案例演示：把数据存在手机内存／sd卡。
存在手机内存
XML：
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| <?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.xxhuang.myapplication.MainActivity">
<EditText
android:id="@+id/et_number"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入账号"/>
<EditText
android:id="@+id/et_password"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:password="true"
android:hint="请输入密码"/>
<CheckBox
android:id="@+id/ck_remmber"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="记住密码"
android:checked="true"/>
<Button
android:id="@+id/bt_login"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="登录"/>
</LinearLayout>
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MainActivity:
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| public class MainActivity extends AppCompatActivity {
private EditText etNumber;
private EditText etPassword;
private Button btLogin;
private CheckBox ckRemmber;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
etNumber = (EditText) findViewById(R.id.et_number);
etPassword = (EditText) findViewById(R.id.et_password);
btLogin = (Button) findViewById(R.id.bt_login);
ckRemmber = (CheckBox) findViewById(R.id.ck_remmber);
Map<String,String> loadMap = Util.load();
if (loadMap != null){
etNumber.setText(loadMap.get("number"));
etPassword.setText(loadMap.get("password"));
}
etNumber.setSelection(etNumber.length());
btLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String number = etNumber.getText().toString();
String password = etPassword.getText().toString();
if (TextUtils.isEmpty(number) || TextUtils.isEmpty(password)){
Toast.makeText(MainActivity.this,"输入框不能为空",Toast.LENGTH_SHORT).show();
}
if (ckRemmber.isChecked() && !TextUtils.isEmpty(number) && !TextUtils.isEmpty(password)){
boolean isSuccess = Util.save(number, password);
if (isSuccess){
Toast.makeText(MainActivity.this,"保存成功",Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(MainActivity.this,"保存失败",Toast.LENGTH_SHORT).show();
}
}
}
});
}
}
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Util类：
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| public class Util{
public static boolean save(String number,String password){
try{
String path = "/data/data/com.example.xxhuang.myapplication/huang.text";
FileOutputStream fos = new FileOutputStream(path);
String data = number + "##" +password;
fos.write(data.getBytes());
fos.flush();
fos.close();
return true;
}catch (Exception e){
e.printStackTrace();
}
return false;
}
public static Map<String,String> load() {
try {
String path = "/data/data/com.example.xxhuang.myapplication/huang.text";
FileInputStream fis = new FileInputStream(path);
BufferedReader buffer = new BufferedReader(new InputStreamReader(fis));
String s = buffer.readLine();
if (!TextUtils.isEmpty(s)) {
String[] sqlit = s.split("##");
Map<String, String> loadMap = new HashMap<String, String>();
loadMap.put("number", sqlit[0]);
loadMap.put("password", sqlit[1]);
return loadMap;
}
}catch(Exception e){
e.printStackTrace();
}
return null;
}
}
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这样写，每次更改包名地址，path链接都需要改变，优化写法：
Util类：
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public static boolean save(Context context ,String number,String password){
try{
File fileDir = context.getFilesDir();
File file = new File(fileDir,"xxhuang.text");
FileOutputStream fos = new FileOutputStream(file);
...
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| public static Map<String,String> load(Context context) {
try {
File fileDir = context.getFilesDir();
File file = new File(fileDir,"xxhuang.text");
FileInputStream fis = new FileInputStream(file);
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MainActivity
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Map<String,String> loadMap = Util.load(this);
boolean isSuccess = Util.save(MainActivity.this, number, password);
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存在sd卡
得到sd卡的文件路径对象就是（其他和存储在手机内存是一样的意思）。
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| public class Util{
public static boolean save(Context context ,String number,String password){
try{
String state = Environment.getExternalStorageState();
if (!Environment.MEDIA_MOUNTED.equals(state)){
return false;
}
File sdCard = Environment.getExternalStorageDirectory();
File file = new File(sdCard,"xxhuang.text");
FileOutputStream fos = new FileOutputStream(file);
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| public static Map<String,String> load(Context context) {
try {
String state = Environment.getExternalStorageState();
if (!Environment.MEDIA_MOUNTED.equals(state)){
return null;
}
File sdCard = Environment.getExternalStorageDirectory();
File file = new File(sdCard,"xxhuang.text");
FileInputStream fis = new FileInputStream(file);
BufferedReader buffer = new BufferedReader(new InputStreamReader(fis));
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添加往sd卡写入的权限。
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| <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
|