Android data storage-file storage

There are five ways to store data on the Android platform:
1. File storage data;
2. Use sharedpreferences to store data;
3. SQLite database stores data;
4. Use contentprovider to store data;
5. network storage data;
Here we will introduce file storage:
The file storage method is a commonly used method. It reads/writes files in Android and implements I/OProgramIs exactly the same,
Openfileinput () and openfileoutput () methods are provided to read files on the device. In this way, data is stored in the Files folder under data/<package name>.
Of course, files can also be read from the raw folder or asset folder of the program.

 

Import Java. io. fileinputstream; <br/> Import Java. io. fileoutputstream; <br/> Import Java. io. inputstream; </P> <p> Import Org. apache. HTTP. util. encodingutils; </P> <p> Import android. app. activity; <br/> Import android. OS. bundle; <br/> Import android. view. view; <br/> Import android. view. view. onclicklistener; <br/> Import android. widget. button; <br/> Import android. widget. textview; </P> <p> public class fileactivity E Xtends activity {<br/> Public static final string encoding = "UTF-8"; // encoding format <br/> string filename = "test.txt "; // file name <br/> string message = "this is an example of file I/O. "; // Data information written and read <br/> textview TV; <br/> button btn1; <br/> button btn2; <br/> button btn3; <br/>/** called when the activity is first created. */<br/> @ override <br/> Public void oncreate (bundle savedinstancestate) {<br/> super. oncreate (savedinstancestate); <br/> setcontentview (R. layout. main); <br/> TV = (textview) findviewbyid (R. id. TV); <br/> btn1 = (button) findviewbyid (R. id. btn1); <br/> btn2 = (button) findviewbyid (R. id. btn2); <br/> btn3 = (button) findviewbyid (R. id. btn3); <br/> writefiledata (filename, message); <br/> btn1.setonclicklistener (New onclicklistener () {</P> <p> @ override <br/> Public void onclick (view v) {<br/> // todo auto-generated method stub <br/> TV. settext (readfiledata (filename); <br/>}< br/>}); <br/> btn2.setonclicklistener (New onclicklistener () {</P> <p> @ override <br/> Public void onclick (view v) {<br/> // todo auto-generated method stub <br/> TV. settext (getfromrow ("test1.txt"); </P> <p >}< br/>}); <br/> btn3.setonclicklistener (New onclicklistener () {</P> <p> @ override <br/> Public void onclick (view v) {<br/> // todo auto-generated method stub <br/> TV. settext (getfromasset ("test2.txt"); <br/>}< br/> }); </P> <p >}< br/> // write the specified data to the specified file <br/> Public void writefiledata (string filename, string message) {<br/> try {<br/> fileoutputstream fout = openfileoutput (filename, mode_private); <br/> byte [] bytes = message. getbytes (); // convert the string to be written to a byte array <br/> fout. write (bytes); // write the byte array to the file <br/> fout. close (); <br/>}catch (exception e) {<br/> E. printstacktrace (); <br/>}< br/> // open a specified file and read its data, returns a String object <br/> Public String readfiledata (string filename) {<br/> string result = ""; <br/> try {<br/> fileinputstream fin = openfileinput (filename); // obtain the fileinputstream object <br/> int length = fin. available (); // get the object length <br/> byte [] buffer = new byte [length]; <br/> fin. read (buffer); <br/> result = encodingutils. getstring (buffer, encoding); // converts a byte array to a string in the specified format. <br/> fin. close (); <br/>}catch (exception e) {<br/> E. printstacktrace (); <br/>}< br/> return result; <br/>}</P> <p> // method: get the file from the raw folder in resource and read the data <br/> Public String getfromrow (string filename) {<br/> string result = ""; <br/> try {<br/> inputstream in = getresources (). openrawresource (R. raw. test1); <br/> int length = in. available (); <br/> byte [] buffer = new byte [length]; <br/> in. read (buffer); <br/> result = encodingutils. getstring (buffer, encoding); <br/> in. close (); <br/>}catch (exception e) {<br/> E. printstacktrace (); <br/>}< br/> return result; <br/>}< br/> // obtain the file from the asset and read the data <br/> Public String getfromasset (string filename) {<br/> string result = ""; <br/> try {<br/> inputstream in = getresources (). getassets (). open (filename); <br/> int length = in. available (); // get the number of bytes of the object <br/> byte [] buffer = new byte [length]; // create a byte array <br/> in. read (buffer); // read the data in the file to the byte array <br/> result = encodingutils. getstring (buffer, encoding); <br/>} catch (exception e) {<br/> E. printstacktrace (); <br/>}< br/> return result; <br/>}< br/>