Android之Adapter优化

做过Android开发的都知道，Adapter的使用频率很高。无论是ListView、GridView、Gallery都需要设置Adapter，而且它们的Adapter几乎一样，让我们来看看我们经常用到的Adapter吧,我们可以边看边思考到底有多少东西是我们经常需要重复的:

先从构造说起：LayoutInflater重复

[java] view plain copy print ?

public MyAdapter1(Context context, int resId, List data) {
mData = data;
mContext = context;
mInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mLayoutResId = resId;
}

在说说其他需要重写的方法：以下3个方法都是重复的写（无任何技术含量）

[java] view plain copy print ?

@Override
public int getCount() {
return mData.size();
}
@Override
public Object getItem(int arg0) {
return mData.get(arg0);
}
@Override
public long getItemId(int arg0) {
return arg0;
}

在看看最重要的getView方法：无非就是重用View，setTag (ViewHolder),除了ViewHolder的get和set内容不一样其他都是在重复(伤不起有木有~！)。 [java] view plain copy print ?

public View getView(int position, View view, ViewGroup viewgroup) {
if (view == null) {
mHolder = new ViewHolder();
view = mInflater.inflate(mLayoutResId, null);
mHolder.tvText = (TextView) view.findViewById(android.R.id.text1);
view.setTag(mHolder);
} else {
mHolder = (ViewHolder) view.getTag();
}
mHolder.tvText.setText(mData.get(position).toString());
return view;
}
static class ViewHolder {
TextView tvText;
}

我们完全可以写两个基类把重复的东西抽取出来把代码优化一下，看一下优化后的代码吧：（在git看到的） [java] view plain copy print ?

package com.cym.chadtestdemo;
import java.util.List;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import com.chronocloud.lib.base.BaseAdapterHelper;
import com.chronocloud.lib.base.BaseQuickAdapter;
/**
*
* @ClassName: MyAdapter
* @Description: TODO 简化后的Adapter
* @author Chad.Cym
* @date 2014年8月25日下午8:22:31
*
* @param
*/
public class MyAdapter extends BaseQuickAdapter {
public MyAdapter(Context context, int layoutResId, List data) {
super(context, layoutResId, data);
}
@Override
protected void convert(BaseAdapterHelper helper, T item) {
helper.setText(android.R.id.text1, item.toString());
}
@Override
protected BaseAdapterHelper getAdapterHelper(int position,
View convertView, ViewGroup parent) {
return BaseAdapterHelper.get(context, convertView, parent, layoutResId);
}
}

优化后只需要设置控件内容即可，不需要重复之前的所有重复代码了。我们来看看抽取出来的基类： [java] view plain copy print ?

package com.chronocloud.lib.base;
/**
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.text.util.Linkify;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AlphaAnimation;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.Checkable;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.RatingBar;
import android.widget.TextView;
/**
* Allows an abstraction of the ViewHolder pattern.
*
*
* Usage
*
*
*
```
 
```
* return BaseAdapterHelper.get(context, convertView, parent, R.layout.item)
* .setText(R.id.tvName, contact.getName())
* .setText(R.id.tvEmails, contact.getEmails().toString())
* .setText(R.id.tvNumbers, contact.getNumbers().toString()).getView();
*
*/
public class BaseAdapterHelper {
/** Views indexed with their IDs */
private final SparseArray views;
private final Context context;
private int position;
private View convertView;
/**
* Package private field to retain the associated user object and detect a
* change
*/
Object associatedObject;
private BaseAdapterHelper(Context context, ViewGroup parent, int layoutId,
int position) {
this.context = context;
this.position = position;
this.views = new SparseArray();
convertView = LayoutInflater.from(context) //
.inflate(layoutId, parent, false);
convertView.setTag(this);
}
/**
* This method is the only entry point to get a BaseAdapterHelper.
*
* @param context
* The current context.
* @param convertView
* The convertView arg passed to the getView() method.
* @param parent
* The parent arg passed to the getView() method.
* @return A BaseAdapterHelper instance.
*/
public static BaseAdapterHelper get(Context context, View convertView,
ViewGroup parent, int layoutId) {
return get(context, convertView, parent, layoutId, -1);
}
/** This method is package private and should only be used by QuickAdapter. */
static BaseAdapterHelper get(Context context, View convertView,
ViewGroup parent, int layoutId, int position) {
if (convertView == null) {
return new BaseAdapterHelper(context, parent, layoutId, position);
}
// Retrieve the existing helper and update its position
BaseAdapterHelper existingHelper = (BaseAdapterHelper) convertView
.getTag();
existingHelper.position = position;
return existingHelper;
}
/**
* This method allows you to retrieve a view and perform custom operations
* on it, not covered by the BaseAdapterHelper.
* If you think it's a common use case, please consider creating a new issue
* at https://github.com/JoanZapata/base-adapter-helper/issues.
*
* @param viewId
* The id of the view you want to retrieve.
*/
public extends View> T getView(int viewId) {
return retrieveView(viewId);
}
/**
* Will set the text of a TextView.
*
* @param viewId
* The view id.
* @param value
* The text to put in the text view.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setText(int viewId, String value) {
TextView view = retrieveView(viewId);
view.setText(value);
return this;
}
/**
* Will set the image of an ImageView from a resource id.
*
* @param viewId
* The view id.
* @param imageResId
* The image resource id.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setImageResource(int viewId, int imageResId) {
ImageView view = retrieveView(viewId);
view.setImageResource(imageResId);
return this;
}
/**
* Will set background color of a view.
*
* @param viewId
* The view id.
* @param color
* A color, not a resource id.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setBackgroundColor(int viewId, int color) {
View view = retrieveView(viewId);
view.setBackgroundColor(color);
return this;
}
/**
* Will set background of a view.
*
* @param viewId
* The view id.
* @param backgroundRes
* A resource to use as a background.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setBackgroundRes(int viewId, int backgroundRes) {
View view = retrieveView(viewId);
view.setBackgroundResource(backgroundRes);
return this;
}
/**
* Will set text color of a TextView.
*
* @param viewId
* The view id.
* @param textColor
* The text color (not a resource id).
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setTextColor(int viewId, int textColor) {
TextView view = retrieveView(viewId);
view.setTextColor(textColor);
return this;
}
/**
* Will set text color of a TextView.
*
* @param viewId
* The view id.
* @param textColorRes
* The text color resource id.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setTextColorRes(int viewId, int textColorRes) {
TextView view = retrieveView(viewId);
view.setTextColor(context.getResources().getColor(textColorRes));
return this;
}
/**
* Will set the image of an ImageView from a drawable.
*
* @param viewId
* The view id.
* @param drawable
* The image drawable.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setImageDrawable(int viewId, Drawable drawable) {
ImageView view = retrieveView(viewId);
view.setImageDrawable(drawable);
return this;
}
/**
* Will download an image from a URL and put it in an ImageView.
* It uses Square's Picasso library to download the image asynchronously and
* put the result into the ImageView.
* Picasso manages recycling of views in a ListView.
* If you need more control over the Picasso settings, use
* {BaseAdapterHelper#setImageBuilder}.
*
* @param viewId
* The view id.
* @param imageUrl
* The image URL.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setImageUrl(int viewId, String imageUrl) {
ImageView view = retrieveView(viewId);
ImageLoader.getInstance().displayImage(imageUrl, view);
return this;
}
public BaseAdapterHelper setImageUrl(int viewId, String imageUrl,
DisplayImageOptions options) {
ImageView view = retrieveView(viewId);
ImageLoader.getInstance().displayImage(imageUrl, view, options);
return this;
}
/**
* Add an action to set the image of an image view. Can be called multiple
* times.
*/
public BaseAdapterHelper setImageBitmap(int viewId, Bitmap bitmap) {
ImageView view = retrieveView(viewId);
view.setImageBitmap(bitmap);
return this;
}
/**
* Add an action to set the alpha of a view. Can be called multiple times.
* Alpha between 0-1.
*/
public BaseAdapterHelper setAlpha(int viewId, float value) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
retrieveView(viewId).setAlpha(value);
} else {
// Pre-honeycomb hack to set Alpha value
AlphaAnimation alpha = new AlphaAnimation(value, value);
alpha.setDuration(0);
alpha.setFillAfter(true);
retrieveView(viewId).startAnimation(alpha);
}
return this;
}
/**
* Set a view visibility to VISIBLE (true) or GONE (false).
*
* @param viewId
* The view id.
* @param visible
* True for VISIBLE, false for GONE.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setVisible(int viewId, boolean visible) {
View view = retrieveView(viewId);
view.setVisibility(visible ? View.VISIBLE : View.GONE);
return this;
}
/**
* Add links into a TextView.
*
* @param viewId
* The id of the TextView to linkify.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper linkify(int viewId) {
TextView view = retrieveView(viewId);
Linkify.addLinks(view, Linkify.ALL);
return this;
}
/** Apply the typeface to the given viewId, and enable subpixel rendering. */
public BaseAdapterHelper setTypeface(int viewId, Typeface typeface) {
TextView view = retrieveView(viewId);
view.setTypeface(typeface);
view.setPaintFlags(view.getPaintFlags() | Paint.SUBPIXEL_TEXT_FLAG);
return this;
}
/**
* Apply the typeface to all the given viewIds, and enable subpixel
* rendering.
*/
public BaseAdapterHelper setTypeface(Typeface typeface, int... viewIds) {
for (int viewId : viewIds) {
TextView view = retrieveView(viewId);
view.setTypeface(typeface);
view.setPaintFlags(view.getPaintFlags() | Paint.SUBPIXEL_TEXT_FLAG);
}
return this;
}
/**
* Sets the progress of a ProgressBar.
*
* @param viewId
* The view id.
* @param progress
* The progress.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setProgress(int viewId, int progress) {
ProgressBar view = retrieveView(viewId);
view.setProgress(progress);
return this;
}
/**
* Sets the progress and max of a ProgressBar.
*
* @param viewId
* The view id.
* @param progress
* The progress.
* @param max
* The max value of a ProgressBar.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setProgress(int viewId, int progress, int max) {
ProgressBar view = retrieveView(viewId);
view.setMax(max);
view.setProgress(progress);
return this;
}
/**
* Sets the range of a ProgressBar to 0...max.
*
* @param viewId
* The view id.
* @param max
* The max value of a ProgressBar.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setMax(int viewId, int max) {
ProgressBar view = retrieveView(viewId);
view.setMax(max);
return this;
}
/**
* Sets the rating (the number of stars filled) of a RatingBar.
*
* @param viewId
* The view id.
* @param rating
* The rating.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setRating(int viewId, float rating) {
RatingBar view = retrieveView(viewId);
view.setRating(rating);
return this;
}
/**
* Sets the rating (the number of stars filled) and max of a RatingBar.
*
* @param viewId
* The view id.
* @param rating
* The rating.
* @param max
* The range of the RatingBar to 0...max.
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setRating(int viewId, float rating, int max) {
RatingBar view = retrieveView(viewId);
view.setMax(max);
view.setRating(rating);
return this;
}
/**
* Sets the on click listener of the view.
*
* @param viewId
* The view id.
* @param listener
* The on click listener;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setOnClickListener(int viewId,
View.OnClickListener listener) {
View view = retrieveView(viewId);
view.setOnClickListener(listener);
return this;
}
/**
* Sets the on touch listener of the view.
*
* @param viewId
* The view id.
* @param listener
* The on touch listener;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setOnTouchListener(int viewId,
View.OnTouchListener listener) {
View view = retrieveView(viewId);
view.setOnTouchListener(listener);
return this;
}
/**
* Sets the on long click listener of the view.
*
* @param viewId
* The view id.
* @param listener
* The on long click listener;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setOnLongClickListener(int viewId,
View.OnLongClickListener listener) {
View view = retrieveView(viewId);
view.setOnLongClickListener(listener);
return this;
}
/**
* Sets the tag of the view.
*
* @param viewId
* The view id.
* @param tag
* The tag;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setTag(int viewId, Object tag) {
View view = retrieveView(viewId);
view.setTag(tag);
return this;
}
/**
* Sets the tag of the view.
*
* @param viewId
* The view id.
* @param key
* The key of tag;
* @param tag
* The tag;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setTag(int viewId, int key, Object tag) {
View view = retrieveView(viewId);
view.setTag(key, tag);
return this;
}
/**
* Sets the checked status of a checkable.
*
* @param viewId
* The view id.
* @param checked
* The checked status;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setChecked(int viewId, boolean checked) {
Checkable view = (Checkable) retrieveView(viewId);
view.setChecked(checked);
return this;
}
/**
* Sets the adapter of a adapter view.
*
* @param viewId
* The view id.
* @param adapter
* The adapter;
* @return The BaseAdapterHelper for chaining.
*/
public BaseAdapterHelper setAdapter(int viewId, Adapter adapter) {
AdapterView view = retrieveView(viewId);
view.setAdapter(adapter);
return this;
}
/** Retrieve the convertView */
public View getView() {
return convertView;
}
/**
* Retrieve the overall position of the data in the list.
*
* @throws IllegalArgumentException
* If the position hasn't been set at the construction of the
* this helper.
*/
public int getPosition() {
if (position == -1)
throw new IllegalStateException(
"Use BaseAdapterHelper constructor "
+ "with position if you need to retrieve the position.");
return position;
}
@SuppressWarnings("unchecked")
private extends View> T retrieveView(int viewId) {
View view = views.get(viewId);
if (view == null) {
view = convertView.findViewById(viewId);
views.put(viewId, view);
}
return (T) view;
}
}

[java] view plain copy print ?

package com.chronocloud.lib.base;
/**
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import android.content.Context;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.FrameLayout;
import android.widget.ProgressBar;
import java.util.ArrayList;
import java.util.List;
/**
* Abstraction class of a BaseAdapter in which you only need
* to provide the convert() implementation.
* Using the provided BaseAdapterHelper, your code is minimalist.
* @param The type of the items in the list.
*/
public abstract class BaseQuickAdapterextends BaseAdapterHelper> extends BaseAdapter {
protected static final String TAG = BaseQuickAdapter.class.getSimpleName();
protected final Context context;
protected final int layoutResId;
protected final List data;
protected boolean displayIndeterminateProgress = false;
/**
* Create a QuickAdapter.
* @param context The context.
* @param layoutResId The layout resource id of each item.
*/
public BaseQuickAdapter(Context context, int layoutResId) {
this(context, layoutResId, null);
}
/**
* Same as QuickAdapter#QuickAdapter(Context,int) but with
* some initialization data.
* @param context The context.
* @param layoutResId The layout resource id of each item.
* @param data A new list is created out of this one to avoid mutable list
*/
public BaseQuickAdapter(Context context, int layoutResId, List data) {
this.data = data == null ? new ArrayList() : new ArrayList(data);
this.context = context;
this.layoutResId = layoutResId;
}
@Override
public int getCount() {
int extra = displayIndeterminateProgress ? 1 : 0;
return data.size() + extra;
}
@Override
public T getItem(int position) {
if (position >= data.size()) return null;
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public int getItemViewType(int position) {
return position >= data.size() ? 1 : 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (getItemViewType(position) == 0) {
final H helper = getAdapterHelper(position, convertView, parent);
convert(helper, getItem(position));
return helper.getView();
}
return createIndeterminateProgressView(convertView, parent);
}
private View createIndeterminateProgressView(View convertView, ViewGroup parent) {
if (convertView == null) {
FrameLayout container = new FrameLayout(context);
container.setForegroundGravity(Gravity.CENTER);
ProgressBar progress = new ProgressBar(context);
container.addView(progress);
convertView = container;
}
return convertView;
}
@Override
public boolean isEnabled(int position) {
return position < data.size();
}
public void add(T elem) {
data.add(elem);
notifyDataSetChanged();
}
public void addAll(List elem) {
data.addAll(elem);
notifyDataSetChanged();
}
public void set(T oldElem, T newElem) {
set(data.indexOf(oldElem), newElem);
}
public void set(int index, T elem) {
data.set(index, elem);
notifyDataSetChanged();
}
public void remove(T elem) {
data.remove(elem);
notifyDataSetChanged();
}
public void remove(int index) {
data.remove(index);
notifyDataSetChanged();
}
public void replaceAll(List elem) {
data.clear();
data.addAll(elem);
notifyDataSetChanged();
}
public boolean contains(T elem) {
return data.contains(elem);
}
/** Clear data list */
public void clear() {
data.clear();
notifyDataSetChanged();
}
public void showIndeterminateProgress(boolean display) {
if (display == displayIndeterminateProgress) return;
displayIndeterminateProgress = display;
notifyDataSetChanged();
}
/**
* Implement this method and use the helper to adapt the view to the given item.
* @param helper A fully initialized helper.
* @param item The item that needs to be displayed.
*/
protected abstract void convert(H helper, T item);
/**
* You can override this method to use a custom BaseAdapterHelper in order to fit your needs
*
* @param position The position of the item within the adapter's data set of the item whose view we want.
* @param convertView The old view to reuse, if possible. Note: You should check that this view
* is non-null and of an appropriate type before using. If it is not possible to convert
* this view to display the correct data, this method can create a new view.
* Heterogeneous lists can specify their number of view types, so that this View is
* always of the right type (see {@link #getViewTypeCount()} and
* {@link #getItemViewType(int)}).
* @param parent The parent that this view will eventually be attached to
* @return An instance of BaseAdapterHelper
*/
protected abstract H getAdapterHelper(int position, View convertView, ViewGroup parent);
}

效果很明显，简单多了吧，希望能对大家有帮助。源码地址：https://github.com/JoanZapata/base-adapter-helper

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