java 数据库读取图片出来全部是1KB

public static void readDB2Image() {

String targetPath = "D:/123/1png";

Connection conn = null;

PreparedStatement ps = null;

ResultSet rs = null;

try {

conn = DBUtilgetConn();

String sql = "select from map where id =";

ps = connprepareStatement(sql);

pssetInt(1, 1);

rs = psexecuteQuery();

while (rsnext()) {

InputStream in = rsgetBinaryStream("photo");

ImageUtilreadBin2Image(in, targetPath);

}

} catch (Exception e) {

eprintStackTrace();

} finally {

DBUtilcloseConn(conn);

if (rs != null) {

try {

rsclose();

} catch (SQLException e) {

eprintStackTrace();

}

}

if (ps != null) {

try {

psclose();

} catch (SQLException e) {

eprintStackTrace();

}

}

}

在OracleQueryBean类中增加一个函数，来进行读取，具体代码如下：

/

根据在数据库中的ID进行读取

@param strID 字段ID

@param w 需要缩到的宽度

@param h 需要缩到高度

@return

/

public byte[] GetImgByteById(String strID, int w, int h){

//Systemoutprintln("Get img data which id is " + nID);

if(myConnection == null)

thisgetConnection();

byte[] data = null;

try {

Statement stmt = myConnectioncreateStatement();

ResultSet myResultSet = stmtexecuteQuery("select " + thisstrIDName + " from " + thisstrTabName + " where " + thisstrIDName + "=" + strID);

StringBuffer myStringBuffer = new StringBuffer();

if (myResultSetnext()) {

javasqlBlob blob = myResultSetgetBlob(thisstrImgName);

InputStream inStream = blobgetBinaryStream();

try {

long nLen = bloblength();

int nSize = (int) nLen;

//Systemoutprintln("img data size is :" + nSize);

data = new byte[nSize];

inStreamread(data);

inStreamclose();

} catch (IOException e) {

Systemoutprintln("获取数据失败,原因:" + egetMessage());

}

data = ChangeImgSize(data, w, h);

}

Systemoutprintln(myStringBuffertoString());

myConnectioncommit();

myConnectionclose();

} catch (SQLException ex) {

Systemoutprintln(exgetMessage());

}

return data;

}

页面使用OracleQueryBean来根据用户提供的id进行查询，在读取并进行缩放后，通过jsp页面进行展示，具体代码如下：

<%@ page language="java" contentType="text/html;;charset=gbk" %>

<jsp:useBean id="OrcleQuery" scope="page" class="HLFtiDemoOracleQueryBean" />

<%

responsesetContentType("image/jpeg");

//在数据库中的 ID

String strID = requestgetParameter("id");

//要缩略或放大的宽度

String strWidth = requestgetParameter("w");

//要缩略或放大的高度

String strHeight = requestgetParameter("h");

byte[] data = null;

if(strID != null){

int nWith = IntegerparseInt(strWidth);

int nHeight = IntegerparseInt(strHeight);

//获取的byte数据

data = OrcleQueryGetImgByteById(strID, nWith, nHeight);

ServletOutputStream op = responsegetOutputStream();

opwrite(data, 0, datalength);

opclose();

op = null;

responseflushBuffer();

//清除输出流，防止释放时被捕获异常

outclear();

out = pageContextpushBody();

}

%>

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