Android手机操作系统中实现图片浏览

如何才能在Android手机操作系统中实现图片浏览的功能呢？我们今天就可以通过一段代码示例来对此进行一个充分的了解，以方便我们将来的应用。

Android 手机操作系统的应用方式灵活，简单，深受广大编程爱好者的喜爱。尤其是它的开源代码，使得我们能够方便的得到自己想要的功能需求。今天我们就为大家带来了有关Android图片浏览的相关方法。

首先是Android图片浏览中layout xml:

                    < ?xml version = "1.0"  encoding = "utf-8" ?>   
            <  RelativeLayout  xmlns:android = "http://schemas.Android.com/apk/res/Android"   
            Android:layout_width = "fill_parent"   
            Android:layout_height = "fill_parent" >   
            <  ImageSwitcher  Android:id = "@+id/switcher"  
            Android:layout_width = "fill_parent"  
            Android:layout_height = "fill_parent"  
            Android:layout_alignParentTop = "true"  
            Android:layout_alignParentLeft = "true"  
            />  
            <  Gallery  Android:id = "@+id/gallery"  
            Android:background = "#55000000"  
            Android:layout_width = "fill_parent"  
            Android:layout_height = "60dp"  
            Android:layout_alignParentBottom = "true"  
            Android:layout_alignParentLeft = "true"  
            Android:gravity = "center_vertical"  
            Android:spacing = "16dp"  
            />  
            < /RelativeLayout >

layout里面用到了前面所说的两个控件，ImageSwitcher用啦显示全图，Gallery用来显示缩略图。着重看看 ImageSwitcher,在ImageSwitcher1中需要实现ViewSwitcher.ViewFactory这个接口，这个接口里有个方法 makeView，这样就产生了用来显示图片的view. ImageSwitcher调用过程是这样的，首先要有一个Factory为它提供一个View，然后ImageSwitcher就可以初始化各种资源了。注意在使用一个ImageSwitcher之前，一定要调用setFactory方法，要不setImageResource这个方法会报空指针异常。

下面是Android图片浏览代码：

                    packagecom.zx.imageswitcher;   
            import Android.app.Activity;  
            import Android.content.Context;  
            import Android.os.Bundle;  
            import Android.view.View;  
            import Android.view.ViewGroup;  
            import Android.view.animation.AnimationUtils;  
            import Android.widget.AdapterView;  
            import Android.widget.BaseAdapter;  
            import Android.widget.Gallery;  
            import Android.widget.ImageSwitcher;  
            import Android.widget.ImageView;  
            import Android.widget.ViewSwitcher;  
            import Android.widget.Gallery.LayoutParams;  
            publicclassImageSwitcherTestextendsActivityimplements  
            AdapterView.OnItemSelectedListener,ViewSwitcher.ViewFactory{  
            privateImageSwitchermSwitcher;  
            privateInteger[] mThumbIds ={  
            R.drawable.sample_thumb_0,R.drawable.sample_thumb_1,  
            R.drawable.sample_thumb_2,R.drawable.sample_thumb_3,  
            R.drawable.sample_thumb_4,R.drawable.sample_thumb_5,  
            R.drawable.sample_thumb_6,R.drawable.sample_thumb_7};  
            privateInteger[] mImageIds ={  
            R.drawable.sample_0,R.drawable.sample_1,R.drawable.sample_2,  
            R.drawable.sample_3,R.drawable.sample_4,R.drawable.sample_5,  
            R.drawable.sample_6,R.drawable.sample_7};  
            /**Calledwhentheactivityisfirstcreated.*/  
            @Override  
            publicvoidonCreate(BundlesavedInstanceState){  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
            mSwitcher =(ImageSwitcher)findViewById(R.id.switcher);  
            mSwitcher.setFactory(this);  
            mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,  
            Android.R.anim.fade_in));  
            mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,  
            Android.R.anim.fade_out));  
            Gallery g =(Gallery)findViewById(R.id.gallery);  
            g.setAdapter(newImageAdapter(this));  
            g.setOnItemSelectedListener(this);  
            }  
            /*  
            *overrideforViewSwitcher.ViewFactory#makeView()  
            */  
            publicViewmakeView(){  
            ImageView i = new ImageView(this);  
            i.setBackgroundColor(0xFF000000);  
            i.setScaleType(ImageView.ScaleType.FIT_CENTER);  
            i.setLayoutParams(newImageSwitcher.LayoutParams
 (LayoutParams.FILL_PARENT,  
            LayoutParams.FILL_PARENT));  
            returni;  
            }  
            /*  
            *overridefor  
            *AdapterView.OnItemSelectedListener#onItemSelected()  
            */  
            publicvoidonItemSelected(AdapterViewparent,
 Viewv,intposition,longid){  
            mSwitcher.setImageResource(mImageIds[position]);  
            }  
            /*  
            *overrideforAdapterView.OnItemSelectedListener
 #onNothingSelected()  
            */  
            publicvoidonNothingSelected(AdapterView <  ?> arg0){  
            //TODOAuto-generatedmethodstub  
            }  
            publicclassImageAdapterextendsBaseAdapter{  
            publicImageAdapter(Contextc){  
            mContext = c ;  
            }  
            publicintgetCount(){  
            returnmThumbIds.length;  
            }  
            publicObjectgetItem(intposition){  
            returnposition;  
            }  
            publiclonggetItemId(intposition){  
            returnposition;  
            }  
            publicViewgetView(intposition,ViewconvertView,
 ViewGroupparent){  
            ImageView i = new ImageView(mContext);  
            i.setImageResource(mThumbIds[position]);  
            i.setAdjustViewBounds(true);  
            i.setLayoutParams(newGallery.LayoutParams(  
            LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));  
            i.setBackgroundResource(R.drawable.picture_frame);  
            returni;  
            }  
            privateContextmContext;  
            }  
            }

从Android图片浏览的代码中看到还实现了AdapterView.OnItemSelectedListener，这样就需要重写 onItemSelected()方法，然后在该方法中：mSwitcher.setImageResource(mImageIds[position]);这样就实现了图片在ImageSwitcher 中的切换。

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