标签：android database sharedpreferences 登录 append
在我们平时使用的手机应用都可以实现只需要登陆一次账号后，第二次进入应用直接跳转到效果界面的效果，还有QQ的登陆框是如何记忆我们的隐身登陆，保存账号选项的呢，这些都是通过使用SharedPreferences共享参数效果实现的，而无须使用数据库来存储。以下我们直接看详细代码分析。
package com.example.account.login;
import java.util.HashMap;
import java.util.Map;
import com.android.dao.MySQLiteOpenHelper;
import com.example.account.MainActivity;
import com.example.account.R;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class LoginActivity extends Activity {
private EditText e1, e2;
private SQLiteOpenHelper helper;
private boolean flag, flag2, flag3;
private HashMap<String, Object> map;
@SuppressWarnings("unchecked")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
TextView textView = (TextView) this.findViewById(R.id.textView1);
e1 = (EditText) this.findViewById(R.id.editText1);
e2 = (EditText) this.findViewById(R.id.editText2);
//从共享参数获取数据
map = (HashMap<String, Object>) getMsg("login");
if (map != null && !map.isEmpty()) {
if ((Boolean) map.get("login2")) {
//若值为true,用户无需输入密码，直接跳转进入操作界面
Intent intent = new Intent(LoginActivity.this,
MainActivity.class);
startActivity(intent);
}
}
helper = new MySQLiteOpenHelper(this);
textView.setText("登录界面");
Button button = (Button) findViewById(R.id.button2);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (!e1.getText().toString().isEmpty()
&& !e2.getText().toString().isEmpty()) {
//从数据库获取账号信息
SQLiteDatabase database = helper.getReadableDatabase();
Cursor cursor = database.query("user", new String[] {
"username", "password" }, null, null, null, null,
null);
while (cursor.moveToNext()) {
flag = e1
.getText()
.toString()
.equals(cursor.getString(cursor
.getColumnIndex("username")));
flag2 = e2
.getText()
.toString()
.equals(cursor.getString(cursor
.getColumnIndex("password")));
if (flag && flag2) {
Intent intent = new Intent(LoginActivity.this,
MainActivity.class);
startActivity(intent);
//登陆跳转动画
overridePendingTransition(R.anim.zoomin,
R.anim.zoomout);
Toast.makeText(LoginActivity.this, "登录成功",
Toast.LENGTH_SHORT).show();
flag3 = true;
//登陆成功后将flag设置为ture存入共享参数中
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("login2", flag3);
saveMsg("login", map);
}
}
if (!flag3) {
Toast.makeText(LoginActivity.this, "您输入的帐号或密码有误",
Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(LoginActivity.this, "请正确输入您的帐号密码",
Toast.LENGTH_SHORT).show();
}
}
});
Button button2 = (Button) findViewById(R.id.button1);
button2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(LoginActivity.this,
RegisterActivity.class);
startActivity(intent);
}
});
}
//将数据存储进入共享参数
public boolean saveMsg(String fileName, Map<String, Object> map) {
boolean flag = false;
// 一般Mode都使用private,比较安全
SharedPreferences preferences = getSharedPreferences(fileName,
Context.MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
// Map类提供了一个称为entrySet()的方法，这个方法返回一个Map.Entry实例化后的对象集。
// 接着，Map.Entry类提供了一个getKey()方法和一个getValue()方法，
// 因此，上面的代码可以被组织得更符合逻辑
for (Map.Entry<String, Object> entry : map.entrySet()) {
String key = entry.getKey();
Object object = entry.getValue();
// 根据值得不同类型，添加
if (object instanceof Boolean) {
Boolean new_name = (Boolean) object;
editor.putBoolean(key, new_name);
} else if (object instanceof Integer) {
Integer integer = (Integer) object;
editor.putInt(key, integer);
} else if (object instanceof Float) {
Float f = (Float) object;
editor.putFloat(key, f);
} else if (object instanceof Long) {
Long l = (Long) object;
editor.putLong(key, l);
} else if (object instanceof String) {
String s = (String) object;
editor.putString(key, s);
}
}
flag = editor.commit();
return flag;
}
// 读取数据
public Map<String, ?> getMsg(String fileName) {
Map<String, ?> map = null;
// 读取数据用不到edit
SharedPreferences preferences = getSharedPreferences(fileName,
Context.MODE_APPEND);
//Context.MODE_APPEND可以对已存在的值进行修改
map = preferences.getAll();
return map;
}
}
Android开发之自动登录功能的实现,布布扣,bubuko.com
标签：android database sharedpreferences 登录 append
原文地址：http://blog.csdn.net/gerogelin/article/details/35219377
