java ImageIO处理 |
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javax.imageio
使用 ImageIO 类的静态方法可以执行许多常见的图像 I/O 操作。
此包包含一些基本类和接口，有的用来描述图像文件内容（包括元数据和缩略图）(IIOImage)；
有的用来控制图像读取过程（ImageReader、ImageReadParam）和控制图像写入过程（ImageWriter 和 ImageWriteParam）；
[java]
package com.mapbar.graphics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Iterator;
import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.stream.ImageInputStream;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
/**
*
* Class ImageIOTest.java
*
* Description javax.imageio 操作
*
* Company mapbar
*
* author Chenll E-mail: Chenll@mapbar.com
*
* Version 1.0
*
* Date 2012-7-23 上午11:16:17
*/
public class ImageIOTest {
/**
* Java Image I/O API 支持的读入，写出普通的格式，如果需要开发其它格式，还需要第三方插件，eg JIMI, JMagic
*/
public void formatImageNames() {
String[] imageFormats = ImageIO.getReaderFormatNames();
// [jpg, BMP, bmp, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
System.out.println(Arrays.asList(imageFormats));
String[] imageFormats1 = ImageIO.getWriterFormatNames();
// [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
System.out.println(Arrays.asList(imageFormats1));
}
/**
* Image I/O高级操作 ImageReader ImageWriter 通过ImageReader
* 可以获取图片信息而不用把整张图片数据都读入内存。
*
* @throws IOException
*/
public void imageReaderOp() throws IOException {
Iterator<ImageReader> readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
// 构造输入源
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
// 输入源和ImageReader关联
reader.setInput(iis, true);
// 获取第一张图片的高度,试图解码文件的必要部分，去获取图片的宽度，而不用读取任何一个象素
int imageIndex = 0;
int width = reader.getWidth(imageIndex);
}
/**
* 控制图片操作，ImageReadParam 可以让程序更好的控制内存，比如指定一个感兴趣的区域
*
* @throws IOException
*/
public void imageReadParamOp() throws IOException {
int imageIndex = 0;
Iterator<ImageReader> readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
reader.setInput(iis, true);
ImageReadParam irp = reader.getDefaultReadParam();
int halfWidth = reader.getWidth(imageIndex) / 2;
int halfHeight = reader.getHeight(imageIndex) / 2;
Rectangle rect = new Rectangle(0, 0, halfWidth, halfHeight);
irp.setSourceRegion(rect);
BufferedImage bi = reader.read(imageIndex, irp);
ImageIO.write(bi, "JPG", new File("E:\\big_half.JPG"));
}
/**
* 图片元信息
*
* @throws IOException
*/
public void ImageMetadata() throws IOException {
int imageIndex = 0;
Iterator<ImageReader> readers = ImageIO
.getImageReadersByFormatName("JPG");
ImageReader reader = readers.next();
File bigFile = new File("E:\\big.JPG");
ImageInputStream iis = ImageIO.createImageInputStream(bigFile);
reader.setInput(iis, true);
IIOMetadata metadata = reader.getImageMetadata(imageIndex);
}
/**
* 生成缩略图
*
* @throws IOException
*/
public void generateSmall() throws IOException {
File bigFile = new File("E:\\big.JPG");
Image image = ImageIO.read(bigFile);
int width = image.getWidth(null); // 3264
int height = image.getHeight(null); // 2448
BufferedImage buffi = new BufferedImage(width / 2, height / 2,
BufferedImage.TYPE_INT_RGB);
Graphics g = buffi.getGraphics();
g.drawImage(image, 0, 0, width / 2, height / 2, null);
g.dispose();
ImageIO.write(buffi, "JPG", new File("E:\\small.JPG"));// width:1632 height:1224
}
public static void main(String[] args) throws IOException {
ImageIOTest iot = new ImageIOTest();
iot.generateSmall();
iot.formatImageNames();
iot.imageReaderOp();
iot.imageReadParamOp();
iot.ImageMetadata();
}
}
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