作业：把用户的注册信息存储到文件里，登录成功后读出并显示出来

activity_practice2的layout文件：

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent"
 6     android:paddingBottom="@dimen/activity_vertical_margin"
 7     android:paddingLeft="@dimen/activity_horizontal_margin"
 8     android:paddingRight="@dimen/activity_horizontal_margin"
 9     android:paddingTop="@dimen/activity_vertical_margin"
10     tools:context="com.hanqi.testapp3.PractiseActivity2"
11     android:orientation="vertical">
12 
13     <LinearLayout
14         android:layout_width="match_parent"
15         android:layout_height="wrap_content"
16         android:orientation="horizontal">
17         <TextView
18             android:layout_width="wrap_content"
19             android:layout_height="wrap_content"
20             android:text="用户名："/>
21         <EditText
22             android:layout_width="match_parent"
23             android:layout_height="wrap_content"
24             android:id="@+id/et_username"/>
25     </LinearLayout>
26     <LinearLayout
27         android:layout_width="match_parent"
28         android:layout_height="wrap_content"
29         android:orientation="horizontal">
30         <TextView
31             android:layout_width="wrap_content"
32             android:layout_height="wrap_content"
33             android:text="密码："/>
34         <EditText
35             android:layout_width="match_parent"
36             android:layout_height="wrap_content"
37             android:id="@+id/et_password"
38             android:inputType="textPassword"/>
39     </LinearLayout>
40     <LinearLayout
41         android:layout_width="match_parent"
42         android:layout_height="wrap_content"
43         android:orientation="horizontal">
44         <Button
45         android:layout_width="0dp"
46         android:layout_height="wrap_content"
47         android:text="登陆"
48         android:onClick="bt_dl_onClick"
49         android:layout_weight="1"/>
50         <Button
51             android:layout_width="0dp"
52             android:layout_height="wrap_content"
53             android:text="注册"
54             android:onClick="bt_zc_onClick"
55             android:layout_weight="1"/>
56     </LinearLayout>
57 
58     <!--<Button-->
59         <!--android:layout_width="match_parent"-->
60         <!--android:layout_height="wrap_content"-->
61         <!--android:text="fdasf"-->
62         <!--android:onClick="bt_onClick"-->
63         <!--android:id="@+id/bt_1"/>-->
64 </LinearLayout>
View Code

activity_practice2_2的layout文件： 

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent"
 6     android:paddingBottom="@dimen/activity_vertical_margin"
 7     android:paddingLeft="@dimen/activity_horizontal_margin"
 8     android:paddingRight="@dimen/activity_horizontal_margin"
 9     android:paddingTop="@dimen/activity_vertical_margin"
10     tools:context="com.hanqi.testapp3.PractiseActivity2_2">
11 
12         <EditText
13             android:layout_width="match_parent"
14             android:layout_height="wrap_content"
15             android:hint="用户名称"
16             android:id="@+id/et_username_1"/>
17         <EditText
18             android:layout_width="match_parent"
19             android:layout_height="wrap_content"
20             android:hint="登陆密码"
21             android:id="@+id/et_password_1"
22             android:layout_below="@id/et_username_1"
23             android:inputType="textPassword"/>
24         <EditText
25             android:layout_width="match_parent"
26             android:layout_height="wrap_content"
27             android:hint="个性签名"
28             android:id="@+id/et_gxqm"
29             android:layout_below="@id/et_password_1"/>
30 
31         <LinearLayout
32             android:layout_width="match_parent"
33             android:layout_height="wrap_content"
34             android:layout_alignParentBottom="true">
35             <Button
36                 android:layout_width="wrap_content"
37                 android:layout_height="wrap_content"
38                 android:text="确定"
39                 android:layout_weight="1"
40                 android:onClick="bt_qd_onClick"/>
41             <Button
42                 android:layout_width="wrap_content"
43                 android:layout_height="wrap_content"
44                 android:text="取消"
45                 android:layout_weight="1"
46                 android:onClick="bt_qx_onClick"/>
47         </LinearLayout>
48     <!--<Button-->
49         <!--android:layout_width="match_parent"-->
50         <!--android:layout_height="wrap_content"-->
51         <!--android:text="fdasf"-->
52         <!--android:onClick="bt_onClick"-->
53         <!--android:id="@+id/bt_1"-->
54         <!--android:layout_below="@+id/et_gxqm"/>-->
55 </RelativeLayout>
View Code

activity_practice2_3的layout文件：

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent"
 6     android:paddingBottom="@dimen/activity_vertical_margin"
 7     android:paddingLeft="@dimen/activity_horizontal_margin"
 8     android:paddingRight="@dimen/activity_horizontal_margin"
 9     android:paddingTop="@dimen/activity_vertical_margin"
10     tools:context="com.hanqi.testapp3.PractiseActivity2_3">
11 
12     <TextView
13         android:layout_width="match_parent"
14         android:layout_height="wrap_content"
15         android:id="@+id/tv_username"
16         android:textSize="30dp"/>
17     <TextView
18         android:layout_width="match_parent"
19         android:layout_height="wrap_content"
20         android:id="@+id/tv_gxqm"
21         android:layout_below="@id/tv_username"
22         android:textSize="30dp"/>
23 </RelativeLayout>
View Code

PractiseActivity2的java类：

  1 package com.hanqi.testapp3;
  2 
  3 import android.content.Intent;
  4 import android.os.Bundle;
  5 import android.support.v7.app.AppCompatActivity;
  6 import android.view.View;
  7 import android.widget.EditText;
  8 import android.widget.Toast;
  9 
 10 import java.io.FileInputStream;
 11 
 12 public class PractiseActivity2 extends AppCompatActivity {
 13 
 14     EditText et_username;
 15     EditText et_password;
 16 
 17 //    Button bt_1;
 18     @Override
 19     protected void onCreate(Bundle savedInstanceState) {
 20         super.onCreate(savedInstanceState);
 21         setContentView(R.layout.activity_practise2);
 22         et_username = (EditText)findViewById(R.id.et_username);
 23         et_password = (EditText)findViewById(R.id.et_password);
 24         //bt_1 = (Button)findViewById(R.id.bt_1);
 25     }
 26     public void bt_zc_onClick(View v)
 27     {
 28         Intent intent = new Intent(this,PractiseActivity2_2.class);
 29         startActivity(intent);
 30     }
 31 
 32     public void bt_dl_onClick(View v)
 33     {
 34         String str1 = "";
 35         String str2 = "";
 36         String str3 = "";
 37         String uc = et_username.getText().toString();
 38         String pw = et_password.getText().toString();
 39 
 40         try {
 41             FileInputStream fis = openFileInput("practise2-1.txt");
 42             byte[] b = new byte[1024];
 43             int i;
 44 
 45             while ((i=fis.read(b))>0)
 46             {
 47                 String str = new String(b,0,i);
 48                 str1 += str;
 49             }
 50             fis.close();
 51 
 52             FileInputStream fis2 = openFileInput("practise2-2.txt");
 53             byte[] b2 = new byte[1024];
 54             int i2 = 0;
 55             while ((i2=fis2.read(b2))>0)
 56             {
 57                 String str = new String(b2,0,i2);
 58                 str2 += str;
 59             }
 60             fis2.close();
 61 
 62             FileInputStream fis3 = openFileInput("practise2-3.txt");
 63             byte[] b3 = new byte[1024];
 64             int i3 = 0;
 65             while ((i3=fis3.read(b3))>0)
 66             {
 67                 String str = new String(b3,0,i3);
 68                 str3 += str;
 69             }
 70             fis3.close();
 71         }
 72        catch (Exception e)
 73        {
 74 
 75        }
 76         if (uc.trim().length()==0||pw.trim().length()==0)
 77         {
 78             Toast.makeText(PractiseActivity2.this, "用户名和密码不能为空", Toast.LENGTH_SHORT).show();
 79             return;
 80         }
 81         if (str1 ==null||(str1!=null&&!str1.equals(uc)))
 82         {
 83             Toast.makeText(PractiseActivity2.this, "用户未注册", Toast.LENGTH_SHORT).show();
 84             return;
 85         }
 86         if (!str2.equals(pw))
 87         {
 88             Toast.makeText(PractiseActivity2.this, "密码错误", Toast.LENGTH_SHORT).show();
 89             return;
 90         }
 91         else
 92         {
 93             Toast.makeText(PractiseActivity2.this, "用户验证成功", Toast.LENGTH_SHORT).show();
 94             Intent intent = new Intent(this,PractiseActivity2_3.class);
 95             startActivity(intent);
 96             finish();
 97         }
 98     }
 99 //    public void bt_onClick(View v)
100 //    {
101 //        try {
102 //            FileInputStream fis = openFileInput("practise2-1.txt");
103 //            byte[] b = new byte[1024];
104 //            int i;
105 //
106 //            while ((i=fis.read(b))>0)
107 //            {
108 //                String str = new String(b,0,i);
109 //                str1 += str;
110 //            }
111 //
112 //            fis.close();
113 //        }
114 //        catch (Exception e)
115 //        {
116 //
117 //        }
118 //        bt_1.setText(str1);
119 //    }
120 }
View Code

PractiseActivity2_2的java类：

 1 package com.hanqi.testapp3;
 2 
 3 import android.content.Intent;
 4 import android.support.v7.app.AppCompatActivity;
 5 import android.os.Bundle;
 6 import android.view.View;
 7 import android.widget.EditText;
 8 import android.widget.Toast;
 9 
10 import java.io.FileOutputStream;
11 import java.io.PrintStream;
12 
13 public class PractiseActivity2_2 extends AppCompatActivity {
14 
15     EditText et_username_1;
16     EditText et_password_1;
17     EditText et_gxqm;
18     @Override
19     protected void onCreate(Bundle savedInstanceState) {
20         super.onCreate(savedInstanceState);
21         setContentView(R.layout.activity_practise2_2);
22         et_username_1 = (EditText)findViewById(R.id.et_username_1);
23         et_password_1 = (EditText)findViewById(R.id.et_password_1);
24         et_gxqm = (EditText)findViewById(R.id.et_gxqm);
25     }
26     public void bt_qd_onClick(View v)
27     {
28         String username = et_username_1.getText().toString();
29         if (username ==null||username.trim().length()==0)
30         {
31             Toast.makeText(PractiseActivity2_2.this, "请填写用户名", Toast.LENGTH_SHORT).show();
32             return;
33         }
34         String password = et_password_1.getText().toString();
35         if (password ==null||password.trim().length()==0)
36         {
37             Toast.makeText(PractiseActivity2_2.this, "请填写密码", Toast.LENGTH_SHORT).show();
38             return;
39         }
40         String gxqm = et_gxqm.getText().toString();
41         if (gxqm ==null||gxqm.trim().length()==0)
42         {
43             Toast.makeText(PractiseActivity2_2.this, "个性签名为必填内容", Toast.LENGTH_SHORT).show();
44             return;
45         }
46         try {
47             FileOutputStream fos = openFileOutput("practise2-1.txt",MODE_PRIVATE);
48             PrintStream ps = new PrintStream(fos);
49             ps.print(username);
50             FileOutputStream fos2 = openFileOutput("practise2-2.txt",MODE_PRIVATE);
51             PrintStream ps2 = new PrintStream(fos2);
52             ps2.print(password);
53             FileOutputStream fos3 = openFileOutput("practise2-3.txt",MODE_PRIVATE);
54             PrintStream ps3 = new PrintStream(fos3);
55             ps3.print(gxqm);
56             ps.close();
57             ps2.close();
58             ps3.close();
59             fos.close();
60             Toast.makeText(PractiseActivity2_2.this, "保存成功", Toast.LENGTH_SHORT).show();
61         }
62         catch (Exception e)
63         {
64 
65         }
66         Intent intent = new Intent(this,PractiseActivity2.class);
67         startActivity(intent);
68         finish();
69     }
70     public void bt_qx_onClick(View v)
71     {
72         setResult(RESULT_CANCELED, null);
73         finish();
74     }
75 
76 }
View Code

PractiseActivity2_3的java类：

 1 package com.hanqi.testapp3;
 2 
 3 import android.support.v7.app.AppCompatActivity;
 4 import android.os.Bundle;
 5 import android.widget.TextView;
 6 
 7 import java.io.FileInputStream;
 8 
 9 public class PractiseActivity2_3 extends AppCompatActivity {
10 
11     TextView tv_username;
12     TextView tv_gxqm;
13 
14     String str1 = "";
15     String str3 = "";
16     @Override
17     protected void onCreate(Bundle savedInstanceState) {
18         super.onCreate(savedInstanceState);
19         setContentView(R.layout.activity_practise2_3);
20         tv_username = (TextView)findViewById(R.id.tv_username);
21         tv_gxqm = (TextView)findViewById(R.id.tv_gxqm);
22 
23         try {
24             FileInputStream fis = openFileInput("practise2-1.txt");
25             byte[] b = new byte[1024];
26             int i;
27 
28             while ((i=fis.read(b))>0)
29             {
30                 String str = new String(b,0,i);
31                 str1 += str;
32             }
33 
34             fis.close();
35 
36             FileInputStream fis3 = openFileInput("practise2-3.txt");
37             byte[] b3 = new byte[1024];
38             int i3 = 0;
39             while ((i3=fis3.read(b3))>0)
40             {
41                 String str = new String(b3,0,i3);
42                 str3 += str;
43             }
44             fis3.close();
45         }
46         catch (Exception e)
47         {
48 
49         }
50         tv_username.setText("用户名是：" + str1);
51         tv_gxqm.setText("个性签名是："+str3);
52     }
53 }
View Code

效果为：