原生和js交互 简单代码

清单文件

<uses-permission android:name="android.permission.INTERNET"/>

布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <Button
            android:id="@+id/calljs_but_id"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="调用js方法"/>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#00ff00">

            <WebView
                android:id="@+id/web_id"
                android:layout_width="400dp"
                android:layout_height="400dp"
                />
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

MainActivity

package com.example.dell.webviewjs;

import android.annotation.SuppressLint;
import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    Button tojs;
    WebView webView;
    @SuppressLint("JavascriptInterface")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = findViewById(R.id.web_id);

        tojs = findViewById(R.id.calljs_but_id);

        WebSettings webSettings = webView.getSettings();
        // 设置与Js交互的权限
        webSettings.setJavaScriptEnabled(true);
        // 设置允许JS弹窗
        webSettings.setJavaScriptCanOpenWindowsAutomatically(true);

        //设置对象映射
        webView.addJavascriptInterface(new JsToAndroid() , "test");

        // 先载入JS代码
        // 格式规定为:file:///android_asset/文件名.html
        webView.loadUrl("file:///android_asset/text.html");

        alteView(webView);



        tojs.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String result = "你好";
                //        webView.loadUrl("javascript:returnResult(" + result + ")");

                webView.loadUrl("javascript:returnResult()");

            }
        });

    }


    public class JsToAndroid{
        @JavascriptInterface
        public void hello(final String str ){
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(MainActivity.this , str , Toast.LENGTH_LONG).show();
                }
            });
        }
    }


    public void alteView(WebView webView){

        //    webView.setWebChromeClient(new WebChromeClient());
        webView.setWebChromeClient(new WebChromeClient(){
            @Override
            public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
                Log.e("tag" ,"执行次数");
                AlertDialog.Builder b = new AlertDialog.Builder(MainActivity.this);
                b.setTitle("Alert");
                b.setMessage(message);
                b.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        result.confirm();
                    }
                });
                b.setCancelable(false);
                //     b.create().show();

                return super.onJsAlert(view, url, message, result);
            }
        });
    }
}

在src/main/assets 创建assets 导入一个.html

text.html

<!DOCTYPE html>
<html>
   <head>
      <meta charset="utf-8">
      <title>Carson</title>  
      <script>
         function callAndroid(){
            test.hello("js调用了android中的hello方法");
         }

         function returnResult(){
            alert("result is");
            }
      </script>
   </head>


   <body>
      <button type="button" id="button1" onclick="callAndroid()"> 调用安卓代码 </button>
   </body>


</html>