Android WebView实践
AndroidManifest.xml
<uses-permission android:name="android.permission.INTERNET" />
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<WebView
android:id="@+id/webview"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<ProgressBar
android:id="@+id/progressbar"
style="@android:style/Widget.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="3dip"
android:max="100"
android:progress="0"
android:visibility="gone"/>
</FrameLayout>
MainActivity.java
package cn.litry.win;
import android.os.Build;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.app.AlertDialog;
import android.graphics.Bitmap;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.webkit.JavascriptInterface;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;
import android.widget.Toast;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public class MainActivity extends Activity {
private WebView webView;
private ProgressBar progressBar;
private int exitNum =2;
@SuppressLint("SetJavaScriptEnabled")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i("[T-WebView]", "onCreate");
requestWindowFeature(Window.FEATURE_NO_TITLE);// 不显示title
setContentView(R.layout.activity_main);
progressBar = (ProgressBar) findViewById(R.id.progressbar);// 进度条
webView = (WebView) findViewById(R.id.webview);
// webView.loadUrl("file:///android_asset/test.html");//加载asset文件夹下html
webView.loadUrl("http://baidu.com");// 加载url
// 使用webview显示html代码
// webView.loadDataWithBaseURL(null,"<html><head><title> 欢迎您 </title></head>"<body><h2>使用webview显示
// html代码</h2></body></html>", "text/html" ,"utf-8", null);
webView.addJavascriptInterface(this, "android");// 添加js监听 这样html就能调用客户端
webView.setWebChromeClient(webChromeClient);
webView.setWebViewClient(webViewClient);
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true); // 允许使用js
/**
* LOAD_CACHE_ONLY: 不使用网络，只读取本地缓存数据 LOAD_DEFAULT:
* （默认）根据cache-control决定是否从网络上取数据。 LOAD_NO_CACHE: 不使用缓存，只从网络获取数据.
* LOAD_CACHE_ELSE_NETWORK，只要本地有，无论是否过期，或者no-cache，都使用缓存中的数据。
*/
webSettings.setCacheMode(WebSettings.LOAD_NO_CACHE);// 不使用缓存，只从网络获取数据.
// 支持屏幕缩放
webSettings.setSupportZoom(false);
webSettings.setBuiltInZoomControls(false);
// 不显示webview缩放按钮
// webSettings.setDisplayZoomControls(true);
webSettings.setBuiltInZoomControls(false);// 设置出现缩放工具
webSettings.setUseWideViewPort(false);// 扩大比例的缩放
// webSettings.setLayoutAlgorithm(LayoutAlgorithm.SINGLE_COLUMN);//
// 自适应屏幕
// webSettings.setLoadWithOverviewMode(true);
}
// WebViewClient主要帮助WebView处理各种通知、请求事件
private WebViewClient webViewClient = new WebViewClient() {
@Override
public void onPageFinished(WebView view, String url) {// 页面加载完成
Log.i("[T-WebView]", "onPageFinished: " + url);
progressBar.setVisibility(View.GONE);
}
@Override
public void onPageStarted(WebView view, String url, Bitmap favicon) {// 页面开始加载
Log.i("[T-WebView]", "onPageStarted: " + url);
progressBar.setVisibility(View.VISIBLE);
// Toast.makeText(MainActivity.this, url,Toast.LENGTH_LONG).show();
}
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
if (url.equals("http://www.google.com/")) {
Log.i("[T-WebView]", "shouldOverrideUrlLoading: " + url);
Toast.makeText(MainActivity.this, "拦截该url:" + url, Toast.LENGTH_SHORT)
.show();
return true;// 表示我已经处理过了
}
return super.shouldOverrideUrlLoading(view, url);
}
@SuppressWarnings("deprecation")
@Override
public void onReceivedError(WebView view, int errorCode,
String description, String url) {
super.onReceivedError(view, errorCode, description, url);
Log.i("[T-WebView]", "onReceivedError: " + url);
Toast.makeText(MainActivity.this,
"Code:" + errorCode + " Url:" + url, Toast.LENGTH_SHORT).show();
webView.loadDataWithBaseURL(null,
"<html><head><title>Error</title></head><body><h2>页面访问失败,点击<a href=\""
+ url + "\">这里</a>重新访问</h2></body></html>",
"text/html", "utf-8", null);
}
};
// WebChromeClient主要辅助WebView处理Javascript的对话框、网站图标、网站title、加载进度等
private WebChromeClient webChromeClient = new WebChromeClient() {
// 不支持js的alert弹窗，需要自己监听然后通过dialog弹窗
@Override
public boolean onJsAlert(WebView webView, String url, String message,
JsResult result) {
AlertDialog.Builder localBuilder = new AlertDialog.Builder(
webView.getContext());
Log.i("[T-WebView]", "onJsAlert" + url);
localBuilder.setMessage(message).setPositiveButton("确定", null);
localBuilder.setCancelable(false);
localBuilder.create().show();
// 注意:
// 必须要这一句代码:result.confirm()表示:
// 处理结果为确定状态同时唤醒WebCore线程
// 否则不能继续点击按钮
result.confirm();
return true;
}
// 获取网页标题
@Override
public void onReceivedTitle(WebView view, String title) {
super.onReceivedTitle(view, title);
Log.i("[T-WebView]", "网页标题:" + title);
}
// 加载进度回调
@Override
public void onProgressChanged(WebView view, int newProgress) {
progressBar.setProgress(newProgress);
}
};
public boolean onKeyDown(int keyCode, KeyEvent event) {
Log.i("[T-WebView]", "是否有上一个页面:" + webView.canGoBack());
if (webView.canGoBack() && keyCode == KeyEvent.KEYCODE_BACK) {// 点击返回按钮的时候判断有没有上一页
webView.goBack(); // goBack()表示返回webView的上一页面
exitNum = 2;
return true;
}
{
exitNum -= 1;
Toast.makeText(MainActivity.this, "再按一次返回键推出", Toast.LENGTH_SHORT)
.show();
if (exitNum > 0)
return false;
}
return super.onKeyDown(keyCode, event);
}
/**
* JS调用android的方法
*
* @param str
* @return
*/
@JavascriptInterface
// 仍然必不可少
public void getClient(String str) {
Log.i("[T-WebView]", "html调用客户端:" + str);
}
protected void onDestroy() {
super.onDestroy();
// 释放资源
webView.destroy();
webView = null;
}
}
参考 https://blog.csdn.net/lowprofile_coding/article/details/77928614
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