安卓案例2：簡單登錄界面和保存信息

界面效果：

佈局代碼：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <EditText
        android:id="@+id/et_username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="請輸入用戶名" />

    <EditText
        android:id="@+id/et_userpassword"
        android:password="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="請輸入密碼" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="20dp" >

        <CheckBox
            android:id="@+id/cb_ischeck"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="記住用戶名密碼" />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:onClick="login"
            android:text="登錄" />
    </RelativeLayout>

</LinearLayout>

MainActivity:

package com.dreamtech.login;

import java.util.Map;

import android.os.Bundle;
import android.app.Activity;
import android.text.TextUtils;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private EditText et_name;
    private EditText et_password;
    private CheckBox cb_ischeck;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_name = (EditText) findViewById(R.id.et_username);
        et_password = (EditText) findViewById(R.id.et_userpassword);
        cb_ischeck = (CheckBox) findViewById(R.id.cb_ischeck);

        // 讀取已存的數據
        Map<String, String> maps = UserInfoUtils.readInfo(MainActivity.this);

        if (maps != null) {
            // 取出
            String name = maps.get("name");
            String pwd = maps.get("pwd");
            et_name.setText(name);
            et_password.setText(pwd);
        }
    }

    // 點擊事件
    public void login(View v) {
        String name = et_name.getText().toString().trim();
        String pwd = et_password.getText().toString().trim();
        // 判斷用戶名密碼是否為空
        if (TextUtils.isEmpty(name) || TextUtils.isEmpty(pwd)) {
            Toast.makeText(MainActivity.this, "用戶名或密碼不能為空", Toast.LENGTH_LONG)
                    .show();
        } else {
            // 這裡不做資料庫操作，只是簡單的登錄邏輯
            System.out.println("連接伺服器驗證");
            // 存儲在本地
            if (cb_ischeck.isChecked()) {
                boolean result = UserInfoUtils.saveInfo(MainActivity.this,
                        name, pwd);
                if (result) {
                    Toast.makeText(MainActivity.this, "保存成功！",
                            Toast.LENGTH_LONG).show();
                } else {
                    Toast.makeText(MainActivity.this, "保存失敗", Toast.LENGTH_LONG)
                            .show();
                }
            } else {
                Toast.makeText(MainActivity.this, "請勾選", Toast.LENGTH_LONG)
                        .show();
            }
        }

    }

}

讀寫文件工具類：

package com.dreamtech.login;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import android.content.Context;

public class UserInfoUtils {
    // 保存數據工具類
    public static boolean saveInfo(Context context ,String username, String pwd) {
        try {
            String path = context.getFilesDir().getPath();
            String result = username + "&&" + pwd;
            File file = new File(path,"info.txt");
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(result.getBytes());
            fos.close();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    public static Map<String, String> readInfo(Context context) {
        try {
            String path = context.getFilesDir().getPath();
            Map<String, String> maps = new HashMap<String, String>();
            File file = new File(path,"info.txt");
            FileInputStream fis = new FileInputStream(file);
            BufferedReader bufr = new BufferedReader(new InputStreamReader(fis));
            String content = bufr.readLine();
            String[] splits = content.split("&&");
            String name = splits[0];
            String pwd = splits[1];
            maps.put("name", name);
            maps.put("pwd", pwd);
            fis.close();
            return maps;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}