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Java android中的登录表单验证

java android validation

Java android中的登录表单验证,java,android,validation,Java,Android,Validation,我已经在Android上开发了一个登录表单。我在这里使用了验证。我必须填写任何人（用户名或密码），然后我的应用程序应该显示成功！并且应该转移到其他活动 但是，如果两个字段都为空，则不应显示成功消息，而应显示登录失败 请帮我这个 这是我的Web服务代码： public class XcartLogin { public String authentication(String userName, String password) { String retrievedUser

我已经在Android上开发了一个登录表单。我在这里使用了验证。我必须填写任何人（用户名或密码），然后我的应用程序应该显示成功！并且应该转移到其他活动

但是，如果两个字段都为空，则不应显示成功消息，而应显示登录失败

请帮我这个

这是我的Web服务代码：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
这是对我的android代码的验证：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
尝试使用此条件：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
而不是您的状况：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
尝试使用此条件：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
而不是您的状况：

public class XcartLogin {
    public String authentication(String userName, String password) {
        String retrievedUserName = "";
        String retrievedPassword = "";
        String status = "";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/xcart432-pro", "root", "");
            PreparedStatement statement = con.prepareStatement("SELECT * FROM xcart_customers WHERE login = '" + userName + "'");
            ResultSet result = statement.executeQuery();
            while (result.next()) {
                retrievedUserName = result.getString("login");
                retrievedPassword = result.getString("password");
            }
            if (retrievedUserName.equals(userName) && retrievedPassword.equals(password)) {
                status = "Success!";
            } else {
                status = "Login fail!!!";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return status;
    }
}

if(status.equals("Success!"))
    {
        // ADD  to save  and  read next time
        String strUserName = userName.getText().toString().trim();
        String strPassword = userPassword.getText().toString().trim();
        if (null == strUserName || strUserName.length() == 0)
        {
            // showToast("Enter Your Name");
            userName.setError( "username is required!" );
            isUserValidated = false;
        }
        if (null == strPassword || strPassword.length() == 0)
        {
            // showToast("Enter Your Password");
            isPasswordValidated = false;
            userPassword.setError( "password is required!" );
        } 
    }

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password)&&!(retrievedUserName.equals("") && retrievedPassword.equals("")))

if(retrievedUserName.equals(userName)&&retrievedPassword.equals(password))
首先，您使用PreparedStatement的方式是不正确的。以下是您应该如何修改它：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
然后使用
setString（int-paramIndex，String-value）
设置值，然后调用
executeQuery（）
方法。大概是这样的：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
statement.setString(1, userName);

ResultSet result = statement.executeQuery();

if(userName.equals(retrievedUserName)&&password.equals(retrievedPassword)&&!("".equals(retrievedUserName) && "".equals(retrievedPassword)))
这是安全的，也是在代码中使用PreparedStatement的实际方法

现在，为了测试您的需求，您应该执行以下操作：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
statement.setString(1, userName);

ResultSet result = statement.executeQuery();

if(userName.equals(retrievedUserName)&&password.equals(retrievedPassword)&&!("".equals(retrievedUserName) && "".equals(retrievedPassword)))
请注意，我正在对照retrievedUserName和retrievedPassword检查用户名和密码，反之亦然，因为根据for
getString（int）
，retrievedUserName或retrievedPassword可能为空

返回：列值；如果该值为SQL NULL，则该值 返回的值为空

如果该值为null，那么您将处理
NullPointerException
，我想您可能希望避免这种情况。同样，出于同样的原因，您可能希望在尝试查询数据库之前检查参数的null值

首先，您使用PreparedStatement的方式是不正确的。以下是您应该如何修改它：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
然后使用
setString（int-paramIndex，String-value）
设置值，然后调用
executeQuery（）
方法。大概是这样的：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
statement.setString(1, userName);

ResultSet result = statement.executeQuery();

if(userName.equals(retrievedUserName)&&password.equals(retrievedPassword)&&!("".equals(retrievedUserName) && "".equals(retrievedPassword)))
这是安全的，也是在代码中使用PreparedStatement的实际方法

现在，为了测试您的需求，您应该执行以下操作：

PreparedStatement statement =  con.prepareStatement("SELECT * FROM xcart_customers WHERE login = ?");
statement.setString(1, userName);

ResultSet result = statement.executeQuery();

if(userName.equals(retrievedUserName)&&password.equals(retrievedPassword)&&!("".equals(retrievedUserName) && "".equals(retrievedPassword)))
请注意，我正在对照retrievedUserName和retrievedPassword检查用户名和密码，反之亦然，因为根据for
getString（int）
，retrievedUserName或retrievedPassword可能为空

返回：列值；如果该值为SQL NULL，则该值 返回的值为空

如果该值为null，那么您将处理
NullPointerException
，我想您可能希望避免这种情况。同样，出于同样的原因，您可能希望在尝试查询数据库之前检查参数的null值

在验证代码中的
if（status.equals（“Success！”）
语句之前，应首先执行此操作，以避免在任何文本字段首先为空时查询数据库：

boolean errorOccurred = false;
if (strUserName.equals("")) {
    userName.setError("Username is required!");
    errorOccurred = true;
}

if (strPassword.equals("")) {
    userName.setError("Password is required!");
    errorOccurred = true;
}

if (errorOccurred) {
    return; // avoids executing the part of your code which queries the db
}
检查输入字段的值是否为
null
是毫无意义的，因为如果它们不包含任何内容，它将只是一个空字符串，或者
“
”。然后，为了简化您的Web服务代码

if (result.next()) { // use if instead of while, because ideally, only ONE record should
                     // be returned and hence, no need to loop;

    // then, just get the corresponding password
    retrievedPassword = result.getString("password");
}

if (retrievedPassword.equals(password)) {
    status = "Success!";
}
进一步建议：将“Success！”放在
字符串
常量中，并使用该常量代替文本值。通过这种方式，您犯错误的几率更小，编辑代码也更容易。
在验证代码中的
if（status.equals（“Success！”）
语句之前，您应该首先执行此操作，以避免在任何文本字段为空时查询数据库：


boolean errorOccurred = false;
if (strUserName.equals("")) {
    userName.setError("Username is required!");
    errorOccurred = true;
}

if (strPassword.equals("")) {
    userName.setError("Password is required!");
    errorOccurred = true;
}

if (errorOccurred) {
    return; // avoids executing the part of your code which queries the db
}


检查输入字段的值是否为
null
是毫无意义的，因为如果它们不包含任何内容，它将只是一个空字符串，或者
“
”。然后，为了简化您的Web服务代码


if (result.next()) { // use if instead of while, because ideally, only ONE record should
                     // be returned and hence, no need to loop;

    // then, just get the corresponding password
    retrievedPassword = result.getString("password");
}

if (retrievedPassword.equals(password)) {
    status = "Success!";
}



进一步建议：将“Success！”放在
字符串
常量中，并使用该常量代替文本值。通过这种方式，您犯错误的机会更小，编辑代码也更容易。
甚至正如Sujay建议更改准备好的语句一样。你的是对预备语句的错误用法，甚至正如Sujay所建议的那样，更改预备语句。你的陈述是一种错误的用法，只是离题了。。上述形式的代码对SQL注入非常敏感&您永远不应该从DB检索密码，而应该将其作为参数传递给SQL准备语句。。上述形式的代码对SQL注入非常敏感&您不应该从DB检索密码，而应该将其作为参数传递给SQL语句