Android 自制浏览器 二 前进后退返回主页退出

Posted 2020-10-22

这一次我对网页的浏览添加前进后退，退出，返回主页的功能。
上代码，

public class MainActivity extends Activity implements View.OnClickListener {

    private EditText et_url;

    private Button btn_visit;

    private WebView web;

    private Button btn_home,btn_left,btn_right,btn_exit;

    private boolean isExit;

    private String homeStr = "http://www.baidu.com";

    //-------------------------------------------
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);
        init();
    }

    //-------------------------------------------
    /**
     * 基本数据初始化
     */
    private void init(){

        isExit = false;
        et_url = (EditText)findViewById(R.id.et_url);
        et_url.setText(homeStr);
        btn_visit = (Button)findViewById(R.id.btn_visit);

        web = (WebView)findViewById(R.id.web);
        WebSettings ws = web.getSettings();
        //是否允许脚本支持
        ws.setjavascriptEnabled(true);

        web.setWebViewClient(wvc);
        btn_home = (Button)findViewById(R.id.btn_home);
        btn_left = (Button)findViewById(R.id.btn_left);
        btn_right = (Button)findViewById(R.id.btn_right);
        btn_exit = (Button)findViewById(R.id.btn_exit);

        btn_visit.setOnClickListener(this);
        btn_home.setOnClickListener(this);
        btn_left.setOnClickListener(this);
        btn_right.setOnClickListener(this);
        btn_exit.setOnClickListener(this);

        conn(et_url.getText().toString());

    }

    //-------------------------------------------

    WebViewClient wvc = new WebViewClient(){

        public boolean shouldOverrideUrlLoading(WebView view, String url) {

            view.loadUrl(url);
            et_url.setText(url);

            return true;
        };
    };

    //-------------------------------------------
    /**
     * 访问url
     * @param urlStr
     */
    private void conn(String urlStr){
        String url = "";
        if(urlStr.contains("http://")){
            url = urlStr;
        }else{
            url = "http://"+urlStr;
        }
        web.loadUrl(url);
    }

    //-------------------------------------------
    /**
     * 后退
     */
    private void goBack(){
        if(web.canGoBack()){
            web.goBack();
        }else{
            Toast.makeText(this, "已经是第一页", Toast.LENGTH_SHORT).show();
        }
    }

    //-------------------------------------------
    /**
     * 前进
     */
    private void goForward(){
        if(web.canGoForward()){
            web.goForward();
        }else{
            Toast.makeText(this, "已经是最后一页",Toast.LENGTH_SHORT).show();
        }
    }
    //-------------------------------------------
    /**
     * 退出
     */
    private void exit(){

        AlertDialog.Builder builder = new AlertDialog.Builder(this);

        builder.setTitle("提示")
                .setMessage("确定退出？")
                .setPositiveButton("确定", dialogListener)
                .setNegativeButton("取消", dialogListener)
                .create()
                .show();

    }

    DialogInterface.OnClickListener dialogListener = new DialogInterface.OnClickListener() {

        public void onClick(DialogInterface dialog, int which) {

            switch (which) {
                case DialogInterface.BUTTON_POSITIVE:
                    finish();
                    break;

                default:
                    dialog.cancel();
                    break;
            }
        }
    };

    //-------------------------------------------

    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if(keyCode==KeyEvent.KEYCODE_BACK||web.canGoBack()){
            web.goBack();
            if(!web.canGoBack()){
                if(isExit){
                    return super.onKeyDown(keyCode, event);
                }
                isExit = true;
                Toast.makeText(this, "再按一次退出", Toast.LENGTH_SHORT).show();
            }else{
                isExit = false;
            }
        }
        return true;

    }

    //-------------------------------------------
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_visit:

                conn(et_url.getText().toString());

                break;
            case R.id.btn_home:

                conn(homeStr);
                break;
            case R.id.btn_left:
                goBack();
                break;
            case R.id.btn_right:
                goForward();
                break;
            case R.id.btn_exit:
                exit();
                break;

        }
    }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <ScrollView
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <LinearLayout
            android:orientation="vertical"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content">
            <LinearLayout
                android:id="@+id/layout"
                android:orientation="horizontal"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_margin="10dp">
                <EditText
                    android:id="@+id/et_url"
                    android:layout_width="0dp"
                    android:layout_height="wrap_content"
                    android:layout_weight="1"
                    android:inputType="textUri"
                    android:singleLine="true"
                    android:layout_margin="10dp"/>

                <Button
                    android:id="@+id/btn_visit"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_margin="10dp"
                    android:text="visit"
                    android:textSize="15dp" />

            </LinearLayout>

            <WebView
                android:id="@+id/web"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"/>
        </LinearLayout>
    </ScrollView>
    <LinearLayout
        android:id="@+id/ll_btn"
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal">
        <Button
            android:id="@+id/btn_home"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="home"/>
        <Button
            android:id="@+id/btn_left"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="left"/>
        <Button
            android:id="@+id/btn_right"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="right"/>
        <Button
            android:id="@+id/btn_exit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="exit"/>
    </LinearLayout>

</LinearLayout>

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

因为这其实是从上一篇的基础上加了一些UI设计罢了，没啥知识点，下期我做网页手指触摸放大放小，请期待吧
再见