android webview js交互， 响应webview中的图片点击事件

挺帅的移动开发专栏 /article/8811710.html

最近碰到个新需求需要点击webview中的图片进行放大显示。
整理了下思路，想到了下面的一个可行的方案。

方案思路，
1.在点击图片的时候调用本地的java方法并给出响应的图片地址
2.本地获得图片地址后，开启一个遮罩activity进行显示和处理

第二步的实现很容易实现，关键是第一步的实现，在网页中点击图片不会调用本地的java代码。那么我们需要给这个点击事件加上相应的js函数，让点击事件调用的js函数来调用我们提前准备好的java函数，等我们捕获到图片的url剩下的就好处理了。
关键点就是给普通的html注入我们的js函数，让图片能够响应点击并调用js函数，在通过js函数来调用我们的java函数。听起来好像有点绕，不过也不难，下面我们用代码实现下

对java和js交互还不熟悉的同学，请参照前面的文章
/article/8811704.html

这次实例的主要功能：点击图片在新的activity中展示，对图片能够进行手势操作，包括双指缩放等
效果图



加载webview的activity代码

[java]
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package wst.webview;

import android.annotation.SuppressLint;

import android.app.Activity;

import android.content.Context;

import android.content.Intent;

import android.graphics.Bitmap;

import android.os.Bundle;
import android.webkit.WebView;

import android.webkit.WebViewClient;

@SuppressLint("SetJavaScriptEnabled")

public class MainActivity
extends Activity {

private WebView contentWebView =
null;

@SuppressLint("SetJavaScriptEnabled")

@Override
public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);
contentWebView = (WebView) findViewById(R.id.webview);

// 启用javascript

contentWebView.getSettings().setJavaScriptEnabled(true);

// 随便找了个带图片的网站

contentWebView.loadUrl("http://www.weim.me/12408.html");

// 添加js交互接口类，并起别名 imagelistner

contentWebView.addJavascriptInterface(new JavascriptInterface(this),
"imagelistner");
contentWebView.setWebViewClient(new MyWebViewClient());

}

// 注入js函数监听

private void addImageClickListner() {

// 这段js函数的功能就是，遍历所有的img几点，并添加onclick函数，函数的功能是在图片点击的时候调用本地java接口并传递url过去

contentWebView.loadUrl("javascript:(function(){" +

"var objs = document.getElementsByTagName(\"img\"); " +

"for(var i=0;i<objs.length;i++) " +

"{"
+ " objs[i].onclick=function() " +

" { "

+ " window.imagelistner.openImage(this.src); " +

" } " +

"}" +
"})()");

}

// js通信接口
public class JavascriptInterface {

private Context context;

public JavascriptInterface(Context context) {

this.context = context;

}

public void openImage(String img) {

System.out.println(img);
//
Intent intent = new Intent();

intent.putExtra("image", img);

intent.setClass(context, ShowWebImageActivity.class);

context.startActivity(intent);
System.out.println(img);
}
}

// 监听
private class MyWebViewClient
extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {

return
super.shouldOverrideUrlLoading(view, url);

}

@Override
public void onPageFinished(WebView view, String url) {

view.getSettings().setJavaScriptEnabled(true);

super.onPageFinished(view, url);

// html加载完成之后，添加监听图片的点击js函数

addImageClickListner();

}

@Override

public void onPageStarted(WebView view, String url, Bitmap favicon) {

view.getSettings().setJavaScriptEnabled(true);

super.onPageStarted(view, url, favicon);

}

@Override
public void onReceivedError(WebView view,
int errorCode, String description, String failingUrl) {

super.onReceivedError(view, errorCode, description, failingUrl);

}
}

}

package wst.webview;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;

@SuppressLint("SetJavaScriptEnabled")
public class MainActivity extends Activity {

private WebView contentWebView = null;

@SuppressLint("SetJavaScriptEnabled")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
contentWebView = (WebView) findViewById(R.id.webview);
// 启用javascript
contentWebView.getSettings().setJavaScriptEnabled(true);
// 随便找了个带图片的网站
contentWebView.loadUrl("http://www.weim.me/12408.html");
// 添加js交互接口类，并起别名 imagelistner
contentWebView.addJavascriptInterface(new JavascriptInterface(this), "imagelistner");
contentWebView.setWebViewClient(new MyWebViewClient());

}

// 注入js函数监听
private void addImageClickListner() {
// 这段js函数的功能就是，遍历所有的img几点，并添加onclick函数，函数的功能是在图片点击的时候调用本地java接口并传递url过去
contentWebView.loadUrl("javascript:(function(){" +
"var objs = document.getElementsByTagName(\"img\"); " +
"for(var i=0;i<objs.length;i++)  " +
"{"
+ "    objs[i].onclick=function()  " +
"    {  "
+ "        window.imagelistner.openImage(this.src);  " +
"    }  " +
"}" +
"})()");
}

// js通信接口
public class JavascriptInterface {

private Context context;

public JavascriptInterface(Context context) {
this.context = context;
}

public void openImage(String img) {
System.out.println(img);
//
Intent intent = new Intent();
intent.putExtra("image", img);
intent.setClass(context, ShowWebImageActivity.class);
context.startActivity(intent);
System.out.println(img);
}
}

// 监听
private class MyWebViewClient extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {

return super.shouldOverrideUrlLoading(view, url);
}

@Override
public void onPageFinished(WebView view, String url) {

view.getSettings().setJavaScriptEnabled(true);

super.onPageFinished(view, url);
// html加载完成之后，添加监听图片的点击js函数
addImageClickListner();

}

@Override
public void onPageStarted(WebView view, String url, Bitmap favicon) {
view.getSettings().setJavaScriptEnabled(true);

super.onPageStarted(view, url, favicon);
}

@Override
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {

super.onReceivedError(view, errorCode, description, failingUrl);

}
}

}

展示图片的activity代码

[java]
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package wst.webview;

import java.io.IOException;

import java.io.InputStream;

import java.net.URL;

import android.app.Activity;

import android.graphics.drawable.BitmapDrawable;

import android.graphics.drawable.Drawable;

import android.os.Bundle;
import android.widget.TextView;

public class ShowWebImageActivity
extends Activity {
private TextView imageTextView =
null;
private String imagePath =
null;
private ZoomableImageView imageView =
null;

@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.show_webimage);
this.imagePath = getIntent().getStringExtra("image");

this.imageTextView = (TextView) findViewById(R.id.show_webimage_imagepath_textview);

imageTextView.setText(this.imagePath);

imageView = (ZoomableImageView) findViewById(R.id.show_webimage_imageview);

try {
imageView.setImageBitmap(((BitmapDrawable) ShowWebImageActivity.loadImageFromUrl(this.imagePath)).getBitmap());

} catch (IOException e) {

e.printStackTrace();
}
}

public static Drawable loadImageFromUrl(String url)
throws IOException {

URL m = new URL(url);

InputStream i = (InputStream) m.getContent();
Drawable d = Drawable.createFromStream(i,
"src");
return d;
}
}

package wst.webview;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import android.app.Activity;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.widget.TextView;

public class ShowWebImageActivity extends Activity {
private TextView imageTextView = null;
private String imagePath = null;
private ZoomableImageView imageView = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.show_webimage);
this.imagePath = getIntent().getStringExtra("image");

this.imageTextView = (TextView) findViewById(R.id.show_webimage_imagepath_textview);
imageTextView.setText(this.imagePath);
imageView = (ZoomableImageView) findViewById(R.id.show_webimage_imageview);

try {
imageView.setImageBitmap(((BitmapDrawable) ShowWebImageActivity.loadImageFromUrl(this.imagePath)).getBitmap());
} catch (IOException e) {
e.printStackTrace();
}
}

public static Drawable loadImageFromUrl(String url) throws IOException {

URL m = new URL(url);
InputStream i = (InputStream) m.getContent();
Drawable d = Drawable.createFromStream(i, "src");
return d;
}
}

图片布局文件

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

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical"
>

<!-- TODO 默认占位图 -->

<wst.webview.ZoomableImageView

android:id="@+id/show_webimage_imageview"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:scaleType="matrix"

android:src="@drawable/icon"
/>

<TextView

android:id="@+id/show_webimage_imagepath_textview"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:gravity="center"

android:textColor="#ffff0000"
/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<!-- TODO 默认占位图 -->

<wst.webview.ZoomableImageView
android:id="@+id/show_webimage_imageview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="matrix"
android:src="@drawable/icon" />

<TextView
android:id="@+id/show_webimage_imagepath_textview"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#ffff0000" />

</LinearLayout>

希望对大家有所帮助
源代码附上

http://download.csdn.net/detail/wangtingshuai/5109179