【JDBC-Druid-JdbcTemplate】使用JdbcTemplate（通过Druid连接池）的方式操作数据库

1）导入依赖

<dependency>
    <groupId>org.springframeworkgroupId>
    <artifactId>spring-beansartifactId>
    <version>5.0.0.RELEASEversion>
dependency>
<dependency>
    <groupId>org.springframeworkgroupId>
    <artifactId>spring-coreartifactId>
    <version>5.0.0.RELEASEversion>
dependency>
<dependency>
    <groupId>org.springframeworkgroupId>
    <artifactId>spring-contextartifactId>
    <version>5.0.0.RELEASEversion>
dependency>
<dependency>
    <groupId>org.springframeworkgroupId>
    <artifactId>spring-jdbcartifactId>
    <version>5.0.0.RELEASEversion>
dependency>
<dependency>
    <groupId>org.springframeworkgroupId>
    <artifactId>spring-txartifactId>
    <version>5.0.0.RELEASEversion>
dependency>

<dependency>
    <groupId>com.alibabagroupId>
    <artifactId>druidartifactId>
    <version>1.2.6version>
dependency>
<dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>8.0.23version>
dependency>
<dependency>
    <groupId>junitgroupId>
    <artifactId>junitartifactId>
    <version>4.12version>
    
dependency>

2）定义JdbcUtils工具类

2.1.定义工具类获取DruidDataSource

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

public class JdbcUtils {
    private static DruidDataSource dataSource;
	//获取DruidDataSource 
    public static DruidDataSource getDataSource() {
        dataSource = new DruidDataSource();
        dataSource.setInitialSize(1);
        dataSource.setMaxActive(2);
        dataSource.setMaxWait(3000);
        return dataSource;
    }
	
	//通过getDataSource()获取到的dataSource来创建JDBC连接信息
	//传参的方式获取连接
    public static JdbcTemplate sourceJdbcTemplate(String url, String username, String password) {
        DruidDataSource dataSource = getDataSource();
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return new JdbcTemplate(dataSource);
    }

	//通过getDataSource()获取到的dataSource来创建JDBC连接信息
	//写死的方式获取连接
    public static JdbcTemplate mysqlJdbcTemplate() {
        DruidDataSource dataSource = getDataSource();
        dataSource.setUrl(Config.mysqlUrl);
        dataSource.setUsername(Config.mysqlUsername);
        dataSource.setPassword(Config.mysqlPassword);
        return new JdbcTemplate(dataSource);
    }

	//通过properties配置文件的方式获取连接
    public static DataSource getDataSourceFactory() {
        Properties properties = new Properties();
        try {
        properties.load(JdbcUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
            try {
                dataSource = (DruidDataSource) DruidDataSourceFactory.createDataSource(properties);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return dataSource;
    }
	
	//通过properties配置文件的方式获取连接，需要释放资源
    public static void close(Connection conn, PreparedStatement ps, ResultSet rs) {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (ps != null) {
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

2.2.配置druid.properties

注意：

如果平时只需要连接一个数据库，不需要对数据库进行频繁切换的情况下，那么可以通过properties配置文件的方式获取数据库连接，方法为上面的getDataSourceFactory()，但是需要配置druid.properties。

druid.properties：

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://192.168.1.1:3306/test
username=root
password=123456
initialSize=1
maxActive=2
maxWait=3000

3）通过定义好的JdbcUtils工具类使用JdbcTemplate（Druid连接池）

使用Junit进行测试（下面只是样例，无法正常执行，仅供参考）:

public class Demo {
    private static DataSource dataSource;
    private static JdbcTemplate jdbcTemplate;
    private static Connection conn;
    private static PreparedStatement ps;
    private static ResultSet rs;

    @Test
    public void test1() {
        DataSource dataSourceFactory = JdbcUtils.getDataSourceFactory();
        try {
            conn = dataSourceFactory.getConnection();
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            while (rs.next()) {
                int a = rs.getInt(1);
                int b = rs.getInt(2);
                int c = rs.getInt(3);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtils.close(conn, ps, rs);
        }
    }
    
	@Test
	//JdbcTemplate.queryForList(sql，返回类型.class)直接返回一个List集合
	public void test2(String httpUrl, String username, String password, String sourceDatabase, String likeTable) {
        String sql = null;
        jdbcTemplate = JdbcUtils.sourceJdbcTemplate(httpUrl, username, password);
        if (likeTable == null || "".equals(likeTable)) {
            sql = "SELECT lower(table_name) FROM information_schema.tables where table_schema = '" + sourceDatabase + "' and table_type != 'VIEW';";
        } else {
            sql = "SELECT lower(table_name) FROM information_schema.tables where table_schema = '" + sourceDatabase + "' and table_name like '" + likeTable + "' and table_type != 'VIEW';";
        }
        return jdbcTemplate.queryForList(sql, String.class);
    }

	@Test
	//JdbcTemplate.query(sql，new RowMapper(返回的数据类型，可以为bean类型))直接返回一个List集合
	//如果循环执行JdbcTemplate.query()，那么每次循环都会返回一个List1，需要外部定义一个List2，使用List2.addAll(List1)的方式对每次循环产生的List1进行收集。
    public void test3(String httpUrl, String username, String password, String sourceDatabase, List<String> mysqlLackTables, int dataSourceInfoId, String sourceName) {
        List<TableComment> tableComments = new ArrayList<>();
        jdbcTemplate = JdbcUtils.sourceJdbcTemplate(httpUrl, username, password);
        String sql = "SELECT lower(TABLE_NAME), TABLE_COMMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = '" + sourceDatabase + "' and lower(TABLE_NAME) = lower('%s')";
        for (String mysqlLackTable : mysqlLackTables) {
            tableComments.addAll(jdbcTemplate.query(String.format(sql, mysqlLackTable), new RowMapper<TableComment>() {
                @Override
                public TableComment mapRow(ResultSet rs, int i) throws SQLException {
                    TableComment tableComment = new TableComment();
                    tableComment.setTableName(rs.getString(1));
                    tableComment.setTableComment(rs.getString(2));
                    return tableComment;
                }
            }));
        }
    }
    
	@Test
	//JdbcTemplate.update(sql)对数据进行更新，写入，删除操作
	public void test4(List<TableComment> list, int dataSourceInfoId, String sourceName) {
        jdbcTemplate = JdbcUtils.mysqlJdbcTemplate();
        String sql = "insert into `data_resource_table_info` (s_table_name,s_table_name_zh,d_table_name,d_table_name_zh,approve_sts,data_source_id,data_source_name,sts,sts_date,create_user_id,create_time,update_user_id,update_time,remarks) values('%s','%s','%s','%s','C'," + dataSourceInfoId + ",'" + sourceName + "','A',NOW(),1,NOW(),1,NOW(),null)";
        list.stream().forEach(tableComment -> {
            String tableName = tableComment.getTableName();
            String comment = tableComment.getTableComment();
            jdbcTemplate.update(String.format(sql, tableName, comment, tableName, comment));
        });
    }
}