講解Java從數(shù)據(jù)庫(kù)中讀取Blob對(duì)象圖片并顯示的方法范文本文實(shí)例講述了java從數(shù)據(jù)庫(kù)中讀取Blob對(duì)象圖片并顯示的辦法。分享給大家供大家參考。具體實(shí)現(xiàn)辦法如下：

第一種辦法：

大致辦法就是，從數(shù)據(jù)庫(kù)中讀出Blob的流來(lái)，寫(xiě)到頁(yè)面中去：

復(fù)制代碼代碼如下:Connectionconn=onnection();

Stringsql="SELECTpictureFROMteacherWHEREid=1";

PreparedStatementps=null;

ResultSetrs=null;

InputStreamis=null;

OutputStreamos=null;

try{

ps=areStatement(sql);

rs=uteQuery();

if(()){

is=inaryStream(1);

}

ontentType("text/html");

os=utputStream();

intnum;

bytebuf[]=newbyte[1024];

while((num=(buf))!=-1){

e(buf,0,num);

}

}catch(SQLExceptione){

tStackTrace();

}

try{

e();

e();

e();

e();

}catch(SQLExceptione){

tStackTrace();

}

在頁(yè)面中：

復(fù)制代碼代碼如下:Stringpath=ontextPath();

StringbasePath=cheme()+"://"+erverName()+":"+erverPort()+path+"/";

%>

搞定。

第二種辦法：

整個(gè)流程分為四步，連接oracle數(shù)據(jù)庫(kù)->讀取blob圖片字段->對(duì)圖片進(jìn)行縮放->把圖片展示在jsp頁(yè)面上。

復(fù)制代碼代碼如下:import.*;

import.*;

importeIO;

importeredImage;

importneTransformOp;

importneTransform;

publicclassOracleQueryBean{

privatefinalStringoracleDriverName="leDriver";

privateConnectionmyConnection=null;

privateStringstrTabName;

privateStringstrIDName;

privateStringstrImgName;

publicOracleQueryBean(){

try{

ame(oracleDriverName);

}catch(ClassNotFoundExceptionex){

tln("加載jdbc驅(qū)動(dòng)失敗,原因:"+essage());

}

}

publicConnectiongetConnection(){

try{

//用戶(hù)名+密碼;下列使用的Test就是Oracle里的表空間

//從配置文件中讀取數(shù)據(jù)庫(kù)信息

GetParaoGetPara=newGetPara();

StringstrIP=ara("serverip");

StringstrPort=ara("port");

StringstrDBName=ara("dbname");

StringstrUser=ara("user");

StringstrPassword=ara("password");

abName=ara("tablename");

DName=ara("imgidname");

mgName=ara("imgname");

StringoracleUrlToConnect="jdbc:oracle:thin:@"+strIP+":"+strPort+":"+strDBName;

nnection=onnection(oracleUrlToConnect,strUser,strPassword);

}catch(Exceptionex){

tln("Cannotgetconnection:"+essage());

tln("請(qǐng)檢測(cè)配置文件中的.數(shù)據(jù)庫(kù)信息是否正確.");

}

returnnnection;

}

}

2.讀取blob字段

在OracleQueryBean類(lèi)中增加一個(gè)函數(shù)，來(lái)進(jìn)行讀取，具體代碼如下：

復(fù)制代碼代碼如下:publicbyte[]GetImgByteById(StringstrID,intw,inth){

//tln("Getimgdatawhichidis"+nID);

if(myConnection==null)

onnection();

byte[]data=null;

try{

Statementstmt=teStatement();

ResultSetmyResultSet=uteQuery("select"+DName+"from"+abName+"where"+DName+"="+strID);

StringBuffermyStringBuffer=newStringBuffer();

if(()){

blob=lob(mgName);

InputStreaminStream=inaryStream();

try{

longnLen=th();

intnSize=(int)nLen;

//tln("imgdatasizeis:"+nSize);

data=newbyte[nSize];

(data);

e();

}catch(IOExceptione){

tln("獲取圖片數(shù)據(jù)失敗,原因:"+essage());

}

data=ChangeImgSize(data,w,h);

}

tln(ring());

it();

e();

}catch(SQLExceptionex){

tln(essage());

}

returndata;

}

3.縮放圖片

因?yàn)閳D片的大小可能不一致，但是在頁(yè)面中輸出的大小需要統(tǒng)一，所以需要

在OracleQueryBean類(lèi)中增加一個(gè)函數(shù)，來(lái)進(jìn)行縮放，具體代碼如下：

復(fù)制代碼代碼如下:privatebyte[]ChangeImgSize(byte[]data,intnw,intnh){

byte[]newdata=null;

try{

BufferedImagebis=(newByteArrayInputStream(data));

intw=idth();

inth=eight();

doublesx=(double)nw/w;

doublesy=(double)nh/h;

AffineTransformtransform=newAffineTransform();

oScale(sx,sy);

AffineTransformOpato=newAffineTransformOp(transform,null);

//原始顏色

BufferedImagebid=newBufferedImage(nw,nh,_3BYTE_BGR);

er(bis,bid);

//轉(zhuǎn)換成byte字節(jié)

ByteArrayOutputStreambaos=newByteArrayOutputStream();

e(bid,"jpeg",baos);

newdata=teArray();

}catch(IOExceptione){

tStackTrace();

}

returnnewdata;

}

4.展示在頁(yè)面

頁(yè)面使用OracleQueryBean來(lái)根據(jù)用戶(hù)提供的圖片id進(jìn)行查詢(xún)，在讀取并進(jìn)行縮放后，通過(guò)jsp頁(yè)面進(jìn)行展示，具體代碼如下：

復(fù)制代碼代碼如下:

response.setContentType("image/jpeg");

//圖片在數(shù)據(jù)庫(kù)中的ID

StringstrID=arameter("id");

//要縮略或放大圖片的寬度

StringstrWidth=arameter("w");

//要縮略或放大圖片的高度

StringstrHeight=arameter("h");

byte[]data=null;

if(strID!=null){

intnWith=eInt(strWidth);

intnHeight=eInt(strHeight);

//獲取圖片的byte數(shù)據(jù)

data=mgByteById(strID,nWith,nHeight);

ServletOutputStreamop=utputStream();

e(data,0,th);

e();

op=null;

hBuffer();

//去除輸出流，避免釋放時(shí)被捕獲異常

r();

out=Body();

}

%>

5.OracleQueryBean查詢(xún)類(lèi)的整體代碼

文件代碼如下所示：

復(fù)制代碼代碼如下:import.*;

import.*;

importeIO;

importeredImage;

importneTransformOp;

importneTransform;

publicclassOracleQueryBean{

privatefinalStringoracleDriverName="leDriver";

privateConnectionmyConnection=null;

privateStringstrTabName;

privateStringstrIDName;

privateStringstrImgName;

publicOracleQueryBean(){

try{

ame(oracleDriverName);

}catch(ClassNotFoundExceptionex){

tln("加載jdbc驅(qū)動(dòng)失敗,原因:"+essage());

}

}

publicConnectiongetConnection(){

try{

//用戶(hù)名+密碼;下列使用的Test就是Oracle里的表空間

//從配置文件中讀取數(shù)據(jù)庫(kù)信息

GetParaoGetPara=newGetPara();

StringstrIP=ara("serverip");

StringstrPort=ara("port");

StringstrDBName=ara("dbname");

StringstrUser=ara("user");

StringstrPassword=ara("password");

abName=ara("tablename");

DName=ara("imgidname");

mgName=ara("imgname");

StringoracleUrlToConnect="jdbc:oracle:thin:@"+strIP+":"+strPort+":"+strDBName;

nnection=onnection(oracleUrlToConnect,strUser,strPassword);

}catch(Exceptionex){

tln("Cannotgetconnection:"+essage());

tln("請(qǐng)檢測(cè)配置文件中的數(shù)據(jù)庫(kù)信息是否正確.");

}

returnnnection;

}

publicbyte[]GetImgByteById(StringstrID,intw,inth){

//tln("Getimgdatawhichidis"+nID);

if(myConnection==null)

onnection();

byte[]data=null;

try{

Statementstmt=teStatement();

ResultSetmyResultSet=uteQuery("select"+DName+"from"+abName+"where"+DName+"="+strID);

StringBuffermyStringBuffer=newStringBuffer();

if(()){

blob=lob(mgName);

InputStreaminStream=inaryStream();

try{

longnLen=th();

intnSize=(int)nLen;

//tln("imgdatasizeis:"+nSize);

data=newbyte[nSize];

(data);

e();

}catch(IOExceptione){

tln("獲取圖片數(shù)據(jù)失敗,原因:"+essage());

}

data=ChangeImgSize(data,w,h);

}

tln(ring());

it();

e();

}catch(SQLExceptionex){

tln(essage());

}

returndata;

}

publicbyte[]GetImgByteById(StringstrID){

//tln("Getimgdatawhichidis"+nID);

if(myConnection==null)

onnection();

byte[]data=null;

try{

Statementstmt=teStatement();

ResultSetmyResultSet=uteQuery("select"+DName+"from"+abName+"where"+DName+"="+strID);

StringBuffermyStringBuffer=newStringBuffer();

if(()){

blob=lob(mgName);

InputStreaminStream=inaryStream();

try{

longnLen=th();

intnSize=(int)nLen;

data=newbyte[nSize];

(data);

e();

}catch(IOExceptione){

tln("獲取圖片數(shù)據(jù)失敗,原因:"+essage());

}

}

tln(ring());

it();

e();

}catch(SQLExceptionex){

tln(essage());

}

returndata;

}

privatebyte[]ChangeImgSize(byte[]data,intnw,intnh){

byte[]newdata=null;

try{

BufferedImagebis=(newByteArrayInputStream(data));

intw=idth();

inth=eight();

doublesx=(double)nw/w;

doublesy=(double)nh/h;

AffineTransformtransform=newAffineTransform();

oScale(sx,sy);

AffineTransformOpato=newAffineTransformOp(transform,null);

//原始顏色

BufferedImagebid=newBufferedImage(nw,nh,_3BYTE_BGR);

er(bis,bid);

//轉(zhuǎn)換成byte字節(jié)

ByteArrayOutputStreambaos=newByteArrayOutputStream();

e(bid,"jpeg",baos);

newdata=teArray();

}catch(IOExceptione){

tStackTrace();

}

returnnewdata;

}

}

下面是我的存儲(chǔ)讀取blob圖片的案例

復(fù)制代碼代碼如下:import.*;

import.*;

publicclassInsertPhoto{

publicstaticvoidmain(String[]args)throwsException{

ame("er");

Connectioncon=onnection("jdbc:mysql://);

Filef=newFile("e:/123.jpg");

FileInputStreamfis=newFileInputStream(f);

Stringsql="intophoto(photo,photoName)values(";

PreparedStatementpstmt=areStatement(sql);

inaryStream(1,fis,(int)th());

tring(2,"測(cè)試圖片");

uteUpdate();

e();

e();

e();

}

}

復(fù)制代碼代碼如下:importeredImage;

importeredInputStream;

importception;

importtStream;

importutStream;

importection;

importerManager;

importltSet;

importxception;

importement;

importeIO;

importServlet;

importServletRequest;

importServletResponse;

importcom.sun.image.codec.jpeg.JPEGCodec;

importcom.sun.image.codec.jpeg.JPEGImageEncoder;

publicclassReadPhotoextendsHttpServlet{

privatestaticfinallongserialVersionUID=1L;

publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse){

if(arameter("id")!=null){

response.setContentType("image/jpeg");

try{

InputStreamis=query_getPhotoImageBlob(eInt(arameter("id")));

if(is!=null){

is=newBufferedInputStream(is);

BufferedImagebi=(is);

OutputStreamos=utputStream();

JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(os