Android中關於IO儲存的小記

經過Shared Preferences存儲數據java

private SharedPreferences mrsoft;//建立對象

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_qq2);
        final EditText qqzh = findViewById(R.id.qqzh);
        final EditText qqmm = findViewById(R.id.qqmm);
        Button qqdl=findViewById(R.id.qqdl);


        mrsoft = getSharedPreferences("mrsoft", MODE_PRIVATE);
       String username= mrsoft.getString("username",null);//獲取帳號，默認值設爲mr
        String password= mrsoft.getString("password",null);
        if(username!=null && password!=null)
        {
            qqzh.setText(username);
            qqmm.setText(password);

           // if (username.equals(mr)&&password.equals(mrsofts)) {
             // Intent intent = new Intent(qq2.this, duo.class);
              // startActivity(intent);
            //}
        }

qqdl.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    String in_username = qqzh.getText().toString();
                    String in_password = qqmm.getText().toString();
                    SharedPreferences.Editor editor = mrsoft.edit();
                    //if (in_username.equals(mr) && in_password.equals(mrsofts)) {
                    editor.putString("username1", in_username);
                    editor.putString("password1", in_password);
                    Log.i("調試是否獲取到", "執行到此");

                    Intent intent = new Intent(qq2.this, duo.class);
                    startActivity(intent);
                    Toast.makeText(qq2.this, "已保存密碼", Toast.LENGTH_SHORT).show();

                    editor.commit();
                    //}
                    //else {
                    // Toast.makeText(qq2.this,"帳號或密碼錯誤",Toast.LENGTH_SHORT).show();
                    //}

                }
            });
        }

總結對於Shared Preferences來講他出存儲的位置在data/data目錄下手機沒法直接查看，並且以xml文件的方式存儲到本地；xml文件以下所示ide

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="specialtext">hajsdh><?//</string>
<string name="username">dsa</string>
<string name="password">dasdasd</string>
<int name="int" value="47" />
<boolean name="or" value="true" />
</map>

儲存的步驟：
1.經過mrsoft = getSharedPreferences("mrsoft", MODE_PRIVATE);方法先獲取到一個sharp對象
2.經過SharedPreferences.Editor editor = mrsoft.edit();獲取到sharp的一個內部對象editor才能進行存儲操做
3.直接put便可，有點相似map集合前key後 valueeditor.putString("username1", in_username); editor.putString("password1", in_password);

this

讀取的操做：
1.經過mrsoft = getSharedPreferences("mrsoft", MODE_PRIVATE);方法先獲取到一個sharp對象
2.這樣便可String username= mrsoft.getString("username",null);//獲取帳號，默認值設爲mr String password= mrsoft.getString("password",null);

spa

經過IO流對象存儲讀取對象調試

public class jishi extends AppCompatActivity {

   byte[] buffer=null;
    File file;
    private EditText jis;
    private FileInputStream fis;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_jishi);
        Button baochun = findViewById(R.id.baochun);
        jis = findViewById(R.id.ji);
        file=new File(Environment.getExternalStorageDirectory(),"new.txt");

        try {
            fis = new FileInputStream(file);
            buffer =new byte[fis.available()];
            fis.read(buffer);


        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {

            try {
                fis.close();
                String data=new String(buffer);
                jis.setText(data);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }


        baochun.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                FileOutputStream fos=null;
                String text= jis.getText().toString();

                try {
                    fos=new FileOutputStream(file);
                    fos.write(text.getBytes());
                    fos.flush();
                    Toast.makeText(jishi.this,"保存成功",Toast.LENGTH_SHORT).show();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                    Toast.makeText(jishi.this,"文件不存在異常",Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    e.printStackTrace();
                    Toast.makeText(jishi.this,"io異常",Toast.LENGTH_SHORT).show();
                }finally {
                    if(fos!=null)
                    {
                        try {
                            fos.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }


            }
        });
    }


}

建立io對象：而後獲取讀取沒什麼區別，就是讀取流中I有個code

fis = new FileInputStream(file);
            buffer =new byte[fis.available()];
            fis.read(buffer);

看這個片斷，再也不經過指定byte【1024】來指定了xml