android raw读取超过1M文件的方法

来源：互联网发布：淘宝手机模版编辑：程序博客网时间：2024/05/11 16:05

近日在琢磨android系统,程序中用到了sqlite数据库,一切代码妥当,在发布时遇到点问题,就是raw单个文件不能超过1M,否则会报错"Data exceeds UNCOMPRESS_DATA_MAX ",而我的数据库的初始容量就是5M啦,网上寻找多时,大致分成两种方法:
1>是将文件移动到sdcard中.这样倒是不受文件大小限制,不过对于apk的发布....不用我多说了吧.
2>将单个文件分割成多个1M以下的小文件....这个倒是个方法.只是用上去总是有点别扭.需要找文件分割工具...或者自己写一个.

于是,自然想到用压缩的方法.android的sdk完全采用了java的zip压缩类.这就为我实现压缩提供了极大方便.经过测试,本人的sqlite库,原始大小为5M,用zip压缩后700K,哈哈,完全满足系统限制.然后在读取时,解压缩到apk的数据库默认目录下即可. 不在废话,以下是本人的代码:

```
import java.io.BufferedInputStream;
```
```
import java.io.File;
```
```
import java.io.FileOutputStream;
```
```
import java.io.IOException;
```
```
import java.io.InputStream;
```
```
import java.io.OutputStream;
```
```
import java.util.zip.ZipEntry;
```
```
import java.util.zip.ZipInputStream;
```
```
import android.app.ProgressDialog;
```
```
import android.content.Context;
```
```
import android.database.Cursor;
```
```
import android.database.SQLException;
```

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

```
import android.os.AsyncTask;
```
```
public class DBSourse {
```

    private static final String DATABASE_NAME = "Test.db";

    private static final int DATABASE_VERSION = 1;

```
    private DatabaseHelper mDbHelper;
```
```
    private SQLiteDatabase mDb;
```
```
    private final Context mCtx;
```

    private static int mDBRawResource = 0;

    public DBSourse(Context ctx,int DBRawResource) {

```
        this.mCtx = ctx;
```
```
        mDBRawResource = DBRawResource;
```
```
    }
```
```
    public DBSourse(Context ctx) {
```
```
        this.mCtx = ctx;
```
```
        if (mDBRawResource == 0)
```

            new Exception("必须指定以zip压缩的数据库Raw文件");

```
    }
```

    public static class DatabaseHelper extends SQLiteOpenHelper {

        DatabaseHelper(Context context) {

            super(context, DATABASE_NAME, null, DATABASE_VERSION);

```
        }
```
```
        @Override
```

        public void onCreate(SQLiteDatabase db) {

```
        }
```
```
        @Override
```

        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

```
        }
```
```
    }
```
```
    
```
```
    
```

    class DBDialogTask extends AsyncTask<String, Integer, Integer> {

```
        ProgressDialog m_pDialog;
```
```
        int StreamLen;
```
```
        @Override
```

        protected Integer doInBackground(String... params) { // 后台进程执行的具体计算在这里实现

            String dbPathString = params[0];

```
            int len = 1024;//
```

            int readCount = 0, readSum = 0;

            byte[] buffer = new byte[len];

```
            InputStream inputStream;
```
```
            OutputStream output;
```
```
            try {
```

                inputStream = mCtx.getResources().openRawResource(mDBRawResource); //这里就是Raw文件引用位置

                output = new FileOutputStream(dbPathString);

```
                
```

                ZipInputStream zipInputStream = new ZipInputStream(

                        new BufferedInputStream(inputStream));

                ZipEntry zipEntry = zipInputStream.getNextEntry();

                BufferedInputStream b = new BufferedInputStream(

                        zipInputStream);

                StreamLen = (int) zipEntry.getSize();

                while ((readCount = b.read(buffer)) != -1) {

                //    readCount = b.read(buffer);

                    output.write(buffer,0,readCount);

                    readSum = readSum + readCount;

                    publishProgress(readSum);

```
                }
```
```
                output.flush();
```
```
                output.close();
```
```
            } catch (IOException e) {
```
```
                e.printStackTrace();
```
```
            }
```
```
            return StreamLen;
```
```
        }
```
```
        @Override
```

        // 运行于UI线程。如果在doInBackground(Params...)

        // 中使用了publishProgress(Progress...)，就会触发这个方法。在这里可以对进度条控件根据进度值做出具体的响应。

        protected void onProgressUpdate(Integer... values) {

            super.onProgressUpdate(values);

            if (m_pDialog.getMax() != StreamLen)

                m_pDialog.setMax(StreamLen);

            m_pDialog.setProgress(values[0]);

```
        }
```
```
        @Override
```

        // 执行预处理，它运行于UI线程，可以为后台任务做一些准备工作，比如绘制一个进度条控件。

```
        protected void onPreExecute() {
```
```
            super.onPreExecute();
```

            m_pDialog = new ProgressDialog(mCtx);

            m_pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

            m_pDialog.setTitle("提示");

            m_pDialog.setMessage("正在升级数据库,请勿关闭应用程序");

```
            m_pDialog.show();
```
```
        }
```
```
        @Override
```

        // 运行于UI线程，可以对后台任务的结果做出处理，结果就是doInBackground(Params...)的返回值

        protected void onPostExecute(Integer result) {

            super.onPostExecute(result);

            m_pDialog.setProgress(result);

```
            m_pDialog.cancel();
```

            if (onDBInstalledListener != null)

                onDBInstalledListener.OnDBInstalled();

```
        }
```
```
    }    
```
```
    
```

    protected OnDBInstalledListener onDBInstalledListener;

```
    
```

    public void setOnDBInstalledListener(OnDBInstalledListener onDBInstalledListener) {

        this.onDBInstalledListener = onDBInstalledListener;

```
    }
```
```
    
```
```
    public void InstallDatabase() {
```

        mDbHelper = new DatabaseHelper(mCtx);

        SQLiteDatabase sdbreader = mDbHelper.getReadableDatabase();

        File dbfile = new File(sdbreader.getPath());

        if (dbfile.length()<4096){//依据数据库大小判断,是否需要执行安装.暂时没仔细想别的办法

            DBDialogTask dialogTask = new DBDialogTask();

            dialogTask.execute(sdbreader.getPath());

```
        }else{
```

            if (onDBInstalledListener != null)

                onDBInstalledListener.OnDBInstalled(); //这里可以委托一个方法,用以安装完数据库后的初始化工作

```
        }
```
```
    }
```

    public DBSourse open() throws SQLException {

```
        if( mDbHelper == null)
```

            mDbHelper = new DatabaseHelper(mCtx);

```
        if (mDb == null)
```

            mDb = mDbHelper.getWritableDatabase();

```
        if (!mDb.isOpen())
```

            mDb = mDbHelper.getWritableDatabase();

```
        return this;
```
```
    }
```
```
    public void close() {
```
```
        mDbHelper.close();
```
```
    }
```
```
    
```
```
    public Cursor GetSomeData() {
```
```
        return mDb.query("table",
```

                new String[] { "_id", "a1", "a2" }, "a1 = 1",

                null, null, null, "a2");

```
    }
```
```
    
```

    public interface OnDBInstalledListener{

```
        void OnDBInstalled();
```
```
    }
```
```
}
```

然后在需要调用数据库的地方,创建此类,调用InstallDatabase方法.由线程从raw中解压数据库资源...为了在数据库安装完成后执行某些操作还可以绑定方法OnDBInstalledListener

对了,忘记说了,将sqlite数据库从ddms中导出后,用zip压缩,然后存入raw文件夹即可.(别问我怎么将文件压缩成zip.还有别压缩成rar格式.).至于当压缩后的文件依然超过1M怎么办呢?我倒是没琢磨,不过初步考虑有两种方法:1>分割压缩后的文件(这个方法纯属于杂交...).2>分卷压缩.我倾向于这个办法,不过没有考虑如何实现.哪位大牛实现了,烦劳通告一下.呵呵

有事儿联系.完事.