File文件存储

文件存储的核心是Context提供了一个openFileOutput()与openFileInput()俩个方法

课程demo

public class MainActivity extends AppCompatActivity {private EditText edit;    private TextView tx;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        edit= (EditText) findViewById(R.id.edit);        tx= (TextView) findViewById(R.id.tx);    }    @Override    protected void onDestroy() {        super.onDestroy();     String input=edit.getText().toString();        save(input);    }//保存数据思想：通过openFileOutput方法，得到一个FileOutputStream对象，将其包裹在OutputStreamWriter上，也生成一个对象，继续包裹在BufferedWriter上，得到一个对象调用write()方法，把数据传入

    private void save(String input) {        FileOutputStream fileout=null;        BufferedWriter writer=null;        try {   //data:文件名 Context.MODE_PRIVATE:访问权限            fileout=openFileOutput("data", Context.MODE_PRIVATE);            writer=new BufferedWriter(new OutputStreamWriter(fileout));            writer.write(input);        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        finally {            if(writer!=null)                try {                    writer.close();                } catch (IOException e) {                    e.printStackTrace();                }        }    }    public void doclick(View v) {        switch (v.getId()) {            case R.id.bt:            String text = load();            tx.setText(text);        }    }//取出数据    public String load()    {        FileInputStream input=null;        BufferedReader read=null;//StringBuilder的对象的append方法可以将字符连接起来        StringBuilder content=new StringBuilder();        try {            input=openFileInput("data");            read=new BufferedReader(new InputStreamReader(input));            String line="";            while((line=read.readLine())!=null){                content.append(line);            }        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return content.toString();    }}