news_client/app/src/main/java/com/example/myapplication/NewsActivity.java

package com.example.myapplication;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class NewsActivity extends AppCompatActivity {

    private WebView webView;
    private long exitTime = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Intent intent = getIntent();
        //获得转跳的url
        String content_url = intent.getStringExtra("content_url");
        setContentView(R.layout.news_web);
        webView = findViewById(R.id.new_web);
        webView.setWebViewClient(new WebViewClient() {
            //设置在webView点击打开的新网页在当前界面显示,而不跳转到新的浏览器中
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
                return super.shouldOverrideUrlLoading(view, request);
            }
        });
        webView.getSettings().setJavaScriptEnabled(true);
        webView.loadUrl(content_url);
    }

    /**
     * 返回的方法
     */
    @Override
    public void onBackPressed() {
        if (webView.canGoBack()) {
            webView.goBack();
        } else {
            if ((System.currentTimeMillis() - exitTime) > 2000) {
                finish();
//                Toast.makeText(getApplicationContext(), "再按一次退出程序",
//                        Toast.LENGTH_SHORT).show();
//                exitTime = System.currentTimeMillis();
            } else {
                super.onBackPressed();
            }

        }
    }
}