将对象映射到数据库的关系上类对应表,字段对应列,聚合字段对应一对多或者多对多,这样用起来很方便,可以只写java就完成数据库 *** 作可能还要写jpql,对于简单的逻辑可以用criteria,纯对象化的查询,java有个ORM的规范,叫JPA,hibernate实现了JPA,它还有EclipseLink等实现。
假设有这么个对象:import java.io.Serializable
public class MyObject implements Serializable {
private static final long serialVersionUID = 1L
private int i
public int getI() {
return i
}
public void setI(int i) {
this.i = i
}
}
//测试 的方法如下
import java.io.ByteArrayInputStream
import java.io.ByteArrayOutputStream
import java.io.IOException
import java.io.ObjectInputStream
import java.io.ObjectOutputStream
import java.sql.Connection
import java.sql.DriverManager
import java.sql.PreparedStatement
import java.sql.ResultSet
public class test {
public static void main(String[] args) throws IOException,
ClassNotFoundException {
MyObject obj = new MyObject()
obj.setI(4567)
write(Object2Bytes(obj))
// read()
}
public static void write(byte[] b) throws ClassNotFoundException {
System.out.println(b.length)
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver")
try {
Connection con = DriverManager.getConnection("jdbc:odbc:temp")
String sql = "insert into tab values(?)"
PreparedStatement pstmt = con.prepareStatement(sql)
pstmt.setBytes(1, b)
pstmt.execute()
pstmt.close()
con.close()
} catch (Exception e) {
e.printStackTrace()
}
}
public static void read() throws ClassNotFoundException {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver")
try {
Connection con = DriverManager.getConnection("jdbc:odbc:temp")
String sql = "select * from tab"
PreparedStatement pstmt = con.prepareStatement(sql)
ResultSet res = pstmt.executeQuery()
while (res != null &&res.next()) {
byte[] b = res.getBytes("key")
System.out.println(b.length)
MyObject obj = (MyObject) Bytes2Object(b)
System.out.println(obj.getI())
}
pstmt.close()
con.close()
} catch (Exception e) {
e.printStackTrace()
}
}
// 将对象转换成字节数组
public static byte[] Object2Bytes(Object obj) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream()
ObjectOutputStream oos = new ObjectOutputStream(baos)
oos.writeObject(obj)
return baos.toByteArray()
}
// 将字节数组转换成为对象
public static Object Bytes2Object(byte[] b) throws IOException,
ClassNotFoundException {
ByteArrayInputStream bais = new ByteArrayInputStream(b)
ObjectInputStream ois = new ObjectInputStream(bais)
Object obj = ois.readObject()
return obj
}
}
java解析json格式文件,再保存在数据库的方法:1:定义一个实体类
2:用json lib将json字符串转为Java对象
3:用jdbc或hibernate将java对象存入数据库
直接读写文件,再把读出来的文件内容格式化成json,再用JDBC、Mybatis或者其他框架将json数据存入数据库。
假设实体类是这样的:
public class ElectSet {public String xueqi
public String xuenian
public String startTime
public String endTime
public int menshu
public String isReadDB
//{"xueqi":,"xuenian":,"startTime":,"endTime":,"renshu":,"isReadDB":}
public String getXueqi() {
return xueqi
}
public void setXueqi(String xueqi) {
this.xueqi = xueqi
}
public String getXuenian() {
return xuenian
}
public void setXuenian(String xuenian) {
this.xuenian = xuenian
}
public String getStartTime() {
return startTime
}
public void setStartTime(String startTime) {
this.startTime = startTime
}
public String getEndTime() {
return endTime
}
public void setEndTime(String endTime) {
this.endTime = endTime
}
public int getMenshu() {
return menshu
}
public void setMenshu(int menshu) {
this.menshu = menshu
}
public String getIsReadDB() {
return isReadDB
}
public void setIsReadDB(String isReadDB) {
this.isReadDB = isReadDB
}
}
有一个json格式的文件,存的信息如下:
Sets.json:
{"xuenian":"2007-2008","xueqi":"1","startTime":"2009-07-19 08:30","endTime":"2009-07-22 18:00","menshu":"10","isReadDB":"Y"}
具体 *** 作:
/*
* 取出文件内容,填充对象
*/
public ElectSet findElectSet(String path){
ElectSet electset=new ElectSet()
String sets=ReadFile(path)//获得json文件的内容
JSONObject jo=JSONObject.fromObject(sets)//格式化成json对象
//System.out.println("------------" jo)
//String name = jo.getString("xuenian")
//System.out.println(name)
electset.setXueqi(jo.getString("xueqi"))
electset.setXuenian(jo.getString("xuenian"))
electset.setStartTime(jo.getString("startTime"))
electset.setEndTime(jo.getString("endTime"))
electset.setMenshu(jo.getInt("menshu"))
electset.setIsReadDB(jo.getString("isReadDB"))
return electset
}
//设置属性,并保存
public boolean setElect(String path,String sets){
try {
writeFile(path,sets)
return true
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace()
return false
}
}
//读文件,返回字符串
public String ReadFile(String path){
File file = new File(path)
BufferedReader reader = null
String laststr = ""
try {
//System.out.println("以行为单位读取文件内容,一次读一整行:")
reader = new BufferedReader(new FileReader(file))
String tempString = null
int line = 1
//一次读入一行,直到读入null为文件结束
while ((tempString = reader.readLine()) != null) {
//显示行号
System.out.println("line " line ": " tempString)
laststr = laststr tempString
line
}
reader.close()
} catch (IOException e) {
e.printStackTrace()
} finally {
if (reader != null) {
try {
reader.close()
} catch (IOException e1) {
}
}
}
return laststr
}
将获取到的字符串,入库即可。
欢迎分享,转载请注明来源:内存溢出
评论列表(0条)