Android开发官方文档---Sharing Files

（1）指定FileProvider

<manifestxmlns:android="http://schemas.android.com/apk/res/android" 

   package="com.example.myapp"> 

    <application 

        ...> 

       <provider 

            android:name="android.support.v4.content.FileProvider" 

            android:authorities="com.example.myapp.fileprovider"  //分享的URI地址

            android:grantUriPermissions="true" 

            android:exported="false"> 

            <meta-data 

               android:name="android.support.FILE_PROVIDER_PATHS" 

                android:resource="@xml/filepaths" /> 

//filepaths是一个xml文件，记录分享的文件路径

//resource属性不能直接设置成文件路径，XML文件时唯一的指定方式

       </provider> 

        ... 

    </application> 

</manifest>

 

res/xml/filepaths.xml

<paths> 

    <files-pathpath="images/" name="myimages" /> <!-- 内置存储路径-->

     <external-path> <!-- 外存储路径-->

     <cache-path> <!--内置存储缓存路径-->

</paths>

 

假设要获取images/文件夹下的default_image.jpg，最后获取的资源路径为：

content://com.example.myapp.fileprovider/myimages/default_image.jpg

 

 

创建选择页面Activity

（1）配置清单文件，action设置为pick，category设置为DEFAULT和OPENABLE，数据类型设置为分享的文件类型

<manifestxmlns:android="http://schemas.android.com/apk/res/android"> 

    ... 

       <application> 

        ... 

            <activity 

               android:name=".FileSelectActivity" 

                android:label="@"FileSelector" > 

                <intent-filter> 

                    <action 

                       android:name="android.intent.action.PICK"/> 

                    <category 

                       android:name="android.intent.category.DEFAULT"/> 

                    <category 

                       android:name="android.intent.category.OPENABLE"/> 

                    <dataandroid:mimeType="text/plain"/> 

                    <dataandroid:mimeType="image/*"/> 

                </intent-filter> 

            </activity>

（2）Activity中代码

public classMainActivity extends Activity { 

    // The path to the root of thisapp's internal storage 

    private File mPrivateRootDir; 

    // The path to the"images" subdirectory 

    private File mImagesDir; 

    // Array of files in the imagessubdirectory 

    File[] mImageFiles; 

    // Array of filenames correspondingto mImageFiles 

    String[] mImageFilenames; 

    // Initialize the Activity 

    @Override 

    protected void onCreate(BundlesavedInstanceState) { 

       ... 

        // Setup an Intent to send back to apps that request a file 

        mResultIntent = newIntent("com.example.myapp.ACTION_RETURN_FILE"); 

        // Getthe files/ subdirectory of internal storage 

        mPrivateRootDir = getFilesDir(); 

        // Getthe files/images subdirectory; 

        mImagesDir = new File(mPrivateRootDir, "images"); 

        // Getthe files in the images subdirectory 

        mImageFiles = mImagesDir.listFiles(); 

     

//-------------把 mImageFiles 放到 ListView 中-----------------------------------------------------------

//Define a listener that responds to clicks on a file in the ListView 

        mFileListView.setOnItemClickListener( 

                newAdapterView.OnItemClickListener() { 

            @Override 

            /* 

             * When a filename in the ListView is clicked, get its 

             * content URI and send it to the requesting app 

             */ 

            public void onItemClick(AdapterView<?>adapterView, 

                    Viewview, 

                    intposition, 

                    longrowId) { 

                /* 

                 * Get a File for the selected filename. 

                 * Assume that the file names are inthe 

                 * mImageFilename array. 

                 */ 

                File requestFile = new File(mImageFiles [position]); 

                /* 

                 * Most file-related method calls needto be in 

                 * try-catch blocks. 

                 */ 

                // Use the FileProvider to get acontent URI 

                try { 

                          fileUri = FileProvider.getUriForFile( MainActivity.this, 

                                                                                                           "com.example.myapp.fileprovider", 

                                                                                                   requestFile); 

        if (fileUri != null){ 

                //---------------------设置文件权限-----------------------------------

                    mResultIntent.addFlags( Intent.FLAG_GRANT_READ_URI_PERMISSION); 

  // ----------------Put the Uri and MIME type in the resultIntent --------------------------------

           mResultIntent.setDataAndType(  fileUri, getContentResolver().getType(fileUri)); 

           // Set the result 

           MainActivity.this.setResult(Activity.RESULT_OK,  mResultIntent); 

               }  else { 

                       mResultIntent.setDataAndType(null, ""); 

                       MainActivity.this.setResult(RESULT_CANCELED, mResultIntent); 

               } 

                } catch (IllegalArgumentException e){ 

                   Log.e("File Selector", 

                         "The selected file can't be shared: " + 

                          clickedFilename); 

                } 

            } 

       }); 

    } 

}

 

获取共享文件

使用startActivityForResult指定action和MIME类型

public classMainActivity extends Activity { 

    private IntentmRequestFileIntent; 

    private ParcelFileDescriptormInputPFD; 

    ... 

    @Override 

    protected void onCreate(BundlesavedInstanceState) { 

       super.onCreate(savedInstanceState); 

        setContentView(R.layout.activity_main); 

        mRequestFileIntent = new Intent(Intent.ACTION_PICK); 

        mRequestFileIntent.setType("image/jpg"); 

       ... 

    } 

    ... 

    protected void requestFile() { 

       /** 

         * When theuser requests a file, send an Intent to the 

         * server app. 

         * files. 

         */ 

            startActivityForResult(mRequestFileIntent,0); 

       ... 

    } 

   

     /* 

     * When the Activity of the app thathosts files sets a result and calls 

     * finish(), this method is invoked.The returned Intent contains the 

     * content URI of a selected file. Theresult code indicates if the 

     * selection worked or not. 

     */ 

    @Override 

    public void onActivityResult(intrequestCode, int resultCode,  Intent returnIntent) { 

        // Ifthe selection didn't work 

        if(resultCode != RESULT_OK) { 

            // Exit without doing anything else 

            return; 

        } else{ 

            // Get the file's content URI from the incoming Intent 

            UrireturnUri = returnIntent.getData();  //从返回的Intent中获取文件Uri

            /* 

             * Try to open the file for "read" access using the 

             * returned URI. If the file isn't found, write to the 

             * error log and return. 

             */ 

            try { 

                /* 

                 * Get the content resolver instancefor this context, and use it 

                 * to get a ParcelFileDescriptor forthe file. 

                 */ 

                 mInputPFD = getContentResolver().openFileDescriptor(returnUri,"r"); 

   } catch(FileNotFoundException e) { 

               e.printStackTrace(); 

                Log.e("MainActivity","File not found."); 

                return; 

            } 

            // 获取文件描述器 

            FileDescriptor fd = mInputPFD.getFileDescriptor(); 

   // 获取 MIME 类型

   String mimeType =getContentResolver().getType(returnUri); 

            ... 

/**

* FileProvider  提供默认的query()方法实现，返回名称（DISPLAY_NAME）和文件大小（SIZE）两列

* DISPLAY_NAME：是一个字符串跟File.getName()返回值一样

* SIZE：文件字节大小long型，跟File.length() 返回一样

*/

   Cursor returnCursor=  getContentResolver().query(returnUri,null, null, null, null); 

   /* 

     * Get thecolumn indexes of the data in the Cursor, 

     * move to thefirst row in the Cursor, get the data, 

     * and displayit. 

     */ 

    intnameIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME); 

    intsizeIndex = returnCursor.getColumnIndex(OpenableColumns.SIZE); 

    returnCursor.moveToFirst(); 

   TextView nameView = (TextView) findViewById(R.id.filename_text); 

   TextView sizeView = (TextView) findViewById(R.id.filesize_text); 

    nameView.setText(returnCursor.getString(nameIndex)); 

    sizeView.setText(Long.toString(returnCursor.getLong(sizeIndex))); 

    ...

 

       } 

    }

}