一般的输入输出流保存数据进文件

1、视图

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:paddingBottom="@dimen/activity_vertical_margin"
 6     android:paddingLeft="@dimen/activity_horizontal_margin"
 7     android:paddingRight="@dimen/activity_horizontal_margin"
 8     android:paddingTop="@dimen/activity_vertical_margin"
 9     tools:context=".MainActivity" >
10
11     <EditText
12         android:id="@+id/et_username"
13         android:layout_width="wrap_content"
14         android:layout_height="wrap_content"
15         android:layout_alignParentLeft="true"
16         android:layout_alignParentTop="true"
17         android:layout_marginLeft="20dp"
18         android:layout_marginTop="22dp"
19         android:ems="10" >
20
21
22     </EditText>
23
24     <EditText
25         android:id="@+id/et_password"
26         android:layout_width="wrap_content"
27         android:layout_height="wrap_content"
28         android:layout_alignLeft="@+id/et_username"
29         android:layout_below="@+id/et_username"
30         android:layout_marginTop="44dp"
31         android:inputType="textPassword"
32         android:ems="10" />
33
34     <Button
35         android:onClick="login"
36         android:id="@+id/button1"
37         android:layout_width="wrap_content"
38         android:layout_height="wrap_content"
39         android:layout_alignBaseline="@+id/cb"
40         android:layout_alignBottom="@+id/cb"
41         android:layout_alignParentRight="true"
42         android:layout_marginRight="32dp"
43         android:text="@string/login" />
44
45     <TextView
46         android:id="@+id/textView1"
47         android:layout_width="wrap_content"
48         android:layout_height="wrap_content"
49         android:layout_alignLeft="@+id/et_username"
50         android:layout_alignParentTop="true"
51         android:text="@string/please_input_username"
52         android:textSize="14sp"/>
53
54     <TextView
55         android:id="@+id/textView2"
56         android:layout_width="wrap_content"
57         android:layout_height="wrap_content"
58         android:layout_alignLeft="@+id/et_password"
59         android:layout_below="@+id/et_username"
60         android:layout_marginTop="24dp"
61         android:text="@string/please_input_password"
62         android:textSize="14sp" />
63
64     <CheckBox
65         android:checked="true"
66         android:id="@+id/cb"
67         android:layout_width="wrap_content"
68         android:layout_height="wrap_content"
69         android:layout_alignLeft="@+id/et_password"
70         android:layout_below="@+id/et_password"
71         android:layout_marginTop="27dp"
72         android:text="@string/is_remeber_password" />
73
74 </RelativeLayout>

2、activity代码

 1 package com.example.login;
 2
 3 import java.util.Map;
 4
 5 import com.example.login.service.LoginService;
 6
 7 import android.os.Bundle;
 8 import android.app.Activity;
 9 import android.text.TextUtils;
10 import android.view.Menu;
11 import android.view.View;
12 import android.widget.CheckBox;
13 import android.widget.EditText;
14 import android.widget.Toast;
15
16 public class MainActivity extends Activity {
17
18     private EditText et_username;
19     private EditText et_password;
20     private CheckBox cb;
21     @Override
22     protected void onCreate(Bundle savedInstanceState) {
23         super.onCreate(savedInstanceState);
24         setContentView(R.layout.activity_main);
25         et_username = (EditText)findViewById(R.id.et_username);
26         et_password = (EditText)findViewById(R.id.et_password);
27         cb = (CheckBox)findViewById(R.id.cb);
28
29         Map<String,String> map = LoginService.getUserInfo(this);
30         if(map != null){
31             et_username.setText(map.get("username"));
32             et_password.setText(map.get("password"));
33         }
34     }
35
36     public void login(View view)
37     {
38         String username = et_username.getText().toString().trim();
39         String password = et_password.getText().toString().trim();
40         if(TextUtils.isEmpty(username) || TextUtils.isEmpty(password)){
41             Toast.makeText(this, "用户名或者密码不能为空", Toast.LENGTH_SHORT).show();
42             return;
43         }
44
45         if(cb.isChecked()){
46             //保存用户信息
47             boolean result = LoginService.savaUserInfo(this,username, password);
48             if(result){
49                 Toast.makeText(this, "保存用户信息成功!", Toast.LENGTH_SHORT).show();
50             }else{
51                 Toast.makeText(this, "保存用户信息失败!", Toast.LENGTH_SHORT).show();
52             }
53         }
54
55         if("zhangsan".equals(username) && "123".equals(password)){
56             Toast.makeText(this, "登陆成功!", Toast.LENGTH_SHORT).show();
57         }else{
58             Toast.makeText(this, "用户名或者密码不正确!", Toast.LENGTH_SHORT).show();
59         }
60     }
61
62
63 }

3、采用普通输入输出流保存数据

 1 package com.example.login.service;
 2
 3 import java.io.BufferedReader;
 4 import java.io.File;
 5 import java.io.FileInputStream;
 6 import java.io.FileNotFoundException;
 7 import java.io.FileOutputStream;
 8 import java.io.InputStreamReader;
 9 import java.util.HashMap;
10 import java.util.Map;
11
12 import android.content.Context;
13
14 public class LoginService {
15     public static boolean savaUserInfo(Context context, String username, String password)
16     {
17         try{
18             //File file = new File("/data/data/com.example.login/info.txt");
19             File file = new File(context.getFilesDir(),"info.txt");
20             FileOutputStream fos = new FileOutputStream(file);
21             fos.write((username + "##" + password).getBytes());
22             fos.close();
23             return true;
24         }catch(Exception e){
25             e.printStackTrace();
26             return false;
27         }
28     }
29
30     public static Map<String,String> getUserInfo(Context context)
31     {
32         File file = new File(context.getFilesDir(),"info.txt");
33         try{
34             FileInputStream fis = new FileInputStream(file);
35             BufferedReader br = new BufferedReader(new InputStreamReader(fis));
36             String str = br.readLine();
37             String[] infos = str.split("##");
38             Map<String,String> map = new HashMap<String,String>();
39             map.put("username", infos[0]);
40             map.put("password", infos[1]);
41             return map;
42         }catch(Exception e){
43             e.printStackTrace();
44             return null;
45         }
46     }
47
48 }