Android在线更新 远程安装程序

原文：http://blog.csdn.net/jasper_success/article/details/7984065

第一步：使用java.net的URLConnection对象来创建连接

第二步：通过InputStream将下载的文件写入存储卡内缓存

第三步：下载完毕之后，通过自定义的openFile()方法打开文件，判断文件类型，若为APK，开始安装

第四步：准备离开Installer程序的同时，通过自制的delFile()方法，删除缓存内文件

/**
 * 远程下载安装Android程序
 *
 * @ClassName InstallOnlineActivity
 * @author Jet
 * @date 2012-9-14
 */
public class InstallOnlineActivity extends Activity {
    private TextView mTextView;
    private EditText mEditText;
    private Button mButton;
    private String currentFilePath = "";
    private String currentTempFilePath = "";
    private String strURL = "";
    private String fileEx = "";
    private String fileName = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.installonline);
        mTextView = (TextView) findViewById(R.id.installonline_text1);
        mEditText = (EditText) findViewById(R.id.installonline_edittext1);
        mButton = (Button) findViewById(R.id.installonline_button1);
        mButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // 将文件下载到本地
                mTextView.setText("下载中...");
                strURL = mEditText.getText().toString();
                // 截取文件后缀
                fileEx = strURL.substring(strURL.lastIndexOf('.') + 1,
                        strURL.length()).toLowerCase();
                // 截取文件名
                fileName = strURL.substring(strURL.lastIndexOf('/') + 1,
                        strURL.lastIndexOf('.'));
                getFile(strURL);
            }

        });
    }

    private void getFile(final String strPath) {
        if (currentFilePath.equals(strPath)) {
            getDataSource(strPath);
        }
        currentFilePath = strPath;
        Runnable r = new Runnable() {

            @Override
            public void run() {
                getDataSource(strPath);
            }
        };
        new Thread(r).start();
    }

    private void getDataSource(String url) {
        if (!URLUtil.isNetworkUrl(url)) {
            mTextView.setText("请填写正确的URL");
        } else {
            try {
                URL myUrl = new URL(url);
                // 取得连接
                URLConnection conn = myUrl.openConnection();
                // 连接
                conn.connect();
                // 获得输入流
                InputStream is = conn.getInputStream();
                if (is == null) {
                    throw new RuntimeException("stream is null");
                }
                // 创建临时文件
                File myTempFile = File.createTempFile(fileName, "." + fileEx);
                // 取得临时文件存放路径
                currentTempFilePath = myTempFile.getAbsolutePath();
                FileOutputStream fos = new FileOutputStream(myTempFile);
                byte[] buf = new byte[128];
                do {
                    // 返回现在所读缓冲区的大小
                    int numread = is.read(buf);
                    if (numread <= 0) {
                        break;
                    }
                    fos.write(buf, 0, numread);
                } while (true);
                // 打开文件进行安装
                openFile(myTempFile);
                is.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void openFile(File file) {
        Intent intent = new Intent();
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setAction(android.content.Intent.ACTION_VIEW);
        String type = getMimeType(file);
        intent.setDataAndType(Uri.fromFile(file), type);
        startActivity(intent);
    }

    private String getMimeType(File file) {
        String type = "";
        String fname = file.getName();
        // 获得扩展名
        String end = fname
                .substring(fname.lastIndexOf('.') + 1, fname.length())
                .toLowerCase();
        // 按扩展名的类型决定MimeType
        if ("m4a".equals(end) || "mp3".equals(end) || "mid".equals(end)
                || "xmf".equals(end) || "ogg".equals(end) || "wav".equals(end)) {
            type = "audio";
        } else if ("3gp".equals(end) || "mp4".equals(end)) {
            type = "video";
        } else if ("jpg".equals(end) || "gif".equals(end) || "png".equals(end)
                || "jpeg".equals(end) || "bmp".equals(end)) {
            type = "image";
        } else if ("apk".equals(end)) {
            type = "application/vnd.android.package-archive";
        } else {
            type = "*";
        }
        if ("apk".equals(end)) {

        } else {
            type += "/*";
        }
        return type;
    }
    private void delFile(String fileName){
        File file = new File(fileName);
        if(file.exists()){
            file.delete();
        }
    }
    @Override
    protected void onPause() {
        mTextView = (TextView) findViewById(R.id.installonline_text1);
        mTextView.setText("下载成功");
        super.onPause();
    }
    @Override
    protected void onResume() {
        //删除临时文件
        delFile(currentTempFilePath);
        super.onResume();
    }
}