本文实例总结了java jdbc连接数据库常见操作。分享给大家供大家参考，具体如下：
db.properties配置文件(mysql数据库)
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# db.propertiesjdbc.driver=com.mysql.jdbc.driverjdbc.url=jdbc:mysql://localhost:3306/demo?useunicode=true&characterencoding=utf-8jdbc.username=rootjdbc.password=123456# paramter for basicdatasourceinitsize=2maxactive=2 |
db.properties配置文件(oracle数据库)
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# db.propertiesjdbc.driver=oracle.jdbc.oracledriverjdbc.url=jdbc:oracle:thin:localhost:1521:orcljdbc.username=rootjdbc.password=123456# paramter for basicdatasourceinitsize=2maxactive=2 |
jdbc直接连接数据库
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package jdbc;import java.io.ioexception;import java.io.inputstream;import java.sql.connection;import java.sql.drivermanager;import java.sql.sqlexception;import java.util.properties;/** * jdbc连接数据库管理工具类 */public class jdbc { static string driver; static string url; static string username; static string password; static { try { properties cfg = new properties(); inputstream in = jdbc.class.getclassloader().getresourceasstream("db.properties"); cfg.load(in); //将文件内容加载到properties对象中(以散列表形式存在) driver = cfg.getproperty("jdbc.driver"); url = cfg.getproperty("jdbc.url"); username = cfg.getproperty("jdbc.username"); password = cfg.getproperty("jdbc.password"); in.close(); } catch (ioexception e) { e.printstacktrace(); throw new runtimeexception(e); } } /** * 创建数据库连接 */ public static connection getconnection() { try { class.forname(driver); //注册驱动 connection conn = drivermanager.getconnection(url, username, password); return conn; } catch (exception e) { e.printstacktrace(); throw new runtimeexception(e); } } /* * 关闭数据库的连接 */ public static void close(connection conn) { if (conn != null) { try { conn.close(); } catch (sqlexception e) { e.printstacktrace(); } } }} |
通过连接池连接数据库
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package jdbc;import java.io.ioexception;import java.io.inputstream;import java.sql.connection;import java.sql.sqlexception;import java.util.properties;import org.apache.commons.dbcp.basicdatasource;/** * 连接池版本的数据库连接管理工具类 */public class dbutils { private static string driver; private static string url; private static string username; private static string password; private static int initsize; private static int maxactive; private static basicdatasource dbs; static { dbs = new basicdatasource(); properties cfg = new properties(); try { inputstream in = dbutils.class.getclassloader().getresourceasstream("db.properties"); cfg.load(in); // 初始化参数 driver = cfg.getproperty("jdbc.driver"); url = cfg.getproperty("jdbc.url"); username = cfg.getproperty("jdbc.username"); password = cfg.getproperty("jdbc.password"); initsize = integer.parseint(cfg.getproperty("initsize")); maxactive = integer.parseint(cfg.getproperty("maxactive")); in.close(); // 初始化连接池 dbs.setdriverclassname(driver); dbs.seturl(url); dbs.setusername(username); dbs.setpassword(password); dbs.setinitialsize(initsize); dbs.setmaxactive(maxactive); } catch (ioexception e) { e.printstacktrace(); throw new runtimeexception(e); } } /** * 创建数据库连接,从连接池中获取连接,如果连接池满了,则等待. */ public static connection getconnection() { try { connection conn = dbs.getconnection(); return conn; } catch (sqlexception e) { e.printstacktrace(); throw new runtimeexception(e); } } /* * 关闭数据库的连接,归还到连接池 */ public static void close(connection conn) { if (conn != null) { try { conn.close(); } catch (sqlexception e) { e.printstacktrace(); } } } //回滚，仅在禁用自动提交时使用 public static void rollback(connection conn) { if (conn != null) { try { conn.rollback(); } catch (sqlexception e) { e.printstacktrace(); } } }} |
连接数据库后的使用
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connection conn=null;try{ conn=dbutils.getconnection(); statement st=conn.createstatement(); string sql="select id, name from people"; resultset rs=st.executequery(sql); while(rs.next()){ int id=rs.getint("id"); string name=rs.getstring("name"); system.out.println(id+","+name); } //结果集元数据 resultsetmetadata meta = rs.getmetadata(); int n = meta.getcolumncount(); //多少列 for(int i=1; i<=n; i++){ string name= meta.getcolumnname(i); //获取列名 system.out.println(name); } rs.close();//释放查询结果 st.close();//释放语句对象}catch(exception e){ e.printstacktrace();}finally { dbutils.close(conn);} |
预编译sql执行 及 取消自动提交
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try { conn = dbutils.getconnection(); conn.setautocommit(false); //取消自动提交, 后续手动提交 string sql="update people set name=? where id=? "; preparedstatement ps= conn.preparestatement(sql); //按照顺序发送参数 ps.setstring(1, "lao wang"); ps.setint(2, 100); //执行"执行计划" int n=ps.executeupdate(); conn.commit(); //手动提交} catch (exception e) { e.printstacktrace(); dbutils.rollback(conn); //异常回滚}finally{ dbutils.close(conn);} |
statement的addbatch(sql)和executebatch()方法可以批量执行sql。
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statement st=conn.createstatement();st.addbatch(sql1); //sql1 添加到statement的缓存中st.addbatch(sql2);st.addbatch(sql3);int[] ary=st.executebatch(); //执行一批sql |
preparedstatement也支持批量参数的处理
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preparedstatement ps = conn.preparestatement(sql);ps.setint(1, 1);ps.setstring(2, "wang");ps.addbatch(); //将参数添加到ps缓存区ps.setint(1, 2);ps.setstring(2, "li");ps.addbatch(); //将参数添加到ps缓存区int[] ary = ps.executebatch(); // 批量执行 |
preparedstatement ps = conn.preparestatement(sql);
还可以传入第二个参数用以获取自增主键或者序号自增的列
希望本文所述对大家java程序设计有所帮助。
原文链接：https://blog.csdn.net/n447194252/article/details/71123917
