Android基础#22：Android handler用法详解2，例2

Love The Way You Lie 2023-10-17 12:11 34阅读 0赞

**内容简介：**

上一篇讲解了Handler的基本原理和用法，本篇再给出一个实例。

**直接看代码：**

public class MyAboutActivity extends Activity {
    
        public ProgressDialog mProgressDialog;
        private Handler mHandler = new Handler();
    
        @Override
    
    
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.my_about);
            Dialog dialog = new AlertDialog.Builder(MyAboutActivity.this)
                    .setTitle("应用升级").
                            setMessage("发现新版本，请升级！")
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog,
                                            int which) {
                            mProgressDialog = new ProgressDialog(MyAboutActivity.this);
                            mProgressDialog.setTitle("正在升级中");
                            mProgressDialog.setMessage("请稍候...");
                            mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
                            downFile("http://localhost:8080/test/apk/test1.apk");
                        }
                    }).setNegativeButton("取消", 
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                                    int whichButton) {
                                    //do your something
                                }
                            }).create();
            dialog.show();
        }
    
        private void downFile(final String url) {
            mProgressDialog.show();
            new Thread() {
                public void run() {
                    HttpClient client = new DefaultHttpClient();
                    //代表连接的url
                    HttpGet get = new HttpGet(url);
                    HttpResponse response;
                    try {
                        response = client.execute(get);
                        HttpEntity entity = response.getEntity();
                        long length = entity.getContentLength();
                        InputStream is = entity.getContent();
                        FileOutputStream fileOutputStream = null;
                        if (is != null) {
                            File file = new File(Environment.getExternalStorageDirectory(), "test1.apk");
                            fileOutputStream = new FileOutputStream(file);
                            byte[] buf = new byte[1024];
                            int ch = -1;
                            int count = 0;
                            while ((ch = is.read(buf)) != -1) {
                                fileOutputStream.write(buf, 0, ch);
                                count += ch;
                                if (length > 0) {
                                }
                            }
                        }
                        fileOutputStream.flush();
                        if (fileOutputStream != null) {
                            fileOutputStream.close();
                        }
                        downLoadApk();
                    } catch (ClientProtocolException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }.start();
        }
    
        private void downLoadApk() {
            mHandler.post(new Runnable() {
                public void run() {
                    mProgressDialog.cancel();
                    updateApp();
                }
            });
        }
    
        private void updateApp() {
            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(Uri.fromFile(new File("/sdcard/test1.apk")), "application/vnd.android.package-archive");
            startActivity(intent);
        }
    
    }

**说明：**

调用流程： 在onCreate， 创建dialog，如果用户点击“确定”，就调用到downFile，然后，downFile ->downLoadApk ->mHandler.post。

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