// 數(shù)據(jù)庫(kù)中大對(duì)象類型的典型映射
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Lob;
@Entity
public class Document {
    @Id
    private Long id;
    private String name;
    @Lob // 默認(rèn)情況下，字節(jié)數(shù)組被映射為BLOB
    private byte[] content;
    // 注意：默認(rèn)情況下，不標(biāo)記@Lob的byte[]可能會(huì)被映射為VARBINARY或其他二進(jìn)制類型
    // 這些類型通常有大小限制，不適合存儲(chǔ)大型二進(jìn)制數(shù)據(jù)
    // 構(gòu)造函數(shù)、getter和setter方法省略
    public Document() {}
    public Document(Long id, String name, byte[] content) {
        this.id = id;
        this.name = name;
        this.content = content;
    }
    // getter和setter方法
}

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Lob;
import javax.persistence.Column;
@Entity
public class ContentStorage {
    @Id
    private Long id;
    private String name;
    @Lob
    @Column(name = "binary_data", columnDefinition = "BLOB")
    private byte[] binaryContent; // 將被映射為BLOB
    @Lob
    @Column(name = "character_data", columnDefinition = "CLOB")
    private String textContent; // 將被映射為CLOB
    @Lob
    private char[] characterArray; // 也會(huì)被映射為CLOB
    @Lob
    private java.sql.Blob databaseBlob; // 允許直接使用JDBC Blob類型
    @Lob
    private java.sql.Clob databaseClob; // 允許直接使用JDBC Clob類型
    // 構(gòu)造函數(shù)、getter和setter方法省略
    // 獲取二進(jìn)制內(nèi)容的大小（以字節(jié)為單位）
    public int getBinaryContentSize() {
        return binaryContent != null ? binaryContent.length : 0;
    }
    // 獲取文本內(nèi)容的字符數(shù)
    public int getTextContentLength() {
        return textContent != null ? textContent.length() : 0;
    }
}

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import javax.persistence.*;
@Entity
public class ImageStorage {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String fileName;
    private String contentType;
    @Lob
    private byte[] imageData;
    // 文件上傳輔助方法
    public void loadFromFile(String filePath) throws IOException {
        File file = new File(filePath);
        this.fileName = file.getName();
        this.contentType = determineContentType(file);
        this.imageData = Files.readAllBytes(file.toPath());
    }
    // 文件保存輔助方法
    public void saveToFile(String destinationPath) throws IOException {
        if (imageData != null) {
            Files.write(Paths.get(destinationPath, fileName), imageData);
        }
    }
    // 確定文件內(nèi)容類型的輔助方法
    private String determineContentType(File file) {
        // 這里可以使用更復(fù)雜的文件類型檢測(cè)邏輯
        String name = file.getName().toLowerCase();
        if (name.endsWith(".jpg") || name.endsWith(".jpeg")) {
            return "image/jpeg";
        } else if (name.endsWith(".png")) {
            return "image/png";
        } else if (name.endsWith(".gif")) {
            return "image/gif";
        } else if (name.endsWith(".pdf")) {
            return "application/pdf";
        }
        return "application/octet-stream";
    }
    // 構(gòu)造函數(shù)、getter和setter方法省略
}

import javax.persistence.*;
import java.io.*;
@Entity
public class ArticleContent {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    @Lob
    private String content; // 將被映射為CLOB
    // 處理富文本內(nèi)容的輔助方法
    public String getFormattedContent() {
        if (content == null) {
            return "";
        }
        // 可以添加格式化邏輯，如HTML轉(zhuǎn)義、Markdown渲染等
        return content;
    }
    // 從文件加載內(nèi)容
    public void loadContentFromFile(String filePath) throws IOException {
        StringBuilder contentBuilder = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = reader.readLine()) != null) {
                contentBuilder.append(line).append("\n");
            }
        }
        this.content = contentBuilder.toString();
    }
    // 將內(nèi)容保存到文件
    public void saveContentToFile(String filePath) throws IOException {
        if (content != null) {
            try (BufferedWriter writer = new BufferedWriter(new FileWriter(filePath))) {
                writer.write(content);
            }
        }
    }
    // 字?jǐn)?shù)統(tǒng)計(jì)方法
    public int getWordCount() {
        if (content == null || content.trim().isEmpty()) {
            return 0;
        }
        // 簡(jiǎn)單的字?jǐn)?shù)統(tǒng)計(jì)實(shí)現(xiàn)
        return content.split("\\s+").length;
    }
    // 構(gòu)造函數(shù)、getter和setter方法省略
}

import javax.persistence.*;
import org.hibernate.annotations.BatchSize;
import org.hibernate.annotations.LazyCollection;
import org.hibernate.annotations.LazyCollectionOption;
@Entity
public class OptimizedDocument {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String description;
    // 使用延遲加載策略
    @Basic(fetch = FetchType.LAZY)
    @Lob
    private byte[] content;
    // 元數(shù)據(jù)存儲(chǔ)在單獨(dú)字段中，以避免不必要地加載大對(duì)象
    private long contentSize;
    private String contentType;
    private String checksum; // 可以存儲(chǔ)MD5或SHA1值
    // 關(guān)聯(lián)的注釋或標(biāo)簽
    @ElementCollection
    @CollectionTable(name = "document_tags", joinColumns = @JoinColumn(name = "document_id"))
    @Column(name = "tag")
    @LazyCollection(LazyCollectionOption.FALSE) // 不延遲加載標(biāo)簽
    @BatchSize(size = 20) // 批量加載提高性能
    private java.util.Set<String> tags = new java.util.HashSet<>();
    // 檢查內(nèi)容是否已加載
    public boolean isContentLoaded() {
        return content != null;
    }
    // 內(nèi)容加載方法
    public byte[] getContent() {
        if (content == null) {
            // 這里可以添加日志或性能監(jiān)控
            System.out.println("Lazy loading content for document: " + id);
        }
        return content;
    }
    // 安全地設(shè)置內(nèi)容并更新元數(shù)據(jù)
    public void setContent(byte[] newContent, String contentType) {
        this.content = newContent;
        this.contentSize = newContent != null ? newContent.length : 0;
        this.contentType = contentType;
        // 可以在這里計(jì)算并設(shè)置校驗(yàn)和
    }
    // 構(gòu)造函數(shù)、getter和setter方法省略
}

import java.io.*;
import java.sql.Blob;
import java.sql.SQLException;
import javax.persistence.*;
import javax.sql.rowset.serial.SerialBlob;
@Entity
public class StreamedDocument {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    // 使用JDBC Blob類型
    @Lob
    private Blob documentContent;
    // 流式讀取方法
    public InputStream getContentStream() throws SQLException {
        if (documentContent != null) {
            return documentContent.getBinaryStream();
        }
        return null;
    }
    // 流式寫(xiě)入方法
    public void setContentFromStream(InputStream inputStream) throws SQLException, IOException {
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        int nRead;
        byte[] data = new byte[16384]; // 16KB buffer
        while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
            buffer.write(data, 0, nRead);
        }
        buffer.flush();
        byte[] bytes = buffer.toByteArray();
        // 創(chuàng)建JDBC Blob
        this.documentContent = new SerialBlob(bytes);
    }
    // 從文件加載內(nèi)容
    public void loadFromFile(String filePath) throws IOException, SQLException {
        try (FileInputStream fis = new FileInputStream(filePath)) {
            setContentFromStream(fis);
            this.name = new File(filePath).getName();
        }
    }
    // 將內(nèi)容保存到文件
    public void saveToFile(String filePath) throws IOException, SQLException {
        if (documentContent != null) {
            try (InputStream is = documentContent.getBinaryStream();
                 FileOutputStream fos = new FileOutputStream(filePath)) {
                byte[] buffer = new byte[16384]; // 16KB buffer
                int bytesRead;
                while ((bytesRead = is.read(buffer)) != -1) {
                    fos.write(buffer, 0, bytesRead);
                }
                fos.flush();
            }
        }
    }
    // 構(gòu)造函數(shù)、getter和setter方法省略
}