Android transfers files through contentprovider

We know that data interaction between two Android applications requires contentprovider, which is usually a database operation.
Today, the project needs to use the contentprovider of Android to interact with files on the normal SD card, so I wrote this small example:
Androidmanifest. xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.h3c.test"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk android:minSdkVersion="15" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>    <application        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >        <activity            android:label="@string/app_name"            android:name=".NotepadTestActivity" >            <intent-filter >                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>                <provider android:name=".TestContentProvider" android:authorities="com.h3c.test" />    </application></manifest>

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 ){ // 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);} // This method is very important and must be rewritten. Otherwise, the filenotfound exception @ override public parcelfiledescriptor openfile (URI Uri, string mode) is reported by default) 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. packageman Ager. 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. onc Reate (savedinstancestate); setcontentview (R. layout. notepad); button = (button) findviewbyid (R. id. notepad); button. setonclicklistener (New onclicklistener () {@ override public void onclick (view v) {try {// directly read the file // 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 (); // directly write the file // 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 (); // content stream write // 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 (); // read the content stream 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 ();}}});}}