一、 MyApplication类的编写：
新建一个类MyApplication，继承自Application。代码如下：
MyApplication.java:
1 package com.smyhvae.homepicdemo; 2 3 import android.app.Application; 4 import android.os.Handler; 5 import android.os.Looper; 6 7 /** 8 * Created by smyhvae on 2015/5/13. 9 */ 10 public class MyApplication extends Application { 11 //获取到主线程的上下文 12 private static MyApplication mContext = null; 13 //获取到主线程的handler 14 private static Handler mMainThreadHandler = null; 15 //获取到主线程的looper 16 private static Looper mMainThreadLooper = null; 17 //获取到主线程 18 private static Thread mMainThead = null; 19 //获取到主线程的id 20 private static int mMainTheadId; 21 22 @Override 23 public void onCreate() { 24 // TODO Auto-generated method stub 25 super.onCreate(); 26 this.mContext = this; 27 this.mMainThreadHandler = new Handler(); 28 this.mMainThreadLooper = getMainLooper(); 29 this.mMainThead = Thread.currentThread(); 30 //android.os.Process.myUid() 获取到用户id 31 //android.os.Process.myPid()获取到进程id 32 //android.os.Process.myTid()获取到调用线程的id 33 this.mMainTheadId = android.os.Process.myTid(); 34 } 35 36 public static MyApplication getApplication() { 37 return mContext; 38 } 39 40 public static Handler getMainThreadHandler() { 41 return mMainThreadHandler; 42 } 43 44 public static Looper getMainThreadLooper() { 45 return mMainThreadLooper; 46 } 47 48 public static Thread getMainThread() { 49 return mMainThead; 50 } 51 52 public static int getMainThreadId() { 53 return mMainTheadId; 54 } 55 56 }
上面的所有代码每次在开发一个新的app时都需要用到的，然后具体到不同的项目，再继续添加不同的东西。
然后记得在清单文件中进行声明：
1 <application 2 android:allowBackup="true" 3 android:icon="@mipmap/ic_launcher" 4 android:label="@string/app_name" 5 android:theme="@style/AppTheme" 6 android:name=".MyApplication">
需要声明的是上方代码的第6行android:name的属性。
二、UI工具类的编写：
这个工具类也是在app开发中经常用到的。可以直接copy。代码如下：
UIUtils.java:
1 package com.smyhvae.homepicdemo.utils; 2 3 import android.content.Context; 4 import android.content.Intent; 5 import android.content.res.ColorStateList; 6 import android.content.res.Resources; 7 import android.graphics.drawable.Drawable; 8 import android.os.Handler; 9 import android.view.LayoutInflater; 10 import android.view.View; 11 12 import com.smyhvae.homepicdemo.MyApplication; 13 14 /** 15 * Created by smyhvae on 2015/5/13. 16 */ 17 18 public class UIUtils { 19 20 21 public static Context getContext() { 22 return MyApplication.getApplication(); 23 } 24 25 public static Thread getMainThread() { 26 return MyApplication.getMainThread(); 27 } 28 29 public static long getMainThreadId() { 30 return MyApplication.getMainThreadId(); 31 } 32 33 /** dip转换px */ 34 public static int dip2px(int dip) { 35 final float scale = getContext().getResources().getDisplayMetrics().density; 36 return (int) (dip * scale + 0.5f); 37 } 38 39 /** pxz转换dip */ 40 public static int px2dip(int px) { 41 final float scale = getContext().getResources().getDisplayMetrics().density; 42 return (int) (px / scale + 0.5f); 43 } 44 45 /** 获取主线程的handler */ 46 public static Handler getHandler() { 47 return MyApplication.getMainThreadHandler(); 48 } 49 50 /** 延时在主线程执行runnable */ 51 public static boolean postDelayed(Runnable runnable, long delayMillis) { 52 return getHandler().postDelayed(runnable, delayMillis); 53 } 54 55 /** 在主线程执行runnable */ 56 public static boolean post(Runnable runnable) { 57 return getHandler().post(runnable); 58 } 59 60 /** 从主线程looper里面移除runnable */ 61 public static void removeCallbacks(Runnable runnable) { 62 getHandler().removeCallbacks(runnable); 63 } 64 65 public static View inflate(int resId){ 66 return LayoutInflater.from(getContext()).inflate(resId,null); 67 } 68 69 /** 获取资源 */ 70 public static Resources getResources() { 71 72 return getContext().getResources(); 73 } 74 75 /** 获取文字 */ 76 public static String getString(int resId) { 77 return getResources().getString(resId); 78 } 79 80 /** 获取文字数组 */ 81 public static String[] getStringArray(int resId) { 82 return getResources().getStringArray(resId); 83 } 84 85 /** 获取dimen */ 86 public static int getDimens(int resId) { 87 return getResources().getDimensionPixelSize(resId); 88 } 89 90 /** 获取drawable */ 91 public static Drawable getDrawable(int resId) { 92 return getResources().getDrawable(resId); 93 } 94 95 /** 获取颜色 */ 96 public static int getColor(int resId) { 97 return getResources().getColor(resId); 98 } 99 100 /** 获取颜色选择器 */ 101 public static ColorStateList getColorStateList(int resId) { 102 return getResources().getColorStateList(resId); 103 } 104 //判断当前的线程是不是在主线程 105 public static boolean isRunInMainThread() { 106 return android.os.Process.myTid() == getMainThreadId(); 107 } 108 109 public static void runInMainThread(Runnable runnable) { 110 if (isRunInMainThread()) { 111 runnable.run(); 112 } else { 113 post(runnable); 114 } 115 } 116 117 public static void startActivity(Intent intent){ 118 // BaseActivity activity = BaseActivity.getForegroundActivity(); 119 // if(activity != null){ 120 // activity.startActivity(intent); 121 // }else{ 122 // intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 123 // getContext().startActivity(intent); 124 // } 125 } 126 127 /** 对toast的简易封装。线程安全，可以在非UI线程调用。 */ 128 public static void showToastSafe(final int resId) { 129 showToastSafe(getString(resId)); 130 } 131 132 /** 对toast的简易封装。线程安全，可以在非UI线程调用。 */ 133 public static void showToastSafe(final String str) { 134 if (isRunInMainThread()) { 135 showToast(str); 136 } else { 137 post(new Runnable() { 138 @Override 139 public void run() { 140 showToast(str); 141 } 142 }); 143 } 144 } 145 146 private static void showToast(String str) { 147 // BaseActivity frontActivity = BaseActivity.getForegroundActivity(); 148 // if (frontActivity != null) { 149 // Toast.makeText(frontActivity, str, Toast.LENGTH_LONG).show(); 150 // } 151 } 152 }