dboperation.java

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/*
 * Created on 2005-5-21
 *
 */
package net.mcool.www.util.db;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * @author a
 *  
 */
public class DbOperation {
    private Connection conn;

    private Statement stmt;

    private PreparedStatement pstmt;

    private ResultSet rs;

    /**
     * 初始化。
     * 
     * @return
     */
    public boolean init() {
        conn = DbUtil.getConnection();
//        if (conn == null) {
//            conn = DbUtil.getDirectConnection();
//        }
        if (conn != null) {
            return true;
        }
        return false;
    }

    /**
     * 开始一次事务。
     * 
     * @return
     */
    public boolean startTransaction() {
        try {
            conn.setAutoCommit(false);
            return true;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 事务完成。
     * 
     * @return
     */
    public boolean commitTransaction() {
        try {
            conn.commit();
            return true;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 初始化Statement。
     * 
     * @return
     */
    public boolean initStatement() {
        if (stmt != null) {
            return true;
        }
        try {
            stmt = conn.createStatement();
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    /**
     * 执行查询，返回结果集。
     * 
     * @param query
     * @return
     */
    public ResultSet executeQuery(String query) {
        if (!initStatement()) {
            return null;
        }
        //System.out.println(query);
        try {
            rs = stmt.executeQuery(query);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }

    /**
     * 执行更新，返回结果。
     * 
     * @param query
     * @return
     */
    public boolean executeUpdate(String query) {
        if (!initStatement()) {
            return false;
        }
        //System.out.println(query);
        try {
            stmt.executeUpdate(query);
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    /**
     * 准备PreparedStatement。
     * 
     * @param query
     * @return
     */
    public boolean prepareStatement(String query) {
        //System.out.println(query);
        try {
            pstmt = conn.prepareStatement(query);
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    public PreparedStatement getPStmt() {
        return pstmt;
    }

    public boolean executePstmt() {
        if (pstmt != null) {
            try {
                pstmt.execute();
            } catch (SQLException e) {
                e.printStackTrace();
                return false;
            }
        }
        return true;
    }

    /**
     * 释放资源。
     */
    public void release() {
        try {
            if (rs != null) {
                rs.close();
            }
            if (stmt != null) {
                stmt.close();
            }
            if (pstmt != null) {
                pstmt.close();
            }
//            if (conn != null) {
//                conn.close();
//            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public int getMaxId(String tableName) {
        try {
            String query = "SELECT max(id) AS max_id FROM " + tableName;
            rs = executeQuery(query);
            if (rs.next()) {
                return rs.getInt("max_id");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0;
    }
}