android如何创建自己的监听接口.doc

android如何创建自己的监听接口第一步：创建接口和方法public interface OnUsernameAvailableListener public abstract void onAvailableChecked(String username, boolean available);第二步：定义变量保存listenerOnUsernameAvailableListener onUsernameAvailableListener = null;第三步：提供方法允许用户设置Listener/ Allows the user to set an Listener and react to the eventpublic void setOnUsernameAvailableListener(OnUsernameAvailableListener listener) onUsernameAvailableListener = listener;第四步：提供方法允许用户获得Listenerpublic final OnUsernameAvailableListener getOnUsernameAvailableListener() return onUsernameAvailableListener;第五步：添加方法，此方法每次在监听事件被触发的时候调用/ This function is called after the check was completeprivate void OnUserChecked(String username, boolean available)/ Check if the Listener was set, otherwise well get an Exception when we try to call itif(onUsernameAvailableListener!=null) / Only trigger the event, when we have a usernameif(!TextUtils.isEmpty(username)onUsernameAvailableListener.onAvailableChecked(username, available);完成。附完整代码：package com.tseng.examples;import com.tseng.examples.CheckUsernameEditText.OnUsernameAvailableListener;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class RegisterExample extends Activity / Declare our Views, so we can access them laterprivate CheckUsernameEditText etUsername;private EditText etPassword;private EditText etPassword2;private Button btnRegister;private Button btnCancel;private TextView lblUserStatus; /* Called when the activity is first created. */ Override public void onCreate(Bundle savedInstanceState) super.onCreate(savedInstanceState); / Set Activity Layout setContentView(R.layout.main); / Get the EditText and Button References etUsername = (CheckUsernameEditText)findViewById(R.id.username); etPassword = (EditText)findViewById(R.id.password); etPassword2 = (EditText)findViewById(R.id.password2); btnRegister = (Button)findViewById(R.id.register_button); btnCancel = (Button)findViewById(R.id.cancel_button); lblUserStatus = (TextView)findViewById(R.id.userstatus); / Set our new Listener to the Username EditText view etUsername.setOnUsernameAvailableListener(new OnUsernameAvailableListener()Overridepublic void onAvailableChecked(String username, boolean available) / Handle the event hereif(!available)etUsername.setTextColor(Color.RED);lblUserStatus.setText(username + is already taken. Please choose another login name.); else etUsername.setTextColor(Color.GREEN);lblUserStatus.setText(username + is available.); ); / Set Click Listener btnRegister.setOnClickListener(new OnClickListener() Overridepublic void onClick(View v) / create Account); btnCancel.setOnClickListener(new OnClickListener() Overridepublic void onClick(View v) / Close the applicationfinish();); package com.tseng.examples;import java.lang.reflect.Array;import android.content.Context;import android.text.TextUtils;import android.util.AttributeSet;import android.view.KeyEvent;import android.view.View;import android.view.View.OnKeyListener;import android.widget.EditText;import android.widget.TextView;public class CheckUsernameEditText extends EditText implements OnKeyListener OnUsernameAvailableListener onUsernameAvailableListener = null;final private static String registeredUsers = new String / This is just a fixed List for tutorial purposes/ in a real application youd check this server sided or inside the databasetseng,admin,root,joedoe,john;public CheckUsernameEditText(Context context) super(context);/ Set KeyListener to ourselfthis.setOnKeyListener(this);public CheckUsernameEditText(Context context, AttributeSet attrs, int defStyle) super(context, attrs, defStyle);/ Set KeyListener to ourselfthis.setOnKeyListener(this);public CheckUsernameEditText(Context context, AttributeSet attrs) super(context, attrs);/ Set KeyListener to ourselfthis.setOnKeyListener(this);/ Allows the user to set an Listener and react to the eventpublic void setOnUsernameAvailableListener(OnUsernameAvailableListener listener) onUsernameAvailableListener = listener;/ This function is called after the check was completeprivate void OnUserChecked(String username, boolean available)/ Check if the Listener was set, otherwise well get an Exception when we try to call itif(onUsernameAvailableListener!=null) / Only trigger the event, when we have a usernameif(!TextUtils.isEmpty(username)onUsernameAvailableListener.onAvailableChecked(username, available);Overridepublic boolean onKey(View v, int keycode, KeyEvent keyevent) / We only want to handle ACTION_UP events, when user releases a keyif(keyevent.getAction()=KeyEvent.ACTION_DOWN)return false;boolean available = true;/ Whenever a user press a key, check if the username is availableString username = getText().toString().toLowerCase();if(!TextUtils.isEmpty(username)/ Only perform check, if we have anything inside the EditText boxfor(int i=0; iregisteredUsers.length; i+) if(registeredUsersi.equals(username)available = false;/ Finish the loop, as the name is already takenbreak;/ Tr