mybatis/request/servlet综合案例

案例：用户登录&用户注册

1.用户登录

首先在我们之前建立了maven插件以及servlet的工程里首先配置好mybatis需要的环境

<properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <maven.compiler.source>1.7</maven.compiler.source>
  <maven.compiler.target>1.7</maven.compiler.target>
</properties>
​
<dependencies>
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.11</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
  </dependency>
  <dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.6</version>
  </dependency>
  <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.5</version>
  </dependency>
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.46</version>
  </dependency>
  <!--        junit 单元测试-->
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>3.8.2</version>
    <scope>test</scope>
  </dependency>
  <!-- 添加slf4j日志api -->
  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.20</version>
  </dependency>
  <!-- 添加logback-classic依赖 -->
  <dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
  </dependency>
  <!-- 添加logback-core依赖 -->
  <dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-core</artifactId>
    <version>1.2.3</version>
  </dependency>
</dependencies>
<build>

接着在目录下创建一个pojo用于存放封装对象的类

 

写好user的属性以及set、get方法

接着写接口和对应的增删改方法（简单的增删改就写注解就好了，不用写配置文件了）

在对应准备好的页面里定义跳转的页面

接着·我们就可以完成对应的servlet的代码（这里要用到servlet，mybatis，request相关的知识）

@WebServlet(name = "loginServlet", value = "/loginServlet")
public class loginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
        User user=userMapper.select(username,password);
        if(user!=null){
            response.setHeader("content-type","text/html;charset=utf-8");
            //用response 设置响应数据
            response.getWriter().write("<h1>"+username+",欢迎您！<h1>");
        }else{
            response.setHeader("content-type","text/html;charset=utf-8");
            //用response 设置响应数据
            response.getWriter().write(username+"用户不存在或密码错误");
        }
        sqlSession.close();
    }
​
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

2.注册界面也是一样的

（1）接口中方法的书写（用注解完成sql语句）

（2）对应html页面写好form属性

（3）servlet完成代码（这是难点）

@WebServlet(name = "registerServlet", value = "/registerServlet")
public class registerServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        username=new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);
//        username="%"+username+"%";
//        ssw paord="%"+password+"%";
        User user=new User();
        user.setUsername(username);
        user.setPassword(password);
        response.setHeader("content-type","text/html;charset=utf-8");
        String resource = "mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
        User user2=userMapper.select(username,password);
        if(user2!=null){
            //用response 设置响应数据
            response.getWriter().write("用户已存在");
        }else {
            userMapper.insert(user);
            User user1=userMapper.select(username,password);
            if(user1!=null){
               response.getWriter().write(username+"用户注册成功！");
            }
        }
        sqlSession.commit();/*需要手动提交数据才能更改数据库数据*/
        sqlSession.close();
    }
​
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

（注意：如果要更改数据库的数据要在释放前手动提交表单）

其实最容易出错的还是maven环境和mybatis环境的搭建，建议工程开始前先借鉴mybatis快速入门搭建环境看看能否启动成功

而maven环境就用maven插件（安装插件再到pom中配置相关maven插件)就好了

<plugins>
  <plugin>
    <groupId>org.apache.tomcat.maven</groupId>
    <artifactId>tomcat7-maven-plugin</artifactId>
    <version>2.2</version>
  </plugin>
</plugins>

这样就是简单的案例，以后常练习