Android仿微信朋友圈图片查看器

来源：互联网发布：linux下如何删除用户编辑：程序博客网时间：2024/05/01 15:00

看博文之前，希望大家先打开自己的微信点到朋友圈中去，仔细观察是不是发现朋友圈里的有个“九宫格”的图片区域，点击图片又会跳到图片的详细查看页面，并且支持图片的滑动和缩放？这个功能是不是很常用呢？！那么我今天正好做了这个Demo，下面为大家讲解一下。首先按照惯例先看一下效果图吧，尤其不会录制gif动画（哎~没办法，模拟器不支持多点触控，刚好我的手机又没有Root，不能录屏，悲催啊，大家见谅，想要看真实效果的话，烦请移到博文最下方，点击下载源码，运行后再看效果哈~~），这里先就拿几张静态的图片顶替一下好了。见谅！

主页ListView的效果：点击九宫格图片跳转到大图多点触控，缩放图片

效果嘛，将就着看吧！实在看不明白就想想微信朋友圈，或者拖到下方，点击下载源码！这里，首先分析一下主界面吧，布局都是很简单的，主界面仅仅就是一个ListView的控件，ListView的Item上值得注意的是，Item上包含了一个GridView，这个GridView呗用作实现“九宫格”的效果，主界面布局就是一个ListView，这里不说了，我们先来看看ListView的Item的布局吧，以下是item_list.xml

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<!--?xml version=1.0encoding=utf-8?-->
<relativelayout android:layout_height="match_parent"android:layout_width="match_parent"android:paddingbottom="5dp"android:paddingtop="5dp"xmlns:android="http://schemas.android.com/apk/res/android">
 
    <imageview android:background="@drawable/ic_launcher"android:id="@+id/iv_avatar"android:layout_height="50dp"android:layout_width="50dp"android:scaletype="centerCrop">
 
    <textview android:id="@+id/tv_title"android:layout_height="wrap_content"android:layout_marginleft="5dp"android:layout_torightof="@id/iv_avatar"android:layout_width="wrap_content"android:text="爷，今天心情好！"android:textsize="16sp">
 
    <textview android:id="@+id/tv_content"android:layout_below="@+id/tv_title"android:layout_height="wrap_content"android:layout_marginleft="5dp"android:layout_margintop="3dp"android:layout_torightof="@id/iv_avatar"android:layout_width="wrap_content"android:text="今天又是雾霾！"android:textsize="16sp">
 
    <com.example.imagedemo.noscrollgridview android:columnwidth="70dp"android:gravity="center"android:horizontalspacing="2.5dp"android:id="@+id/gridview"android:layout_below="@id/tv_content"android:layout_height="wrap_content"android:layout_marginleft="5dp"android:layout_margintop="3dp"android:layout_torightof="@id/iv_avatar"android:layout_width="220dp"android:numcolumns="3"android:stretchmode="columnWidth"android:verticalspacing="2.5dp">
 
</com.example.imagedemo.noscrollgridview></textview></textview></imageview></relativelayout>

好了，大家看到了，布局也是极其简单的，但是有个问题就是ListView嵌套进了GridView，那么就会出现一个问题，导致GridView显示的不全，那么该怎么解决这个问题呢？其实也简单，就是重写一个GridView，测量一下GridView的高度，再设置上去。具体解决方案请看上篇博文ListView嵌套GridView显示不全解决方法或者源码，如下NoScrollGridView.java

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packagecom.example.imagedemo;
 
importandroid.content.Context;
importandroid.util.AttributeSet;
importandroid.widget.GridView;
 
/**
 * 自定义的“九宫格”——用在显示帖子详情的图片集合 解决的问题：GridView显示不全，只显示了一行的图片，比较奇怪，尝试重写GridView来解决
 *
 * @author lichao
 * @since 2014-10-16 16:41
 *
 */
publicclass NoScrollGridView extendsGridView {
 
    publicNoScrollGridView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }
 
    publicNoScrollGridView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }
 
    publicNoScrollGridView(Context context, AttributeSet attrs, intdefStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    }
 
    @Override
    protectedvoid onMeasure(intwidthMeasureSpec, intheightMeasureSpec) {
        // TODO Auto-generated method stub
        intexpandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,
                MeasureSpec.AT_MOST);
        super.onMeasure(widthMeasureSpec, expandSpec);
    }
 
}

接下来看看ListView上面Item的实体是什么样的数据结构，这就显得非常简单了。

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publicclass ItemEntity {
    privateString avatar; // 用户头像URL
    privateString title; // 标题
    privateString content; // 内容
    privateArrayList<string> imageUrls; // 九宫格图片的URL集合
 
    publicItemEntity(String avatar, String title, String content,
            ArrayList<string> imageUrls) {
        super();
        this.avatar = avatar;
        this.title = title;
        this.content = content;
        this.imageUrls = imageUrls;
    }
       ...
}</string></string>

好了，有了ListView，那么不可避免的就是做Item上的数据适配了。继承一个BaseAdapter，代码如下，都比较简单：

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/**
 * 首页ListView的数据适配器
 *
 * @author Administrator
 *
 */
publicclass ListItemAdapter extendsBaseAdapter {
 
    privateContext mContext;
    privateArrayList<itementity> items;
 
    publicListItemAdapter(Context ctx, ArrayList<itementity> items) {
        this.mContext = ctx;
        this.items = items;
    }
 
    @Override
    publicint getCount() {
        returnitems == null? 0: items.size();
    }
 
    @Override
    publicObject getItem(intposition) {
        returnitems.get(position);
    }
 
    @Override
    publiclong getItemId(intposition) {
        returnposition;
    }
 
    @Override
    publicView getView(intposition, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if(convertView == null) {
            holder = newViewHolder();
            convertView = View.inflate(mContext, R.layout.item_list, null);
            holder.iv_avatar = (ImageView) convertView
                    .findViewById(R.id.iv_avatar);
            holder.tv_title = (TextView) convertView
                    .findViewById(R.id.tv_title);
            holder.tv_content = (TextView) convertView
                    .findViewById(R.id.tv_content);
            holder.gridview = (NoScrollGridView) convertView
                    .findViewById(R.id.gridview);
            convertView.setTag(holder);
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
        ItemEntity itemEntity = items.get(position);
        holder.tv_title.setText(itemEntity.getTitle());
        holder.tv_content.setText(itemEntity.getContent());
        // 使用ImageLoader加载网络图片
        DisplayImageOptions options = newDisplayImageOptions.Builder()//
                .showImageOnLoading(R.drawable.ic_launcher)// 加载中显示的默认图片
                .showImageOnFail(R.drawable.ic_launcher)// 设置加载失败的默认图片
                .cacheInMemory(true)// 内存缓存
                .cacheOnDisk(true)// sdcard缓存
                .bitmapConfig(Config.RGB_565)// 设置最低配置
                .build();//
        ImageLoader.getInstance().displayImage(itemEntity.getAvatar(),
                holder.iv_avatar, options);
        finalArrayList<string> imageUrls = itemEntity.getImageUrls();
        if(imageUrls == null|| imageUrls.size() == 0) { // 没有图片资源就隐藏GridView
            holder.gridview.setVisibility(View.GONE);
        }else{
            holder.gridview.setAdapter(newNoScrollGridAdapter(mContext,
                    imageUrls));
        }
        // 点击回帖九宫格，查看大图
        holder.gridview.setOnItemClickListener(newOnItemClickListener() {
 
            @Override
            publicvoid onItemClick(AdapterView<!--?--> parent, View view,
                    intposition, longid) {
                // TODO Auto-generated method stub
                imageBrower(position, imageUrls);
            }
        });
        returnconvertView;
    }
 
    /**
     * 打开图片查看器
     *
     * @param position
     * @param urls2
     */
    protectedvoid imageBrower(intposition, ArrayList<string> urls2) {
        Intent intent = newIntent(mContext, ImagePagerActivity.class);
        // 图片url,为了演示这里使用常量，一般从数据库中或网络中获取
        intent.putExtra(ImagePagerActivity.EXTRA_IMAGE_URLS, urls2);
        intent.putExtra(ImagePagerActivity.EXTRA_IMAGE_INDEX, position);
        mContext.startActivity(intent);
    }
 
    /**
     * listview组件复用，防止“卡顿”
     *
     * @author Administrator
     *
     */
    classViewHolder {
        privateImageView iv_avatar;
        privateTextView tv_title;
        privateTextView tv_content;
        privateNoScrollGridView gridview;
    }
}</string></string></itementity></itementity>

这里有需要解释的地方了，看看listview上的图片处理，由于图片都是从网络获取的，为了避免图片过多造成OOM，那么这里加载图片的时候必不可少的需要做内存优化，图片的优化方式有很多，我这里采取了最简单最直接得方式，使用了开源的ImageLoader这个图片加载框架，这个框架简直是太优秀了，减少了开发者一系列不必要而且时常会出现的麻烦，关于ImageLoader并不是本篇博文需要讲解的知识，关于ImageLoader，欢迎在GitHub主页上下载，地址是https://github.com/nostra13/Android-Universal-Image-Loader，既然使用了ImageLoader这个框架，就不得不在程序上做一些初始化的操作，首先需要自定义一个全局的上下文Application类，将ImageLoader的相关属性初始化上去，直接看代码好了，见名知意：MyApplication.java

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publicclass MyApplication extendsApplication {
    @Override
    publicvoid onCreate() {
        super.onCreate();
        DisplayImageOptions defaultOptions = newDisplayImageOptions.Builder() //
                .showImageForEmptyUri(R.drawable.ic_launcher)//
                .showImageOnFail(R.drawable.ic_launcher)//
                .cacheInMemory(true)//
                .cacheOnDisk(true)//
                .build();//
        ImageLoaderConfiguration config = newImageLoaderConfiguration//
        .Builder(getApplicationContext())//
                .defaultDisplayImageOptions(defaultOptions)//
                .discCacheSize(50* 1024* 1024)//
                .discCacheFileCount(100)// 缓存一百张图片
                .writeDebugLogs()//
                .build();//
        ImageLoader.getInstance().init(config);
    }
}

定义这个Application之后，需要在清单文件中配置一下，在Manifest.xml中的Application节点上添加：

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android:name=com.example.imagedemo.MyApplication

此外由于ImageLoader是网络获取图片，又需要本地sdcard缓存图片，所以需要加上一下的权限，这是Imageloader标准权限：

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<uses-permission android:name="android.permission.INTERNET">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE">
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission></uses-permission></uses-permission>

再看看上面的Item上数据，里面有个GridView，显然这个GridView也是需要做数据适配的，这个数据反应的是从网络加载图片，比较简单，看代码NoScrollGridAdapter.java

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      ......
@Override
    publicView getView(intposition, View convertView, ViewGroup parent) {
        View view = View.inflate(ctx, R.layout.item_gridview, null);
        ImageView imageView = (ImageView) view.findViewById(R.id.iv_image);
        DisplayImageOptions options = newDisplayImageOptions.Builder()//
                .cacheInMemory(true)//
                .cacheOnDisk(true)//
                .bitmapConfig(Config.RGB_565)//
                .build();
        ImageLoader.getInstance().displayImage(imageUrls.get(position),
                imageView, options);
        returnview;
    }
     ......

这样，所有的数据适配就做好了，接下来就需要做图片查看器了，当我们点击ListView上Item里的“九宫格”——NoScrollGridView的某张图片的时候，需要把这个图片的url传给一个图片查看器，图片查看器里会根据传递进来的url去网络加载这张图片，那么其实图片查看器就是一个新的单独的Activity，这个Activity会包含一个ViewPager，用来管理多张图片的查看。image_detail_pager.xml

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<!--?xml version=1.0encoding=utf-8?-->
<framelayout android:layout_height="match_parent"android:layout_width="match_parent"xmlns:android="http://schemas.android.com/apk/res/android">
 
    <com.example.imagedemo.hackyviewpager android:background="@android:color/black"android:id="@+id/pager"android:layout_height="match_parent"android:layout_width="match_parent">
 
    <textview android:background="@android:color/transparent"android:gravity="center"android:id="@+id/indicator"android:layout_gravity="bottom"android:layout_height="wrap_content"android:layout_width="match_parent"android:text="@string/viewpager_indicator"android:textcolor="@android:color/white"android:textsize="18sp">
 
</textview></com.example.imagedemo.hackyviewpager></framelayout>

HackyViewPager.java

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publicclass HackyViewPager extendsViewPager {
 
    privatestatic final String TAG = HackyViewPager;
 
    publicHackyViewPager(Context context) {
        super(context);
    }
 
    publicHackyViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
 
    @Override
    publicboolean onInterceptTouchEvent(MotionEvent ev) {
        try{
            returnsuper.onInterceptTouchEvent(ev);
        }catch(IllegalArgumentException e) {
            // 不理会
            Log.e(TAG, hacky viewpager error1);
            returnfalse;
        }catch(ArrayIndexOutOfBoundsException e) {
            // 不理会
            Log.e(TAG, hacky viewpager error2);
            returnfalse;
        }
    }
 
}

ImagePagerActivity.java

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/**
 * 图片查看器
 */
publicclass ImagePagerActivity extendsFragmentActivity {
    privatestatic final String STATE_POSITION = STATE_POSITION;
    publicstatic final String EXTRA_IMAGE_INDEX = image_index;
    publicstatic final String EXTRA_IMAGE_URLS = image_urls;
 
    privateHackyViewPager mPager;
    privateint pagerPosition;
    privateTextView indicator;
 
    @Override
    publicvoid onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.image_detail_pager);
 
        pagerPosition = getIntent().getIntExtra(EXTRA_IMAGE_INDEX, 0);
        ArrayList<string> urls = getIntent().getStringArrayListExtra(
                EXTRA_IMAGE_URLS);
 
        mPager = (HackyViewPager) findViewById(R.id.pager);
        ImagePagerAdapter mAdapter = newImagePagerAdapter(
                getSupportFragmentManager(), urls);
        mPager.setAdapter(mAdapter);
        indicator = (TextView) findViewById(R.id.indicator);
 
        CharSequence text = getString(R.string.viewpager_indicator, 1, mPager
                .getAdapter().getCount());
        indicator.setText(text);
        // 更新下标
        mPager.setOnPageChangeListener(newOnPageChangeListener() {
 
            @Override
            publicvoid onPageScrollStateChanged(intarg0) {
            }
 
            @Override
            publicvoid onPageScrolled(intarg0, floatarg1, intarg2) {
            }
 
            @Override
            publicvoid onPageSelected(intarg0) {
                CharSequence text = getString(R.string.viewpager_indicator,
                        arg0 + 1, mPager.getAdapter().getCount());
                indicator.setText(text);
            }
 
        });
        if(savedInstanceState != null) {
            pagerPosition = savedInstanceState.getInt(STATE_POSITION);
        }
 
        mPager.setCurrentItem(pagerPosition);
    }
 
    @Override
    publicvoid onSaveInstanceState(Bundle outState) {
        outState.putInt(STATE_POSITION, mPager.getCurrentItem());
    }
 
    privateclass ImagePagerAdapter extendsFragmentStatePagerAdapter {
 
        publicArrayList<string> fileList;
 
        publicImagePagerAdapter(FragmentManager fm, ArrayList<string> fileList) {
            super(fm);
            this.fileList = fileList;
        }
 
        @Override
        publicint getCount() {
            returnfileList == null? 0: fileList.size();
        }
 
        @Override
        publicFragment getItem(intposition) {
            String url = fileList.get(position);
            returnImageDetailFragment.newInstance(url);
        }
 
    }
}
</string></string></string>

已知图片查看的界面是继承自FragmentActivity的，所以支持显示的界面必须需要Fragment来实现，那么就自定义个Frangment吧，用这个Fragment来从url中获取图片资源，显示图片。image_detail_fragment.xml

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<!--?xml version=1.0encoding=utf-8?-->
<framelayout android:background="@android:color/black"android:layout_height="match_parent"android:layout_width="match_parent"xmlns:android="http://schemas.android.com/apk/res/android">
 
    <imageview android:adjustviewbounds="true"android:contentdescription="@string/app_name"android:id="@+id/image"android:layout_height="match_parent"android:layout_width="match_parent"android:scaletype="centerCrop">
 
    <progressbar android:id="@+id/loading"android:layout_gravity="center"android:layout_height="wrap_content"android:layout_width="wrap_content"android:visibility="gone">
 
</progressbar></imageview></framelayout>

ImageDetailFragment.java

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/**
 * 单张图片显示Fragment
 */
publicclass ImageDetailFragment extendsFragment {
    privateString mImageUrl;
    privateImageView mImageView;
    privateProgressBar progressBar;
    privatePhotoViewAttacher mAttacher;
 
    publicstatic ImageDetailFragment newInstance(String imageUrl) {
        finalImageDetailFragment f = newImageDetailFragment();
 
        finalBundle args = newBundle();
        args.putString(url, imageUrl);
        f.setArguments(args);
 
        returnf;
    }
 
    @Override
    publicvoid onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mImageUrl = getArguments() != null? getArguments().getString(url)
                :null;
    }
 
    @Override
    publicView onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        finalView v = inflater.inflate(R.layout.image_detail_fragment,
                container,false);
        mImageView = (ImageView) v.findViewById(R.id.image);
        mAttacher = newPhotoViewAttacher(mImageView);
 
        mAttacher.setOnPhotoTapListener(newOnPhotoTapListener() {
 
            @Override
            publicvoid onPhotoTap(View arg0, floatarg1, floatarg2) {
                getActivity().finish();
            }
        });
 
        progressBar = (ProgressBar) v.findViewById(R.id.loading);
        returnv;
    }
 
    @Override
    publicvoid onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
 
        ImageLoader.getInstance().displayImage(mImageUrl, mImageView,
                newSimpleImageLoadingListener() {
                    @Override
                    publicvoid onLoadingStarted(String imageUri, View view) {
                        progressBar.setVisibility(View.VISIBLE);
                    }
 
                    @Override
                    publicvoid onLoadingFailed(String imageUri, View view,
                            FailReason failReason) {
                        String message = null;
                        switch(failReason.getType()) {
                        caseIO_ERROR:
                            message = 下载错误;
                            break;
                        caseDECODING_ERROR:
                            message = 图片无法显示;
                            break;
                        caseNETWORK_DENIED:
                            message = 网络有问题，无法下载;
                            break;
                        caseOUT_OF_MEMORY:
                            message = 图片太大无法显示;
                            break;
                        caseUNKNOWN:
                            message = 未知的错误;
                            break;
                        }
                        Toast.makeText(getActivity(), message,
                                Toast.LENGTH_SHORT).show();
                        progressBar.setVisibility(View.GONE);
                    }
 
                    @Override
                    publicvoid onLoadingComplete(String imageUri, View view,
                            Bitmap loadedImage) {
                        progressBar.setVisibility(View.GONE);
                        mAttacher.update();
                    }
                });
    }
}

写到这里，此篇博文也宣告结束了。需要提出的是，我这里的图片查看器实现的图片的缩放效果使用的是开源组件PhotoView，关于PhotoView的github项目地址在这里，https://github.com/chrisbanes/PhotoView 需要点进去这个项目的网址，去下载源码，将源码全部拷贝到项目中来，使用也是相当方便的，demo如下:

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ImageView mImageView;
PhotoViewAttacher mAttacher;
 
@Override
publicvoid onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    // Any implementation of ImageView can be used!
    mImageView = (ImageView) findViewById(R.id.iv_photo);
 
    // Set the Drawable displayed
    Drawable bitmap = getResources().getDrawable(R.drawable.wallpaper);
    mImageView.setImageDrawable(bitmap);
 
    // Attach a PhotoViewAttacher, which takes care of all of the zooming functionality.
    mAttacher = newPhotoViewAttacher(mImageView);
}
 
 
// If you later call mImageView.setImageDrawable/setImageBitmap/setImageResource/etc then you just need to call
attacher.update();

刚开始这个图片查看器是我自己自定义View来实现的，其实需要实现图片的手势识别+多点触控+缩放，是可以使用矩阵Matrix来实现的，只不过这样显得特别的麻烦不说，而且极易出现BUG，这对于某些“急功近利”的项目来说，是个不好的兆头。所以，我这里摒弃了我用Matrix自定义的效果，改用github大牛为我们写好的开源组件，这样效率就上去了，大家也可以用Matrix自己去实现一下图片的多点触摸缩放的效果，关于Matrix的学习，请参加我以前的博文，Android自定义控件——3D画廊和图像矩阵。其实关于android上的图片缩放真没什么其它的方式，唯一能使用的还是Matrix这个类，不信先来瞧瞧Github大牛写的开源组件PhotoView是怎么实现的，查看以下部分源码：

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// These are set so we don't keep allocating them on the heap
    privatefinal Matrix mBaseMatrix = newMatrix();
    privatefinal Matrix mDrawMatrix = newMatrix();
    privatefinal Matrix mSuppMatrix = newMatrix();
    privatefinal RectF mDisplayRect = newRectF();
    privatefinal float[] mMatrixValues = newfloat[9];

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/**
    * Set's the ImageView's ScaleType to Matrix.
    */
   privatestatic void setImageViewScaleTypeMatrix(ImageView imageView) {
       /**
        * PhotoView sets it's own ScaleType to Matrix, then diverts all calls
        * setScaleType to this.setScaleType automatically.
        */
       if(null!= imageView && !(imageView instanceofIPhotoView)) {
           if(!ScaleType.MATRIX.equals(imageView.getScaleType())) {
               imageView.setScaleType(ScaleType.MATRIX);
           }
       }
   }

以上只是PhotoView的部分源码，一目了然的发现它的实现也是基于Matrix的，时间与篇幅的局限性，大家需要更好的了解PhotoView的实现的话，就下载它的源码查看吧，要理解大神的想法是需要一些扎实的基础，关于PhotoView的具体实现细节，我也弄不太明白，可能是我对Matrix了解的不深刻吧，希望以后加强学习，也希望以后跟你们交流学习，共同进步！

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