Google Android SDK开发范例大全 (一)

以下范例是取自《Google Android SDK开发范例大全》，列举了一些个人认为比较简单实用的范例片段。

若无特别说明，均写在onCreate方法里，相关资源文件不一一列举，如有需要请联系本人。

一、读取手机分辨率

DisplayMetrics dm = new DisplayMetrics();getWindowManager().getDefaultDisplay().getMetrics(dm);        final String str = "手机分辨率是:" + dm.widthPixels + "," + dm.heightPixels;textView.setText(str);

二、按钮事件

button1.setOnClickListener(new Button.OnClickListener(){     @Override     public void onClick(View v) {         //编写相关触发事件  }}；

三、弹出用户UI交互对话框

//点击按钮弹出提示框        button1.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View v) {new AlertDialog.Builder(MainActivity.this).setTitle(R.string.app_about) //对话框标题.setMessage(R.string.app_msg) //对话框内容.setPositiveButton(R.string.hello_world, //对话框按钮new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {//对话框按钮触发事件}}).show();}                });

四、拖动相片特效

GalleryActivity.java

((Gallery) findViewById(R.id.myGallery1)).setAdapter(new ImageAdapter(this));

ImageAdapter.java

private Context myContext;/** * 使用R.drawable里的图片作为图库源，类型为整数数组 * 如果是android.R.drawable 就是读取系统自带的图库源 * */private int[] myImageIds = {R.drawable.one,R.drawable.two,R.drawable.three};/** 构造器只有一个参数，即要存储Context **/public ImageAdapter(Context c){this.myContext = c;}/** 返回所有已定义的图片总数量 **/@Overridepublic int getCount() {return this.myImageIds.length;}/** 利用getItem方法，取得目前容器中图像的数组 **/@Overridepublic Object getItem(int position) {return position;}@Overridepublic long getItemId(int position) {return position;}/** 取得目前欲显示的图像View，传入数组ID值使之读取与成像 **/@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ImageView i = new ImageView(this.myContext);i.setImageResource(this.myImageIds[position]);i.setScaleType(ImageView.ScaleType.FIT_XY);/** 设置这个ImageView对象的宽高，单位为dip **/i.setLayoutParams(new Gallery.LayoutParams(400, 400));return i;}/** 依据距离中央的位移量 利用getScale返回的大小(0.0f to 1.0f) **/public float getScale(boolean focused,int offset){return Math.max(0, 1.0f/(float)Math.pow(2, Math.abs(offset)));}

五、Menu菜单

主要是onCreateOptionsMenu,onOptionsItemSelected这两个方法

 /** 创建Menu菜单 **/@Overridepublic boolean onCreateOptionsMenu(Menu menu) {menu.add(0, 0, 0, R.string.about);menu.add(0, 1, 1, R.string.exit);return super.onCreateOptionsMenu(menu);}/** Menu菜单选项的后续事件 **/@Overridepublic boolean onOptionsItemSelected(MenuItem item) {super.onOptionsItemSelected(item);switch (item.getItemId()) {case 0:break;case 1:openOptionDialog();break;}return true;}public void openOptionDialog(){new AlertDialog.Builder(MainActivity.this)//.setTitle(R.string.app_about) //对话框标题.setMessage(R.string.exit_msg) //对话框内容.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {//对话框按钮触发事件}}).setPositiveButton(R.string.sure, //对话框按钮new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {finish();}}).show();}

六、程序加载中，请稍后...ProgressDialog与线程整合

 @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_progress);                textView = (TextView)findViewById(R.id.progressView);        button = (Button)findViewById(R.id.progressBtn);        button.setOnClickListener(myShowProgressBar);    }        Button.OnClickListener myShowProgressBar = new Button.OnClickListener(){@Overridepublic void onClick(View v) {final CharSequence strDialogTitle = getString(R.string.about);final CharSequence strDialogBody = getString(R.string.app_msg);myDialog = ProgressDialog.show(ProgressActivity.this,  //当前activitystrDialogTitle,         //ProgressDialog 标题strDialogBody);         //ProgressDialog 内容textView.setText(strDialogBody);new Thread(){public void run(){try{//此处可添加后台执行代码片段//加载3秒sleep(3000);}catch(Exception e){e.printStackTrace();}finally{//卸载所创建的myDialog对象myDialog.dismiss();}}}.start();  //开始运行线程}    };

七、具有选择功能的对话框

ItemActivity

@Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_item);                textView = (TextView)findViewById(R.id.itemView);        button = (Button)findViewById(R.id.itemBtn);        button.setOnClickListener(myItemClickListener);    }        Button.OnClickListener myItemClickListener =     new Button.OnClickListener(){@Overridepublic void onClick(View v) {new AlertDialog.Builder(ItemActivity.this).setTitle(R.string.about).setItems(R.array.item_list, new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {CharSequence strDialogBody = getString(R.string.alert_body);String[] arylist = getResources().getStringArray(R.array.item_list);new AlertDialog.Builder(ItemActivity.this)//值得注意的时候arylist[which] 就是int which,获取到用户点击哪一个.setMessage(strDialogBody + arylist[which]).setNegativeButton(R.string.sure, new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {//可后续处理点击itemlist的动作}}).show();}}).show();}    };

八、文本框输入结束立即显示到TextView

showView = (TextView)findViewById(R.id.showEdit);        final EditText editText = (EditText)findViewById(R.id.editTextid);        editText.setOnKeyListener(new EditText.OnKeyListener(){@Overridepublic boolean onKey(View v, int keyCode, KeyEvent event) {showView.setText(editText.getText());return false;}                });

九、Toast消息框的提示使用方法

以第八范例为基础，关键字:Toast

Editable str;str = editText.getText();Toast.makeText(ItemActivity.this, "重大消息：" + str, Toast.LENGTH_LONG).show();

十、自定义下拉菜单模式，Spinner 与 setDropDownViewResource

private Spinner spinner;private static final String[] spinnerList = {"广东","北京","香港"}; private ArrayAdapter<String> adapter;

spinner = (Spinner)findViewById(R.id.spinnerid);        //使用android提供的resourceid        adapter = new ArrayAdapter(this,android.R.layout.simple_spinner_item,spinnerList);        /**         * 使用setDropDownViewResource可为自定义样式         * adapter.setDropDownViewResource(resource);         */        //把arrayAdapter添加到Spinner        spinner.setAdapter(adapter);

 spinner.setOnItemSelectedListener(new Spinner.OnItemSelectedListener(){@Overridepublic void onItemSelected(AdapterView<?> arg0, View arg1,int arg2, long arg3) {showView.setText("选择的是:" + spinnerList[arg2]);//将spinner显示arg0.setVisibility(View.VISIBLE);}@Overridepublic void onNothingSelected(AdapterView<?> arg0) {// TODO Auto-generated method stub}                });

添加spinner

addbtn.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View v) {String newText = spinnerEdittext.getText().toString();//判断添加的值是否与已有相等for(int i=0;i<adapter.getCount();i++){if(newText.equals(adapter.getItem(i))){return;}}if(newText != ""){//添加到adapteradapter.add(newText);//adapter的positionint position = adapter.getPosition(newText);//下拉框选中显示新添加的值spinner.setSelection(position);//清空spinnerEdittext.setText("");}}                });

删除spinner

removebtn.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View v) {if(spinner.getSelectedItem() != null){//删除当前选项adapter.remove(spinner.getSelectedItem().toString());}}                });