[Apache commons系列]DBUtils 示例代码

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　　DbUtils是一个小型的类库，这里通过具体实例来说明如何使用DbUtils。示例分为3个类：DbUtilsExample演示了如何使用DbUtils 类；QueryRunnerExample 演示了如何使用QueryRunner 、ResultSetHandler ；User 类为一个JavaBean，对应于数据库中的表格。示例采用MySQL为数据库，使用JDBC4.0驱动（最大的区别就是不需要写Class.forName().newInstance() ）。

依赖包：

• commons-dbcp-1.2.2.jar：提供数据库连接池
• commons-dbutils-1.3.jar：DbUtils包
• commons-lang-2.4.jar：提供常用的工具方法
• commons-pool-1.5.3.jar：提供DBCP对象池化机制
• mysql-connector-java-5.1.10-bin.jar：MySQL JDBC4.0驱动

建表语句：

DROP TABLE IF EXISTS `user`;
CREATE TABLE  `user` (
  `USERNAME` varchar(30) NOT NULL,
  `PASSWORDHASH` varchar(256),
  PRIMARY KEY (`USERNAME`),
  KEY `USERNAME` (`USERNAME`)
);

DbUtilsExample.java ：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.apache.commons.dbutils.DbUtils;
public class DbUtilsExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://127.0.0.1:3306/test";
        String user = "test";
        String password = "test";
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            conn = DriverManager.getConnection(url, user, password);
            stmt = conn.createStatement();
            stmt
                    .executeUpdate("INSERT INTO user (USERNAME, PASSWORDHASH) values ('testUser', '123456')");
            DbUtils.closeQuietly(stmt);
            DbUtils.commitAndCloseQuietly(conn);
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
            DbUtils.rollbackAndCloseQuietly(conn);
        }
        PreparedStatement psmt = null;
        try {
            conn = DriverManager.getConnection(url, user, password);
            psmt = conn.prepareStatement("SELECT USERNAME, PASSWORDHASH FROM user");
            rs = psmt.executeQuery();
            while (rs.next()) {
                System.out.println(rs.getString(1) + "/t" + rs.getString(2));
            }
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
        } finally {
            DbUtils.closeQuietly(conn, psmt, rs);
        }
        try {
            conn = DriverManager.getConnection(url, user, password);
            stmt = conn.createStatement();
            stmt.executeUpdate("DELETE FROM user WHERE USERNAME='testUser'");
            DbUtils.closeQuietly(stmt);
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
        } finally {
            DbUtils.printWarnings(conn);
            DbUtils.closeQuietly(conn);
        }
    }
}

QueryRunnerExample.java ：

import static java.lang.System.out;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import org.apache.commons.dbutils.handlers.KeyedHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.apache.commons.lang.StringUtils;
public class QueryRunnerExample {
    public static void main(String[] args) throws SQLException {
        QueryRunnerExample example = new QueryRunnerExample();
        example.batch();
        example.fillStatement();
        example.query();
        example.update();
        example.closeDataSource();
    }
    private DataSource dataSource = null;
    private QueryRunner runner = null;
    public QueryRunnerExample() {
        initDataSource();
        runner = new QueryRunner(dataSource);
    }
    private void batch() {
        String sql = "INSERT INTO user (USERNAME, PASSWORDHASH) values (?, ?)";
        try {
            out.println("/n" + StringUtils.center("Test QueryRunner batch", 80, '*'));
            int[] result = runner.batch(sql, new Object[][] { { "user1", "pwd1" },
                    { "user2", "pwd2" }, { "user3", "pwd3" }, { "user4", "pwd4" } });
            out.printf("运行结果：%s/n", Arrays.toString(result));
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
        }
    }
    private void closeDataSource() throws SQLException {
        ((BasicDataSource) dataSource).close();
    }
    private void fillStatement() throws SQLException {
        String sql = "INSERT INTO user (USERNAME, PASSWORDHASH) VALUES (?, ?)";
        Connection conn = null;
        try {
            out.println("/n" + StringUtils.center("Test QueryRunner fillStatement", 80, '*'));
            conn = dataSource.getConnection();
            PreparedStatement psmt = conn.prepareStatement(sql);
            runner.fillStatementWithBean(psmt, new User("testUser5", "pwd5"), "userName",
                    "passwordHash");
            out.println(psmt.executeUpdate());
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
        } finally {
            DbUtils.commitAndCloseQuietly(conn);
        }
    }
    private DataSource initDataSource() {
        if (dataSource == null) {
            BasicDataSource basicDs = new BasicDataSource();
            basicDs.setUrl("jdbc:mysql://127.0.0.1:3306/test");
            basicDs.setUsername("test");
            basicDs.setPassword("test");
            this.dataSource = basicDs;
        }
        return dataSource;
    }
    private void query() throws SQLException {
        out.println("/n" + StringUtils.center("Test QueryRunner query", 80, '*'));
        String sql = "SELECT * FROM user WHERE USERNAME LIKE ?";
        out.println("1.Test QueryRunner query, ArrayHandler");
        //把ResultSet第一行包装成Object[]
        Object[] r1 = runner.query(sql, new ArrayHandler(), "user%");
        out.println("  " + Arrays.deepToString(r1));
        out.println("2.Test QueryRunner query, ArrayListHandler");
        //把ResultSet包装成List<Object[]>
        List<Object[]> r2 = runner.query(sql, new ArrayListHandler(), "user%");
        out.println("  " + Arrays.deepToString(r2.toArray()));
        out.println("3.Test QueryRunner query, BeanHandler");
        //把ResultSet第一行包装成一个JavaBean
        User r3 = runner.query(sql, new BeanHandler<User>(User.class), "user%");
        out.println("  " + r3.toString());
        out.println("4.Test QueryRunner query, BeanListHandler");
        //把ResultSet第一行包装成一个List<JavaBean>；
        List<User> r4 = runner.query(sql, new BeanListHandler<User>(User.class), "user%");
        out.println("  " + Arrays.deepToString(r4.toArray()));
        out.println("5.Test query, ColumnListHandler");
        //抽取ResultSet指定的列，以List<Object>对象的形式返回，默认第一列
        List<Object> r5 = runner.query(sql, new ColumnListHandler(2), "user%");
        out.println("  " + Arrays.deepToString(r5.toArray()));
        out.println("6.Test QueryRunner query, KeyedHandler");
        //包装ResultSet，以Map<Object,Map<String,Object>>对象形式返回，第一个Object是指定的列值，第二个Map中String是列名且对大小写不敏感
        Map<Object, Map<String, Object>> r6 = runner.query(sql, new KeyedHandler(2), "user%");
        out.println("  " + r6.toString());
        out.println("7.Test QueryRunner query, MapHandler");
        //把ResultSet第一行包装成Map<String, Object>，key对大小写不敏感
        Map<String, Object> r7 = runner.query(sql, new MapHandler(), "user%");
        out.println("  " + r7.toString());
        out.println("8.Test QueryRunner query, MapListHandler");
        //把ResultSet包装成List<Map<String,Object>>>，Map的key对大小写不敏感
        List<Map<String, Object>> r8 = runner.query(sql, new MapListHandler(), "user%");
        out.println("  " + r8.toString());
        out.println("9.Test QueryRunner query, ScalarHandler");
        //抽取ResultSet第一行指定列，以Object对象形式返回
        Object r9 = runner.query(sql, new ScalarHandler("passwordhash"), "user%");
        out.println("  " + r9.toString());
    }
    private void update() {
        String sql = "DELETE FROM user WHERE PASSWORDHASH LIKE ?";
        try {
            out.println("/n" + StringUtils.center("Test QueryRunner update", 80, '*'));
            out.println(runner.update(sql, "pwd%"));
        } catch (SQLException ex) {
            DbUtils.printStackTrace(ex);
        }
    }
}