Android PopupWindow 实现自定义菜单弹窗效果

先看最终效果图：

原理一个将PopupWindow绑在一个TextView上，处理TextView点击事件来弹框，右边EditText实现输入框，把EditText拿上来是因为在实习过程中碰到不少细节问题。代码：
main.xml //主页面布局

    

        
    

    




    //因为一个控件只能有一张背景图片，所以把“资讯”的另一张背景图片放在布局上

        
    

    
        
    

popup_item.xml // PopupWindow 弹框内容，这里只是简单的TextView,涉及ListView的话要复杂些

main.java

public class SearchActivity extends Activity {
private PopupWindow window = null;
private LayoutInflater inflater;
private TextView txt_choosecategory;
private TextView message;
private TextView picture;
private TextView video;
private EditText edt_inputcagegory;
private Button btn_header_back;
private View view;
private ListView listView;
private String return_result;
private String category_id;
private String keyword;
    private SearchTask searchTask;
private String category;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search);
    initHeader();
    initBodyer();
}

private boolean isInput() {
    if (isNullorSpace(edt_inputcagegory.getText().toString())) {
        return false;
    }
    return true;
}

private void initBodyer() {
//      final InputMethodManager imm = (InputMethodManager)      //getSystemService(Context.INPUT_METHOD_SERVICE);
    txt_choosecategory = (TextView) findViewById(R.id.search_category);
    edt_inputcagegory = (EditText) findViewById(R.id.input_search_cagegory);
    edt_inputcagegory.setImeOptions(EditorInfo.IME_ACTION_SEARCH); //这行代码的作用是把键盘右下角的“回车”键变成“搜索”键
    txt_choosecategory.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if (window != null) {  //一定要先判断是否为空！
                if (window.isShowing()) {//isShowing()方法判断当前是否已经弹窗,返回true则关闭PopupWindow
                    window.dismiss();
                    window = null;
                }
            } else {
                showWindow();实际这里是实现点击一次弹出PopupWindow，再点击一次关闭掉。
            }

        }
    });
    edt_inputcagegory
            .setOnEditorActionListener(new OnEditorActionListener() {

                @Override
                public boolean onEditorAction(TextView v, int actionId,
                        KeyEvent event) {//对键盘的搜索键监听事件
                    if (actionId == EditorInfo.IME_ACTION_SEARCH) {
                        if (isInput()) {
                            search();
                        } else {
//edt_inputcagegory.requestFocus();                                                          //imm.showSoftInputFromInputMethod(edt_inputcagegory.getWindowToken(), 0);
Toast.makeText(Main.this,"搜索内容不能为空"，Toast.LENGH_SHORT);                         

                        }
                    }

                    return false;
                }
            });
}

private void initHeader() {
    btn_header_back = (Button) findViewById(R.id.btn_header_back);
    btn_header_back.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            finish();
        }
    });
}
    private boolean isNullorSpace(String str) {
    if (!"".equals(str.trim()) & (str != null))
        return false;
    return true;
}

private void search() {
    //Handle search
}

private void showWindow() {
    inflater = (LayoutInflater) this
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    view = inflater.inflate(R.layout.item_search_category, null, false);//加载布局
    message = (TextView) view.findViewById(R.id.search_message);
    video = (TextView) view.findViewById(R.id.search_video);
    picture = (TextView) view.findViewById(R.id.search_picture);
    message.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            txt_choosecategory.setText(R.string.message);  //错误代码
            window.dismiss();
            window = null;
        }
    });
    video.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            txt_choosecategory.setText(R.string.video);//错误代码
            window.dismiss();
            window = null;
        }
    });
    picture.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            txt_choosecategory.setText(R.string.picture);//错误代码
            window.dismiss();
            window = null;
        }
    });
    if (window == null) {
        window = new PopupWindow(view, LayoutParams.WRAP_CONTENT,
                LayoutParams.WRAP_CONTENT);//创建PopupWindow,第一个参数是将要展示的内容布局，第二、三个是布局大小（LayoutParamas.WRAP_CONTENT,LayoutParams.WRAP_CONTENT要求API >=11）
    }
    // int[] location = new int[2];
    // window.showAsDropDown(txt_choosecategory);
    // window.showAtLocation(txt_choosecategory, Gravity.NO_GRAVITY,
    // location[0], location[1]);
    window.showAtLocation(txt_choosecategory, Gravity.NO_GRAVITY, 15, 160);//设置PopupWindow位置，第一个参数是指定PopupWindow依附的View,第二个是坐标偏移量相对的起始点，Gravity.NO_GRAVITY= Gravity.LEFT | Gravity.TOP,最后两个是偏移量，这个写死了应该对屏幕适配不太好，而且很麻烦囧，暂时还没找到方便的方法..欢迎大侠指路.
}

需要注意的是：1.本人一开始用PopupWindow就曾经报错： "Unable to add window -- token null is not valid"，原因在stackoverflow上找到：To avoid BadTokenException, you need to defer showing the popup until after all the lifecycle methods are called (-> activity window is displayed)，简而言之就是要在布局全部加载完之后再去加载PopupWindow,显示PopupWindow过早就会直接crash.
2.在Activity取出string资源文件值，textView.setText(R.string.XXX)是错误的写法应g改为-->textView.setText(getString(R.string.xxx))或者getResources().getString(R.string.xxx)，原因：http://stackoverflow.com/questions/11536326/android-settext-r-string-values

（第一句一语道破天机，R.string.xxx仅仅是资源的ID，所以R.String.xxx得到的是资源的编号）