book/RegisterActivity.java

package com.grassroots.booktracker.activity;

import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.ActivityInfo;
import android.graphics.Color;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

import com.grassroots.booktracker.R;
import com.grassroots.booktracker.utils.MD5Utils;


public class RegisterActivity extends AppCompatActivity {
    private TextView tv_main_title;//标题
    private TextView tv_back;//返回按钮
    private Button btn_register;//注册按钮
    //用户名，密码，再次输入的密码的控件
    private EditText et_user_name, et_psw, et_psw_again;
    //用户名，密码，再次输入的密码的控件的获取值
    private String userName, psw, pswAgain;
    //标题布局
    private RelativeLayout rl_title_bar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //设置页面布局 ,注册界面
        setContentView(R.layout.activity_register);
        //设置此界面为竖屏
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        init();
    }

    private void init() {
        //从main_title_bar.xml 页面布局中获取对应的UI控件
        tv_main_title = findViewById(R.id.tv_main_title);
        tv_main_title.setText("注册");
        tv_back = findViewById(R.id.tv_back);
        //布局根元素
        rl_title_bar = findViewById(R.id.title_bar);
        rl_title_bar.setBackgroundColor(Color.TRANSPARENT);
        //从activity_register.xml 页面中获取对应的UI控件
        btn_register = findViewById(R.id.btn_register);
        et_user_name = findViewById(R.id.et_user_name);
        et_psw = findViewById(R.id.et_psw);
        et_psw_again = findViewById(R.id.et_psw_again);
        tv_back.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //返回键
                RegisterActivity.this.finish();
            }
        });
        //注册按钮
        btn_register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //获取输入在相应控件中的字符串
                getEditString();
                //判断输入框内容
                if (TextUtils.isEmpty(userName)) {
                    Toast.makeText(RegisterActivity.this, "请输入用户名", Toast.LENGTH_SHORT).show();
                } else if (TextUtils.isEmpty(psw)) {
                    Toast.makeText(RegisterActivity.this, "请输入密码", Toast.LENGTH_SHORT).show();
                } else if (TextUtils.isEmpty(pswAgain)) {
                    Toast.makeText(RegisterActivity.this, "请再次输入密码", Toast.LENGTH_SHORT).show();
                } else if (!psw.equals(pswAgain)) {
                    Toast.makeText(RegisterActivity.this, "输入两次的密码不一样", Toast.LENGTH_SHORT).show();
                    /**
                     *从SharedPreferences中读取输入的用户名，判断SharedPreferences中是否有此用户名
                     */
                } else if (isExistUserName(userName)) {
                    Toast.makeText(RegisterActivity.this, "此账户名已经存在", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(RegisterActivity.this, "注册成功", Toast.LENGTH_SHORT).show();
                    //把账号、密码和账号标识保存到sp里面
                    /**
                     * 保存账号和密码到SharedPreferences中
                     */
                    saveRegisterInfo(userName, psw);
                    //注册成功后把账号传递到LoginActivity.java中
                    // 返回值到loginActivity显示
                    Intent data = new Intent();
                    data.putExtra("userName", userName);
                    setResult(RESULT_OK, data);
                    //RESULT_OK为Activity系统常量，状态码为-1，
                    // 表示此页面下的内容操作成功将data返回到上一页面，如果是用back返回过去的则不存在用setResult传递data值
                    RegisterActivity.this.finish();
                }
            }
        });
    }

    /**
     * 获取控件中的字符串
     */
    private void getEditString() {
        userName = et_user_name.getText().toString().trim();
        psw = et_psw.getText().toString().trim();
        pswAgain = et_psw_again.getText().toString().trim();
    }

    /**
     * 从SharedPreferences中读取输入的用户名，判断SharedPreferences中是否有此用户名
     */
    private boolean isExistUserName(String userName) {
        boolean has_userName = false;
        //mode_private SharedPreferences sp = getSharedPreferences( );
        // "loginInfo", MODE_PRIVATE
        SharedPreferences sp = getSharedPreferences("loginInfo", MODE_PRIVATE);
        //获取密码
        String spPsw = sp.getString(userName, "");//传入用户名获取密码
        //如果密码不为空则确实保存过这个用户名
        if (!TextUtils.isEmpty(spPsw)) {
            has_userName = true;
        }
        return has_userName;
    }

    /**
     * 保存账号和密码到SharedPreferences中SharedPreferences
     */
    private void saveRegisterInfo(String userName, String psw) {
        String md5Psw = MD5Utils.md5(psw);//把密码用MD5加密
        //loginInfo表示文件名, mode_private SharedPreferences sp = getSharedPreferences( );
        SharedPreferences sp = getSharedPreferences("loginInfo", MODE_PRIVATE);
        //获取编辑器， SharedPreferences.Editor  editor -> sp.edit();
        SharedPreferences.Editor editor = sp.edit();
        //以用户名为key，密码为value保存在SharedPreferences中
        //key,value,如键值对，editor.putString(用户名，密码）;
        editor.putString(userName, md5Psw);
        //提交修改 editor.commit();
        editor.commit();
    }
}