Question

JAVA怎么把存入mysql数据库按指定目录读到本地磁盘

Answer 1

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
* java读取数据库内容并存放到文件中
*
* @author young
*
*/
public class JavaToSQLTest {
public static void main(String[] args) throws FileNotFoundException {
// // 关联文件
// File file = new File("F:\\workspace\\one\\test.txt");
// // java IO流和文件关联
// PrintWriter pw = new PrintWriter(file);
PrintWriter pw = null;
FileWriter fw = null;
// 定义数据库驱动
String driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
// 数据库连接URL
String url = "jdbc:sqlserver://localhost:1433;DatabaseName = soft";
Connection conn = null;
String id;
String fname, lname;
try {
// pw.println("emp_id\t\tfname\t\tlname");
// pw.println("------\t\t------\t\t------");
// 加载数据库驱动
Class.forName(driver);
// 创建数据库连接
conn = DriverManager.getConnection(url, "sa", "1234");
// 创建预编译SQL对象
PreparedStatement ps = conn
.prepareStatement("select emp_id, fname, lname from emps");
// 执行SQL,获取结果集rs
ResultSet rs = ps.executeQuery();
// 处理结果集
while (rs.next()) {
id = rs.getString("emp_id");
fname = rs.getString("fname");
lname = rs.getString("lname");
String filename = id + ".txt";
// 关联文件
File file = new File(filename);
if(!file.exists()){
// 判断文件不存在就new新文件,写数据
try {
file.createNewFile();
// java IO流和文件关联
pw = new PrintWriter(file);
pw.print(id + "\t");
pw.print(fname + "\t\t");
pw.print(lname);
pw.println();
pw.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}else{
// 判断文件存在,就以FileWriter文件追加的方式写文件
try {
fw = new FileWriter(filename,true);
fw.write(id + "\t");
fw.write(fname + "\t\t");
fw.write(lname);
fw.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("加载数据库失败");
System.exit(1);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("数据库连接错误");
System.exit(1);
} finally {
if (conn != null) {
try {
// 关闭数据库连接
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (pw != null) {
// 关闭IO流
pw.close();
}
if(fw != null){
try {
fw.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

}
}