MyBatis学习（四）

Web中应用MyBatis

package com.xiaoguan.bank.dao;

import com.xiaoguan.bank.pojo.Account;

/**
 * 账户DAO对象，负责t_act的CRUD
 */
public interface AccountDao {
    /**
     * 根据账户查询账户信息
     * @param act 账号
     * @return 账户信息
     */
    Account selectByActno(String act);

    /**
     * 更新账户信息
     * @param act 账号类
     * @return 更新条数
     */
    int updateByActno(Account act);

}

package com.xiaoguan.bank.exceptions;

/**
 * 余额不足异常
 */
public class MoneyNotEnough extends Exception{
    public MoneyNotEnough() {
    }

    public MoneyNotEnough(String message) {
        super(message);
    }
}

package com.xiaoguan.bank.exceptions;

/**
 * 转账异常
 */
public class TransferException extends Exception{
    public TransferException() {

    }

    public TransferException(String message) {
        super(message);
    }
}

package com.xiaoguan.bank.pojo;

import java.util.Objects;

/**
 * 账户类，封装账户表
 */
public class Account {
    private Long id;
    private String actno;
    private Double balance;

    public Account() {

    }

    public Account(Long id, String actno, Double balance) {
        this.id = id;
        this.actno = actno;
        this.balance = balance;
    }

    public Long getId() {
        return id;
    }

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

    public String getActno() {
        return actno;
    }

    public void setActno(String actno) {
        this.actno = actno;
    }

    public Double getBalance() {
        return balance;
    }

    public void setBalance(Double balance) {
        this.balance = balance;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Account account = (Account) o;
        return Objects.equals(getId(), account.getId()) && Objects.equals(getActno(), account.getActno()) && Objects.equals(getBalance(), account.getBalance());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getId(), getActno(), getBalance());
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", actno='" + actno + '\'' +
                ", balance=" + balance +
                '}';
    }
}

package com.xiaoguan.bank.service;

import com.xiaoguan.bank.exceptions.MoneyNotEnough;
import com.xiaoguan.bank.exceptions.TransferException;

/**
 * 账户业务类
 */
public interface AccountService {
    /**
     * 账户转账业务
     * @param fromAct 转出账户
     * @param toAct 转入账户
     * @param money 转账金额
     */
    void transfer(String fromAct ,String toAct ,double money) throws MoneyNotEnough, TransferException;
}

package com.xiaoguan.bank.utils;

import org.apache.ibatis.javassist.CannotCompileException;
import org.apache.ibatis.javassist.ClassPool;
import org.apache.ibatis.javassist.CtClass;
import org.apache.ibatis.javassist.CtMethod;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.session.SqlSession;

import java.lang.reflect.Method;
import java.util.Arrays;

/**
 * 工具类,可以动态生成Dao的实现类
 */
public class GenerateDaoproxy {
    public static Object generate(SqlSession sqlSession,Class daoInterface){
        ClassPool pool = ClassPool.getDefault();
        CtClass ctClass = pool.makeClass(daoInterface.getName()+"Proxy");//本质是动态生成一个代理类
        CtClass ctInterface = pool.makeInterface(daoInterface.getName());
        ctClass.addInterface(ctInterface);
        //实现接口中的方法
        Method[] declaredMethods = daoInterface.getDeclaredMethods();
        Arrays.stream(declaredMethods).forEach(method -> {
            CtMethod ctMethod = null;
            try {
                StringBuilder methodCode=new StringBuilder();
                //Account selectByActno(String act);
                methodCode.append("public ");
                methodCode.append(method.getReturnType().getName()+" ");
                methodCode.append(method.getName());
                methodCode.append("(");
                //方法的形式参数列表
                Class<?>[] parameterTypes = method.getParameterTypes();
                for (int i = 0; i < parameterTypes.length; i++) {
                    Class<?> parameterType = parameterTypes[i];
                    methodCode.append(parameterType.getName());
                    methodCode.append(" ");
                    methodCode.append("arg"+i);
                    if (i!=parameterTypes.length-1){
                        methodCode.append(",");
                    }
                }
                methodCode.append(")");
                methodCode.append("{");
                //需要方法体中的代码
                methodCode.append("org.apache.ibatis.session.SqlSession sqlSession = com.xiaoguan.bank.utils.SqlSessionUtils.openSession();");
                //需要知道是什么类型的sql语句
                String sqlId=daoInterface.getName()+"."+method.getName();
                SqlCommandType sqlCommandType = sqlSession.getConfiguration().getMappedStatement(sqlId).getSqlCommandType();
                if (sqlCommandType== SqlCommandType.INSERT) {

                }
                if (sqlCommandType== SqlCommandType.DELETE) {

                }
                if (sqlCommandType== SqlCommandType.UPDATE) {
                    methodCode.append("return sqlSession.update(\""+sqlId+"\", arg0);");
                }
                if (sqlCommandType== SqlCommandType.SELECT) {
                    methodCode.append("return ("+method.getReturnType().getName()+")sqlSession.selectOne(\""+sqlId+"\", arg0);");

                }
                methodCode.append("}");
                ctMethod = CtMethod.make(methodCode.toString(), ctClass);
                ctClass.addMethod(ctMethod);
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
        Object obj=null;
        try {
            Class<?> aClass = ctClass.toClass();
            obj = aClass.newInstance();
        } catch (CannotCompileException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        return obj;
    }
}

package com.xiaoguan.bank.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;

/**
 * MyBatis工具类
 */
public class SqlSessionUtils {
    private static SqlSessionFactory sqlSessionFactory;
    private SqlSessionUtils() {}
    static {
        try {
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private static ThreadLocal<SqlSession> local=new ThreadLocal<>();
    /**
     * 获取会话对象
     * @return 会话对象
     */
    public static SqlSession openSession(){
        SqlSession sqlSession = local.get();
        if (sqlSession==null) {
            sqlSession=sqlSessionFactory.openSession();
            local.set(sqlSession);
        }
        return sqlSession;

    }

    /**
     * 关闭sqlSession对象
     * @param sqlSession
     */
    public static void close(SqlSession sqlSession){
        if (sqlSession != null) {
            sqlSession.close();
            //移除sqlSession对象和当前线程绑定关系
            local.remove();
        }
    }
}

package com.xiaoguan.bank.web;

import com.xiaoguan.bank.exceptions.MoneyNotEnough;
import com.xiaoguan.bank.exceptions.TransferException;
import com.xiaoguan.bank.service.AccountService;
import com.xiaoguan.bank.service.impl.AccountServiceImpl;
import com.xiaoguan.bank.utils.SqlSessionUtils;
import org.apache.ibatis.session.SqlSession;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/transfer")
public class AccountServlet extends HttpServlet {
    private AccountService accountService = new AccountServiceImpl();
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String fromActno = request.getParameter("fromActno");
        String toActno = request.getParameter("toActno");
        Double money =Double.parseDouble(request.getParameter("money"));
        //调用service方法完成转账，（调业务层）
        try {
            accountService.transfer(fromActno,toActno,money);
            //到这里表示转账成功了
            response.setContentType("text/html;charset=UTF-8");
            response.sendRedirect(request.getContextPath()+"/success.html");
        } catch (MoneyNotEnough e) {
            SqlSession sqlSession = SqlSessionUtils.openSession();
            SqlSessionUtils.close(sqlSession);
            response.sendRedirect(request.getContextPath()+"/error1.html");
        } catch (TransferException e) {
            SqlSession sqlSession = SqlSessionUtils.openSession();
            sqlSession.rollback();
            SqlSessionUtils.close(sqlSession);
            response.sendRedirect(request.getContextPath()+"/error2.html");
        } catch (Exception e){
            SqlSession sqlSession = SqlSessionUtils.openSession();
            sqlSession.rollback();
            SqlSessionUtils.close(sqlSession);
            response.sendRedirect(request.getContextPath()+"/error2.html");
        }
        //调用View完成展示结果
    }
}

<?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.xiaoguan.bank.dao.AccountDao">
    <!--要想使用代理机制namespace必须为接口全名，id为接口里面的方法名-->
    <select id="selectByActno" resultType="com.xiaoguan.bank.pojo.Account">
        select * from t_act where actno=#{actno};
    </select>
    <update id="updateByActno">
        update t_act set balance=#{balance} where actno=#{actno};
    </update>
</mapper>

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=68963120g

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

<configuration debug="false">
    <!-- 控制台输出 -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
    </appender>
    <!-- 按照每天生成日志文件 -->
    <!--mybatis log configure-->
    <logger name="com.apache.ibatis" level="TRACE"/>
    <logger name="java.sql.Connection" level="DEBUG"/>
    <logger name="java.sql.Statement" level="DEBUG"/>
    <logger name="java.sql.PreparedStatement" level="DEBUG"/>

    <!-- 日志输出级别,logback日志级别包括五个：TRACE < DEBUG < INFO < WARN < ERROR -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILE"/>
    </root>

</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>
    <properties resource="jdbc.properties"/>
    <environments default="mybatis">
        <environment id="mybatis">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="AccountMapper.xml"/>
    </mappers>
</configuration>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
                      https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
         version="6.0"
         metadata-complete="false">
<!--    <servlet>-->
<!--        <servlet-name>test</servlet-name>-->
<!--        <servlet-class>com.xiaoguan.bank.web.AccountServlet</servlet-class>-->
<!--    </servlet>-->
<!--    <servlet-mapping>-->
<!--        <servlet-name>test</servlet-name>-->
<!--        <url-pattern>/transfer</url-pattern>-->
<!--    </servlet-mapping>-->
</web-app>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>转账报告</title>
</head>
<body>
<h1 >余额不足！！！</h1>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>转账报告</title>
</head>
<body>
<h1 >转账失败，未知原因！！！</h1>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>账户银行转账</title>
</head>
<body>
  <form action="/bank/transfer" method="post">
    转出账号：<input type="text" name="fromActno"><br>
    转入账号：<input type="text" name="toActno"><br>
    转账金额：<input type="text" name="money"><br>
    <input type="submit" value="转账">
  </form>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>转账报告</title>
</head>
<body>
<h1 >转账成功！！！</h1>
</body>
</html>

Javassist生成类

package com.xiaoguan.javassist.bank.dao;

public interface AccountDao {
     void delete();
     int  insert(String actno);
     int update(String actno,Double balance);
     String selectByActno(String actno);

}

package com.xiaoguan.javassist;

import com.xiaoguan.javassist.bank.dao.AccountDao;
import javassist.CannotCompileException;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import org.junit.Test;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;

public class JavassistTest {
    @Test
    public void testGenerateAccountDaoImpl() throws Exception {
        ClassPool pool = ClassPool.getDefault();
        CtClass ctClass = pool.makeClass("com.xiaoguan.bank.dao.impl.AccountDaoImpl");
        CtClass ctInterface = pool.makeInterface("com.xiaoguan.javassist.bank.dao.AccountDao");
        ctClass.addInterface(ctInterface);
        Method[] declaredMethod = AccountDao.class.getDeclaredMethods();
        Arrays.stream(declaredMethod).forEach(method -> {
            try {
                StringBuilder methodCode=new StringBuilder();
                methodCode.append("public ");
                methodCode.append(method.getReturnType().toString().replace("class",""));//
                methodCode.append(" ");
                methodCode.append(method.getName());//追加方法名
                methodCode.append("(");
                //拼接参数
                Class<?>[] parameterTypes = method.getParameterTypes();
                for (int i = 0; i < parameterTypes.length; i++) {
                    Class<?> parameterType = parameterTypes[i];
                    methodCode.append(parameterType.getName());
                    methodCode.append(" ");
                    methodCode.append("arg"+i);
                    if(i!=parameterTypes.length-1){
                        methodCode.append(",");
                    }
                }
                methodCode.append("){System.out.println(8888);");
                String simpleName = method.getReturnType().getSimpleName();
                if ("void".equals(simpleName)) {

                } else if ("int".equals(simpleName)) {
                    methodCode.append("return 1;");
                } else if ("String".equals(simpleName)) {
                    methodCode.append("return \"Hello\";");
                }
                methodCode.append("}");
                System.out.println(methodCode);
                CtMethod ctMethod = CtMethod.make(methodCode.toString(), ctClass);
                ctClass.addMethod(ctMethod);
            } catch (Exception e) {
                e.printStackTrace();
            }
        });
        Class<?> aClass = ctClass.toClass();
        AccountDao accountDao = (AccountDao) aClass.newInstance();
        accountDao.insert("aaaa");
        accountDao.delete();
        accountDao.update("111",12.0);
        accountDao.selectByActno("111");

    }
    @Test
    public void testGenerateImpl() throws Exception {
        ClassPool pool = ClassPool.getDefault();
        CtClass ctClass = pool.makeClass("com.xiaoguan.bank.dao.impl.AccountDaoImpl");
        CtClass ctInterface = pool.makeInterface("com.xiaoguan.javassist.bank.dao.AccountDao");
        ctClass.addInterface(ctInterface);
        CtMethod ctMethod = CtMethod.make("public void delete(){System.out.print(\"hello delete!\");}", ctClass);

        ctClass.addMethod(ctMethod);
        Class<?> aClass = ctClass.toClass();
        AccountDao account = (AccountDao) aClass.newInstance();
        account.delete();
    }
    @Test
    public void testGenerateFirstClass() throws CannotCompileException, ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        //获取类池，这个类池就是用来生成class的
        ClassPool pool = ClassPool.getDefault();
        //制造类
        CtClass ctClass = pool.makeClass("com.xiaoguan.bank.dao.impl.AccountDaoImpl");
        String methodCode="public void insert(){System.out.print(123456789);}";
        CtMethod ctMethod = CtMethod.make(methodCode, ctClass);
        ctClass.addMethod(ctMethod);
        ctClass.toClass();
        //类加载到JVM中
        Class<?> aClass = Class.forName("com.xiaoguan.bank.dao.impl.AccountDaoImpl");
        Object obj = aClass.newInstance();
        Method insertMethod = aClass.getDeclaredMethod("insert");
        insertMethod.invoke(obj);

    }
}