Android开发之WebView的使用进阶

String topPage = "/index.php";
public boolean onKeyDown(int keyCode, KeyEvent event)
{
   if ((keyCode == KeyEvent.KEYCODE_BACK))
   {
      String currentUrl = webview.getUrl();
      if(currentUrl.equals(topPage))
      {
          this.finish();
      }
      else
      {
          webview.goBack();
      }
      return true;
   }
   return false;
}

public UserDefinedDialog(Context context, String message,
                         View.OnClickListener onclicklistener,
                         View.OnClickListener cancelListener)
{
  super(context,R.style.Theme_Dialog);
  this.ctx = context;
  this.msg = message;
  if (onclicklistener != null)
  {
    this.okListener=onclicklistener;
  }
  if(cancelListener != null)
  {
    IsTwoButton=true;
    this.cancelListener=cancelListener;
  }
}

protected void onCreate(Bundle savedInstanceState)
{
   super.onCreate(savedInstanceState);
 
   requestWindowFeature(Window.FEATURE_NO_TITLE);
   setContentView(R.layout.alertdialog);
 
   tvtitle = (TextView) findViewById(R.id.dialogtitle);
   tvcontent = (TextView) findViewById(R.id.dialogcontent);
 
   btnleft = (Button) findViewById(R.id.btnleft);
   btnright = (Button) findViewById(R.id.btnright);
 
   btnleft.setOnClickListener(this);
   btnright.setOnClickListener(this);
 
   btncenter = (Button) findViewById(R.id.btncenter);
   btncenter.setOnClickListener(this);
   if(IsTwoButton)
   {
     btnleft.setVisibility(View.VISIBLE);
     btnright.setVisibility(View.VISIBLE);
     btncenter.setVisibility(View.GONE);
   }
   tvtitle.setText("提示");
   tvcontent.setText(msg);
 
   WindowManager m;
   m = (WindowManager)ctx.getSystemService(Context.WINDOW_SERVICE);
   Display d = m.getDefaultDisplay();
   LayoutParams p = getWindow().getAttributes();
   //设置对话框宽高
   p.height = (int) (d.getHeight() * 0.3);
   p.width = (int) (d.getWidth() * 0.9);
   //设置对话框透明度
   p.alpha = 0.8f;
   //让背景变黑
   p.dimAmount = 0.7f;
   getWindow().setAttributes(p);
   getWindow().setGravity(Gravity.CENTER);
}

public void onClick(View v)
{
  switch (v.getId())
  {
    case R.id.btnleft:
        if(cancelListener != null){
           cancelListener.onClick(v);
        }
        break;
    case R.id.btncenter:
        if(okListener != null){
           okListener.onClick(v);
        }
        break;
    case R.id.btnright:
        if(okListener != null){
           okListener.onClick(v);
        }
        break;
  }
  this.cancel();
}

new UserDefinedDialog(this,
                     "我是一个按钮的对话框，默认效果取消",
                     null, null).show();
 
new UserDefinedDialog(this, "我是两个按钮的对话框",
    new OnClickListener() {
        public void onClick(View v) {
              //dosomething
        }
    },
    new OnClickListener() {
        public void onClick(View v) {
              //dosomething}
    }).show();