layout：
javaBean
//学生类
public class Student {
private int stu_id; //学号
private String stu_name; //姓名
private char stu_sex;//性别
private float weight;//体重
private String stu_pwd; //密码
public Student(int stu_id, String stu_pwd) {
this.stu_id = stu_id;
this.stu_pwd = stu_pwd;
}
public Student(int stu_id, String stu_name, String stu_pwd) {
this.stu_id = stu_id;
this.stu_name = stu_name;
this.stu_pwd = stu_pwd;
}
public String getStu_pwd() {
return stu_pwd;
}
public void setStu_pwd(String stu_pwd) {
this.stu_pwd = stu_pwd;
}
public float getWeight() {
return weight;
}
public void setWeight(float weight) {
this.weight = weight;
}
public int getStu_id() {
return stu_id;
}
public void setStu_id(int stu_id) {
this.stu_id = stu_id;
}
public String getStu_name() {
return stu_name;
}
public void setStu_name(String stu_name) {
this.stu_name = stu_name;
}
public char getStu_sex() {
return stu_sex;
}
public void setStu_sex(char stu_sex) {
this.stu_sex = stu_sex;
}
}
UsrDBHelper class
public class UsrDBHelper extends SQLiteOpenHelper {
public static final String DB_NAME = "student.db";
public static final int DB_VERSION=1;
public static final String TABLE_NAME="info"; //表名
public UsrDBHelper( Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String create_table_sql="CREATE TABLE IF NOT EXISTS "+TABLE_NAME+" ("+
"ID INTEGER PRIMARY KEY NOT NULL," +
"NAME VARCHAR,SEX VARCHAR,WEIGHT REAL,PASSWORD VARCHAR)";
db.execSQL(create_table_sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
Dao class
public class Dao {
private UsrDBHelper mHelper;
public Dao(Context context) {
mHelper = new UsrDBHelper(context);
}
//注册 只需姓名学号和密码
public void insert(Student student) {
SQLiteDatabase db = mHelper.getWritableDatabase();
String insert_sql = "INSERT INTO " + UsrDBHelper.TABLE_NAME +
" (ID,NAME,PASSWORD) VALUES (?,?,?)";
Object[] obj = {
student.getStu_id(), student.getStu_name(), student.getStu_pwd()};
db.execSQL(insert_sql, obj);
db.close();
}
public String query(Student student) {
//查询某一行
SQLiteDatabase db = mHelper.getReadableDatabase();
String query_sql = "select * from " + UsrDBHelper.TABLE_NAME + " where id = " + student.getStu_id();
Cursor cursor=db.rawQuery(query_sql,null);
if (0 == cursor.getCount()) {
return null;
}
cursor.moveToFirst();
int stu_id= cursor.getInt(0);
System.out.println(stu_id);
String stu_pwd= cursor.getString(4);
cursor.close();
db.close();
return stu_id+";"+stu_pwd;
}
Activity
Login class
public class Login extends AppCompatActivity implements View.OnClickListener {
private EditText et_stuId;
private EditText et_stuPwd;
private Button btn_login;
private TextView tv_register;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.stu_login);
initView();
}
private void initView() {
et_stuId = (EditText) findViewById(R.id.et_stuid);
et_stuPwd = (EditText) findViewById(R.id.et_stupwd);
btn_login = (Button) findViewById(R.id.btn_login);
tv_register = (TextView) findViewById(R.id.tv_register);
btn_login.setOnClickListener(this);
tv_register.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_login:
login();
break;
case R.id.tv_register:
Intent intent=new Intent(this,Register.class);
startActivity(intent);
}
}
public void login() {
String stu_id = et_stuId.getText().toString().trim();
String stu_pwd = et_stuPwd.getText().toString().trim();
if (TextUtils.isEmpty(stu_id) || TextUtils.isEmpty(stu_pwd)) {
Toast.makeText(this, "账号和密码不能为空", Toast.LENGTH_SHORT).show();
} else {
Student student = new Student(Integer.parseInt(stu_id), stu_pwd);
Dao dao = new Dao(this);
String result = dao.query(student);
if (result == null || result.length() == 0) {
Toast.makeText(this, "用户不存在，请先注册", Toast.LENGTH_SHORT).show();
} else{
String[] a = result.split(";");
String id = a[0];
String pwd = a[1];
if (stu_id.equals(id) && stu_pwd.equals(pwd)) {
Toast.makeText(this, "登陆成功", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "用户或密码错误，登陆失败", Toast.LENGTH_SHORT).show();
}
}
}
}
}
Register class
public class Register extends AppCompatActivity implements View.OnClickListener {
private EditText et_register_stuid;
private EditText et_register_pwd;
private EditText et_register_name;
private Button btn_register;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.stu_register);
initView();
}
private void initView() {
et_register_stuid = (EditText) findViewById(R.id.et_register_stuid);
et_register_pwd = (EditText) findViewById(R.id.et_register_pwd);
et_register_name = (EditText) findViewById(R.id.et_register_name);
btn_register = (Button) findViewById(R.id.btn_register);
btn_register.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_register:
register();
break;
}
}
public void register() {
String id=et_register_stuid.getText().toString().trim();
String name=et_register_name.getText().toString().trim();
String pwd=et_register_pwd.getText().toString().trim();
if(TextUtils.isEmpty(id)||TextUtils.isEmpty(name)||TextUtils.isEmpty(pwd)){
Toast.makeText(this, "不能为空", Toast.LENGTH_SHORT).show();
}else{
Student student= new Student(Integer.parseInt(id),name,pwd);
Dao dao=new Dao(this);
if(dao.query(student)!=null){
Toast.makeText(this, "用户已存在，请直接登陆", Toast.LENGTH_SHORT).show();
}else{
dao.insert(student);
Toast.makeText(this, "注册成功", Toast.LENGTH_SHORT).show();
}
finish();
}
}
}