		@Override
		public int getPositionForSection(int sectionIndex) {  /*根据右边索引adbcd...获取左边listView的位置*/
			// If there is no item for current section, previous section will be
			// selected
			// 如果当前部分没有对应item，则之前的部分将被选择  （比如用户点击索引Y，左边list中没有y开头的，则会选择y之前的x,x也没有就找w，一直往前查，直到遇到第一个有对应item的，否则不进行定位）
			for (int i = sectionIndex; i >= 0; i--) {
				for (int j = 0; j < getCount(); j++) {
					System.out.println(getCount());
					if (i == 0) { // #
						// For numeric section 数字
						for (int k = 0; k <= 9; k++) {// 1...9
							// 字符串第一个字符与1~9之间的数字进行匹配
							if (StringMatcher.match(
									String.valueOf(getItem(j).charAt(0)),
									String.valueOf(k)))
								return j;
						}
					} else { // A~Z
						if (StringMatcher.match(
								String.valueOf(getItem(j).charAt(0)),
								String.valueOf(mSections.charAt(i))))
							return j;
					}
				}
			}
			return 0;
		}  

		@Override
		public int getSectionForPosition(int position) {
			return 0;
		}  

		@Override
		public Object[] getSections() {
			String[] sections = new String[mSections.length()];
			for (int i = 0; i < mSections.length(); i++)
				sections[i] = String.valueOf(mSections.charAt(i));
			return sections;
		}
	}
}