将Oracle中Blob字段存储的图片转换成字节流直接输出到浏览器

数据库中blob字段存储的图片，通过Controller输出到浏览器客户端并显示出来。

实现方式：SpringMVC，关键部分代码片段如下：

1，编写铺助类及函数 

package com.acc.sp.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.Map;

import javax.servlet.http.HttpServletResponse;

import oracle.sql.CLOB;
 /*
 * Author WangSl
 * Version 1.0
 * Aug 29, 2012 2:38:05 PM
 */
public class StringUtil {
//数组转换成","分隔的连接数据
public static String getFormItemValue(Object obj) {
String ret = "";
if (obj == null) {
ret = "";
} else if (obj instanceof String) {
ret = obj.toString();
} else if (obj instanceof String[]) {
String arr[] = (String[]) obj;
for (int i = 0; i < arr.length; i++) {
ret += arr[i] + ",";
}
if (ret.endsWith(",")) {
ret = ret.substring(0, ret.length() - 1);
}
}
return ret;
}
//","分隔后的数据 添加单引号
public static String getOneSysbolFormItemValue(Object obj) {
String ret = "";
String otRet = "";
if (obj == null) {
ret = "";
} else if (obj instanceof String) {
ret = obj.toString();
if(ret.indexOf(",") > -1){
String arr[] = ret.split(",");
for (int i = 0; i < arr.length; i++) {
otRet += "'"+arr[i] + "',";
}
ret = otRet;
}
} else if (obj instanceof String[]) {
String arr[] = (String[]) obj;
for (int i = 0; i < arr.length; i++) {
ret += "'"+arr[i] + "',";
}

}
if (ret.endsWith(",")) {
ret = ret.substring(0, ret.length() - 1);
}
return ret;
}
//将Map中的Clob列数据转换成String，并返回String
public String getClob2String(Map map, String column) {
String str = "";
Object clob = map.get(column);
str = this.getClob2String(clob);
return str;
}

//将Map中的Clob列数据转换成String，重新存入到Map中，并返回Map
public Map getClob2StringInMap(Map map, String column) {
String str = "";
Object clob = map.get(column);
str = this.getClob2String(clob);
map.remove(column);
map.put(column, str);
return map;
}

//clob 转换 String (传入 clob 类型的 obj 当参数)
public static String getClob2String(Object obj) {
String str = "";
try {
CLOB clob = (CLOB) obj;
if (clob == null || clob.length() == 0) {
str = "";
} else {
long clen = clob.length();
char clobArray[] = new char[(int) clen];
int readednum = clob.getChars(1, (int) clen, clobArray);
StringBuffer sb = new StringBuffer();
sb.append(clobArray);
str = sb.toString();
}
} catch (SQLException e) {
e.printStackTrace();
}
return str;
}

//  输出 blob  字段图片  (传入 blob 类型的 obj 当参数)
 public static void outPutBlobImg(Object obj,HttpServletResponse response) {
Blob imgBlob = null;
OutputStream out=null;
InputStream fis = null;
try {
imgBlob = (Blob)obj;
if(obj==null || imgBlob.length()==0){
return ;
}
out = response.getOutputStream();
fis = imgBlob.getBinaryStream();
for (int b = fis.read(); b != -1; b = fis.read()) {
out.write(b);
}
} catch (IOException e1) {
e1.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally {
try {
fis.close();
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}

}

}
 public static void main(String[] args) {
System.out.println( getOneSysbolFormItemValue("a,"));
}
}

2，显示图片的Controller对应的方法

// 显示图片信息
@RequestMapping(value = "/imgstrb64")
public void getImgBase64StrById(HttpServletRequest request, HttpServletResponse response) throws IOException {
response.setContentType("text/text;charset=UTF-8");
response.setHeader("Cache-Control", "no-cache");
PrintWriter out =response.getWriter();
Map param = this.getParameter(request);
List list = this.spJobService.findImgById(param);
String imgStr = "";
if (null != list && !list.isEmpty()) {
Iterator ite = list.iterator();
if (ite.hasNext()) {
Map map = (Map) ite.next();
if (map != null && !map.isEmpty()) {
if (map.get("IMG") != null) {
imgStr = com.acc.sp.util.StringUtil.getClob2String(map.get("IMG"));
}
}
}
}
    out.print(imgStr);
    out.flush();
    out.close();
}

3，输入imgstrb64访问路径测试