Android WebView和JS交互

原文链接：http://blog.youkuaiyun.com/chenfeng0104/article/details/7023448

public class MainActivity extends Activity {

	private WebView mWebView;

	@SuppressLint("JavascriptInterface")
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		mWebView = (WebView) findViewById(R.id.web_view);

		//在java中调用js方法
		findViewById(R.id.web_view_invoke_js).setOnClickListener(
				new OnClickListener() {

					@Override
					public void onClick(View v) {
						//注意这里url的写法！！！
						/**
						 * 
						 */
						String url="javascript:invokedByJava('java_data')";
						mWebView.loadUrl(url);
					}
				});

		mWebView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
		mWebView.getSettings().setBuiltInZoomControls(true);
		mWebView.getSettings().setJavaScriptEnabled(true);

		/*
		 * WebView默认用系统自带浏览器处理页面跳转。 为了让页面跳转在当前WebView中进行，重写WebViewClient。
		 * 但是按BACK键时，不会返回跳转前的页面，而是退出本Activity。重写onKeyDown()方法来解决此问题。
		 */
		mWebView.setWebViewClient(new WebViewClient() {

			@Override
			public boolean shouldOverrideUrlLoading(WebView view, String url) {
				view.loadUrl(url);
				return true;
			}

			@Override
			public void onPageStarted(WebView view, String url, Bitmap favicon) {
				// TODO Auto-generated method stub
				super.onPageStarted(view, url, favicon);
			}

			@Override
			public void onPageFinished(WebView view, String url) {
				// TODO Auto-generated method stub
				super.onPageFinished(view, url);
			}

			@Override
			public void onReceivedError(WebView view, int errorCode,
					String description, String failingUrl) {
				Toast.makeText(MainActivity.this, "Oh no! " + description,
						Toast.LENGTH_SHORT).show();
			}

		});
		
		mWebView.setWebChromeClient(new WebChromeClient(){

			/** 
             * 处理JavaScript Alert事件 
             * 
             */  
			@Override
			public boolean onJsAlert(WebView view, String url, String message,
					final JsResult result) {
				
				//用Android组件替换  
                new AlertDialog.Builder(MainActivity.this)  
                    .setTitle("JS提示")  
                    .setMessage(message)  
                    .setPositiveButton(android.R.string.ok, new AlertDialog.OnClickListener() {  
                        public void onClick(DialogInterface dialog, int which) {  
                            result.confirm();  
                        }  
                    })  
                    .setCancelable(false)  
                    .create().show();
				return true;
			}
			
			
			
		});

		//在js中调用java方法
		//
		//第一个参数是自定义类对象，映射成JS对象 
        //第二个参数是第一个参数的JS别名 
		mWebView.addJavascriptInterface(new JsToJava(), "stub");
		//默认页面,在assets文件夹下
		mWebView.loadUrl("file:///android_asset/jsdemo.html");

		final EditText mEditText = (EditText) findViewById(R.id.web_view_text);

		findViewById(R.id.web_view_search).setOnClickListener(
				new OnClickListener() {
					@Override
					public void onClick(View view) {
						String url = mEditText.getText().toString();
						if (url == null || "".equals(url)) {
							Toast.makeText(MainActivity.this, "请输入URL",
									Toast.LENGTH_SHORT).show();
						} else {
							if (!url.startsWith("http:")
									&& !url.startsWith("file:")) {
								url = "http://" + url;
							}
							mWebView.loadUrl(url);
						}
					}
				});
	}

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// 处理WebView跳转返回
		if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
			mWebView.goBack();
			return true;
		}
		return super.onKeyDown(keyCode, event);
	}

	private class JsToJava {
		public void jsMethod(String fromJS) {

			System.out.println("jsMethod:" + fromJS);
			Toast.makeText(getApplicationContext(), "JS调用了Java方法。。。", 0).show();
		}

	}
}