Android應用自動更新的實現

那如何實現軟件自動更新，下面是具體實例：

效果圖：

具體步驟：

1. 在服務器上部署更新所用的xml文件：version.xml

<update>
    <version>2</version>
    <name>baiduxinwen.apk</name>
    <url>http://gdown.baidu.com/data/wisegame/e5f5c3b8e59401c8/baiduxinwen.apk</url>
</update>

2. 在客戶端實現更新操作

  涉及到三個技術：

   1.xml文件的解析

   2.HttpURLConnection連接

   3.文件流I/O

這里創建一個解析xml文件的服務類:ParXmlService.java

package com.xiaowu.news.update;

import java.io.InputStream;
import java.util.HashMap;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class ParseXmlService {
    public HashMap<String, String> parseXml (InputStream inStream) throws Exception{
        HashMap<String, String> hashMap = new HashMap<String, String>();
        //創建DocumentBuilderFactory，該對象將創建DocumentBuilder。
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        //創建DocumentBuilder，DocumentBuilder將實際進行解析以創建Document對象
        DocumentBuilder builder = factory.newDocumentBuilder();
        //解析該文件以創建Document對象
        Document document = builder.parse(inStream);
        //獲取XML文件根節點 
        Element root = document.getDocumentElement();
        //獲得所有子節點
        NodeList childNodes = root.getChildNodes();
        for(int i = 0; i < childNodes.getLength(); i++) {
            Node childNode = (Node) childNodes.item(i);
            if(childNode.getNodeType() == Node.ELEMENT_NODE) {
                Element childElement = (Element) childNode;
                //版本號 
                if("version".equals(childElement.getNodeName())) {
                    hashMap.put("version", childElement.getFirstChild().getNodeValue());
                //軟件名稱 
                } else if("name".equals(childElement.getNodeName())) {
                    hashMap.put("name", childElement.getFirstChild().getNodeValue());
                //下載地址
                } else if("url".equals(childElement.getNodeName())) {
                    hashMap.put("url", childElement.getFirstChild().getNodeValue());
                }
            }

        }
        return hashMap;
    }
}

package com.xiaowu.news.update;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;

import javax.net.ssl.HttpsURLConnection;

import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.DialogInterface.OnClickListener;
import android.content.pm.PackageManager.NameNotFoundException;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.Toast;

import com.xiaowu.news.R;

/**
 * 
 * @author wwj
 * @date 2012/11/17
 * 實現軟件更新的管理類
 */
public class UpdateManager {

    //下載中...
    private static final int DOWNLOAD = 1;
    //下載完成
    private static final int DOWNLOAD_FINISH = 2;
    //保存解析的XML信息
    HashMap<String , String> mHashMap;
    //下載保存路徑
    private String mSavePath;
    //記錄進度條數量
    private int progress;
    //是否取消更新
    private boolean cancelUpdate = false;
    //上下文對象
    private Context mContext;
    //進度條
    private ProgressBar mProgressBar;
    //更新進度條的對話框
    private Dialog mDownloadDialog;


    private Handler mHandler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            switch(msg.what){
            //下載中。。。
            case DOWNLOAD:
                //更新進度條
                System.out.println(progress);
                mProgressBar.setProgress(progress);
                break;
            //下載完成
            case DOWNLOAD_FINISH:
                // 安裝文件
                installApk();
                break;
            }
        };
    };


    public UpdateManager(Context context) {
        super();
        this.mContext = context;
    }


    /**
     * 檢測軟件更新
     */
    public void checkUpdate() {
        if (isUpdate()) {
            //顯示提示對話框
            showNoticeDialog();
        } else {
            Toast.makeText(mContext, R.string.soft_update_no, Toast.LENGTH_SHORT).show();
        }

    }

    private void showNoticeDialog() {
        // TODO Auto-generated method stub
        //構造對話框
        AlertDialog.Builder builder = new Builder(mContext);
        builder.setTitle(R.string.soft_update_title);
        builder.setMessage(R.string.soft_update_info);
        //更新
        builder.setPositiveButton(R.string.soft_update_updatebtn, new OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
                dialog.dismiss();
                // 顯示下載對話框
                showDownloadDialog();
            }
        });
        // 稍后更新
        builder.setNegativeButton(R.string.soft_update_later, new OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
                dialog.dismiss();
            }
        });
        Dialog noticeDialog = builder.create();
        noticeDialog.show();
    }

    private void showDownloadDialog() {
        // 構造軟件下載對話框
        AlertDialog.Builder builder = new Builder(mContext);
        builder.setTitle(R.string.soft_updating);
        // 給下載對話框增加進度條
        final LayoutInflater inflater = LayoutInflater.from(mContext);
        View view = inflater.inflate(R.layout.softupdate_progress, null);
        mProgressBar = (ProgressBar) view.findViewById(R.id.update_progress);
        builder.setView(view);
        builder.setNegativeButton(R.string.soft_update_cancel, new OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
                dialog.dismiss();
                // 設置取消狀態
                cancelUpdate = true;
            }
        });
        mDownloadDialog = builder.create();
        mDownloadDialog.show();
        //下載文件
        downloadApk();
    }

    /**
     * 下載APK文件
     */
    private void downloadApk() {
        // TODO Auto-generated method stub
        // 啟動新線程下載軟件
        new DownloadApkThread().start();
    }


    /**
     * 檢查軟件是否有更新版本
     * @return
     */
    public boolean isUpdate() {
        // 獲取當前軟件版本
        int versionCode = getVersionCode(mContext);
        //把version.xml放到網絡上，然后獲取文件信息
        InputStream inStream = ParseXmlService.class.getClassLoader().getResourceAsStream("version.xml");
        // 解析XML文件。 由于XML文件比較小，因此使用DOM方式進行解析
        ParseXmlService service = new ParseXmlService();
        try {
            mHashMap = service.parseXml(inStream);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        if(null != mHashMap) {
            int serviceCode = Integer.valueOf(mHashMap.get("version"));
            //版本判斷
            if(serviceCode > versionCode) {
                return true;
            }
        }
        return false;
    }

    /**
     * 獲取軟件版本號
     * @param context
     * @return
     */
    private int getVersionCode(Context context) {
        // TODO Auto-generated method stub
        int versionCode = 0;

        // 獲取軟件版本號，對應AndroidManifest.xml下android:versionCode
        try {
            versionCode = context.getPackageManager().getPackageInfo(
                    "com.xiaowu.news", 0).versionCode;
        } catch (NameNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return versionCode;
    }

    /**
     * 下載文件線程
     * @author Administrator
     *
     */
    private class DownloadApkThread extends Thread {
        @Override
        public void run() {
            try
            {
                //判斷SD卡是否存在，并且是否具有讀寫權限
                if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
                {
                    // 獲取SDCard的路徑
                    String sdpath = Environment.getExternalStorageDirectory() + "/";
                    mSavePath = sdpath + "download";
                    URL url = new URL(mHashMap.get("url"));
                    // 創建連接
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.connect();
                    // 獲取文件大小
                    int length = conn.getContentLength();
                    // 創建輸入流
                    InputStream is = conn.getInputStream();

                    File file = new File(mSavePath);
                    // 如果文件不存在，新建目錄
                    if (!file.exists())
                    {
                        file.mkdir();
                    }
                    File apkFile = new File(mSavePath, mHashMap.get("name"));
                    FileOutputStream fos = new FileOutputStream(apkFile);
                    int count = 0;
                    // 緩存
                    byte buf[] = new byte[1024];
                    // 寫入到文件中
                    do
                    {
                        int numread = is.read(buf);
                        count += numread;
                        // 計算進度條的位置
                        progress = (int) (((float) count / length) * 100);
                        // 更新進度
                        mHandler.sendEmptyMessage(DOWNLOAD);
                        if (numread <= 0)
                        {
                            // 下載完成
                            mHandler.sendEmptyMessage(DOWNLOAD_FINISH);
                            break;
                        }
                        // 寫入文件
                        fos.write(buf, 0, numread);
                    } while (!cancelUpdate);//點擊取消就停止下載
                    fos.close();
                    is.close();
                }
            } catch (MalformedURLException e)
            {
                e.printStackTrace();
            } catch (IOException e)
            {
                e.printStackTrace();
            }
            // 取消下載對話框顯示
            mDownloadDialog.dismiss();
        }
    }

    /**
     * 安裝APK文件
     */
    private void installApk()
    {
        File apkfile = new File(mSavePath, mHashMap.get("name"));
        if (!apkfile.exists())
        {
            return;
        }
        Intent i = new Intent(Intent.ACTION_VIEW);
        i.setDataAndType(Uri.parse("file://" + apkfile.toString()), "application/vnd.android.package-archive");
        mContext.startActivity(i);
    }
}