java+pgsql实现保存图片到数据库，以及读取数据库存储的图片；java将图片保存到本地、保存到数据库、java将图片保存到本地并保存到数据库、java从数据库postgresql读取图片

java将图片保存到本地；

pom.xml

<dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.4.7</version>
</dependency>
<dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
</dependency>

java类-将图片直接保存到本地

String fileUrl = "http://image.nmc.cn/assets/img/w/40x40/3/0.png";
//将文件下载后保存在E盘，返回结果为下载文件大小
long size = HttpUtil.downloadFile(fileUrl, FileUtil.file("e:/"));
System.out.println("Download size: " + size);

java类-将图片直接保存到数据库

HttpResponse maiImg = HttpRequest.get("http://image.nmc.cn/assets/img/w/40x40/3/0.png").execute();
InputStream maiImgInpuStream = maiImg.bodyStream(); //图片转换成流
jdbc往数据库汇总插入数据
//pstmt.setString(2, mai.getFileName());
//pstmt.setString(3, mai.getUrl());
pstmt.setBinaryStream(4, maiImgInpuStream, maiImgInpuStream.available());

java类将图片下载到本地，并将图片保存到数据库

逻辑：运用方法一，把图片下载到本地，在从本地读取图片为流的格式，然后把图片保存到数据库

String fileUrl = "http://image.nmc.cn/assets/img/w/40x40/3/0.png";
//将文件下载后保存在E盘，返回结果为下载文件大小
long size = HttpUtil.downloadFile(fileUrl, FileUtil.file("e:/"));
System.out.println("Download size: " + size);
        try {
            FileInputStream fis = new FileInputStream(new File("e://3.png"));
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
//jdbc插入数据
pstmt.setBinaryStream(3,fis,fis.avaliable())

java类从数据库中读取图片

// 读取数据库中图片
     public static void readDBImage() {
         String targetPath = "D:/image/1.png";
         Connection conn = null;
         PreparedStatement ps = null;
         ResultSet rs = null;
         try {
             conn = JdbcUtil.getConn();
             String sql = "select * from photo where id =?";
             ps = conn.prepareStatement(sql);
             ps.setInt(1,1);
             rs = ps.executeQuery();
             while (rs.next()) {
                 InputStream in = rs.getBinaryStream("photo");
                 ImageUtil.readBinImage(in, targetPath);
             }
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             DBUtil.closeConn(conn);
             if (rs != null) {
                 try {
                     rs.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
             if (ps != null) {
                 try {
                     ps.close();
                 } catch (SQLException e) {
                     e.printStackTrace();
                 }
             }
         }
     }
public class ImageUtil {
    // 读取本地图片获取输入流
    public static FileInputStream readImage(String path) throws IOException {
        return new FileInputStream(new File(path));
    }
    // 读取表中图片获取输出流
    public static void readBinImage(InputStream in, String targetPath) {
        File file = new File(targetPath);
        String path = targetPath.substring(0, targetPath.lastIndexOf("/"));
        if (!file.exists()) {
            new File(path).mkdir();
        }
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
            int len = 0;
            byte[] buf = new byte[1024];
            while ((len = in.read(buf)) != -1) {
                fos.write(buf, 0, len);
            }
           fos.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (null != fos) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}