导出epub时，图片使用LazyResource来避免OOM

app/src/main/java/io/legado/app/help/BookHelp.kt

@@ -113,7 +113,7 @@ object BookHelp {
         )
     }
 
-    private fun getImageSuffix(src: String): String {
+    fun getImageSuffix(src: String): String {
         var suffix = src.substringAfterLast(".").substringBefore(",")
         if (suffix.length > 5) {
             suffix = ".jpg"

app/src/main/java/io/legado/app/ui/book/cache/CacheViewModel.kt

@@ -24,7 +24,6 @@ import me.ag2s.epublib.epub.EpubWriter
 import me.ag2s.epublib.util.ResourceUtil
 import java.io.ByteArrayOutputStream
 import java.io.File
-import java.io.FileInputStream
 import java.io.FileOutputStream
 import java.nio.charset.Charset
 
@@ -184,6 +183,7 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
         }
     }
 
+
     private fun exportEpub(file: File, book: Book) {
         val filename = "${book.name} by ${book.author}.epub"
         val epubBook = EpubBook()
@@ -254,9 +254,12 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
     }
 
     private fun setPic(src: String, book: Book, epubBook: EpubBook) {
+
+        val href = "${MD5Utils.md5Encode16(src)}${BookHelp.getImageSuffix(src)}"
         val vFile = BookHelp.getImage(book, src)
+        val fp = FileResourceProvider(vFile.parent)
         if (vFile.exists()) {
-            val img = Resource(FileInputStream(vFile), MD5Utils.md5Encode16(src) + ".jpg")
+            val img = LazyResource(fp, href)
             epubBook.resources.add(img)
         }
     }
@@ -275,7 +278,10 @@ class CacheViewModel(application: Application) : BaseViewModel(application) {
                 matchResult.groupValues[1].let {
                     val src = NetworkUtils.getAbsoluteURL(chapter.url, it)
                     setPic(src, book, epubBook)
-                    text1 = text1.replace(src, MD5Utils.md5Encode16(src) + ".jpg")
+                    text1 = text1.replace(
+                        src,
+                        "${MD5Utils.md5Encode16(src)}${BookHelp.getImageSuffix(src)}"
+                    )
 
                 }
             }

epublib/src/main/java/me/ag2s/epublib/domain/FileResourceProvider.java

@@ -0,0 +1,38 @@
+package me.ag2s.epublib.domain;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * 用于创建epub，添加大文件（如大量图片）时容易OOM，使用LazyResource，避免OOM.
+ *
+ */
+
+public class FileResourceProvider implements LazyResourceProvider {
+    //需要导入资源的父目录
+    String dir;
+
+    /**
+     * 创建一个文件夹里面文件夹的LazyResourceProvider，用于LazyResource。
+     * @param dir 文件的目录
+     */
+    public FileResourceProvider(String dir) {
+        this.dir = dir;
+    }
+
+    /**
+     * 创建一个文件夹里面文件夹的LazyResourceProvider，用于LazyResource。
+     * @param dirfile 文件夹
+     */
+    @SuppressWarnings("unused")
+    public FileResourceProvider(File dirfile) {
+        this.dir = dirfile.getPath();
+    }
+
+    @Override
+    public InputStream getResourceStream(String href) throws IOException {
+        return new FileInputStream(new File(dir, href));
+    }
+}

epublib/src/main/java/me/ag2s/epublib/util/IOUtil.java

@@ -450,6 +450,7 @@ public class IOUtil {
                 output.write(buffer, 0, n);
                 count += n;
             }
+            input.close();
         }
         return count;
     }