【Java EE 学习 17 下】【数据库导出到Excel】【多条件查询方法】

一、导出到Excel

　　1.使用DatabaseMetaData分析数据库的数据结构和相关信息。

　　　　（1）测试得到所有数据库名：

private static DataSource ds=DataSourceUtils_C3P0.getDataSource();
Connection conn=ds.getConnection();
        DatabaseMetaData dbmd=conn.getMetaData();
        ResultSet rs=dbmd.getCatalogs();
        while(rs.next())
        {
            System.out.println(rs.getString("TABLE_CAT"));
        }
        String dbName=dbmd.getDatabaseProductName();
        String dbVersion=dbmd.getDatabaseProductVersion();
        System.out.println(dbName+":"+dbVersion);

　　　　运行结果：

information_schema
bms
bookstore
contacts
day20
mysql
performance_schema
shopping
test
user
users
MySQL:5.5.25

　　　　（2）根据数据库名得到所有表名

public void testGetTalbesByDBName() throws SQLException
    {
        Connection conn=ds.getConnection();
        DatabaseMetaData dbmd=conn.getMetaData();
        ResultSet rs=dbmd.getTables("test", "test", null, new String[]{"TABLE"});
        while(rs.next())
        {
            System.out.println(rs.getString("TABLE_NAME"));
        }
    }

　　　　运行结果：

people
user

　　2.使用ResultSetMetaData分析表结构。

public void testTest1() throws SQLException
    {
        Connection conn=ds.getConnection();
        Statement st=conn.createStatement();
        ResultSet rs=st.executeQuery("select id,name,age,sex from people");
        ResultSetMetaData rsmd=rs.getMetaData();
        int columnsCount=rsmd.getColumnCount();
        System.err.println("一共有"+columnsCount+"列！");
        for(int i=0;i<columnsCount;i++)
        {
            String columnName=rsmd.getColumnName(i+1);
            System.out.print(columnName+"		");
        }
        System.out.println();
        while(rs.next())
        {
            for(int i=0;i<columnsCount;i++)
            {
                String columnName=rsmd.getColumnName(i+1);
                System.out.print(rs.getString(columnName)+"		");
            }
            System.out.println();
        }
        conn.close();
    }

　　运行结果：

id        name        age        sex        
001        张三        12        男        
002        李四        13        男        
003        王五        15        男        

　　3.使用第三方jar包测试操作Excel文件。

　　　　（1）POI下载：http://poi.apache.org/download.html

　　　　（2）测试POI

package day17.kdyzm.Test;

import java.io.FileOutputStream;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

public class TestPOI {
    public static void main(String[] args) throws Exception {
        FileOutputStream fos=new FileOutputStream("first.xls");
        Workbook workbook=new HSSFWorkbook();
        Sheet sheet=workbook.createSheet("第一张表");
        Row row=sheet.createRow(0);
        Cell cell1=row.createCell(0);
        cell1.setCellValue("第一行第一列第一个数据");
        Cell cell2=row.createCell(1);
        cell2.setCellValue("第一行第二列第一个数据");
        workbook.close();
        workbook.write(fos);
        fos.close();
    }
}

运行结果：

　　

　　4.导出数据库到Excel，每一个标签页对应着一张表，而且要求灵活更换内容。

package day17.kdyzm.exportToExcel;

import java.io.FileOutputStream;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

import day17.regular.utils.DataSourceUtils_C3P0;

/**
 * 将数据库中的表数据导出到Excel表格中
 * @author kdyzm
 *
 */
public class ExportDataToExcel {
    private static String dbname="bookstore";
    public static void main(String[] args) throws Exception {
        List<String>tablenames=getAllTableNames(dbname);
        backupToXls(tablenames);
    }
    //通过所有的表名将数据被分到xls文件中
    private static void backupToXls(List<String> tablenames) throws Exception {
        Connection conn=DataSourceUtils_C3P0.getConnection();
        Workbook wb=new HSSFWorkbook(); 
        FileOutputStream fos=new FileOutputStream(dbname+".xls");
        Statement st=conn.createStatement();
         for(String tablename:tablenames)
         {
             Sheet sheet=wb.createSheet(tablename);
             String sql="select * from "+dbname+"."+tablename;
             ResultSet rs=st.executeQuery(sql);
             ResultSetMetaData rsmt=rs.getMetaData();
             int columns=rsmt.getColumnCount();
             //写入第一行tablehead
             Row tablehead=sheet.createRow(0);
             for(int i=0;i<columns;i++)
             {
                 String columnName=rsmt.getColumnName(i+1);
                 Cell cell=tablehead.createCell(i);
                 cell.setCellValue(columnName);
             }
             //写入数据
             int index=1;
             while(rs.next())
             {
                 Row row=sheet.createRow(index++);
                 for(int i=0;i<columns;i++)
                 {
                     String columnName=rsmt.getColumnName(i+1);
                     String value=rs.getString(columnName);
                     Cell cell=row.createCell(i);
                     cell.setCellValue(value);
                 }
             }
         }
         wb.write(fos);
         wb.close();
         fos.close();
         conn.close();
    }
    //首先获得所有的表名列表
    private static List<String> getAllTableNames(String dbname) throws SQLException {
        Connection conn=DataSourceUtils_C3P0.getConnection();
        DatabaseMetaData dmd=conn.getMetaData();
        ResultSet rs=dmd.getTables(dbname, dbname, null, new String[]{"TABLE"});
        List<String>tablenames=new ArrayList<String>();
        while(rs.next())
        {
            tablenames.add(rs.getString("TABLE_NAME"));
        }
        conn.close();
        return tablenames;
    }
}

运行结果：

　　　　

二、多条件查询方法简介

　　1.核心思想： where 1=1 使用的要恰到好处

　　2.实现方法：

package day17.kdyzm.searchByMultipleInput;
public class People {
    private String id;
    private String name;
    private int age;
    private String sex;
    
    public People() {
    }
    public People(String id, String name, int age, String sex) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    @Override
    public String toString() {
        return "People [id=" + id + ", name=" + name + ", age=" + age
                + ", sex=" + sex + "]";
    }
}

package day17.kdyzm.searchByMultipleInput;


import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import javax.sql.DataSource;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import day17.regular.utils.DataSourceUtils_C3P0;

/**
 * 多条件查询方法:可以极大提高代码书写效率
 * 结合dbutils
 * 结合java Bean
 * @author kdyzm
 *
 */
public class SearchByMultipleInput {
    public static void main(String args[]) throws SQLException{
        DataSource ds=DataSourceUtils_C3P0.getDataSource();
        String sql="select * from people where 1=1";
        People p=new People();
        p.setId(null);
        p.setName(null);
        p.setAge(0);
        p.setSex("女");
        List<String>list=new ArrayList<String>();
        if(p.getId()!=null){
            sql=sql+" and id=?";
            list.add(p.getId());
        }
        if(p.getName()!=null){
            sql=sql+" and name like ?";
            list.add("%"+p.getName()+"%");
        }
        if(p.getAge()!=0){
            sql=sql+" and age=?";
            list.add(p.getAge()+"");
        }
        if(p.getSex()!=null){
            sql=sql+" and sex=?";
            list.add(p.getSex());
        }
        QueryRunner run=new QueryRunner(ds);
        List<People>peoples=run.query(sql,new BeanListHandler<People>(People.class),list.toArray());
        for(People pp:peoples)
        {
            System.out.println(pp);
        }
    }
}