问题
I need to know how feasible is it to write a function in java to read a ppm file and convert it to jpg
or bmp
format.
Anyone has experience with this? I am able to achieve the goal using tools such as ImageMagick
but I want to do it in pure Java
way.
回答1:
I would search for ImageMagick Application Programmer Interfaces. They have interfaces for every significant language.
I find the Java philosophy is to extensively research what already exists, find the best solution for your needs, then write the minimal code needed to interface to it. This is a pure Java way.
回答2:
Beside the old Sun JAI implementation there are additional ImageIO plugins TwelveMonkeys ImageIO which extend the ImageIO implementation in the JDK/JRE.
Below is a small example using those plugins. The example depends on version 3.1-SNAPSHOT
(earlier release version does not provide PNM support). So you need to build the plugin project first.
./pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>sub.optimal</groupId>
<artifactId>JAI-Demo</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>com.twelvemonkeys.imageio</groupId>
<artifactId>imageio-pnm</artifactId>
<version>3.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.twelvemonkeys.imageio</groupId>
<artifactId>imageio-jpeg</artifactId>
<version>3.1-SNAPSHOT</version>
</dependency>
</dependencies>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.3.2</version>
<executions>
<execution>
<goals>
<goal>java</goal>
</goals>
</execution>
</executions>
<configuration>
<killAfter>-1</killAfter>
<mainClass>sub.optimal.jai.Main</mainClass>
<systemProperties>
<systemProperty>
<key>user.dir</key>
<value>${project.build.directory}\classes</value>
</systemProperty>
</systemProperties>
</configuration>
</plugin>
</plugins>
</build>
</project>
./src/main/java/sub/optimal/jai/Main.java
package sub.optimal.jai;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Arrays;
import javax.imageio.ImageIO;
/**
*
* @author SubOptimal
*/
public class Main {
public static void main(String[] args) throws IOException {
String outFormat = "%-17s: %s%n";
String filesDirectory = System.getProperty("user.dir");
System.out.printf(outFormat, "files directory", filesDirectory);
System.out.printf(outFormat, "supported formats", Arrays.toString(ImageIO.getWriterFormatNames()));
Path inputFile = Paths.get(filesDirectory, "pond.ppm");
System.out.printf(outFormat, "input file", inputFile.toAbsolutePath());
InputStream is = Files.newInputStream(inputFile, StandardOpenOption.READ);
BufferedImage image = ImageIO.read(is);
File outputFile = Paths.get(filesDirectory, "output.jpg").toAbsolutePath().toFile();
System.out.printf(outFormat, "output file", outputFile.getAbsolutePath());
boolean writeSuccess = ImageIO.write(image, "JPEG", outputFile);
System.out.printf(outFormat, "write successful", writeSuccess);
}
}
./src/main/resources/pond.ppm
The file is one of the images provided in jai-1_1_2-unix-sample.tar.gz
Build and run the example code.
mvn clean compile exec:java
来源:https://stackoverflow.com/questions/28944954/convert-ppm-to-jpg-or-bmp-in-java