Android WebView中图片浏览及缩放效果
本文实例为大家分享了Android WebView图片浏览及缩放效果展示的具体代码,供大家参考,具体内容如下
此工程用到了两个开源库:
PhotoView支持图片的缩放
Android-Universal-Image-Loader图片的异步加载
(android studio)将两个源工程中的library文件夹导入到Demo Module所在的Project中,修改各自的build.gradle文件,让里面的版本号、所用的android包等与Demo Module相同即可。大致如图:
源代码:
主Activity.java
public class MainActivity extends Activity { private WebView webview; private WebSettings wv; private ArrayList<String> listimg; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); webview = (WebView)findViewById(R.id.webview); listimg = new ArrayList<>(); wv = webview.getSettings(); wv.setJavaScriptEnabled(true); webview.addJavascriptInterface(new JavascriptInterface(this), "imagelistner");//绑定javasrcipt接口,imagelistner为接口的别名 webview.loadUrl("http://portal.smu.edu.cn/e/action/ShowInfo2.php?classid=1415&id=63663&tlpid=98"); webview.setWebViewClient(new WebViewClient(){ public boolean shouldOverrideUrlLoading(WebView view, String url) { //点击webView中的键接,依然在此webview中显示,而不跳转到别的浏览器 webview.loadUrl(url); return super.shouldOverrideUrlLoading(view, url); } @Override public void onPageFinished(WebView view, String url) { super.onPageFinished(view, url); addImageListner(); //当页面加载完成,就调用我们的addImageListener()函数 } @Override public void onPageStarted(WebView view, String url, Bitmap favicon) { super.onPageStarted(view, url, favicon); } }); } private void addImageListner() { //遍历页面中所有img的节点,因为节点里面的图片的url即objs[i].src,保存所有图片的src. //为每个图片设置点击事件,objs[i].onclick webview.loadUrl("javascript:(function(){" + "var objs = document.getElementsByTagName(\"img\"); " + "for(var i=0;i<objs.length;i++) " + "{" + "window.imagelistner.readImageUrl(objs[i].src); " + " objs[i].onclick=function() " + " { "+ " window.imagelistner.openImage(this.src); " + " } " + "}" + "})()"); } class JavascriptInterface { private Context context; public JavascriptInterface(Context context) { this.context = context; } @android.webkit.JavascriptInterface public void readImageUrl(String img) { //把所有图片的url保存在ArrayList<String>中 listimg.add(img); } @android.webkit.JavascriptInterface //对于targetSdkVersion>=17的,要加这个声明 public void openImage(String clickimg)//点击图片所调用到的函数 { int index = 0; for(String url:listimg) if(url.equals(clickimg)) index = listimg.indexOf(clickimg);//获取点击图片在整个页面图片中的位置 Intent intent = new Intent(); Bundle bundle = new Bundle(); bundle.putStringArrayList("list_image",listimg); bundle.putInt("index", index); intent.putExtra("bundle", bundle);//将所有图片的url以及点击图片的位置作为参数传给启动的activity intent.setClass(context, ViewPagerActivity.class); context.startActivity(intent);//启动ViewPagerActivity,用于显示图片 } } }
ViewPagerActivity.java
public class ViewPagerActivity extends Activity { private ViewPager mViewPager; private View rootView; private PhotoView image; private TextView indicator; private Bundle bundle; ArrayList<String> listimg; private int index; private int count; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_view_pager); mViewPager = (HackyViewPager) findViewById(R.id.view_pager); setContentView(mViewPager); bundle = getIntent().getBundleExtra("bundle"); listimg = bundle.getStringArrayList("list_image"); index = bundle.getInt("index"); count = listimg.size(); mViewPager.setAdapter(new SamplePagerAdapter()); mViewPager.setCurrentItem(index); } class SamplePagerAdapter extends PagerAdapter { @Override public int getCount() { return count; } @Override //此处用到PhotoView、ImageLoader均为第三方类库的类 public View instantiateItem(ViewGroup container, int position) { rootView = View.inflate(ViewPagerActivity.this, R.layout.viewpager_item, null); image = (PhotoView) rootView.findViewById(R.id.photoview); indicator = (TextView) rootView.findViewById(R.id.indicator); ImageLoader imageloader=ImageLoader.getInstance(); imageloader.init(ImageLoaderConfiguration.createDefault(ViewPagerActivity.this)); imageloader.displayImage(listimg.get(position), image); CharSequence text = getString(R.string.viewpager_indicator, position+1, count); indicator.setText(text); container.addView(rootView, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT); return rootView; } @Override public void destroyItem(ViewGroup container, int position, Object object) { container.removeView((View) object); } @Override public boolean isViewFromObject(View view, Object object) { return view == object; } } }
HackViewPager.java
public class HackyViewPager extends ViewPager { private boolean isLocked; public HackyViewPager(Context context) { super(context); isLocked = false; } public HackyViewPager(Context context, AttributeSet attrs) { super(context, attrs); isLocked = false; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) {//用于处理Touch事件 if (!isLocked) { try { return super.onInterceptTouchEvent(ev); } catch (IllegalArgumentException e) { e.printStackTrace(); return false; } } return false; } @Override public boolean onTouchEvent(MotionEvent event) { return !isLocked && super.onTouchEvent(event); } }
相关的布局文件:
MainActivity布局中只有一个简单的webView;
ViewPagerActivity布局中也只是一个HackViewPager;
HackViewPager中每一个View的布局:
viewpager_item.xml
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <uk.co.senab.photoview.PhotoView android:id="@+id/photoview" android:layout_width="match_parent" android:layout_height="match_parent" /> <TextView android:id="@+id/indicator" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:gravity="center" android:textSize="18sp" android:textColor="@android:color/white" android:text="@string/viewpager_indicator" android:background="@android:color/transparent" /> </RelativeLayout>
用到了一个@string/viewpager_indicator为
<string name="viewpager_indicator">%1$d/%2$d</string>
总结:主要难点还是在获取页面中图片的url,用到的是java函数与javascript的通信。
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