Android之Adapter系列之SimpleAdapter类

SimpleAdapter继承了BaseAdapter，作为一个Adapter的简单实现，SimpleAdapter支持的控件也比较少：checkable控件（例如checkbox，radioButton)、TextView和ImageView。

源码部分

源码路径：framework\base\core\java\android\widget\SimpleAdapter.java

package android.widget;import android.content.Context;import android.view.View;import android.view.ViewGroup;import android.view.LayoutInflater;import android.net.Uri;import java.util.ArrayList;import java.util.List;import java.util.Map;/**  * SimpleAdapter是一个将静态数据映射到在xml中定义的View上的简单的adapter。  * 开发者将数据保存在一个包含maps的ArrayList中。Arraylist中的每一项数据和view  * 中的每一个项对应。map中包含了view中每一行的数据。同样，开发者可以指定xml文件  * 来显示map中对应行的数据或者用map中的keys值来指定view。  *  * 数据的绑定发生在一下两种情况。  * 首先，如果{@link android.widget.SimpleAdapter.ViewBinder} 可见，  * {@link ViewBinder#setViewValue(android.view.View, Object, String)}被调用。  * 如果setViewValue返回true，那么则进行数据绑定。如果返回false，那么下面这些  * 情况将按顺序尝试执行  *   * 如果View实现了Checkable(例如Checkbox)，那么返回值将是boolean类型   * 
 TextView 返回值为String并且 {@link #setViewText(TextView, String)}将被调用  * 
 ImageView 返回值为资源id或者string，并且{@link #setViewImage(ImageView, int)}   * 或者 {@link #setViewImage(ImageView, String)} 被调用   * 
  * 如果没有合适的binding返回，将会抛出 {@link IllegalStateException}异常  */  public class SimpleAdapter extends BaseAdapter implements Filterable {    private int[] mTo;    private String[] mFrom;    private ViewBinder mViewBinder;    private List<? extends Map> mData;    private int mResource;    private int mDropDownResource;    private LayoutInflater mInflater;    private SimpleFilter mFilter;    private ArrayList> mUnfilteredData;    /**     * 构造函数     *      * @param context SimpleAdapter运行的上下文     * @param data 包含map的list列表。列表中给的每一项和view中的每一个item对应。Maps中则包含View * 中每一行的所有数据，并且应该包含“from”中所有指定的项     * @param resource View中item的layout布局id，该view至少包含“to”中指定的项     *            * @param from 一个将要被添加到map中的列名列表，和map中的每一个item对应     * @param to 需要显示view的id和“from”参数对应。必须全是TextView。     *       */        public SimpleAdapter(Context context, List<? extends Map> data,            int resource, String[] from, int[] to) {        mData = data;        mResource = mDropDownResource = resource;        mFrom = from;        mTo = to;        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);    }        /**     * @see android.widget.Adapter#getCount()     */    public int getCount() {        return mData.size();    }    /**     * @see android.widget.Adapter#getItem(int)     */    public Object getItem(int position) {        return mData.get(position);    }    /**     * @see android.widget.Adapter#getItemId(int)     */    public long getItemId(int position) {        return position;    }    /**     * getView直接调用createViewFromResource     */    public View getView(int position, View convertView, ViewGroup parent) {        return createViewFromResource(position, convertView, parent, mResource);    }    /**     * greateViewFromResource进行了convertView的判断后，调用bindView来进行具体view的绑定     */    private View createViewFromResource(int position, View convertView,            ViewGroup parent, int resource) {        View v;        if (convertView == null) {            v = mInflater.inflate(resource, parent, false);        } else {            v = convertView;        }        bindView(position, v);        return v;    }    /**     * 设置用来创建drop down 视图的布局id      * @param resource 定义了drop down 视图的资源文件     * @see #getDropDownView(int, android.view.View, android.view.ViewGroup)     */    public void setDropDownViewResource(int resource) {        this.mDropDownResource = resource;    }    /**     * 同样调用createViewFromResource来生成对应的view     */    @Override    public View getDropDownView(int position, View convertView, ViewGroup parent) {        return createViewFromResource(position, convertView, parent, mDropDownResource);    }    /**     * bindview应该是SimpleAdapter中核心的方法其中position为需要获取的view的位置，view为convertView     */    private void bindView(int position, View view) {        final Map dataSet = mData.get(position);        if (dataSet == null) {            return;        }        final ViewBinder binder = mViewBinder;        final String[] from = mFrom;        final int[] to = mTo;        final int count = to.length;        for (int i = 0; i < count; i++) {            final View v = view.findViewById(to[i]);            if (v != null) {                final Object data = dataSet.get(from[i]);                String text = data == null ? "" : data.toString();                if (text == null) {                    text = "";                }                boolean bound = false;                if (binder != null) {                    bound = binder.setViewValue(v, data, text);                }                if (!bound) {                    if (v instanceof Checkable) {                        if (data instanceof Boolean) {                            ((Checkable) v).setChecked((Boolean) data);                        } else if (v instanceof TextView) {                            // Note: keep the instanceof TextView check at the bottom of these                            // ifs since a lot of views are TextViews (e.g. CheckBoxes).                            setViewText((TextView) v, text);                        } else {                            throw new IllegalStateException(v.getClass().getName() +                                    " should be bound to a Boolean, not a " +                                    (data == null ? "" : data.getClass()));                        }                    } else if (v instanceof TextView) {                        // Note: keep the instanceof TextView check at the bottom of these                        // ifs since a lot of views are TextViews (e.g. CheckBoxes).                        setViewText((TextView) v, text);                    } else if (v instanceof ImageView) {                        if (data instanceof Integer) {                            setViewImage((ImageView) v, (Integer) data);                                                    } else {                            setViewImage((ImageView) v, text);                        }                    } else {                        throw new IllegalStateException(v.getClass().getName() + " is not a " +                                " view that can be bounds by this SimpleAdapter");                    }                }            }        }    }    /**     * 返回一个ViewBinder     */    public ViewBinder getViewBinder() {        return mViewBinder;    }    /**     * 设置ViewBinder     */    public void setViewBinder(ViewBinder viewBinder) {        mViewBinder = viewBinder;    }    /** * 该方法除被宾得View调用，用来给ImageView设置图片 * 如果ViewBinder不存在或者ViewBinder无法和ImageView绑定     */    public void setViewImage(ImageView v, int value) {        v.setImageResource(value);    }    /** * 该方法被bindView调用，用来给ImageView设置图片 * 如果ViewBinder不存在或者ViewBinder无法和ImageView绑定 *     * 默认情况下value被当作image资源，如果无法被当作image资源，那么将会被当作image uri     */    public void setViewImage(ImageView v, String value) {        try {            v.setImageResource(Integer.parseInt(value));        } catch (NumberFormatException nfe) {            v.setImageURI(Uri.parse(value));        }    }    /**   * 该方法被bindView调用，用来给TextView色获知字符 * 如果ViewBinder不存在或者ViewBinder无法和TextView绑定     */    public void setViewText(TextView v, String text) {        v.setText(text);    }    public Filter getFilter() {        if (mFilter == null) {            mFilter = new SimpleFilter();        }        return mFilter;    }    /**     * 这个内部静态接口被外部SimpleAdapter客户端用来修改views * 开发者通过实现这个接口，来修改view，如果这些View不能直接被SIM所支持， * 或者修改view绑定的方式     * @see SimpleAdapter#setViewImage(ImageView, int)     * @see SimpleAdapter#setViewImage(ImageView, String)     * @see SimpleAdapter#setViewText(TextView, String)     */    public static interface ViewBinder {        /**         * 绑定指定的数据到指定的view上         * 如果binding被该方法处理，那么该方法必须返回true，如果返回false，那么SimpleAdapter * 将会自己处理binding过程         * @param view the view to bind the data to         * @param data the data to bind to the view         * @param textRepresentation a safe String representation of the supplied data:         *        it is either the result of data.toString() or an empty String but it         *        is never null         *         * @return true if the data was bound to the view, false otherwise         */        boolean setViewValue(View view, Object data, String textRepresentation);    }    /** * 一个包含了某个前缀的数组过滤器，如果list中的每一项不包含该前缀，那么将会从该list中移除     */    private class SimpleFilter extends Filter {        @Override        protected FilterResults performFiltering(CharSequence prefix) {            FilterResults results = new FilterResults();            if (mUnfilteredData == null) {                mUnfilteredData = new ArrayList>(mData);            }            if (prefix == null || prefix.length() == 0) {                ArrayList> list = mUnfilteredData;                results.values = list;                results.count = list.size();            } else {                String prefixString = prefix.toString().toLowerCase();                ArrayList> unfilteredValues = mUnfilteredData;                int count = unfilteredValues.size();                ArrayList> newValues = new ArrayList>(count);                for (int i = 0; i < count; i++) {                    Map h = unfilteredValues.get(i);                    if (h != null) {                                                int len = mTo.length;                        for (int j=0; j>) results.values;            if (results.count > 0) {                notifyDataSetChanged();            } else {                notifyDataSetInvalidated();            }        }    }}

事例部分

list_item.xml

<?xml version="1.0" encoding="utf-8"?>

SimpleAdapter中包含了一个Interface ViewBinder，这里分两种情况，分别介绍两个事例，第一个，不使用ViewBinder；第二个，使用ViewBinder

SimpleAdapterNoBinder.java

package com.lj.simpleadaptertest;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Random;import android.app.Activity;import android.os.Bundle;import android.widget.ListView;import android.widget.SimpleAdapter;public class SimpleAdapterNoBinder extends Activity {ListView mListView;List> mData = new ArrayList>();public static final String KEY_IMG = "imgage";public static final String KEY_TITLE = "title";public static final String KEY_SUMMARY = "summary";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_no_binder);mListView = (ListView) findViewById(R.id.list_no_binder);               //定义一个mAdapter,设置自定义的layout布局，调用getData返回需要显示的数据SimpleAdapter mAdapter = new SimpleAdapter(this, getData(),R.layout.list_item, new String[] { KEY_IMG, KEY_TITLE,KEY_SUMMARY, }, new int[] { R.id.image, R.id.title,R.id.summary });mListView.setAdapter(mAdapter);}       //map中包含三部分数据，ImageView设置为默认的R.drawable.ic_launcher,两个TextView设置为随机的字符private List> getData() {List> list = new ArrayList>();Map map;for (int i = 0; i < 30; i++) {map = new HashMap();map.put(KEY_IMG, R.drawable.ic_launcher);map.put(KEY_TITLE, getTitleText(8));map.put(KEY_SUMMARY, getTitleText(10));list.add(map);}return list;}private Object getTitleText(int length) {String mString = "qwertyuiopasdfghjklzxcvbnm";Random random = new Random();StringBuffer sb = new StringBuffer();for (int i = 0; i < length; i++) {int number = random.nextInt(mString.length());sb.append(mString.charAt(number));}return sb.toString();}}

SimpleAdapterWithBinder.java

package com.lj.simpleadaptertest;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Random;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Color;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.ImageView;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.TextView;public class SimpleAdapterWithBinder extends Activity {ListView mListView;List> mData = new ArrayList>();public static final String KEY_IMG = "imgage";public static final String KEY_TITLE = "title";public static final String KEY_SUMMARY = "summary";public static final String KEY_CHECK = "check";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_no_binder);mListView = (ListView) findViewById(R.id.list_no_binder);SimpleAdapter mAdapter = new SimpleAdapter(this, getData(),R.layout.list_item, new String[] { KEY_IMG, KEY_TITLE,KEY_SUMMARY, }, new int[] { R.id.image, R.id.title,R.id.summary });mAdapter.setViewBinder(new TestViewBinder());mListView.setAdapter(mAdapter);}private List> getData() {List> list = new ArrayList>();Map map;for (int i = 0; i < 30; i++) {map = new HashMap();map.put(KEY_IMG, R.drawable.ic_launcher);map.put(KEY_TITLE, getTitleText(8));map.put(KEY_SUMMARY, getTitleText(10));map.put(KEY_CHECK, (i / 2 == 0 ? true : false));list.add(map);}return list;}private Object getTitleText(int length) {String mString = "qwertyuiopasdfghjklzxcvbnm";Random random = new Random();StringBuffer sb = new StringBuffer();for (int i = 0; i < length; i++) {int number = random.nextInt(mString.length());sb.append(mString.charAt(number));}return sb.toString();}public Bitmap getBitmap(final String url) {Log.e("lijian", "url = " + url);Bitmap bmp = null;try {URL mUrl = new URL(url);HttpURLConnection conn = (HttpURLConnection) mUrl.openConnection();InputStream is = conn.getInputStream();bmp = BitmapFactory.decodeStream(is);} catch (Exception e) {e.printStackTrace();}return bmp;}/** * 实现ViewBinder接口 *  */class TestViewBinder implements SimpleAdapter.ViewBinder {@Overridepublic boolean setViewValue(View view, Object data,String textRepresentation) {if ((view instanceof ImageView)) {Log.e("lijian", "set internet image data " + data);ImageView mImageView = (ImageView) view;mImageView.setImageResource(R.drawable.error);return true;} else if (view instanceof TextView && view.getId() ==R.id.summary) {TextView mTextView = (TextView) view;mTextView.setText("你好");return true;}return false;}}}

效果图：

Android之Adapter系列之SimpleAdapter类_第1张图片

图 1

Android之Adapter系列之SimpleAdapter类_第2张图片

图二

事例总结

图片以和图片二分别代表不使用ViewBinder和使用ViewBinder的结果，每一个Item的图片和summary字符可以在ViewBinder实现的类中的setViewValue中修改。

源码下载

源码部分

事例部分

事例总结

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