【C3P0】C3P0

1、resources目录下添加c3p0-config.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <!-- 默认配置，如果没有指定则使用这个配置 -->
    <default-config>
        <!-- 初始化池大小 -->
        <property name="initialPoolSize">2</property>
        <!-- 最大空闲时间 -->
        <property name="maxIdleTime">30</property>
        <!-- 最多有多少个连接 -->
        <property name="maxPoolSize">10</property>
        <!-- 最少几个连接 -->
        <property name="minPoolSize">2</property>
        <!-- 每次最多可以执行多少个批处理语句 -->
        <property name="maxStatements">50</property>
    </default-config>

    <!-- 命名的配置 -->
    <named-config name="c3p0">
        <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/c3p0?serverTimezone=CTT</property>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="acquireIncrement">5</property><!-- 如果池中数据连接不够时一次增长多少个 -->
        <property name="initialPoolSize">10</property>
        <property name="minPoolSize">5</property>
        <property name="maxPoolSize">200</property>
        <property name="maxStatements">0</property>
        <property name="maxStatementsPerConnection">5</property> <!-- he's important, but there's only one of him -->
    </named-config>

    <!-- 命名的配置 -->
    <named-config name="mybatis">
        <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/mybatis?serverTimezone=CTT</property>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="acquireIncrement">5</property><!-- 如果池中数据连接不够时一次增长多少个 -->
        <property name="initialPoolSize">10</property>
        <property name="minPoolSize">5</property>
        <property name="maxPoolSize">200</property>
        <property name="maxStatements">0</property>
        <property name="maxStatementsPerConnection">5</property> <!-- he's important, but there's only one of him -->
    </named-config>
</c3p0-config>

2、resources目录下添加log4j.properties配置文件

log4j.rootCategory=info,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyy MMM dd HH:mm:ss,SSS} %p [%t] %C.%M(%L) : %m%n

3、引入pom.xml文件

<?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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.sheep</groupId>
    <artifactId>c3p0-study</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>c3p0-study</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.4</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.22</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
            <scope>provided</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/cn.hutool/hutool-all -->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.5.9</version>
        </dependency>

    </dependencies>

    <build>

        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
                <includes>
                    <include>**/*.xml</include>
                    <include>**/*.properties</include>
                </includes>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <filtering>true</filtering>
                <includes>
                    <include>**/*.xml</include>
                    <include>**/*.properties</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>

4、编写DbUtils.java文件

package com.sheep.utils;

import cn.hutool.db.Db;
import cn.hutool.db.StatementUtil;
import cn.hutool.json.JSONArray;
import cn.hutool.json.JSONException;
import cn.hutool.json.JSONObject;
import com.mchange.v2.c3p0.ComboPooledDataSource;

import javax.sql.DataSource;
import java.sql.*;
import java.util.List;

@SuppressWarnings("all")
public class DbUtils {

    private static DataSource ds = null;

    private static DataSource getDataSource(String dbName) {
        //读取配置文件
        ds = new ComboPooledDataSource(dbName);
        return ds;
    }

    /**
     * 数据库增删改通用操作
     *
     * @param dbName
     * @param sql
     * @param params
     * @return
     */
    public static int update(String dbName, String sql, Object... params) {
        Db db = Db.use(DbUtils.getDataSource(dbName));
        int num = 0;
        try {
            num = db.execute(sql, params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return num;
    }

    /**
     * 数据库查询操作，返回List集合
     *
     * @param dbName
     * @param sql
     * @param beanClass
     * @param params
     * @param <T>
     * @return
     */
    public static <T> List<T> query(String dbName, String sql, Class<T> beanClass, Object... params) {
        Db db = Db.use(DbUtils.getDataSource(dbName));
        List<T> list = null;
        try {
            list = db.query(sql, beanClass, params);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;

    }

    /**
     * 数据库查询操作，返回JSONArray
     *
     * @param dbName
     * @param sql
     * @param params
     * @return
     */
    public static JSONArray query(String dbName, String sql, Object... params) {
        Connection conn = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        try {
            conn = DbUtils.getDataSource(dbName).getConnection();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        //新建JsonArray
        JSONArray jsonArray = new JSONArray();
        try {
            pst = StatementUtil.prepareStatement(conn, sql, params);
            rs = pst.executeQuery();

            ResultSetMetaData data = rs.getMetaData();
            while (rs.next()) {
                JSONObject jsonObject = new JSONObject();
                for (int i = 1; i <= data.getColumnCount(); ++i) {
                    //列名
                    String columnName = data.getColumnName(i);
                    String rst = rs.getString(i);
                    jsonObject.put(columnName, rst);
                }
                jsonArray.put(jsonObject);
            }

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        DbUtils.close(conn, pst, rs);
        return jsonArray;
    }

    private static void close(Connection conn, PreparedStatement pst, ResultSet rs) {
        if (null != rs) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (null != pst) {
            try {
                pst.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (null != conn) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

5、编写Student实体类

package com.sheep.domain;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

@Data
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class Student {

    private Integer id;
    private String name;
    private String email;
    private Integer age;
}

6、编写测试类

package com.sheep;

import cn.hutool.json.JSONArray;
import com.sheep.domain.Student;
import com.sheep.utils.DbUtils;
import org.apache.log4j.Logger;
import org.junit.Test;

import java.util.List;

/**
 * Unit test for simple App.
 */
public class AppTest {
    private static Logger logger = Logger.getLogger(AppTest.class);

    /**
     * 测试查询，返回集合
     */
    @Test
    public void testA() {
        String sql = "select * from  t_student where id=?";
        List<Student> students = DbUtils.query("c3p0", sql, Student.class, "1001");
        students.forEach(s -> logger.info(s));
    }


    /**
     * 测试查询，返回JSON数组
     */
    @Test
    public void testC() {
        String sql = "select * from  t_student where id >= ?";
        JSONArray jsonArray = DbUtils.query("c3p0", sql, 1001);
        jsonArray.forEach(s -> logger.info(s));
    }

    /**
     * 测试增删改
     */
    @Test
    public void testB() {
        String s1 = "insert into  t_student values(?,?,?,?)";
        DbUtils.update("c3p0", s1, 1003, "王五", "wangwu@qq.com", 35);

        String s2 = "delete from  t_student where id=?";
        DbUtils.update("c3p0", s2, 1003);

        String s3 = "update   t_student  set age=? where id=?";
        DbUtils.update("c3p0", s3, 10, 1001);

    }

}

完结。。。