Android开发Tips

1. 模拟系统回收Activity.

使用adb命令可以模拟Android系统自动回收Activity进程, 可以调试这个效果.单进程

adb shell am force-stop [包名]

多进程

adb shell ps | grep [包名]  adb shell kill [PID]

2. Android库动态权限建议

关于提示用户获取权限的解决方案, 可以 参考 .

3. RxJava处理Retry请求服务器

服务器经常会出现异常, 应用需要连续尝试请求, RxJava可以非常简单的实现.

模板

Observable<Boolean> source = ...; // Something that eventually emits true    source      .repeatWhen(completed -> completed.delay(1, TimeUnit.SECONDS))      .takeUntil(result -> result)      .filter(result -> result)      .subscribe(          res -> System.out.println("onNext(" + res + ")"),          err -> System.out.println("onError()"),          () -> System.out.println("onCompleted()")      );

示例

/** * This is a class that should be * mapped on your json response from the server */  class ServerPollingResponse {      boolean isJobDone;        @Override      public String toString() {          return "isJobDone=" + isJobDone;      }  }    Subscription checkJobSubscription = mDataManager.pollServer(inputData)          .repeatWhen(new Func1<Observable<? extends Void>, Observable<?>>() {              @Override              public Observable<?> call(Observable<? extends Void> observable) {                  Log.v(TAG, "repeatWhen, call");                  /** * This is called only once. * 5 means each repeated call will be delayed by 5 seconds */                  return observable.delay(5, TimeUnit.SECONDS);              }          })          .takeUntil(new Func1<ServerPollingResponse, Boolean>() {              @Override              public Boolean call(ServerPollingResponse response) {                  /** Here we can check if the responce is correct and if we should * finish polling * We finish polling when job is done. * In other words : "We stop taking when job is done" */                  Log.v(TAG, "takeUntil, call response " + response);                  return response.isJobDone;              }          })          .filter(new Func1<ServerPollingResponse, Boolean>() {              @Override              public Boolean call(ServerPollingResponse response) {                  /** * We are filtering results if we return "false". * Filtering means that onNext() will not be called. * But onComplete() will be delivered. */                  Log.v(TAG, "filter, call response " + response);                  return response.isJobDone;              }          })          .subscribe(                  new Subscriber<ServerPollingResponse>() {                      @Override                      public void onCompleted() {                          Log.v(TAG, "onCompleted ");                      }                        @Override                      public void onError(Throwable e) {                          Log.v(TAG, "onError ");                      }                        @Override                      public void onNext(ServerPollingResponse response) {                          Log.v(TAG, "onNext response " + response);                          // Do whatever you need. Server polling has been finished                      }                  }          );

参考 和 参考 .

4. Chrome的JsonView插件

添加插件之后, 可以格式化的显示Json数据.

5. 显示Activity栈的Shell命令

Shell命令

adb shell dumpsys activity | sed -n -e '/Stack #/p' -e '/Running activities/,/Run #0/p'

输出结果

  Stack #1:      Running activities (most recent first):        TaskRecord{299f41ea #2269 A=me.chunyu.spike.wcl_activity_launchmode_demo U=0 sz=6}          Run #5: ActivityRecord{33926043 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}          Run #4: ActivityRecord{3f181566 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}          Run #3: ActivityRecord{22737e45 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}          Run #2: ActivityRecord{ce0a990 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}          Run #1: ActivityRecord{3de8e378 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}          Run #0: ActivityRecord{1cb28ec4 u0 me.chunyu.spike.wcl_activity_launchmode_demo/.MainActivity t2269}    Stack #0:      Running activities (most recent first):        TaskRecord{bfee9cf #2241 A=com.miui.home U=0 sz=1}          Run #0: ActivityRecord{279bc098 u0 com.miui.home/.launcher.Launcher t2241}

6. dp和sp的区别

7. AlertDialog获取全部屏幕监听

setCanceledOnTouchOutside(false);

方法二:

setCancelable(false);

调用这个方法时, 按对话框以外的地方不起作用. 按返回键也不起作用.

8. getColor遗弃

最新版本的getColor被遗弃(deprecated), 使用时, 需要添加主题.也可以使用兼容模式, 即

ContextCompat.getColor(context, R.color.your_color);

ContextCompat.getColor 的源码

public static final int getColor(Context context, int id) {      final int version = Build.VERSION.SDK_INT;      if (version >= 23) {          return ContextCompatApi23.getColor(context, id);      } else {          return context.getResources().getColor(id);      }  }

9. libarchive和expat简介

libarchive 2.8.4和expat 2.1.0会产生漏洞, 如需修复, 需要升级Android的编译版本.

10. 网页重定向

默认链接会跳转其他链接, 根据链接内容, 进行相应操作, 如下载Apk等. 如果使用重定向, 则返回false; 如果非重定向, 则返回true.

        WebViewClient webClient = new WebViewClient() {              @Override              public boolean shouldOverrideUrlLoading(WebView view, String url) {                  if (url.endsWith(".apk")) {                      DownloadUtils.downloadFiles(url);                      if (mStartDownloadAppListener != null) {                          mStartDownloadAppListener.doAfter();                      }                      return true;                  }                  return false;              }          };          setWebViewClient(webClient);

OK, that’s all! Enjoy it!

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