Android通过ContentProvider传输文件

我们知道Android两个应用程序之间进行数据交互需要通过ContentProvider，而且通常都是数据库的操作。
今天项目需要使用Android的ContentProvider交互普通SD卡上的文件，于是我写了这个小例子：
AndroidManifest.xml

TestContentProvider.java

package com.h3c.test;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;

import android.content.ContentProvider;
import android.content.ContentProviderOperation;
import android.content.ContentProviderResult;
import android.content.ContentValues;
import android.content.OperationApplicationException;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.net.Uri;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.util.Log;

public class TestContentProvider extends ContentProvider {

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        // TODO Auto-generated method stub
        Log.e("H3c", "delete");
        return 0;
    }

    @Override
    public String getType(Uri uri) {
        // TODO Auto-generated method stub
        Log.e("H3c", "gettype");
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        // TODO Auto-generated method stub
        Log.e("H3c", "insert");
        return null;
    }

    @Override
    public boolean onCreate() {
        // TODO Auto-generated method stub
        Log.e("H3c", "create");
        return false;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        // TODO Auto-generated method stub
        Log.e("H3c", "query");
        return null;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
            String[] selectionArgs) {
        // TODO Auto-generated method stub
        Log.e("H3c", "update");
        return 0;
    }

    @Override
    public AssetFileDescriptor openAssetFile(Uri uri, String mode)
            throws FileNotFoundException {
        // TODO Auto-generated method stub
        Log.e("H3c", "openAssetFile");
        return super.openAssetFile(uri, mode);
    }

    //此方法非常重要，一定要重写，否则默认报FileNotFound异常
    @Override
    public ParcelFileDescriptor openFile(Uri uri, String mode)
            throws FileNotFoundException {
        // TODO Auto-generated method stub
        File root = Environment.getExternalStorageDirectory();
        root.mkdirs();
        File path = new File(root, uri.getEncodedPath());

        Log.e("H3c", "opeFile:"+path);
        int imode = 0;
        if (mode.contains("w")) {
            imode |= ParcelFileDescriptor.MODE_WRITE_ONLY;
            if (!path.exists()) {
                try {
                    path.createNewFile();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        if (mode.contains("r"))
            imode |= ParcelFileDescriptor.MODE_READ_ONLY;
        if (mode.contains("+"))
            imode |= ParcelFileDescriptor.MODE_APPEND;

        return ParcelFileDescriptor.open(path, imode);
    }

}

NotepadTestActivity.java

package com.h3c.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.AssetFileDescriptor;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class NotepadTestActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.notepad);

        Button button = (Button) findViewById(R.id.notepad);
        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                try {
                    // 直接读文件
                    // InputStream is = getContentResolver().openInputStream(
                    // Uri.parse("file:/mnt/sdcard/h3c.txt"));
                    //
                    // File bkFile = new File("/mnt/sdcard/h3c2.txt");
                    // if (!bkFile.exists()) {
                    // bkFile.createNewFile();
                    // }
                    //                    
                    // FileOutputStream out = new FileOutputStream(bkFile);
                    // byte[] b = new byte[1024 * 5]; // 5KB
                    // int len;
                    // while ((len = is.read(b)) != -1) {
                    // out.write(b, 0, len);
                    // }
                    // out.flush();
                    // is.close();
                    // out.close();

                    // 直接写文件
                    // OutputStream out = getContentResolver().openOutputStream(
                    // Uri.parse("file:/mnt/sdcard/h3c.txt"));
                    // FileInputStream in = new FileInputStream(new File(
                    // "/mnt/sdcard/h3c3.txt"));
                    //
                    // byte[] b = new byte[1024 * 5]; // 5KB
                    // int len;
                    // while ((len = in.read(b)) != -1) {
                    // out.write(b, 0, len);
                    // }
                    // out.flush();
                    //                    
                    // in.close();
                    // out.close();

                    // 内容流写
                    // AssetFileDescriptor afd = getContentResolver()
                    // .openAssetFileDescriptor(
                    // Uri.parse("content://com.h3c.test/h3c.txt"),
                    // "wr");
                    // InputStream in = afd.createInputStream();
                    // File bkFile = new File("/mnt/sdcard/h3c2.txt");
                    // if (!bkFile.exists()) {
                    // bkFile.createNewFile();
                    // }
                    //
                    // FileOutputStream out = new FileOutputStream(bkFile);
                    // byte[] b = new byte[1024 * 5]; // 5KB
                    // int len;
                    // while ((len = in.read(b)) != -1) {
                    // out.write(b, 0, len);
                    // }
                    // out.flush();
                    // in.close();
                    // out.close();

                    // 内容流读
                    AssetFileDescriptor afd = getContentResolver()
                            .openAssetFileDescriptor(
                                    Uri.parse("content://com.h3c.test/h3c.txt"),
                                    "wr");
                    OutputStream out = afd.createOutputStream();
                    FileInputStream in = new FileInputStream(new File(
                            "/mnt/sdcard/h3c2.txt"));

                    byte[] b = new byte[1024 * 5]; // 5KB
                    int len;
                    while ((len = in.read(b)) != -1) {
                        out.write(b, 0, len);
                    }
                    out.flush();

                    in.close();
                    out.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

    }
}