Java核心-Utils

#连接设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/36th_rev
username=root
password=123456
#<!-- 初始化连接 -->
initialSize=10
#最大连接数量
maxActive=50
#<!-- 最大空闲连接 -->
maxIdle=20
#<!-- 最小空闲连接 -->
minIdle=5
#<!-- 超时等待时间以毫秒为单位 6000毫秒/1000等于60秒 -->
maxWait=60000
#JDBC驱动建立连接时附带的连接属性属性的格式必须为这样：[属性名=property;]
#注意："user" 与 "password" 两个属性会被明确地传递，因此这里不需要包含他们。
connectionProperties=useSSL=false;characterEncoding=utf8
#指定由连接池所创建的连接的自动提交（auto-commit）状态。
defaultAutoCommit=true
#driver default 指定由连接池所创建的连接的只读（read-only）状态。
#如果没有设置该值，则“setReadOnly”方法将不被调用。（某些驱动并不支持只读模式，如：Informix）
defaultReadOnly=
#driver default 指定由连接池所创建的连接的事务级别（TransactionIsolation）。
#可用值为下列之一：（详情可见javadoc。）NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE
defaultTransactionIsolation=REPEATABLE_READ

BasicDataSourceFactory.createDataSource(properties)

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <!-- 在xml文件中，有一些特殊的字符是不能写的。 & > <, 对于这三个字符，我们要写转义字符
                转义字符            
         &      &amp;
         >      &gt;
         <      &lt;
         >=     &gt;=
         <=     &lt;=
         
         -->
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/36th_rev?useSSL=false&amp;characterEncoding=utf8</property>
        <property name="user">root</property>
        <property name="password">123456</property>
        <property name="acquireIncrement">5</property>
        <property name="initialPoolSize">10</property>
        <property name="minPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>
    
</c3p0-config>

dataSource = new ComboPooledDataSource();

connection = dataSource.getConnection()

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/36th_rev?useSSL=false&characterEncoding=utf8
username=root
password=123456
# 初始化大小，如果不配置，就使用默认值
initialSize=10

DruidDataSourceFactory.createDataSource(properties);

connection = dataSource.getConnection();

// 关闭连接
public static void close(Connection conn) throws SQLException {
  if (conn != null) {
    conn.close();
  }
}
// 安静的关闭连接
public static void closeQuietly(Connection conn) {
  try {
    close(conn);
  } catch (SQLException e) { // NOPMD
    // quiet
  }
}

// QueryRunner 有两个构造方法
// 无参构造
QueryRunner queryRunner = new QueryRunner();
// 通过数据库连接池来构造
DataSource dataSource = DruidUtils.getDataSource();
QueryRunner queryRunner = new QueryRunner(dataSource);

// 无参构造
QueryRunner queryRunner = new QueryRunner();
// 执行SQL语句
int affectedRows = queryRunner.update(DruidUtils.getConnection(),"update account set money = ? where id = ?",1000,1);
System.out.println("affectedRows:" + affectedRows);

//        // 通过数据库连接池来构造
        DataSource dataSource = DruidUtils.getDataSource();
        QueryRunner queryRunner = new QueryRunner(dataSource);
        // 执行SQL语句
        int affectedRows = queryRunner.update("update account set money = ? where id = ?",2000,1);
        System.out.println("affectedRows:" + affectedRows);

// 1. 获取QueryRunner
QueryRunner queryRunner = new QueryRunner(DruidUtils.getDataSource());
// 2. 执行SQL语句
Account account = queryRunner.query("select * from account where id > ?",new BeanHandler<>(Account.class),2); //？表示占位
System.out.println(account);

// 获取QueryRunner
QueryRunner queryRunner = new QueryRunner(DruidUtils.getDataSource());
// 执行SQL
List<Account> list = queryRunner.query("select * from account where id in (?,?,?)",new BeanListHandler<>(Account.class),1,2,3);
System.out.println(list);

//创建QueryRunner对象
QueryRunner queryRunner = new QueryRunner(DruidUtils.getDataSource());
//执行SQL语句
List<String> nameList = queryRunner.query("select name from account where id > ?",new ColumnListHandler<String>(),1);
System.out.println(nameList);

//创建QueryRunner对象
QueryRunner queryRunner = new QueryRunner(DruidUtils.getDataSource());
Long count = queryRunner.query("select count(*) from account where money >5000",new ScalarHandler<Long>());

QueryRunner queryRunner = new QueryRunner(DruidUtils.getDataSource);
List<Map<String,Object>>mapList = queryRunner.query("select id,name,role from account",new MapListHandler());
for(Map<String,Object> map : mapList){
    System.out.println(map);
}