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package com.taobao.api;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * 文件包装类，支持本地文件、字节数组和输入流三种方式。
 * 
 * @author carver.gu
 * @since 1.0, Sep 12, 2009
 */
public class FileItem {

	private Contract contract;

	/**
	 * 基于本地文件的构造器，适用于上传本地文件。
	 * 
	 * @param file 本地文件
	 */
	public FileItem(final File file) {
		this.contract = new LocalContract(file);
	}

	/**
	 * 基于文件绝对路径的构造器，适用于上传本地文件。
	 * 
	 * @param filePath 文件绝对路径
	 */
	public FileItem(String filePath) {
		this(new File(filePath));
	}

	/**
	 * 基于文件名和字节数组的构造器。
	 * 
	 * @param fileName 文件名
	 * @param content 文件字节数组
	 */
	public FileItem(String fileName, byte[] content) {
		this(fileName, content, null);
	}

	/**
	 * 基于文件名、字节数组和媒体类型的构造器。
	 * 
	 * @param fileName 文件名
	 * @param content 文件字节数组
	 * @param mimeType 媒体类型，如：image/jpeg, text/plain
	 */
	public FileItem(String fileName, byte[] content, String mimeType) {
		this.contract = new ByteArrayContract(fileName, content, mimeType);
	}

	/**
	 * 基于文件名和字节流的构造器，适应于全流式上传，减少本地内存开销。
	 * 
	 * @param fileName 文件名
	 * @param stream 文件字节流
	 */
	public FileItem(String fileName, InputStream stream) {
		this(fileName, stream, null);
	}

	/**
	 * 基于文件名、字节流和媒体类型的构造器，适应于全流式上传，减少本地内存开销。
	 * 
	 * @param fileName 文件名
	 * @param stream 文件字节流
	 * @param mimeType 媒体类型，如：image/jpeg, text/plain
	 */
	public FileItem(String fileName, InputStream stream, String mimeType) {
		this.contract = new StreamContract(fileName, stream, mimeType);
	}

	public boolean isValid() {
		return this.contract.isValid();
	}

	public String getFileName() {
		return this.contract.getFileName();
	}

	public String getMimeType() throws IOException {
		return this.contract.getMimeType();
	}

	public long getFileLength() {
		return this.contract.getFileLength();
	}

	public void write(OutputStream output) throws IOException {
		this.contract.write(output);
	}

	private static interface Contract {
		public boolean isValid();
		public String getFileName();
		public String getMimeType();
		public long getFileLength();
		public void write(OutputStream output) throws IOException;
	}

	private static class LocalContract implements Contract {
		private File file;

		public LocalContract(File file) {
			this.file = file;
		}

		public boolean isValid() {
			return this.file != null && this.file.exists() && this.file.isFile();
		}

		public String getFileName() {
			return this.file.getName();
		}

		public String getMimeType() {
			return Constants.MIME_TYPE_DEFAULT;
		}

		public long getFileLength() {
			return this.file.length();
		}

		public void write(OutputStream output) throws IOException {
			InputStream input = null;
			try {
				input = new FileInputStream(this.file);
				byte[] buffer = new byte[Constants.READ_BUFFER_SIZE];
				int n = 0;
				while (-1 != (n = input.read(buffer))) {
					output.write(buffer, 0, n);
				}
			} finally {
				if (input != null) {
					input.close();
				}
			}
		}
	}

	private static class ByteArrayContract implements Contract {
		private String fileName;
		private byte[] content;
		private String mimeType;

		public ByteArrayContract(String fileName, byte[] content, String mimeType) {
			this.fileName = fileName;
			this.content = content;
			this.mimeType = mimeType;
		}

		public boolean isValid() {
			return this.content != null && this.fileName != null;
		}

		public String getFileName() {
			return this.fileName;
		}

		public String getMimeType() {
			if (this.mimeType == null) {
				return Constants.MIME_TYPE_DEFAULT;
			} else {
				return this.mimeType;
			}
		}

		public long getFileLength() {
			return this.content.length;
		}

		public void write(OutputStream output) throws IOException {
			output.write(this.content);
		}
	}

	private static class StreamContract implements Contract {
		private String fileName;
		private InputStream stream;
		private String mimeType;

		public StreamContract(String fileName, InputStream stream, String mimeType) {
			this.fileName = fileName;
			this.stream = stream;
			this.mimeType = mimeType;
		}

		public boolean isValid() {
			return this.stream != null && this.fileName != null;
		}

		public String getFileName() {
			return this.fileName;
		}

		public String getMimeType() {
			if (this.mimeType == null) {
				return Constants.MIME_TYPE_DEFAULT;
			} else {
				return this.mimeType;
			}
		}

		public long getFileLength() {
			return 0L;
		}

		public void write(OutputStream output) throws IOException {
			try {
				byte[] buffer = new byte[Constants.READ_BUFFER_SIZE];
				int n = 0;
				while (-1 != (n = stream.read(buffer))) {
					output.write(buffer, 0, n);
				}
			} finally {
				if (stream != null) {
					stream.close();
				}
			}
		}
	}

}