Android检查更新（是否强制更新）

Android应用客户端通常会需要更新，而且根据需求分为普通更新和强制更新。是否强制更新可通过检查更新时从服务器获取的标志位来判断。

public class UpdateManager {
    private Context mContext; //上下文

    private String apkUrl = 
            "http://183.232.83.10/dd.myapp.com/16891/" +
            "C4F9FF39FAE9184222DC278DC7309611.apk?mkey" +
            "=5541c92b6a9cca8d&f=d388&fsname=com.yangmbin" +
            ".beauty_1.1_2.apk&asr=8eff&p=.apk"; //apk下载地址
    private static final String savePath = "/sdcard/updateAPK/"; //apk保存到SD卡的路径
    private static final String saveFileName = savePath + "apkName.apk"; //完整路径名

    private ProgressBar mProgress; //下载进度条控件
    private static final int DOWNLOADING = 1; //表示正在下载
    private static final int DOWNLOADED = 2; //下载完毕
    private static final int DOWNLOAD_FAILED = 3; //下载失败
    private int progress; //下载进度
    private boolean cancelFlag = false; //取消下载标志位

    private double serverVersion = 2.0; //从服务器获取的版本号
    private double clientVersion = 1.0; //客户端当前的版本号
    private String updateDescription = "更新描述"; //更新内容描述信息
    private boolean forceUpdate = true; //是否强制更新

    private AlertDialog alertDialog1, alertDialog2; //表示提示对话框、进度条对话框

    /** 构造函数 */
    public UpdateManager(Context context) {
        this.mContext = context;
    }

    /** 显示更新对话框 */
    public void showNoticeDialog() {
        //如果版本最新，则不需要更新
        if (serverVersion <= clientVersion)
            return;
        AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
        dialog.setTitle("发现新版本 ：" + serverVersion);
        dialog.setMessage(updateDescription);
        dialog.setPositiveButton("现在更新", new OnClickListener() {
            @Override
            public void onClick(DialogInterface arg0, int arg1) {
                // TODO Auto-generated method stub
                arg0.dismiss();
                showDownloadDialog();
            }
        });
        //是否强制更新
        if (forceUpdate == false) {
            dialog.setNegativeButton("待会更新", new OnClickListener() {
                @Override
                public void onClick(DialogInterface arg0, int arg1) {
                    // TODO Auto-generated method stub
                    arg0.dismiss();
                }
            });
        }
        alertDialog1  = dialog.create();
        alertDialog1.setCancelable(false);
        alertDialog1.show();
    }

    /** 显示进度条对话框 */
    public void showDownloadDialog() {
        AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
        dialog.setTitle("正在更新");
        final LayoutInflater inflater = LayoutInflater.from(mContext);
        View v = inflater.inflate(R.layout.softupdate_progress, null);
        mProgress = (ProgressBar) v.findViewById(R.id.update_progress);
        dialog.setView(v);
        //如果是强制更新，则不显示取消按钮
        if (forceUpdate == false) {
            dialog.setNegativeButton("取消", new OnClickListener() {
                @Override
                public void onClick(DialogInterface arg0, int arg1) {
                    // TODO Auto-generated method stub
                    arg0.dismiss();
                    cancelFlag = false;
                }
            });
        }
        alertDialog2  = dialog.create();
        alertDialog2.setCancelable(false);
        alertDialog2.show();

        //下载apk
        downloadAPK();
    }

    /** 下载apk的线程 */
    public void downloadAPK() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                // TODO Auto-generated method stub
                try {
                    URL url = new URL(apkUrl);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.connect();

                    int length = conn.getContentLength();
                    InputStream is = conn.getInputStream();

                    File file = new File(savePath);
                    if(!file.exists()){  
                        file.mkdir();  
                    }  
                    String apkFile = saveFileName;  
                    File ApkFile = new File(apkFile);  
                    FileOutputStream fos = new FileOutputStream(ApkFile);  

                    int count = 0;  
                    byte buf[] = new byte[1024];  

                    do{                   
                        int numread = is.read(buf);  
                        count += numread;  
                        progress = (int)(((float)count / length) * 100);  
                        //更新进度  
                        mHandler.sendEmptyMessage(DOWNLOADING);  
                        if(numread <= 0){      
                            //下载完成通知安装  
                            mHandler.sendEmptyMessage(DOWNLOADED);  
                            break;  
                        }  
                        fos.write(buf, 0, numread);  
                    }while(!cancelFlag); //点击取消就停止下载.  

                    fos.close();  
                    is.close(); 
                } catch(Exception e) {
                    mHandler.sendEmptyMessage(DOWNLOAD_FAILED);
                    e.printStackTrace();
                }
            }
        }).start();
    }

    /** 更新UI的handler */
    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            switch (msg.what) {
            case DOWNLOADING:
                mProgress.setProgress(progress);
                break;
            case DOWNLOADED:
                if (alertDialog2 != null)
                    alertDialog2.dismiss();
                installAPK();
                break;
            case DOWNLOAD_FAILED:
                Toast.makeText(mContext, "网络断开，请稍候再试", Toast.LENGTH_LONG).show();
                break;
            default:
                break;
            }
        }
    };

    /** 下载完成后自动安装apk */
    public void installAPK() {
        File apkFile = new File(saveFileName);
        if (!apkFile.exists()) {
            return;
        }
        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(Uri.parse("file://" + apkFile.toString()), "application/vnd.android.package-archive");   
        mContext.startActivity(intent); 
    }
}

对话框中进度条用到的布局：softupdate_progress.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <ProgressBar
        android:id="@+id/update_progress"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        style="?android:attr/progressBarStyleHorizontal" />
</RelativeLayout>

使用方法：

//这里来检测版本是否需要更新  
mUpdateManager = new UpdateManager(this);  
mUpdateManager.showNoticeDialog();

检查更新通常是在初始化的时候，请求服务器检查版本，如果有更新，则把相关url、是否强制更新和版本号等信息通过showNoticeDialog的参数传递进去，做相关的初始化即可。