u012440207的专栏

Android接口回调方法处处涉及到，比如常用的Button点击事件就是一个接口回调，可见掌握熟练使用接口回调方法的重要性。

接口回调的简单解释就是：比如我这个类实现了一个接口里的方法doSomething，，然后注册到你这里，然后我就去做别的事情去了， 你在某个触发的时机回头来调用我doSomething的方法。

接口回调一般有两种写法，实现形式不一样，但是具体的内部的实现逻辑是一样。

直接给出代码：

方法一：

package com.callbackdemo;import android.graphics.Bitmap;/** * 接口 * * @author zhongyao */public interface ImageStateInterface {void onImageStart();void onImageSuccess(Bitmap bitmap);void onImageFailed();void OnEnd();}package com.callbackdemo;import android.annotation.SuppressLint;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;/** * Android 接口回调实例 * * @author zhongyao */public class MainActivity extends Activity implements ImageStateInterface {private Button button;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);/** * 实例化控件 */onLincoln();}private void onLincoln() {button = (Button) findViewById(R.id.button1);button.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {DownloadImageUtil downloadImageUtil = new DownloadImageUtil();// 调用StartDownLoad方法，目的是将MainActivity注册到接口那里，使接口知道，需要调用的是哪个类中的实现该接口的方法。downloadImageUtil.StartDownLoad(MainActivity.this,getApplicationContext());}});}@Overridepublic void onImageStart() {Log.d("lincoln", "onImageStart");button.setText("onImageStart");}@Overridepublic void onImageSuccess(final Bitmap bitmap) {Log.d("lincoln", "onImageSuccess");runOnUiThread(new Runnable() {@SuppressLint("NewApi")@Overridepublic void run() {button.setText("onImageSuccess");button.setBackground(new BitmapDrawable(bitmap));}});}@Overridepublic void onImageFailed() {}@Overridepublic void OnEnd() {Toast.makeText(MainActivity.this, "哈哈!!", 0).show();}}package com.callbackdemo;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;/** * 在该类中调用MainActivity已实现的接口中的方法。 * @author zhongyao */public class DownloadImageUtil {public void StartDownLoad(final ImageStateInterface imageStateInterface,final Context context) {//该imageStateInterface使其得知，是从哪里注册过来的，然后根据其来源调用其实现的接口方法。//如下，此时调用的就是MainActivity.this中实现的onImageStart方法。imageStateInterface.onImageStart();new Thread(new Runnable() {@Overridepublic void run() {try {new Thread().sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon);imageStateInterface.onImageSuccess(bitmap);}}).start();imageStateInterface.OnEnd();}}方法二：实现原理一样，只是实现形式不一样而已。package com.callbackdemo;import android.graphics.Bitmap;/** * 接口 * * @author zhongyao */public interface ImageStateInterface {void onImageStart();void onImageSuccess(Bitmap bitmap);void onImageFailed();void OnEnd();}package com.callbackdemo;import android.annotation.SuppressLint;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;/** * Android 接口回调实例 * * @author zhongyao */public class MainActivity extends Activity{private Button button;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);/** * 实例化控件 */onLincoln();}private void onLincoln() {button = (Button) findViewById(R.id.button1);button.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {DownloadImageUtil.StartDownLoad(imageInterface,MainActivity.this);}});}ImageStateInterface imageInterface = new ImageStateInterface() {@Overridepublic void onImageStart() {Log.d("lincoln", "onImageStart");button.setText("onImageStart");}@Overridepublic void onImageSuccess(final Bitmap bitmap) {Log.d("lincoln", "onImageSuccess");runOnUiThread(new Runnable() {@SuppressLint("NewApi")@Overridepublic void run() {button.setText("onImageSuccess");button.setBackground(new BitmapDrawable(bitmap));}});}@Overridepublic void onImageFailed() {}@Overridepublic void OnEnd() {Toast.makeText(MainActivity.this, "哈哈!!", 0).show();}};}package com.callbackdemo;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;/** * 在该类中调用MainActivity已实现的接口中的方法。 * @author zhongyao */public class DownloadImageUtil {public static void StartDownLoad(final ImageStateInterface imageInterface,final Context context) {imageInterface.onImageStart();new Thread(new Runnable() {@Overridepublic void run() {try {new Thread().sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon);imageInterface.onImageSuccess(bitmap);}}).start();imageInterface.OnEnd();}}效果：我就想是一只草原中被牧童遗忘的羊，