Java implementation foundation login page

Posted by neo_phyte on Sun, 30 Jan 2022 16:25:36 +0100

After class practice of Mybatis and web Learning

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First, we identify our needs:

1: We need a login and registration page to operate

2: We need to connect to the database to query whether there is this user, and realize login and registration

After determining the requirements, let's practice

The first is the interface:

css and html front-end knowledge are needed here

I just copied my homework

The specific effects are as follows

Let's mainly talk about the realization of functions

The first is the login interface:

The first step is to create a database to store users

We have three attributes: id, username and password

We create the attribute in User:

After creation, we need getset and tostring;

package com.gao.polo;

public class User {
    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

After this step, we need to think about how to realize the use of mybatis

First, configure the mybatis file

1, Import the corresponding mybatis coordinates and MySQL connector coordinates into maven's pom:

<dependencies>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.2</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.47</version>
    </dependency>
  </dependencies>

Then we need to configure the mybatis settings file:

Under resource, create a mybatis config XML file

Write the following configuration:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>



    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/jd_user?useSSL=false&amp;useServerPrepStmts=true"/>
                <property name="username" value="root"/>
                <property name="password" value="000511"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--scanning mapper-->
        <mapper resource="com\gao\mapper\UserMapper.xml"/>


    </mappers>

</configuration>

Note:

< Mapper resource = "com \ Gao \ Mapper \ usermapper. xml" / > the resource in the project needs to write the directory of Mapper's xml Mapping file in the project

After that, we can now configure the Marrper file

Basic usermapper XML file:

(note that the namespace needs the corresponding interface coordinates)

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.gao.mapper.UserMapper">
    
</mapper>
        <!--UserMapper.xml-->

And UserMapper interfaces:

(build an interface to query users)

(because it is relatively simple, Mapper we wrote this time is implemented with annotations)

public interface UserMapper {
    @Select("select * from jd_user.user_login where username=#{username} and password=#{password}")
    User loginSelect(@Param("username")String username,@Param("password") String password);
}

OK, we have finished the basic preparations for login

Test now

First import Junit into our pom file

<!--junit-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

Create test file

By the way, let's make a sqlsessionfactory factory file in utils first

public class MybatisUtil {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

Then use the factory file to parse the session in test

Use getmaaper to test our mapping file

public class test {

    //Test whether the database connection is successful
    @Test
    public void loginTest ()throws Exception{
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.loginSelect("740803880", "000511");
        System.out.println("user = " + user);
    }
}

ok, let's see the test results

Sure enough, there was a mistake! Let's look for:

Cannot parse our mapper XML file

After careful inquiry, we found that there was no problem. Then look at our target directory

Found that our Mapper didn't xml file

If static resources are placed in src/main/java, they will be ignored by maven during compilation, and there will be no such resources in the target directory. Here, we will use mybatis mapper XML is placed in the dal package to facilitate programming and viewing, so you need to add this directory as a resource directory

<build>
  <!--be careful,If you put static resources in src/main/java in,Then compile time will be maven ignore,stay target These resources will not be available in the directory,here,We will
  mybatis of mapper.xml Put it in dal In the bag,Convenient programming and viewing,Therefore, you need to add this directory as a resource directory.
  -->
  <resources>
    <resource>
      <directory>src/main/java</directory>
      <includes>
        <include>**/*.xml</include>
      </includes>
    </resource>
  </resources>
  </build>

We add this paragraph to maven's configuration file

The test has been successful. Now we have found that the test has been successful

Indicates that the database has been successfully connected

Next, let's configure the web file

First configure maven

Coordinates of importing tomcat plug-in and servlet

The required maven has been configured. The results are as follows

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <packaging>war</packaging>

  <name>LoginAndRegister</name>
  <groupId>com.gao</groupId>
  <artifactId>LoginAndRegister</artifactId>
  <version>1.0-SNAPSHOT</version>
  <dependencies>
    <!--mybatis-->
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.2</version>
    </dependency>
    <!--mysql-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.47</version>
    </dependency>
    <!--junit-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <!--Import servlet tool kit-->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
  <build>
  <!--be careful,If you put static resources in src/main/java in,Then compile time will be maven ignore,stay target These resources will not be available in the directory,here,We will
  mybatis of mapper.xml Put it in dal In the bag,Convenient programming and viewing,Therefore, you need to add this directory as a resource directory.
  -->
  <resources>
    <resource>
      <directory>src/main/java</directory>
      <includes>
        <include>**/*.xml</include>
      </includes>
    </resource>
  </resources>
 <!--Import tomcat Tool class-->
    <plugins>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.2</version>
        <configuration>
          <port>80</port>
          <path>/</path>
        </configuration>
      </plugin>
    </plugins>
  </build>


</project>

After importing, we can create Servlet classes in the new

Let's create a LoginServlet

Mark our Servlet with the annotation @ webservlet

Obtain username and password in the request application

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
}
}

Let's take a look at the html configuration:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>login</title>
    <link href="css/login.css" rel="stylesheet">
</head>

<body>
<div id="loginDiv">
    <form action="/loginServlet" id="form" method="post">
        <h1 id="loginMsg">LOGIN IN</h1>
        <p>account number:<input id="username" name="username" type="text"></p>

        <p>password:<input id="password" name="password" type="password"></p>

        <div id="subDiv">
            <input type="submit" class="button" value="Login" name="login up">
            <a href="register.html"><input type="button" class="button" value="register" name="register"></a>
        </div>
    </form>
</div>

</body>
</html>

Enter the coordinates of our loginservlet after the action at < form action = "/ loginservlet" id = "form" method = "post" > and the mapping is successful

Now let's configure the servlet's code logic

First use the factory to obtain sqlsession

Using sqlSession to obtain and parse our mapper file

Finally, use mapper's login query to find out the user's data form

SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.loginSelect(username, password);

So far, we have finished querying the contents of the database from the user password entered by the user

Finally, we use response plus code logic

response.setContentType("text/html;charset=utf-8");
        PrintWriter writer = response.getWriter();
        if(user !=null){
            writer.write("Input successful");
        }else{
            writer.write("Login failed");
        }

It realizes the verification and login of account password

Let's try to verify it