使用Jquery和servlet检索图像会产生HTTP Status 500错误 [英] Retrieving images using Jquery and servlet produces HTTP Status 500 error
本文介绍了使用Jquery和servlet检索图像会产生HTTP Status 500错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
HTTP Status 500 - class oracle.jdbc.driver.OracleBlobInputStream声明多个JSON字段，名为maxPosition 我是Jquery中的一个新手，我不知道如何使用JSON图像。 我的Servlet是：
protected void doGet（HttpServletRequest request，HttpServletResponse response）throws ServletException，IOException {
String uname; // = request.getParameter（countryCode）;
uname =shyam;
PrintWriter out = response.getWriter（）;
response.setContentType（text / html）;
response.setHeader（Cache-control，no-cache，no-store）;
response.setHeader（Pragma，no-cache）;
response.setHeader（Expires，-1）;
response.setHeader（Access-Control-Allow-Origin，*）;
response.setHeader（Access-Control-Allow-Methods，POST）;
response.setHeader（Access-Control-Allow-Headers，Content-Type）;
response.setHeader（Access-Control-Max-Age，86400）;
Gson gson = new Gson（）;
JsonObject myObj = new JsonObject（）;
ArrayList< ImageFileInfo> imageInfo = getInfo（uname）;
ImageFileInfo info = new ImageFileInfo（）;
JsonElement imageObj = gson.toJsonTree（imageInfo）;
boolean nonNullElemExist = false;
for（ImageFileInfo s：imageInfo）{
if（s！= null）{
nonNullElemExist = true;
break;
}
}
if（nonNullElemExist == true）{
myObj.addProperty（success，false）;
}
else {
myObj.addProperty（success，true）;
}
myObj.add（imageInfo，imageObj）;
out.println（myObj.toString（））;
out.close（）;
}
private ArrayList< ImageFileInfo> getInfo（String uname）{
ArrayList< ImageFileInfo> imageFileList = new ArrayList< ImageFileInfo>（）;
连接conn = null;
PreparedStatement stmt = null;
try {
conn = prepareConnection（）;
StringBuilder sb = new StringBuilder（1024）;
sb.append（select * from）.append（uname.trim（））。append（image）;
String sql = sb.toString（）;
stmt = conn.prepareStatement（sql）;
ResultSet rs = stmt.executeQuery（）;
while（rs.next（））{
ImageFileInfo info = new ImageFileInfo（）;
info.setName（rs.getString（imagename）。trim（））;
info.setDisc（rs.getString（imagedisc）。trim（））;
info.setImageid（rs.getInt（imageid））;
info.setalbumid（rs.getInt（albumid））;
byte imageData [] = rs.getBytes（imagethumb）;
String encoded = DatatypeConverter.printBase64Binary（imageData）;
info.setThumb（encoded）;
byte image1Data [] = rs.getBytes（imagethumb）;
String encoded1 = DatatypeConverter.printBase64Binary（image1Data）;
info.setFull（encoded1）;
}
rs.close（）;
stmt.close（）;
stmt = null;
conn.close（）;
conn = null;
}
catch（异常e）{System.out.println（Error - >+ displayErrorForWeb（e））;;}
finally {
if（stmt！= null）{
try {
stmt.close（）;
} catch（SQLException sqlex）{
// ignore - 因为我们不能在这里做任何事情
}
stmt = null;
}
if（conn！= null）{
try {
conn.close（）;
} catch（SQLException sqlex）{
// ignore - 因为我们不能在这里做任何事情
}
conn = null;
}
}
return imageFileList;
}
而ImageFileInfo.java文件是：
package skypark;
import java.io.InputStream;
public class ImageFileInfo
{
String name = null;
String disc = null;
int imageid = 0;
int albumid = 0;
InputStream thumbarray;
InputStream fullarray;
public void setName（String name）
{
this.name = name;
}
public String getName（）{
return name;
}
public void setDisc（String disc）
{
this.disc = disc;
}
public void setImageid（int Imageid）
{
this.imageid = Imageid;
}
public void setalbumid（int albumid）
{
this.albumid = albumid;
}
public void setThumb（InputStream inputStream）
{
this.thumbarray = inputStream;
}
public void setFull（InputStream binaryStream）{
this.fullarray = binaryStream;
}
}
堆栈跟踪是： p>
java.lang.IllegalArgumentException：class oracle.jdbc.driver.OracleBlobInputStream声明了名为maxPosition
com.google的多个JSON字段。 gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields（ReflectiveTypeAdapterFactory.java:122）
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create（ReflectiveTypeAdapterFactory.java:72）
com.google.gson。 Gson.getAdapter（Gson.java:353）
com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write（TypeAdapterRuntimeTypeWrapper.java:55）
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory $ 1 .wrap .java：586）
com.google.gson.Gson.toJsonTree（Gson.java:479）
com.google.gson.Gson.toJsonTree（Gson.java:458）
skypark.RetriveIm.doGet（RetriveIm.java:66）
javax.servlet.http.HttpServlet.service（HttpServlet.java:621）
javax.servlet.http.HttpServlet.service（ HttpServlet.java:728）
我不知道这个错误告诉了什么。请任何人帮我解决这个......谢谢.....
解决方案
你包括两个 InputStream 您的类中的变量，它们被设置为 OracleBlobInputStream 的实例，您的GSON提供程序无法序列化。您可能想要将图像内容存储为字节（或作为（URL编码）字符串）。
public class ImageFileInfo implements可序列化{
//其他类变量
private byte [] thumbarray;
private byte [] fullarray;
//构造函数，Getters / Setters
}
ImageFile.setThumb（rs.getBytes（imagethumb））;
ImageFile.setFull（rs.getBytes（imagefull））;
在侧面切线上，您似乎正在尝试返回JSON内容，但是您未正确指定您的内容类型为 text / html ，而不是 application / json 。
I need to retrieve images from my database. For this I used jquery and servlet to retrieve all images stored in a table. But when i run the code it produces HTTP Status 500 - class oracle.jdbc.driver.OracleBlobInputStream declares multiple JSON fields named maxPosition I'm a newbie in Jquery I don't know how to use JSON for images.
My Servlet is:
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String uname;// = request.getParameter("countryCode");
uname="shyam";
PrintWriter out = response.getWriter();
response.setContentType("text/html");
response.setHeader("Cache-control", "no-cache, no-store");
response.setHeader("Pragma", "no-cache");
response.setHeader("Expires", "-1");
response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Methods", "POST");
response.setHeader("Access-Control-Allow-Headers", "Content-Type");
response.setHeader("Access-Control-Max-Age", "86400");
Gson gson = new Gson();
JsonObject myObj = new JsonObject();
ArrayList<ImageFileInfo> imageInfo = getInfo(uname);
ImageFileInfo info = new ImageFileInfo();
JsonElement imageObj = gson.toJsonTree(imageInfo);
boolean nonNullElemExist= false;
for (ImageFileInfo s: imageInfo) {
if (s != null) {
nonNullElemExist = true;
break;
}
}
if(nonNullElemExist==true){
myObj.addProperty("success", false);
}
else {
myObj.addProperty("success", true);
}
myObj.add("imageInfo", imageObj);
out.println(myObj.toString());
out.close();
}
private ArrayList<ImageFileInfo> getInfo(String uname) {
ArrayList<ImageFileInfo> imageFileList = new ArrayList<ImageFileInfo>();
Connection conn = null;
PreparedStatement stmt = null;
try {
conn=prepareConnection();
StringBuilder sb=new StringBuilder(1024);
sb.append("select * from ").append(uname.trim()).append("image");
String sql=sb.toString();
stmt = conn.prepareStatement(sql);
ResultSet rs = stmt.executeQuery();
while(rs.next()){
ImageFileInfo info = new ImageFileInfo();
info.setName(rs.getString("imagename").trim());
info.setDisc(rs.getString("imagedisc").trim());
info.setImageid(rs.getInt("imageid"));
info.setalbumid(rs.getInt("albumid"));
byte imageData[] = rs.getBytes("imagethumb");
String encoded = DatatypeConverter.printBase64Binary(imageData);
info.setThumb(encoded);
byte image1Data[] = rs.getBytes("imagethumb");
String encoded1 = DatatypeConverter.printBase64Binary(image1Data);
info.setFull(encoded1);
}
rs.close();
stmt.close();
stmt = null;
conn.close();
conn = null;
}
catch(Exception e){ System.out.println( "Error --> " + displayErrorForWeb(e));;}
finally {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
stmt = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException sqlex) {
// ignore -- as we can't do anything about it here
}
conn = null;
}
}
return imageFileList;
}
And The ImageFileInfo.java file is:
package skypark;
import java.io.InputStream;
public class ImageFileInfo
{
String name = null;
String disc = null;
int imageid=0;
int albumid=0;
InputStream thumbarray;
InputStream fullarray;
public void setName(String name)
{
this.name = name;
}
public String getName() {
return name;
}
public void setDisc(String disc)
{
this.disc = disc;
}
public void setImageid(int Imageid)
{
this.imageid = Imageid;
}
public void setalbumid(int albumid)
{
this.albumid = albumid;
}
public void setThumb(InputStream inputStream)
{
this.thumbarray = inputStream;
}
public void setFull(InputStream binaryStream) {
this.fullarray = binaryStream;
}
}
And Stack trace is:
java.lang.IllegalArgumentException: class oracle.jdbc.driver.OracleBlobInputStream declares multiple JSON fields named maxPosition
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.getBoundFields(ReflectiveTypeAdapterFactory.java:122)
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory.create(ReflectiveTypeAdapterFactory.java:72)
com.google.gson.Gson.getAdapter(Gson.java:353)
com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:55)
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)
com.google.gson.Gson.toJson(Gson.java:586)
com.google.gson.Gson.toJsonTree(Gson.java:479)
com.google.gson.Gson.toJsonTree(Gson.java:458)
skypark.RetriveIm.doGet(RetriveIm.java:66)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
I don't know what this error tells. Please anyone help me to solve this...... thanks.....
解决方案
You included two InputStream variables in your class, which are getting set to instances of OracleBlobInputStream, which your GSON provider cannot serialize. You probably want to store the image content as bytes instead (or as a (URL encoded) string).
public class ImageFileInfo implements Serializable {
// Other class variables
private byte[] thumbarray;
private byte[] fullarray;
// Constructors, Getters/Setters
}
ImageFile.setThumb(rs.getBytes("imagethumb"));
ImageFile.setFull(rs.getBytes("imagefull"));
On a side tangent, it looks like you are trying to return JSON content, but you have incorrectly specified your Content-Type as text/html, instead of application/json.
这篇关于使用Jquery和servlet检索图像会产生HTTP Status 500错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
