关于DBUtils中QueryRunner看批量删除语句batch

Posted 2020-10-15 ppjj

//批量删除

public void delBooks(String[] ids) throws SQLException {
QueryRunner qr = new QueryRunner(C3P0Utils.getDataSource());
Object[][] params = new Object[ids.length][];//高维也就是行数确定执行sql语句的次数，低维也就是列数是给？赋值
for (int i = 0; i < params.length; i++) {//循环行数,决定SQL语句执行的次数
params[i] = new Object[]{ids[i]};//给低维也就是列数“？”赋值，每行只给一列赋值，决定每条SQL语句的参数个数
}
qr.batch("delete from books where id=?", params);
}

源码实现：

public int[] batch(String sql, Object[][] params) throws SQLException {
Connection conn = this.prepareConnection();

return this.batch(conn, true, sql, params);
}

private int[] batch(Connection conn, boolean closeConn, String sql, Object[][] params) throws SQLException {
if (conn == null) {
throw new SQLException("Null connection");
}

if (sql == null) {
if (closeConn) {
close(conn);
}
throw new SQLException("Null SQL statement");
}

if (params == null) {
if (closeConn) {
close(conn);
}
throw new SQLException("Null parameters. If parameters aren\'t need, pass an empty array.");
}

PreparedStatement stmt = null;
int[] rows = null;
try {
stmt = this.prepareStatement(conn, sql);

for (int i = 0; i < params.length; i++) {
this.fillStatement(stmt, params[i]);
stmt.addBatch();
}
rows = stmt.executeBatch();

} catch (SQLException e) {
this.rethrow(e, sql, (Object[])params);
} finally {
close(stmt);
if (closeConn) {
close(conn);
}
}

return rows;
}

解读: 因为params是一个二维数组, 所以往preparedStatement中赋值的时候使用了for循环, 然后通过preparedstatement.addBatch() 进行批量添加, 然后执行executeBatch()进行操作.

 

本文转自：https://www.cnblogs.com/wang-meng/p/5525389.html