JAVA读取CLOB字段
1、将数据库某字段的内容导出到指定的文件
数据库表结构如下：
表MAXPRESENTATION
APP
VARCHAR2(10)
PRESENTATION
CLOB
MAXPRESENTATIONID
NUMBER
ROWSTAMP
VARCHAR2(40)
[注]：以APP字段的内容做为导出的文件名，PRESENTATION字段的内容做为该文件的内容，该字段的编码格式为：UTF-8
程序清单如下：
数据库表结构如下：
表MAXPRESENTATION
APP
VARCHAR2(10)
PRESENTATION
CLOB
MAXPRESENTATIONID
NUMBER
ROWSTAMP
VARCHAR2(40)
[注]：以APP字段的内容做为导出的文件名，PRESENTATION字段的内容做为该文件的内容，该字段的编码格式为：UTF-8
程序清单如下：
package file;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
* 文件导出
*
* @author songl
* @version 1.0 2005.12.2
*/
public class ExpFile {
public static void main(String args[]) throws ClassNotFoundException, IOException {
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
try{
String url = "jdbc:oracle:thin:@IP:1521:system";
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
con = DriverManager.getConnection(url,"maximo","maximo");
stmt = con.createStatement();
System.out.println("请指定导入的文件名：");
InputStreamReader irFile = new InputStreamReader(System.in);
BufferedReader inFile = new BufferedReader(irFile);
String sFile = inFile.readLine();
sFile = sFile.toUpperCase();
if(sFile!=null && !sFile.equalsIgnoreCase("")){
rs = stmt.executeQuery("select * from MAXPRESENTATION
where APP='"+sFile+"'");
}else{
rs = stmt.executeQuery("select * from MAXPRESENTATION");
}
while(rs.next()){
//新建文件
System.out.println(rs.getString(1));
String strName = rs.getString(1);
strName = strName+".xml";
File f1= new File("/epmxes/epmxes/res/presentation",strName);
if(f1.isFile()==false){
try {
f1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
String strNR = null;
//读取文件内容
Clob clob = rs.getClob(2);
strNR = clob.getSubString( (long) 1, (int) clob.length());
//写入文件，此处要用字节流来读取，还要指定编码格式，以免乱码
OutputStreamWriter isw = new OutputStreamWriter(new
FileOutputStream(f1),"UTF-8");
BufferedWriter bw = new BufferedWriter(isw);
bw.write(strNR,0,strNR.length());
bw.close();
}else{
System.out.println("文件："+strName+"已经存在！是否覆盖？y/n");
InputStreamReader ir;
BufferedReader in;
ir=new InputStreamReader(System.in);
in=new BufferedReader(ir);
String s=in.readLine();
if(s.equalsIgnoreCase("y")){
System.out.println("文件："+strName+"被覆盖!");
String strNR = null;
Clob clob = rs.getClob(2);
//读取文件内容
strNR = clob.getSubString( (long) 1, (int) clob.length());
System.out.println("文件内容如下:");
System.out.println(strNR);
//写入文件
OutputStreamWriter isw = new OutputStreamWriter(new
FileOutputStream(f1),"UTF-8");
System.out.println(isw.getEncoding());
BufferedWriter bw = new BufferedWriter(isw);
bw.write(strNR,0,strNR.length());
bw.close();
}else if(s.equalsIgnoreCase("n")){
System.out.println("文件："+strName+"没有被覆盖!");
}else{
System.out.println("输入的字符有误！请重新运行程序！");
}
}
}
}catch(SQLException ex){
ex.printStackTrace();
}finally{
try{
rs.close();
stmt.close();
con.close();
}catch(SQLException ex){
ex.printStackTrace();
}
}
}
}
2、将文件内容存入数据库的表中相应的字段
程序清单如下：
package file;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.Writer;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
* 导入数据库
*
* @author songl
* @version 1.0 2005.12.2
*/
public class ImpDb {
public static void main(String args[]) {
Connection con = null;
ResultSet resultset = null;
Statement statement = null;
Statement pstmt = null;
try{
System.out.println("请指定导入数据库的文件名：");
InputStreamReader irFile = new InputStreamReader(System.in);
BufferedReader inFile = new BufferedReader(irFile);
String sFile = inFile.readLine();
if(sFile!=null && !sFile.equalsIgnoreCase("")){
File f1= new File("/epmxes/epmxes/res/presentation/",sFile+".xml");
if(f1.isFile()==true){
//读取文件内容
InputStreamReader isr = new InputStreamReader(new
FileInputStream(f1),"UTF-8");
BufferedReader br = new BufferedReader(isr);
String strNR = "";
while (true) {
//按行读取
String temp = br.readLine();
if (temp == null){
break;
}
strNR += temp + "\n";
}
br.close();
System.out.println("文件内容如下：");
System.out.println(strNR);
String url = "jdbc:oracle:thin:@IP:1521:system";
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
con = DriverManager.getConnection(url,"maximo","maximo");
//将文件导入数据库
sFile = sFile.toUpperCase();
con.setAutoCommit(false);
String sql = "update MAXPRESENTATION set PRESENTATION =
empty_clob() where APP='" + sFile + "'";
pstmt = con.createStatement();
pstmt.executeUpdate(sql);
statement = con.createStatement();
String sql2="select PRESENTATION from MAXPRESENTATION
where APP='"+sFile+"'";
resultset = statement.executeQuery(sql2);
oracle.sql.CLOB contents = null;
while(resultset.next()) {
//要使用oracle中的resultset对象
contents = (oracle.sql.CLOB)resultset.getClob(
"PRESENTATION");
}
Writer out = contents.getCharacterOutputStream();
out.write(strNR);
out.flush();
out.close();
con.commit();
con.setAutoCommit(true);
System.out.println("导入数据库成功！");
}else{
System.out.println("不存在该文件！");
}
}else{
System.out.println("请输入文件名！");
}
}catch(Exception ex){
try{
if(con!=null){
con.rollback();
}
}catch(SQLException e){
e.printStackTrace();
}
}finally{
try{
if(resultset!=null){
resultset.close();
}
if(statement!=null){
statement.close();
}
if(pstmt!=null){
pstmt.close();
}
if(con!=null){
con.close();
}
}catch(SQLException ex){
ex.printStackTrace();
}
}
}
}