這個demo主要是做判斷版本並在網上下載並安裝apk

需要匯入xutils3架包

Mainactivity（主介面 進行一些操作）

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Environment
 
;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebResourceRequest;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import org.xutils.common.Callback;
 
import org.xutils.http.RequestParams;
import org.xutils.x;
import java.io.File;
public class MainActivity extends AppCompatActivity {
private int versionCode;
private ProgressDialog progressDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView
 
(R.layout.activity_main);
PackageManager packageManager = getPackageManager();
try {
PackageInfo packageInfo = packageManager.getPackageInfo(getPackageName(), 0);
versionCode = packageInfo.versionCode;
showUpdate();
        } catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
        }
    }
private void showUpdate() {
new AlertDialog.Builder(this)
                .setTitle("更新版本")
                .setMessage("當前版本是" + versionCode + " 需要升級")
                .setPositiveButton("下載", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
downloadApk();
                    }
                })
                .setNegativeButton("取消", null)
                .create()
                .show();
    }
private void downloadApk() {
String url = "http://gdown.baidu.com/data/wisegame/f98d235e39e29031/baiduxinwen.apk";
String path = Environment.getExternalStorageDirectory().getPath() + "/teme1/myapk.apk";
File file = new File(path);
File parentFile = file.getParentFile();
if (!parentFile.exists()) {
parentFile.mkdir();
        }
RequestParams params = new RequestParams(url);
params.setAutoRename(false);
params.setAutoResume(true);
//設定儲存路徑
params.setSaveFilePath(path);
x.http().get(params, new Callback.ProgressCallback<File>() {
@Override
public void onSuccess(File result) {
installDownloadApk(result);
            }
@Override
public void onError(Throwable ex, boolean isOnCallback) {
            }
@Override
public void onCancelled(CancelledException cex) {
            }
@Override
public void onFinished() {
cancleProgressDialog();
            }
@Override
public void onWaiting() {
            }
@Override
public void onStarted() {
showProgressDialog();
            }
@Override
public void onLoading(long total, long current, boolean isDownloading) {
int progress = (int) (current / total * 100);
if (progress >= 0 && progress <= 100) {
updataProgressDialog(progress);
                }
            }
        });
    }
//安卓開發 apk安裝
private void installDownloadApk(File result) {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setDataAndType(Uri.fromFile(result), "application/vnd.android.package-archive");
startActivity(intent);
    }
private void cancleProgressDialog() {
if (progressDialog == null) {
return;
        }
if (progressDialog.isShowing()) {
progressDialog.dismiss();
        }
    }
private void updataProgressDialog(int progress) {
if (progressDialog == null) {
return;
        }
progressDialog.setProgress(progress);
    }
private void showProgressDialog() {
progressDialog = new ProgressDialog(this);
//設定progressDialog顯示樣式
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setMessage("我正在下載東西");
progressDialog.setTitle("請等待");
progressDialog.setProgress(0);
progressDialog.show();
    }
}

MyApplication（配置xutils3）

package com.example.lixin.downloadapkdemo.app;
import android.app.Application;
import org.xutils.x;
/**
 * Created by hua on 2017/8/19.
 */
public class MyApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
x.Ext.init(this);
    }
}

manifest（配置檔案）

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.lixin.downloadapkdemo">
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <applicationandroid:name=".app.MyApplication"
android:allowBackup="true" android:icon="@mipmap/ic_launcher"
android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true" android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>