使用sharedPreferences实现密码登录和注册用户名重复检查

本文通过sharedPreferences实现密码登录以及注册用户是否重复的检查。

无法上传截图，直接上代码。实际项目中涉及用户账户密码的基本都是用数据库保存，而且经过加密（MD5 等）。

LoginActivity.java代码

package com.example.test;import java.security.MessageDigest;import java.util.ArrayList;import java.util.HashMap;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class LoginActivity extends Activity {    private int count;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.login);        Button login = (Button) findViewById(R.id.login);        Button register = (Button) findViewById(R.id.register);        final EditText username = (EditText) findViewById(R.id.username);        final EditText password = (EditText) findViewById(R.id.password);        final TextView tips = (TextView) findViewById(R.id.tips);        //int[] num={1,2};        //final HashMap<String,String> hashMap=new HashMap<String,String>();        count = MySharedPreference.getIntValue(LoginActivity.this, "count");        tips.setText("当前共有" + count + "人注册");        login.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                String strUsername = username.getText().toString();                String strPassword = password.getText().toString();                String defaultPass = MySharedPreference.getStringValue(LoginActivity.this, strUsername);                if (defaultPass.equals(strPassword)) {                    //匹配成功登录跳转                    Intent intent = new Intent(LoginActivity.this, FaceActivity.class);                    startActivity(intent);                    finish();                } else {                    showMessage("error");                    password.setText("");                }            }        });        register.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                String strUsername = username.getText().toString();                String strPassword = password.getText().toString();                boolean isNameRepeat = false;                Log.i("czktest", "strUsername=" + strUsername + ",strPassword=" + strPassword);                if (!strUsername.equals("") && !strPassword.equals("")) {                    //hashMap.put("one", strUsername);                    String[] names = new String[10];//最多保存10个用户                    if (count > 0) {                        for (int i = 0; i < count; i++) {//检查是否有用户名重复                            names[i] = String.valueOf(i);                            String name = MySharedPreference.getStringValue(LoginActivity.this, names[i]);                            if (name.equals(strUsername)) {                                showMessage("exist");                                isNameRepeat = true;                                break;                            }                        }                    }                    if (!isNameRepeat) {                        //用户名不重复执行保存（用户名--密码）                        MySharedPreference.register(LoginActivity.this, strUsername, strPassword);                        //用户名不重复执行保存（数组下标--用户名）                        names[count] = String.valueOf(count);                        MySharedPreference.saveNames(LoginActivity.this, names[count], strUsername);                        //用户名不重复执行保存（注册用户数）                        count = count + 1;                        MySharedPreference.saveCount(LoginActivity.this, "count", count);                        tips.setText("当前共有" + count + "人注册");                        showMessage("success");                    }                } else {                    showMessage("");                }            }        });    }    public void showMessage(String str) {        if (str.equals("error")) {            Toast.makeText(LoginActivity.this, "用户名和密码不匹配", Toast.LENGTH_SHORT).show();        } else if (str.equals("success")) {            Toast.makeText(LoginActivity.this, "注册成功", Toast.LENGTH_SHORT).show();        } else if (str.equals("exist")) {            Toast.makeText(LoginActivity.this, "当前用户已被注册", Toast.LENGTH_SHORT).show();        } else {            Toast.makeText(LoginActivity.this, "用户名或密码为空", Toast.LENGTH_SHORT).show();        }    }}

MySharedPreference.java代码

package com.example.test;import android.content.Context;import android.content.SharedPreferences;import android.content.SharedPreferences.Editor;import android.preference.PreferenceManager;public class MySharedPreference {    private static SharedPreferences preContext = null;    private static SharedPreferences getPreference(Context cx) {        return PreferenceManager.getDefaultSharedPreferences(cx);    }        public static void register(Context cx, String username, String password) {        setValue(cx, username, password);    }    public static void saveNames(Context cx, String username, String password) {        setValue(cx, username, password);    }    public static String getStringValue(Context cx, String key) {        if (preContext == null) {            preContext = getPreference(cx);        }        return preContext.getString(key, "error");    }    private static void setValue(Context cx, String key, String val) {        if (preContext == null) {            preContext = getPreference(cx);        }        Editor ed = preContext.edit();        ed.putString(key, val);        boolean ret = ed.commit();    }    public static void saveCount(Context cx, String key, int count) {        setValue(cx, key, count);    }    public static int getIntValue(Context cx, String key) {        if (preContext == null) {            preContext = getPreference(cx);        }        return preContext.getInt(key, 0);    }    private static void setValue(Context cx, String key, int val) {        if (preContext == null) {            preContext = getPreference(cx);        }        Editor ed = preContext.edit();        ed.putInt(key, val);        boolean ret = ed.commit();    }}

login.xml布局代码

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"     android:layout_marginTop="16dp"    android:layout_marginLeft="10dp"    android:layout_marginRight="10dp">    <LinearLayout                 android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">"        <TextView             android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="用户名:"            android:layout_weight="3"            android:gravity="right"/>        <EditText            android:id="@+id/username"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_weight="1"/>"    </LinearLayout>    <LinearLayout                 android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <TextView             android:layout_width="match_parent"            android:layout_height="wrap_content"            android:text="密    码:"            android:layout_weight="3"            android:gravity="right"/>        <EditText            android:id="@+id/password"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:inputType="textPassword"            android:layout_weight="1"/>    </LinearLayout>    <Button        android:id="@+id/login"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="登录"        android:textSize="18dp"        android:gravity="center"/>    <LinearLayout         android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">        <Button            android:id="@+id/register"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="注册"            android:textSize="16dp"/>        <TextView              android:alpha="1"              android:layout_width="0dp"              android:layout_height="wrap_content"              android:layout_weight="1.0"            android:textSize="16dp"            android:gravity="center"            android:id="@+id/tips" />         <Button            android:id="@+id/forgetpass"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="忘记密码"            android:textSize="16dp"            />    </LinearLayout></LinearLayout>