通过okhttp3下载文件实现APP版本更新

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通过okhttp3下载文件实现APP版本更新

做更新的时候要注意7.0版本的路径安全问题，Caused by: android.os.FileUriExposedException

从Android 7.0开始，不再允许在app中把file:// Uri暴露给其他app，否则应用会抛出FileUriExposedException。原因在于，Google认为使用file:// Uri存在一定的风险。比如，文件是私有的，其他app无法访问该文件，或者其他app没有申请READ_EXTERNAL_STORAGE运行时权限。解决方案是，使用FileProvider生成content:// Uri来替代file:// Uri。

概况

思路是这样的,首先在服务器上把已经签名打包的apk放上去,还有一份TXT文件，文件上写着相关的版本号，然后客户端通过对比版本号决定是否下载文件。下载后就打开安装界面安装。 

第一步

把已经签名打包apk和txt文件放上到服务器上，版本号要和txt文件上的描述一致。Android Studio的版本号除了在manifests上，写上code和name(code是面向开发者，name就是用户所看到的版本号），那么我要更新的是2.0版本，那么我应该写2.0，并且要把访问网络和写入数据权限写上 

还要在build.gradle(Module:app）上更改版本号，如果是用eclipse开发就不需要这一步 

 
TXT文件的内容如下，第一行是版本号，第二行版本描述，第三行是apk的下载链接 

第二步

服务器端已经完成，接下来是代码的实现。 
我这里采用okhttp3+mvp模式实现下载文件，如果有对这种模式不清楚的可以看在MVP模式下使用OkHttp3和初试OkHttp3实现登录功能

• Model层有更新版本描述实例UpdateInfo和Okhttp3的get和post方法

• 首先在Presenter上有查询版本号和下载apk这两个方法，这两个都是使用Get请求

• 在View上就需要有一个对应一个触发更新的按钮，显示最新版本的Toast,显示并询问是否更新的Dialog,和显示进度的ProgressDialog，一个跳转到安装界面的操作

Model层

• 首先要有updateInfo,一个版本信息的实例

public class UpdateInfo
{private String version;private String description;private String url;public String getVersion(){return version;}public void setVersion(String version){this.version = version;}public String getDescription(){return description;}public void setDescription(String description){this.description = description;}public String getUrl(){return url;}public void setUrl(String url){this.url = url;}}
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• 另一个是Modle，包装着okhttp3的post和get方法，这里只需要get请求

/*** get请求* @param address* @param callback*/public void get(String address, okhttp3.Callback callback){OkHttpClient client = new OkHttpClient();FormBody.Builder builder = new FormBody.Builder();FormBody body = builder.build();Request request = new Request.Builder().url(address).build();client.newCall(request).enqueue(callback);}
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Presenter层

• 检查是否需要更新

 public void updateAPK() {model = Model.getInstance();model.get("TXT文件的url",new okhttp3.Callback(){@Overridepublic void onFailure(Call call, IOException e) {}@Overridepublic void onResponse(Call call, Response response) throws IOException {String responseBody = response.body().string();StringBuffer sb = new StringBuffer();BufferedReader reader = null;UpdateInfo updateInfo = new UpdateInfo();Log.d("版本", "onResponse: "+responseBody);reader = new BufferedReader(new StringReader(responseBody));updateInfo.setVersion(reader.readLine());//把版本信息读出来updateInfo.setDescription(reader.readLine());updateInfo.setUrl(reader.readLine());String new_version = updateInfo.getVersion();Log.d("版本", "onResponse: "+updateInfo.getVersion());Log.d("版本描述", "onResponse: "+updateInfo.getDescription());Log.d("更新链接", "onResponse: "+updateInfo.getUrl());String now_version = "";try {PackageManager packageManager = context.getPackageManager();PackageInfo packageInfo = packageManager.getPackageInfo(context.getPackageName(),0);now_version = packageInfo.versionName;//获取原版本号} catch (PackageManager.NameNotFoundException e) {e.printStackTrace();}if(new_version.equals(now_version)){view.showError("");Log.d("版本号是", "onResponse: "+now_version);}else{view.showUpdateDialog(updateInfo);}}});}
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• 下载apk

    public void downFile(final String url) {Log.d("SettingPresenter", "downFile: ");model = Model.getInstance();model.get(url,new okhttp3.Callback(){@Overridepublic void onFailure(Call call, IOException e) {view.downFial();}@Overridepublic void onResponse(Call call, Response response) throws IOException {InputStream is = null;//输入流FileOutputStream fos = null;//输出流try {is = response.body().byteStream();//获取输入流long total = response.body().contentLength();//获取文件大小view.setMax(total);//为progressDialog设置大小if(is != null){Log.d("SettingPresenter", "onResponse: 不为空");File file = new File(Environment.getExternalStorageDirectory(),"Earn.apk");// 设置路径fos = new FileOutputStream(file);byte[] buf = new byte[1024];int ch = -1;int process = 0;while ((ch = is.read(buf)) != -1) {fos.write(buf, 0, ch);process += ch;view.downLoading(process);       //这里就是关键的实时更新进度了！}}fos.flush();// 下载完成if(fos != null){fos.close();}view.downSuccess();} catch (Exception e) {view.downFial();Log.d("SettingPresenter",e.toString());} finally {try {if (is != null)is.close();} catch (IOException e) {}try {if (fos != null)fos.close();} catch (IOException e) {}}}//private void down() {// progressDialog.cancel();// }});}
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View层

这一层注意的东西很多，例如Android6.0以上等需要在这里设置一下权限，还有Dialog注意关闭，否则出现窗口泄露问题。话不多说，直接上代码

public class MainActivity extends AppCompatActivity {//下载进度private ProgressDialog progressDialog;private Button button;private SettingPresenter presenter;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);presenter = new SettingPresenter(this,this);button = (Button) findViewById(R.id.button);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {if (Build.VERSION.SDK_INT >= 23) {//如果是6.0以上的int REQUEST_CODE_CONTACT = 101;String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE};//验证是否许可权限for (String str : permissions) {if (MainActivity.this.checkSelfPermission(str) != PackageManager.PERMISSION_GRANTED) {//申请权限MainActivity.this.requestPermissions(permissions, REQUEST_CODE_CONTACT);return;}}}presenter.updateAPK();}});}//显示更新错误public void showError(final String msg) {runOnUiThread(new Runnable() {@Overridepublic void run() {Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();}});}//显示进度条public void showUpdateDialog(final UpdateInfo updateInfo) {runOnUiThread(new Runnable() {@Overridepublic void run() {AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(android.R.drawable.ic_dialog_info);builder.setTitle("请升级APP至版本" + updateInfo.getVersion());builder.setMessage(updateInfo.getDescription());builder.setCancelable(false);builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {downFile(updateInfo.getUrl());} else {Toast.makeText(MainActivity.this,"SD卡不可用，请插入SD卡",Toast.LENGTH_LONG).show();}}});builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {}});builder.create().show();}});}//下载apk操作public void downFile(final String url) {progressDialog = new ProgressDialog(MainActivity.this);    //进度条，在下载的时候实时更新进度，提高用户友好度progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);progressDialog.setTitle("正在下载");progressDialog.setMessage("请稍候...");progressDialog.setProgress(0);progressDialog.show();presenter.downFile(url);Log.d("SettingActivity", "downFile: ");}/*** 进度条实时更新* @param i*/public void downLoading(final int i) {runOnUiThread(new Runnable() {@Overridepublic void run() {progressDialog.setProgress(i);}});}/*** 下载成功*/public void downSuccess() {runOnUiThread(new Runnable() {@Overridepublic void run() {if (progressDialog != null && progressDialog.isShowing()){progressDialog.dismiss();}AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(android.R.drawable.ic_dialog_info);builder.setTitle("下载完成");builder.setMessage("是否安装");builder.setCancelable(false);builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {Intent intent = new Intent(Intent.ACTION_VIEW);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { //aandroid N的权限问题intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);Uri contentUri = FileProvider.getUriForFile(MainActivity.this, "对应的包名.fileprovider", new File(Environment.getExternalStorageDirectory(), "软件名.apk"));//注意修改intent.setDataAndType(contentUri, "application/vnd.android.package-archive");} else {intent.setDataAndType(Uri.fromFile(new File(Environment.getExternalStorageDirectory(), "软件名.apk")), "application/vnd.android.package-archive");intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);}startActivity(intent);}});builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {}});builder.create().show();}});}/*** 下载失败*/public void downFial() {runOnUiThread(new Runnable() {@Overridepublic void run() {progressDialog.cancel();Toast.makeText(MainActivity.this,"更新失败",Toast.LENGTH_LONG).show();}});}public void setMax(final long total) {runOnUiThread(new Runnable() {@Overridepublic void run() {progressDialog.setMax((int) total);}});}
}
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注意：在跳转到安装界面时，android 6.0即android N以上的需要设置权限。

• 首先在Manifests加上

  <provider
            android:name="android.support.v4.content.FileProvider"android:authorities="对应的包名.fileprovider"android:grantUriPermissions="true"android:exported="false"><meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"android:resource="@xml/file_paths" /></provider>
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• 然后在res中创建xml包，存放file_paths.xml文件

<?xml version="1.0" encoding="utf-8"?>
<paths><external-path path="Android/data/com.earn/" name="files_root" /><external-path path="." name="external_storage_root" />
</paths>
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• 文章所用Demo这里下载