Android~AsyncTask下载进度条demo

向右看齐 2022-10-16 07:13 215阅读 0赞

使用AsyncTask实现下载进度条效果

public class AsyncTaskActivity extends Activity implements View.OnClickListener { 
        private Button mBtnStart;
        private Button mBtnCancel;
        private TextView mTVShow;
        private ProgressBar mProgress;
        private MyAsyncTask myAsyncTask;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) { 
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_asynctask);
            initView();
        }
    
        private void initView() { 
            mBtnStart = findViewById(R.id.btnStart);
            mBtnCancel = findViewById(R.id.btnCancel);
            mTVShow = findViewById(R.id.textShow);
            mProgress = findViewById(R.id.progress);
            myAsyncTask = new MyAsyncTask();
    
            mBtnStart.setOnClickListener(this);
            mBtnCancel.setOnClickListener(this);
        }
    
        @Override
        public void onClick(View v) { 
            switch (v.getId()) { 
                case R.id.btnStart:
                    myAsyncTask.execute();
                    break;
                case R.id.btnCancel:
                    myAsyncTask.cancel(true);
                    break;
                default:
                    break;
            }
        }
    
        private class MyAsyncTask extends AsyncTask<String, Integer, String> { 
    
            @Override
            protected void onPreExecute() { 
                super.onPreExecute();
                mTVShow.setText("加载中....");
            }
    
            @Override
            protected String doInBackground(String... strings) { 
                int count = 0;
                while (count < 99) { 
                    count += 1;
                    // 可调用publishProgress（）显示进度, 之后将执行onProgressUpdate（）
                    publishProgress(count);
                    try { 
                        Thread.sleep(1 * 50);
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                }
                return null;
            }
    
            @Override
            protected void onProgressUpdate(Integer... progresses) { 
                super.onProgressUpdate(progresses);
                mProgress.setProgress(progresses[0]);
                mTVShow.setText("loading...." + progresses[0] + "%");
            }
    
            @Override
            protected void onPostExecute(String s) { 
                super.onPostExecute(s);
                // 执行完毕后，则更新UI
                mTVShow.setText("加载完毕");
            }
    
            @Override
            protected void onCancelled() { 
                super.onCancelled();
                mTVShow.setText("已取消加载");
                mProgress.setProgress(0);
            }
        }
    }

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