sf.database.jdbc.sql.ResultSetIteration Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of sorm Show documentation
java jpa tool for spring
The newest version!
package sf.database.jdbc.sql;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sf.database.jdbc.rowmapper.RowMapper;

import java.io.Closeable;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Spliterators;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

/**
 * 实现结果集的迭代接口.
 * @param 
 * @author sxf
 */
public class ResultSetIteration implements Iterator, Iterable, Closeable {
    private static final Logger logger = LoggerFactory.getLogger(ResultSetIteration.class);
    protected ResultSet rs;
    protected ResultSetMetaData rsmd;
    protected RowMapper rm;
    /**
     * 处理的记录位置(第几条记录)：可以只针对某一条记录做特殊处理,从0开始
     */
    protected int rowNum;

    private T object;

    public ResultSetIteration() {

    }

    public ResultSetIteration(ResultSet rs, RowMapper rm) {
        this.rs = rs;
        this.rm = rm;
        if (rs != null) {
            try {
                this.rsmd = rs.getMetaData();
            } catch (SQLException e) {
                rethrow(e);
            }
        }
    }

    /**
     * 重置
     */
    public void reset() {
        rowNum = 0;
        object = null;
        rs = null;
        rsmd = null;
    }

    protected T fetchNext() {
        T result = null;
        try {
            if (rs.next()) {
                result = rm.handle(rs, rsmd, rowNum++);
            }
        } catch (SQLException e) {
            rethrow(e);
        }
        return result;
    }


    /**
     * Iterator接口
     * @return
     */
    @Override
    public boolean hasNext() {
        //!rs.isLast();
        if (object == null) {
            object = fetchNext();
        }
        return object != null;
    }

    /**
     * Iterator接口
     * @return
     */
    @Override
    public T next() {
        // Fill next with object fetched from hasNext()
        T next = object;

        if (next == null) {
            next = fetchNext();
        }

        if (next != null) {
            object = null;
            return next;
        }
        throw new NoSuchElementException();
    }

    public void remove() {
        try {
            this.rs.deleteRow();
        } catch (SQLException e) {
            rethrow(e);
        }
    }

    @Override
    public void close() {
        if (rs != null) {
            try {
                Statement statement = rs.getStatement();
                rs.close();
                if (statement != null) {
                    statement.close();
                }
            } catch (SQLException e) {
                logger.error("", e);
            }
        }
        rs = null;
    }

    /**
     * Iterable接口
     * @return
     */
    @Override
    public Iterator iterator() {
        return this;
    }

    protected void rethrow(SQLException e) {
        throw new RuntimeException(e);
    }

    public ResultSet getRs() {
        return rs;
    }

    public RowMapper getRm() {
        return rm;
    }

    public Stream stream() {
        return StreamSupport.stream(Spliterators.spliteratorUnknownSize(this, 0), false);
    }

    /**
     * Generates an Iterable, suitable for use in for-each loops.
     * @param rs Wrap this ResultSet in an Iterator.
     * @return an Iterable, suitable for use in for-each loops.
     */
    public static  ResultSetIteration iteration(ResultSet rs, RowMapper mapper) {
        return new ResultSetIteration<>(rs, mapper);
    }
}